Science.gov

Sample records for double edged sword

  1. Interpreters: a double-edged sword in nursing practice.

    PubMed

    Maltby, H J

    1999-07-01

    The provision of health services for all Australians is based on equality of access to health care services, regardless of cultural origin or linguistic skill, and on the responsibility of the health system to respond appropriately. Lack of fluency in the English language and lack of bilingual or multilingual nurses are major sources of miscommunication, even with the use of interpreters and translated health information. Many immigrant women find the use of interpreters unacceptable. Nurses are concerned with legal issues. These two viewpoints make the use of interpreters a double-edged sword in practice. The findings of recent research and the literature in relation to language skills and the use of interpreters and translations in the Australian context are explored. Potential resolutions for transcultural nursing practice are provided.

  2. Cancer and viruses: a double-edged sword.

    PubMed

    Butt, Aisha Q; Miggin, Sinéad M

    2012-07-01

    Oncovirus, synonymously called a 'tumour virus', is a virus that can cause cancer. An oncolytic virus preferentially infects the host's cancer cells and lyses them, causing tumour destruction, and is thus referred to as a 'cancer killing virus'. With an estimated 11% of cancer-associated deaths caused by oncoviruses and the possibility that many cancers may be treated by using oncolytic viruses, the role of viruses in cancer may be viewed as a double-edged sword. A total of seven human cancer viruses have been identified as oncoviruses, having been associated with various cancers. Conversely, a large number of oncolytic viruses have shown great potential towards the treatment of certain types of cancer. Proteomics has now been applied towards understanding the complex interplay that exists between oncoviruses and the immune responses that serve to prevent oncoviral diseases. This review attempts to summarise the neoplastic potential of human tumour associated viruses and associated vaccine successes. The potential use of oncolytic viruses for the therapeutic intervention of cancer will also be discussed. Finally, this review will discuss the enormous potential of proteomics technology in the field of oncovirology.

  3. DNA damage tolerance: a double-edged sword guarding the genome

    PubMed Central

    Ghosal, Gargi; Chen, Junjie

    2013-01-01

    Preservation of genome integrity is an essential process for cell homeostasis. During the course of life of a single cell, the genome is constantly damaged by endogenous and exogenous agents. To ensure genome stability, cells use a global signaling network, namely the DNA damage response (DDR) to sense and repair DNA damage. DDR senses different types of DNA damage and coordinates a response that includes activation of transcription, cell cycle control, DNA repair pathways, apoptosis, senescence, and cell death. Despite several repair mechanisms that repair different types of DNA lesions, it is likely that the replication machinery would still encounter lesions that are mis-repaired or not repaired. Replication of damaged genome would result in high frequency of fork collapse and genome instability. In this scenario, the cells employ the DNA damage tolerance (DDT) pathway that recruits a specialized low fidelity translesion synthesis (TLS) polymerase to bypass the lesions for repair at a later time point. Thus, DDT is not a repair pathway per se, but provides a mechanism to tolerate DNA lesions during replication thereby increasing survival and preventing genome instability. Paradoxically, DDT process is also associated with increased mutagenesis, which can in turn drive the cell to cancer development. Thus, DDT process functions as a double-edged sword guarding the genome. In this review, we will discuss the replication stress induced DNA damage-signaling cascade, the stabilization and rescue of stalled replication forks by the DDT pathway and the effect of the DDT pathway on cancer. PMID:24058901

  4. DNA damage response--a double-edged sword in cancer prevention and cancer therapy.

    PubMed

    Tian, Hui; Gao, Zhen; Li, HuiZhong; Zhang, BaoFu; Wang, Gang; Zhang, Qing; Pei, DongSheng; Zheng, JunNian

    2015-03-01

    Genomic stability depends on an efficient DNA damage repair system to keep the chromosomes intact. Unrepaired DNA damage not only causes cell cycle arrest, apoptosis, but also accumulates genome mutations. DNA damage response (DDR) exhibits a critical function on the protection against human cancer, as indicated by the high predisposition to cancer of individuals with germ-line mutations in DDR genes. However, a defective DNA repair is liked intimately with the unchecked proliferation and the intrinsic resistance to clinical DNA-damaging agents. Therefore, abrogation of specific proteins in DNA damage repair pathways is a promising strategy for developing targeted cancer treatments. It may sound paradoxical to inhibit DDR pathway for sensitization of clinical therapy because cancer promotion and malignant transformation are aided by deficient DNA repair pathways. Actually, DDR acts as a positive guardian of genomic stability to prevent from tumorigenesis. On the other hand, DDR also performs as a negative saboteur to resist chemo- and radiotherapy. In this regard, DDR functions as "a double-edged sword" in cancer prevention and cancer therapy. The defective DDR that makes cancer cells of high mutability should alternatively provide therapeutic opportunities that confer the lethality to cancer cells without harming normal cells. PMID:25528631

  5. Peer pressure is a double-edged sword in vaccination dynamics

    NASA Astrophysics Data System (ADS)

    Wu, Zhi-Xi; Zhang, Hai-Feng

    2013-10-01

    Whether or not to change behavior depends not only on the personal success of each individual, but also on the success and/or behavior of others. Using this as motivation, we incorporate the impact of peer pressure into a susceptible-vaccinated-infected-recovered (SVIR) epidemiological model, where the propensity to adopt a particular vaccination strategy depends both on individual success as well as on the strategies of neighbors. We show that plugging into the peer pressure is a double-edged sword, which, on the one hand, strongly promotes vaccination when its cost is below a critical value, but, on the other hand, it can also strongly impede it if the critical value is exceeded. We explain this by revealing a facilitated cluster formation process that is induced by the peer pressure. Due to this, the vaccinated individuals are inclined to cluster together and therefore become unable to efficiently inhibit the spread of the infectious disease if the vaccination is costly. If vaccination is cheap, however, they reinforce each other in using it. Our results are robust to variations of the SVIR dynamics on different population structures.

  6. Economic empowerment and AIDS-related stigma in rural Kenya: a double-edged sword?

    PubMed

    Gnauck, Katherine; Ruiz, Jamie; Kellett, Nicole; Sussman, Andrew; Sullivan, Mary Ann; Montoya, Maria; Levin, Nick; Tomedi, Angelo; Mwanthi, Mutuku A

    2013-01-01

    Economic empowerment, HIV risk and AIDS-related stigma appear intricately intertwined for women in Kenya. Their interaction must be understood in order to implement effective economic interventions that also decrease HIV risk and stigma. We conducted a qualitative study amongst women in a rural Kamba-speaking community of southeastern Kenya to pursue whether engagement in an economic empowerment initiative (a basket weaving cooperative) influences women's perspectives and experiences with HIV risk and AIDS-related stigma. We conducted seven women's focus groups: participants in the local basket-weaving cooperative comprised four focus groups and non-participants comprised the remaining three groups. The HIV status of the women was not known. Three dominant themes emerged from the focus groups: empowerment, pervasive vulnerability and unanticipated social paradoxes. Contradictions found in these themes suggest that economic empowerment can become a double-edged sword. Economic empowerment enhanced perceived individual, domestic and social community status. However, this enhancement was not protective of domestic violence and perceived HIV risk. Social perceptions may have paradoxically contributed barriers to HIV testing and treatment putting women at greater HIV risk. In conclusion, economic empowerment initiatives for women in developing countries in the context of the HIV epidemic should be coupled with peer mediated support and HIV-risk education. PMID:23668536

  7. Economic empowerment and AIDS-related stigma in rural Kenya: a double-edged sword?

    PubMed

    Gnauck, Katherine; Ruiz, Jamie; Kellett, Nicole; Sussman, Andrew; Sullivan, Mary Ann; Montoya, Maria; Levin, Nick; Tomedi, Angelo; Mwanthi, Mutuku A

    2013-01-01

    Economic empowerment, HIV risk and AIDS-related stigma appear intricately intertwined for women in Kenya. Their interaction must be understood in order to implement effective economic interventions that also decrease HIV risk and stigma. We conducted a qualitative study amongst women in a rural Kamba-speaking community of southeastern Kenya to pursue whether engagement in an economic empowerment initiative (a basket weaving cooperative) influences women's perspectives and experiences with HIV risk and AIDS-related stigma. We conducted seven women's focus groups: participants in the local basket-weaving cooperative comprised four focus groups and non-participants comprised the remaining three groups. The HIV status of the women was not known. Three dominant themes emerged from the focus groups: empowerment, pervasive vulnerability and unanticipated social paradoxes. Contradictions found in these themes suggest that economic empowerment can become a double-edged sword. Economic empowerment enhanced perceived individual, domestic and social community status. However, this enhancement was not protective of domestic violence and perceived HIV risk. Social perceptions may have paradoxically contributed barriers to HIV testing and treatment putting women at greater HIV risk. In conclusion, economic empowerment initiatives for women in developing countries in the context of the HIV epidemic should be coupled with peer mediated support and HIV-risk education.

  8. Role of Cytokines as a Double-edged Sword in Sepsis

    PubMed Central

    CHAUDHRY, HINA; ZHOU, JUHUA; ZHONG, YIN; ALI, MIR MUSTAFA; MCGUIRE, FRANKLIN; NAGARKATTI, PRAKASH S.; NAGARKATTI, MITZI

    2014-01-01

    Background Sepsis is a deadly immunological disorder and its pathophysiology is still poorly understood. We aimed to determine if specific pro-inflammatory and anti-inflammatory cytokines can be used as diagnostic and therapeutic targets for sepsis. Materials and Methods Recent publications in the MEDLINE database were searched for articles regarding the clinical significance of inflammatory cytokines in sepsis. Results In response to pathogen infection, pro-inflammatory cytokines [interleukin-6 (IL-6), IL-8, IL-18 and tumor necrosis factor-α (TNF-α)] and anti-inflammatory cytokine (IL-10) increased in patients with sepsis. Importantly, a decrease in IL-6 was associated with a better prognosis and overproduction of IL-10 was found to be the main predictor of severity and fatal outcome. Conclusion Both pro-inflammatory and anti-inflammatory cytokines constitute a double-edged sword in sepsis; on one hand they are critical to eliminate the infection while on the other, excessive production can cause tissue and organ damage. Increase in cytokines such as IL-6, Il-8, IL-10, IL-18 and TNF-α may have implications in diagnosis and treatment of sepsis. PMID:24292568

  9. Heat shock protein 90 inhibition: A potential double- or triple-edged sword in the treatment of mucous membrane pemphigoid.

    PubMed

    Kasperkiewicz, Michael; Płatkowska, Anna; Zalewska, Anna; Zillikens, Detlef

    2015-10-01

    Mucous membrane pemphigoid (MMP) is a subtype of autoimmune subepidermal blistering diseases characterized by autoantibodies to structural components of the hemidesmosome primarily affecting mucous membranes. Inflammation-related progressive scarring can lead to serious complications, including blindness, and the disease may be associated with malignancy. Conventional immunosuppressive treatment is often insufficiently effective and limited due to side effects, warranting new therapeutic options ideally targeting both inflammation and extensively recalcitrant cicatrization. Heat shock protein 90 (Hsp90) is a cell stress-inducible chaperone required for the function of a large number of client proteins, and its pharmacological inhibition has proven to be effective and relatively safe in patients with cancer. Recent observations also suggest a promising role of Hsp90 as drug target in preclinical in vivo murine models of autoimmune diseases such as subepidermal bullous and fibrotic autoimmune disorders comprising epidermolysis bullosa acquisita and systemic sclerosis, respectively, which exhibit some pathophysiological features reminiscent of MMP. This article thus hypothesizes that Hsp90 blockade could represent a double-edged sword in MMP treatment by targeting pathogenic factors of inflammatory blister and fibrosis formation. Moreover, Hsp90 inhibitors could even be proclaimed as a triple-edged sword in case of an underlying malignancy. Future studies investigating the role of Hsp90 in MMP are needed to clarify whether Hsp90 inhibition could become a novel treatment approach for patients with this potentially devastating disease.

  10. Galectins: Double-edged Swords in the Cross-roads of Pregnancy Complications and Female Reproductive Tract Inflammation and Neoplasia

    PubMed Central

    Than, Nandor Gabor; Romero, Roberto; Balogh, Andrea; Karpati, Eva; Mastrolia, Salvatore Andrea; Staretz-Chacham, Orna; Hahn, Sinuhe; Erez, Offer; Papp, Zoltan; Kim, Chong Jai

    2015-01-01

    Galectins are an evolutionarily ancient and widely expressed family of lectins that have unique glycan-binding characteristics. They are pleiotropic regulators of key biological processes, such as cell growth, proliferation, differentiation, apoptosis, signal transduction, and pre-mRNA splicing, as well as homo- and heterotypic cell-cell and cell-extracellular matrix interactions. Galectins are also pivotal in immune responses since they regulate host-pathogen interactions, innate and adaptive immune responses, acute and chronic inflammation, and immune tolerance. Some galectins are also central to the regulation of angiogenesis, cell migration and invasion. Expression and functional data provide convincing evidence that, due to these functions, galectins play key roles in shared and unique pathways of normal embryonic and placental development as well as oncodevelopmental processes in tumorigenesis. Therefore, galectins may sometimes act as double-edged swords since they have beneficial but also harmful effects for the organism. Recent advances facilitate the use of galectins as biomarkers in obstetrical syndromes and in various malignancies, and their therapeutic applications are also under investigation. This review provides a general overview of galectins and a focused review of this lectin subfamily in the context of inflammation, infection and tumors of the female reproductive tract as well as in normal pregnancies and those complicated by the great obstetrical syndromes. PMID:26018511

  11. The double-edged sword of grandiose narcissism: implications for successful and unsuccessful leadership among U.S. Presidents.

    PubMed

    Watts, Ashley L; Lilienfeld, Scott O; Smith, Sarah Francis; Miller, Joshua D; Campbell, W Keith; Waldman, Irwin D; Rubenzer, Steven J; Faschingbauer, Thomas J

    2013-12-01

    Recent research and theorizing suggest that narcissism may predict both positive and negative leadership behaviors. We tested this hypothesis with data on the 42 U.S. presidents up to and including George W. Bush, using (a) expert-derived narcissism estimates, (b) independent historical surveys of presidential performance, and (c) largely or entirely objective indicators of presidential performance. Grandiose, but not vulnerable, narcissism was associated with superior overall greatness in an aggregate poll; it was also positively associated with public persuasiveness, crisis management, agenda setting, and allied behaviors, and with several objective indicators of performance, such as winning the popular vote and initiating legislation. Nevertheless, grandiose narcissism was also associated with several negative outcomes, including congressional impeachment resolutions and unethical behaviors. We found that presidents exhibit elevated levels of grandiose narcissism compared with the general population, and that presidents' grandiose narcissism has been rising over time. Our findings suggest that grandiose narcissism may be a double-edged sword in the leadership domain.

  12. The double-edged sword of grandiose narcissism: implications for successful and unsuccessful leadership among U.S. Presidents.

    PubMed

    Watts, Ashley L; Lilienfeld, Scott O; Smith, Sarah Francis; Miller, Joshua D; Campbell, W Keith; Waldman, Irwin D; Rubenzer, Steven J; Faschingbauer, Thomas J

    2013-12-01

    Recent research and theorizing suggest that narcissism may predict both positive and negative leadership behaviors. We tested this hypothesis with data on the 42 U.S. presidents up to and including George W. Bush, using (a) expert-derived narcissism estimates, (b) independent historical surveys of presidential performance, and (c) largely or entirely objective indicators of presidential performance. Grandiose, but not vulnerable, narcissism was associated with superior overall greatness in an aggregate poll; it was also positively associated with public persuasiveness, crisis management, agenda setting, and allied behaviors, and with several objective indicators of performance, such as winning the popular vote and initiating legislation. Nevertheless, grandiose narcissism was also associated with several negative outcomes, including congressional impeachment resolutions and unethical behaviors. We found that presidents exhibit elevated levels of grandiose narcissism compared with the general population, and that presidents' grandiose narcissism has been rising over time. Our findings suggest that grandiose narcissism may be a double-edged sword in the leadership domain. PMID:24104503

  13. Facebook and its effects on users' empathic social skills and life satisfaction: a double-edged sword effect.

    PubMed

    Chan, Terri H

    2014-05-01

    This study examines how Facebook usage affects individual's empathic social skills and life satisfaction. Following the self-presentational theory, the study explores a key component of the Internet paradox-whether Facebook suppresses or enhances users' interpersonal competence (specifically empathic social skills), given their respective personality makeup. Going further, the study assesses these events' subsequent impacts on users' psychological well-being. Analogous to a double-edged sword, Facebook activities are hypothesized to suppress the positive effect of a user's extraversion orientation on empathic social skills but lessen the negative effect of neuroticism on these skills. The study examines a sample of college-aged Facebook users (n=515), who responded to a large-scale online survey. The findings from a structural equation modeling analysis indicate that while empathic social skills are positively associated with life satisfaction, Facebook activities mainly exert suppression effects. Only upon low usage can Facebook activities lessen the negative effect of neuroticism on empathic social skills, suggesting that Facebook may appear as a less threatening platform for social interactions among neurotics. Yet, results in general suggest that undesirable effects may occur at high levels of Facebook usage whereby both extroverted and neurotic users displace real world social ties to online ones. The findings point to the complex ways in which social media usage may impact the livelihood of users.

  14. Facebook and its effects on users' empathic social skills and life satisfaction: a double-edged sword effect.

    PubMed

    Chan, Terri H

    2014-05-01

    This study examines how Facebook usage affects individual's empathic social skills and life satisfaction. Following the self-presentational theory, the study explores a key component of the Internet paradox-whether Facebook suppresses or enhances users' interpersonal competence (specifically empathic social skills), given their respective personality makeup. Going further, the study assesses these events' subsequent impacts on users' psychological well-being. Analogous to a double-edged sword, Facebook activities are hypothesized to suppress the positive effect of a user's extraversion orientation on empathic social skills but lessen the negative effect of neuroticism on these skills. The study examines a sample of college-aged Facebook users (n=515), who responded to a large-scale online survey. The findings from a structural equation modeling analysis indicate that while empathic social skills are positively associated with life satisfaction, Facebook activities mainly exert suppression effects. Only upon low usage can Facebook activities lessen the negative effect of neuroticism on empathic social skills, suggesting that Facebook may appear as a less threatening platform for social interactions among neurotics. Yet, results in general suggest that undesirable effects may occur at high levels of Facebook usage whereby both extroverted and neurotic users displace real world social ties to online ones. The findings point to the complex ways in which social media usage may impact the livelihood of users. PMID:24606026

  15. Complex regulation of autophagy in cancer - integrated approaches to discover the networks that hold a double-edged sword.

    PubMed

    Kubisch, János; Türei, Dénes; Földvári-Nagy, László; Dunai, Zsuzsanna A; Zsákai, Lilian; Varga, Máté; Vellai, Tibor; Csermely, Péter; Korcsmáros, Tamás

    2013-08-01

    Autophagy, a highly regulated self-degradation process of eukaryotic cells, is a context-dependent tumor-suppressing mechanism that can also promote tumor cell survival upon stress and treatment resistance. Because of this ambiguity, autophagy is considered as a double-edged sword in oncology, making anti-cancer therapeutic approaches highly challenging. In this review, we present how systems-level knowledge on autophagy regulation can help to develop new strategies and efficiently select novel anti-cancer drug targets. We focus on the protein interactors and transcriptional/post-transcriptional regulators of autophagy as the protein and regulatory networks significantly influence the activity of core autophagy proteins during tumor progression. We list several network resources to identify interactors and regulators of autophagy proteins. As in silico analysis of such networks often necessitates experimental validation, we briefly summarize tractable model organisms to examine the role of autophagy in cancer. We also discuss fluorescence techniques for high-throughput monitoring of autophagy in humans. Finally, the challenges of pharmacological modulation of autophagy are reviewed. We suggest network-based concepts to overcome these difficulties. We point out that a context-dependent modulation of autophagy would be favored in anti-cancer therapy, where autophagy is stimulated in normal cells, while inhibited only in stressed cancer cells. To achieve this goal, we introduce the concept of regulo-network drugs targeting specific transcription factors or miRNA families identified with network analysis. The effect of regulo-network drugs propagates indirectly through transcriptional or post-transcriptional regulation of autophagy proteins, and, as a multi-directional intervention tool, they can both activate and inhibit specific proteins in the same time. The future identification and validation of such regulo-network drug targets may serve as novel intervention

  16. Comparative phylogeography highlights the double-edged sword of climate change faced by arctic- and alpine-adapted mammals.

    PubMed

    Lanier, Hayley C; Gunderson, Aren M; Weksler, Marcelo; Fedorov, Vadim B; Olson, Link E

    2015-01-01

    Recent studies suggest that alpine and arctic organisms may have distinctly different phylogeographic histories from temperate or tropical taxa, with recent range contraction into interglacial refugia as opposed to post-glacial expansion out of refugia. We use a combination of phylogeographic inference, demographic reconstructions, and hierarchical Approximate Bayesian Computation to test for phylodemographic concordance among five species of alpine-adapted small mammals in eastern Beringia. These species (Collared Pikas, Hoary Marmots, Brown Lemmings, Arctic Ground Squirrels, and Singing Voles) vary in specificity to alpine and boreal-tundra habitat but share commonalities (e.g., cold tolerance and nunatak survival) that might result in concordant responses to Pleistocene glaciations. All five species contain a similar phylogeographic disjunction separating eastern and Beringian lineages, which we show to be the result of simultaneous divergence. Genetic diversity is similar within each haplogroup for each species, and there is no support for a post-Pleistocene population expansion in eastern lineages relative to those from Beringia. Bayesian skyline plots for four of the five species do not support Pleistocene population contraction. Brown Lemmings show evidence of late Quaternary demographic expansion without subsequent population decline. The Wrangell-St. Elias region of eastern Alaska appears to be an important zone of recent secondary contact for nearctic alpine mammals. Despite differences in natural history and ecology, similar phylogeographic histories are supported for all species, suggesting that these, and likely other, alpine- and arctic-adapted taxa are already experiencing population and/or range declines that are likely to synergistically accelerate in the face of rapid climate change. Climate change may therefore be acting as a double-edged sword that erodes genetic diversity within populations but promotes divergence and the generation of

  17. Sanctuary or double-edged sword? Challenges confronting adolescents living at Nkosi's Haven in Johannesburg, South Africa.

    PubMed

    Dube, Nkosiyazi; Ross, Eleanor

    2012-11-01

    Living in an institution associated with HIV and AIDS is likely to exacerbate difficulties experienced by teenagers who have to cope with the normal stresses of adolescence. The aim of the study was to explore the challenges that adolescents living at Nkosi's Haven encounter and whether they experience any problems when interacting with their peers and other members of the community. The study was located within a qualitative research paradigm and utilised a purposive, non-probability sample of 15 participants recruited from two Nkosi's Havens. A semi-structured interview schedule was employed as the research tool, with in-depth one-on-one interviews adopted as the method of data collection. Thematic content analysis was used to analyse the data collected during the interviews. The main finding that emanated from the study was that Nkosi's Haven is indeed a place of care and nurturing as adolescents are afforded the opportunity to continue with their educational needs while basic and psychosocial needs are also addressed. However, it also emerged that rejection, discrimination, social exclusion and stigmatisation associated with the setting make it difficult for resident adolescents to integrate freely with their peers at school and in the community. The conclusion drawn is that Nkosi's Haven can be regarded as a double-edged sword as it presents both positive and negative factors that impact on its resident adolescents. Results are discussed in terms of their implications for community awareness programmes, policies and practice changes regarding employment and training of staff, and visiting of parents as well as future research. PMID:23234348

  18. Comparative Phylogeography Highlights the Double-Edged Sword of Climate Change Faced by Arctic- and Alpine-Adapted Mammals

    PubMed Central

    Lanier, Hayley C.; Gunderson, Aren M.; Weksler, Marcelo; Fedorov, Vadim B.; Olson, Link E.

    2015-01-01

    Recent studies suggest that alpine and arctic organisms may have distinctly different phylogeographic histories from temperate or tropical taxa, with recent range contraction into interglacial refugia as opposed to post-glacial expansion out of refugia. We use a combination of phylogeographic inference, demographic reconstructions, and hierarchical Approximate Bayesian Computation to test for phylodemographic concordance among five species of alpine-adapted small mammals in eastern Beringia. These species (Collared Pikas, Hoary Marmots, Brown Lemmings, Arctic Ground Squirrels, and Singing Voles) vary in specificity to alpine and boreal-tundra habitat but share commonalities (e.g., cold tolerance and nunatak survival) that might result in concordant responses to Pleistocene glaciations. All five species contain a similar phylogeographic disjunction separating eastern and Beringian lineages, which we show to be the result of simultaneous divergence. Genetic diversity is similar within each haplogroup for each species, and there is no support for a post-Pleistocene population expansion in eastern lineages relative to those from Beringia. Bayesian skyline plots for four of the five species do not support Pleistocene population contraction. Brown Lemmings show evidence of late Quaternary demographic expansion without subsequent population decline. The Wrangell-St. Elias region of eastern Alaska appears to be an important zone of recent secondary contact for nearctic alpine mammals. Despite differences in natural history and ecology, similar phylogeographic histories are supported for all species, suggesting that these, and likely other, alpine- and arctic-adapted taxa are already experiencing population and/or range declines that are likely to synergistically accelerate in the face of rapid climate change. Climate change may therefore be acting as a double-edged sword that erodes genetic diversity within populations but promotes divergence and the generation of

  19. Comparative phylogeography highlights the double-edged sword of climate change faced by arctic- and alpine-adapted mammals.

    PubMed

    Lanier, Hayley C; Gunderson, Aren M; Weksler, Marcelo; Fedorov, Vadim B; Olson, Link E

    2015-01-01

    Recent studies suggest that alpine and arctic organisms may have distinctly different phylogeographic histories from temperate or tropical taxa, with recent range contraction into interglacial refugia as opposed to post-glacial expansion out of refugia. We use a combination of phylogeographic inference, demographic reconstructions, and hierarchical Approximate Bayesian Computation to test for phylodemographic concordance among five species of alpine-adapted small mammals in eastern Beringia. These species (Collared Pikas, Hoary Marmots, Brown Lemmings, Arctic Ground Squirrels, and Singing Voles) vary in specificity to alpine and boreal-tundra habitat but share commonalities (e.g., cold tolerance and nunatak survival) that might result in concordant responses to Pleistocene glaciations. All five species contain a similar phylogeographic disjunction separating eastern and Beringian lineages, which we show to be the result of simultaneous divergence. Genetic diversity is similar within each haplogroup for each species, and there is no support for a post-Pleistocene population expansion in eastern lineages relative to those from Beringia. Bayesian skyline plots for four of the five species do not support Pleistocene population contraction. Brown Lemmings show evidence of late Quaternary demographic expansion without subsequent population decline. The Wrangell-St. Elias region of eastern Alaska appears to be an important zone of recent secondary contact for nearctic alpine mammals. Despite differences in natural history and ecology, similar phylogeographic histories are supported for all species, suggesting that these, and likely other, alpine- and arctic-adapted taxa are already experiencing population and/or range declines that are likely to synergistically accelerate in the face of rapid climate change. Climate change may therefore be acting as a double-edged sword that erodes genetic diversity within populations but promotes divergence and the generation of

  20. Breaking the double-edged sword of effort/trying hard: Developmental equilibrium and longitudinal relations among effort, achievement, and academic self-concept.

    PubMed

    Marsh, Herbert W; Pekrun, Reinhard; Lichtenfeld, Stephanie; Guo, Jiesi; Arens, A Katrin; Murayama, Kou

    2016-08-01

    Ever since the classic research of Nicholls (1976) and others, effort has been recognized as a double-edged sword: while it might enhance achievement, it undermines academic self-concept (ASC). However, there has not been a thorough evaluation of the longitudinal reciprocal effects of effort, ASC, and achievement, in the context of modern self-concept theory and statistical methodology. Nor have there been developmental equilibrium tests of whether these effects are consistent across the potentially volatile early-to-middle adolescence. Hence, focusing on mathematics, we evaluate reciprocal effects models (REMs) over the first 4 years of secondary school (grades 5-8), relating effort, achievement (test scores and school grades), ASC, and ASC × Effort interactions for a representative sample of 3,144 German students (Mage = 11.75 years at Wave 1). ASC, effort, and achievement were positively correlated at each wave, and there was a clear pattern of positive reciprocal positive effects among ASC, test scores, and school grades-each contributing to the other, after controlling for the prior effects of all others. There was an asymmetrical pattern of effects for effort that is consistent with the double-edged sword premise: prior school grades had positive effects on subsequent effort, but prior effort had nonsignificant or negative effects on subsequent grades and ASC. However, on the basis of a synergistic application of new theory and methodology, we predicted and found a significant ASC × Effort interaction, such that prior effort had more positive effects on subsequent ASC and school grades when prior ASC was high-thus providing a key to breaking the double-edged sword. (PsycINFO Database Record PMID:27455188

  1. DNA Polymerases λ and β: The Double-Edged Swords of DNA Repair.

    PubMed

    Mentegari, Elisa; Kissova, Miroslava; Bavagnoli, Laura; Maga, Giovanni; Crespan, Emmanuele

    2016-01-01

    DNA is constantly exposed to both endogenous and exogenous damages. More than 10,000 DNA modifications are induced every day in each cell's genome. Maintenance of the integrity of the genome is accomplished by several DNA repair systems. The core enzymes for these pathways are the DNA polymerases. Out of 17 DNA polymerases present in a mammalian cell, at least 13 are specifically devoted to DNA repair and are often acting in different pathways. DNA polymerases β and λ are involved in base excision repair of modified DNA bases and translesion synthesis past DNA lesions. Polymerase λ also participates in non-homologous end joining of DNA double-strand breaks. However, recent data have revealed that, depending on their relative levels, the cell cycle phase, the ratio between deoxy- and ribo-nucleotide pools and the interaction with particular auxiliary proteins, the repair reactions carried out by these enzymes can be an important source of genetic instability, owing to repair mistakes. This review summarizes the most recent results on the ambivalent properties of these enzymes in limiting or promoting genetic instability in mammalian cells, as well as their potential use as targets for anticancer chemotherapy. PMID:27589807

  2. DNA Polymerases λ and β: The Double-Edged Swords of DNA Repair

    PubMed Central

    Mentegari, Elisa; Kissova, Miroslava; Bavagnoli, Laura; Maga, Giovanni; Crespan, Emmanuele

    2016-01-01

    DNA is constantly exposed to both endogenous and exogenous damages. More than 10,000 DNA modifications are induced every day in each cell’s genome. Maintenance of the integrity of the genome is accomplished by several DNA repair systems. The core enzymes for these pathways are the DNA polymerases. Out of 17 DNA polymerases present in a mammalian cell, at least 13 are specifically devoted to DNA repair and are often acting in different pathways. DNA polymerases β and λ are involved in base excision repair of modified DNA bases and translesion synthesis past DNA lesions. Polymerase λ also participates in non-homologous end joining of DNA double-strand breaks. However, recent data have revealed that, depending on their relative levels, the cell cycle phase, the ratio between deoxy- and ribo-nucleotide pools and the interaction with particular auxiliary proteins, the repair reactions carried out by these enzymes can be an important source of genetic instability, owing to repair mistakes. This review summarizes the most recent results on the ambivalent properties of these enzymes in limiting or promoting genetic instability in mammalian cells, as well as their potential use as targets for anticancer chemotherapy. PMID:27589807

  3. The double-edged sword of genetic accounts of criminality: causal attributions from genetic ascriptions affect legal decision making.

    PubMed

    Cheung, Benjamin Y; Heine, Steven J

    2015-12-01

    Much debate exists surrounding the applicability of genetic information in the courtroom, making the psychological processes underlying how people consider this information important to explore. This article addresses how people think about different kinds of causal explanations in legal decision-making contexts. Three studies involving a total of 600 Mechanical Turk and university participants found that genetic, versus environmental, explanations of criminal behavior lead people to view the applicability of various defense claims differently, perceive the perpetrator's mental state differently, and draw different causal attributions. Moreover, mediation and path analyses highlight the double-edged nature of genetic attributions-they simultaneously reduce people's perception of the perpetrator's sense of control while increasing people's tendencies to attribute the cause to internal factors and to expect the perpetrator to reoffend. These countervailing relations, in turn, predict sentencing in opposite directions, although no overall differences in sentencing or ultimate verdicts were found. PMID:26498975

  4. The double-edged sword of genetic accounts of criminality: causal attributions from genetic ascriptions affect legal decision making.

    PubMed

    Cheung, Benjamin Y; Heine, Steven J

    2015-12-01

    Much debate exists surrounding the applicability of genetic information in the courtroom, making the psychological processes underlying how people consider this information important to explore. This article addresses how people think about different kinds of causal explanations in legal decision-making contexts. Three studies involving a total of 600 Mechanical Turk and university participants found that genetic, versus environmental, explanations of criminal behavior lead people to view the applicability of various defense claims differently, perceive the perpetrator's mental state differently, and draw different causal attributions. Moreover, mediation and path analyses highlight the double-edged nature of genetic attributions-they simultaneously reduce people's perception of the perpetrator's sense of control while increasing people's tendencies to attribute the cause to internal factors and to expect the perpetrator to reoffend. These countervailing relations, in turn, predict sentencing in opposite directions, although no overall differences in sentencing or ultimate verdicts were found.

  5. The Kynurenine Pathway Is a Double-Edged Sword in Immune-Privileged Sites and in Cancer: Implications for Immunotherapy

    PubMed Central

    Routy, Jean-Pierre; Routy, Bertrand; Graziani, Gina M.; Mehraj, Vikram

    2016-01-01

    The term “immune privilege” was originally coined to describe the suppression of inflammatory responses within organs protected by anatomic barriers, ie, the eyes, brain, placenta, and testes. However, cellular and metabolic processes, which orchestrate immune responses, also control inflammation within these sites. Our current understanding of tolerogenic mechanisms has extended the definition of immune privilege to include hair follicles, the colon, and cancer. By catabolizing tryptophan, cells expressing the enzyme indoleamine-2,3-dioxygenase produce kynurenine metabolites, which orchestrate local and systemic responses to control inflammation, thus maintaining immune privilege. This review highlights the double-edged role played by the kynurenine pathway (KP), which establishes and maintains immune-privileged sites while contributing to cancer immune escape. The identification of the underlying molecular drivers of the KP in immune-privileged sites and in cancer is essential for the development of novel therapies to treat autoimmunity and cancer and to improve transplantation outcomes. PMID:27773992

  6. The double-edged sword of ovarian cancer information for women at increased risk who have previously taken part in screening

    PubMed Central

    Smits, Stephanie; Boivin, Jacky; Menon, Usha; Brain, Kate

    2016-01-01

    Background Women at increased risk who decide not to have, or to delay, risk-reducing salpingo-oophorectomy have to rely on early diagnosis through symptom awareness and presenting to primary care as soon as possible in the absence of screening. However, little is known about the acceptability to women of this strategy. We aimed to gain an in-depth understanding of women’s perceptions and previous experiences of ovarian cancer symptom management, and the influences on ovarian cancer awareness and anticipated symptom presentation. Method Qualitative interviews were conducted with eight women at increased risk of ovarian cancer who had previously taken part in ovarian cancer screening and analysed using interpretative phenomenological analysis (IPA). Results Familial experience of ovarian cancer and perceived personal risk shaped women’s perceptions and behavioural responses to disease threat. Ovarian cancer information was perceived to be a double-edged sword, regarded as either useful for increasing knowledge and confidence in discussing symptom concerns with health professionals or to be avoided due to fears about cancer. Conclusion Women may be cautious about searching for information independently and in the absence of routine ovarian screening. Practice implications Thought needs to be given to how best to create and disseminate credible ovarian cancer symptom information materials. PMID:27433283

  7. Risk, Reward, and the Double-Edged Sword: Perspectives on Pharmacogenetic Research and Clinical Testing Among Alaska Native People

    PubMed Central

    Robinson, Renee; Starks, Helene; Burke, Wylie; Dillard, Denise A.

    2013-01-01

    Objectives. Pharmacogenetic research and clinical testing raise important concerns for individuals and communities, especially where past medical research and practice has perpetrated harm and cultivated distrust of health care systems and clinicians. We investigated perceptions of pharmacogenetics among Alaska Native (AN) people. Methods. We held four focus groups for 32 ANs in south central Alaska to elicit views about pharmacogenetics in general and for treatment of cardiovascular disease, breast cancer, depression, and nicotine addiction. We analyzed data for perceived risks and rewards of pharmacogenetics. Results. Potential risks of pharmacogenetics included health care rationing, misuse of information, and stigma to individuals and the AN community. Potential rewards included decreased care costs, improved outcomes, and community development. Participants also discussed 8 contingent conditions that could mitigate risks and increase pharmacogenetic acceptability. Conclusions. Alaska Natives perceive pharmacogenetics as potentially benefitting and harming individuals, communities, and health systems, depending on methods and oversight. Researchers, clinicians, and administrators, especially in community-based clinic and health care systems serving minority populations, must address this “double-edged sword” to effectively conduct pharmacogenetics. PMID:24134351

  8. Thiolate ligands as a double-edged sword for CO oxidation on CeO2-supported Au25(SR)18 nanoclusters

    SciTech Connect

    Wu, Zili; Jiang, Deen; Mann, Amanda K; Mullins, David R; Qiao, Zhen-an; Allard Jr, Lawrence Frederick; Zeng, Chenjie; Jin, Rongchao; Overbury, Steven {Steve} H

    2014-01-01

    The effect of thiolate ligands was explored on the catalysis of CeO2-rod supported Au25(SR)18 (SR = -SCH2-CH2-Ph) by using CO oxidation as a probe reaction. Reaction kinetic tests, in situ IR and X-ray absorption spectroscopy, and density functional theory (DFT) were employed to understand how the thiolate ligands affect the nature of active sites, activation of CO and O2, as well as the reaction mechanism and kinetics. The intact Au25(SR)18 on CeO2-rod is found not able to adsorb CO. Only when the thiolate ligands are partially removed, starting from the interface between Au25(SR)18 and CeO2 at temperatures of 423 K and above, can the adsorption of CO be observed by IR. DFT calculations suggest that CO adsorbs favorably on the exposed gold atoms. Accordingly, the CO oxidation light-off temperature shifts to lower temperature. Several types of Au sites are probed by IR of CO adsorption during the ligand removal process. The cationic Au sites (charged between 0 and +1) are found to play the major role for low temperature CO oxidation. Similar activation energy and reaction rate are found for CO oxidation on differently treated Au25(SR)18/CeO2-rod, suggesting a simple site-blocking effect of the thiolate ligands in Au nanoclusters catalysis. Isotopic labelling experiments clearly indicate that CO oxidation on Au25(SR)18/CeO2-rod proceeds predominantly via the redox mechanism where CeO2 activates O2 while CO is activated on the de-thiolated gold sites. These results points to a double-edged sword role played by the thiolate ligands on Au25 nanoclusters for CO oxidation.

  9. Hexokinase II: cancer's double-edged sword acting as both facilitator and gatekeeper of malignancy when bound to mitochondria.

    PubMed

    Mathupala, S P; Ko, Y H; Pedersen, P L

    2006-08-01

    A key hallmark of many cancers, particularly the most aggressive, is the capacity to metabolize glucose at an elevated rate, a phenotype detected clinically using positron emission tomography (PET). This phenotype provides cancer cells, including those that participate in metastasis, a distinct competitive edge over normal cells. Specifically, after rapid entry of glucose into cancer cells on the glucose transporter, the highly glycolytic phenotype is supported by hexokinase (primarily HK II) that is overexpressed and bound to the outer mitochondrial membrane via the porin-like protein voltage-dependent anion channel (VDAC). This protein and the adenine nucleotide transporter move ATP, newly synthesized by the inner membrane located ATP synthase, to active sites on HK II. The abundant amounts of HK II bind both the ATP and the incoming glucose producing the product glucose-6-phosphate, also at an elevated rate. This critical metabolite then serves both as a biosynthetic precursor to support cell proliferation and as a precursor for lactic acid, the latter exiting cancer cells causing an unfavorable environment for normal cells. Although helping facilitate this chemical warfare, HK II via its mitochondrial location also suppresses the death of cancer cells, thus increasing their possibility for metastasis and the ultimate death of the human host. For these reasons, targeting this key enzyme is currently being investigated in several laboratories in a strategy to develop novel therapies that may turn the tide on the continuing struggle to find effective cures for cancer. One such candidate is 3-bromopyruvate that has been shown recently to eradicate advanced stage, PET positive hepatocellular carcinomas in an animal model without apparent harm to the animals. PMID:16892090

  10. Double-Edge Sword of Sustained ROCK Activation in Prion Diseases through Neuritogenesis Defects and Prion Accumulation

    PubMed Central

    Alleaume-Butaux, Aurélie; Nicot, Simon; Pietri, Mathéa; Baudry, Anne; Dakowski, Caroline; Tixador, Philippe; Ardila-Osorio, Hector; Haeberlé, Anne-Marie; Bailly, Yannick; Peyrin, Jean-Michel; Launay, Jean-Marie; Kellermann, Odile; Schneider, Benoit

    2015-01-01

    In prion diseases, synapse dysfunction, axon retraction and loss of neuronal polarity precede neuronal death. The mechanisms driving such polarization defects, however, remain unclear. Here, we examined the contribution of RhoA-associated coiled-coil containing kinases (ROCK), key players in neuritogenesis, to prion diseases. We found that overactivation of ROCK signaling occurred in neuronal stem cells infected by pathogenic prions (PrPSc) and impaired the sprouting of neurites. In reconstructed networks of mature neurons, PrPSc-induced ROCK overactivation provoked synapse disconnection and dendrite/axon degeneration. This overactivation of ROCK also disturbed overall neurotransmitter-associated functions. Importantly, we demonstrated that beyond its impact on neuronal polarity ROCK overactivity favored the production of PrPSc through a ROCK-dependent control of 3-phosphoinositide-dependent kinase 1 (PDK1) activity. In non-infectious conditions, ROCK and PDK1 associated within a complex and ROCK phosphorylated PDK1, conferring basal activity to PDK1. In prion-infected neurons, exacerbated ROCK activity increased the pool of PDK1 molecules physically interacting with and phosphorylated by ROCK. ROCK-induced PDK1 overstimulation then canceled the neuroprotective α-cleavage of normal cellular prion protein PrPC by TACE α-secretase, which physiologically precludes PrPSc production. In prion-infected cells, inhibition of ROCK rescued neurite sprouting, preserved neuronal architecture, restored neuronal functions and reduced the amount of PrPSc. In mice challenged with prions, inhibition of ROCK also lowered brain PrPSc accumulation, reduced motor impairment and extended survival. We conclude that ROCK overactivation exerts a double detrimental effect in prion diseases by altering neuronal polarity and triggering PrPSc accumulation. Eventually ROCK emerges as therapeutic target to combat prion diseases. PMID:26241960

  11. Double-Edge Sword of Sustained ROCK Activation in Prion Diseases through Neuritogenesis Defects and Prion Accumulation.

    PubMed

    Alleaume-Butaux, Aurélie; Nicot, Simon; Pietri, Mathéa; Baudry, Anne; Dakowski, Caroline; Tixador, Philippe; Ardila-Osorio, Hector; Haeberlé, Anne-Marie; Bailly, Yannick; Peyrin, Jean-Michel; Launay, Jean-Marie; Kellermann, Odile; Schneider, Benoit

    2015-08-01

    In prion diseases, synapse dysfunction, axon retraction and loss of neuronal polarity precede neuronal death. The mechanisms driving such polarization defects, however, remain unclear. Here, we examined the contribution of RhoA-associated coiled-coil containing kinases (ROCK), key players in neuritogenesis, to prion diseases. We found that overactivation of ROCK signaling occurred in neuronal stem cells infected by pathogenic prions (PrPSc) and impaired the sprouting of neurites. In reconstructed networks of mature neurons, PrPSc-induced ROCK overactivation provoked synapse disconnection and dendrite/axon degeneration. This overactivation of ROCK also disturbed overall neurotransmitter-associated functions. Importantly, we demonstrated that beyond its impact on neuronal polarity ROCK overactivity favored the production of PrPSc through a ROCK-dependent control of 3-phosphoinositide-dependent kinase 1 (PDK1) activity. In non-infectious conditions, ROCK and PDK1 associated within a complex and ROCK phosphorylated PDK1, conferring basal activity to PDK1. In prion-infected neurons, exacerbated ROCK activity increased the pool of PDK1 molecules physically interacting with and phosphorylated by ROCK. ROCK-induced PDK1 overstimulation then canceled the neuroprotective α-cleavage of normal cellular prion protein PrPC by TACE α-secretase, which physiologically precludes PrPSc production. In prion-infected cells, inhibition of ROCK rescued neurite sprouting, preserved neuronal architecture, restored neuronal functions and reduced the amount of PrPSc. In mice challenged with prions, inhibition of ROCK also lowered brain PrPSc accumulation, reduced motor impairment and extended survival. We conclude that ROCK overactivation exerts a double detrimental effect in prion diseases by altering neuronal polarity and triggering PrPSc accumulation. Eventually ROCK emerges as therapeutic target to combat prion diseases.

  12. Double-Edge Sword of Sustained ROCK Activation in Prion Diseases through Neuritogenesis Defects and Prion Accumulation.

    PubMed

    Alleaume-Butaux, Aurélie; Nicot, Simon; Pietri, Mathéa; Baudry, Anne; Dakowski, Caroline; Tixador, Philippe; Ardila-Osorio, Hector; Haeberlé, Anne-Marie; Bailly, Yannick; Peyrin, Jean-Michel; Launay, Jean-Marie; Kellermann, Odile; Schneider, Benoit

    2015-08-01

    In prion diseases, synapse dysfunction, axon retraction and loss of neuronal polarity precede neuronal death. The mechanisms driving such polarization defects, however, remain unclear. Here, we examined the contribution of RhoA-associated coiled-coil containing kinases (ROCK), key players in neuritogenesis, to prion diseases. We found that overactivation of ROCK signaling occurred in neuronal stem cells infected by pathogenic prions (PrPSc) and impaired the sprouting of neurites. In reconstructed networks of mature neurons, PrPSc-induced ROCK overactivation provoked synapse disconnection and dendrite/axon degeneration. This overactivation of ROCK also disturbed overall neurotransmitter-associated functions. Importantly, we demonstrated that beyond its impact on neuronal polarity ROCK overactivity favored the production of PrPSc through a ROCK-dependent control of 3-phosphoinositide-dependent kinase 1 (PDK1) activity. In non-infectious conditions, ROCK and PDK1 associated within a complex and ROCK phosphorylated PDK1, conferring basal activity to PDK1. In prion-infected neurons, exacerbated ROCK activity increased the pool of PDK1 molecules physically interacting with and phosphorylated by ROCK. ROCK-induced PDK1 overstimulation then canceled the neuroprotective α-cleavage of normal cellular prion protein PrPC by TACE α-secretase, which physiologically precludes PrPSc production. In prion-infected cells, inhibition of ROCK rescued neurite sprouting, preserved neuronal architecture, restored neuronal functions and reduced the amount of PrPSc. In mice challenged with prions, inhibition of ROCK also lowered brain PrPSc accumulation, reduced motor impairment and extended survival. We conclude that ROCK overactivation exerts a double detrimental effect in prion diseases by altering neuronal polarity and triggering PrPSc accumulation. Eventually ROCK emerges as therapeutic target to combat prion diseases. PMID:26241960

  13. Hexokinase II: Cancer’s double-edged sword acting as both facilitator and gatekeeper of malignancy when bound to mitochondria

    PubMed Central

    Mathupala, SP; Ko, YH; Pedersen, PL

    2012-01-01

    A key hallmark of many cancers, particularly the most aggressive, is the capacity to metabolize glucose at an elevated rate, a phenotype detected clinically using positron emission tomography (PET). This phenotype provides cancer cells, including those that participate in metastasis, a distinct competitive edge over normal cells. Specifically, after rapid entry of glucose into cancer cells on the glucose transporter, the highly glycolytic phenotype is supported by hexokinase (primarily HK II) that is overexpressed and bound to the outer mitochondrial membrane via the porin-like protein voltage-dependent anion channel (VDAC). This protein and the adenine nucleotide transporter move ATP, newly synthesized by the inner membrane located ATP synthase, to active sites on HK II. The abundant amounts of HK II bind both the ATP and the incoming glucose producing the product glucose-6-phosphate, also at an elevated rate. This critical metabolite then serves both as a biosynthetic precursor to support cell proliferation and as a precursor for lactic acid, the latter exiting cancer cells causing an unfavorable environment for normal cells. Although helping facilitate this chemical warfare, HK II via its mitochondrial location also suppresses the death of cancer cells, thus increasing their possibility for metastasis and the ultimate death of the human host. For these reasons, targeting this key enzyme is currently being investigated in several laboratories in a strategy to develop novel therapies that may turn the tide on the continuing struggle to find effective cures for cancer. One such candidate is 3-bromopyruvate that has been shown recently to eradicate advanced stage, PET positive hepatocellular carcinomas in an animal model without apparent harm to the animals. PMID:16892090

  14. Calcium supplement: humanity's double-edged sword.

    PubMed

    Bunyaratavej, Narong; Buranasinsup, Shutipen

    2011-10-01

    The principle aim of the present study is to investigate the dark side of calcium, pollutions in calcium preparation especially lead (Pb), mercury (Hg) and cadmium (Cd). The collected samples were the different calcium salts in the market and 18 preparations which were classified into 3 groups: Calcium carbonate salts, Chelated calcium and natural-raw calcium. All samples were analyzed for lead, cadmium and mercury by inductively Coupled Plasma Mass Spectrometry (ICP-MS) technique, in house method based on AOAC (2005) 999.10 by ICP-MS. The calcium carbonate and the natural-raw calcium in every sample contained lead at 0.023-0.407 mg/kg of calcium powder. Meanwhile, the natural-raw calcium such as oyster, coral and animal bone showed amount of lead at 0.106-0.384 mg/kg with small amounts of mercury and cadmium. The chelated calcium such as calcium gluconate, calcium lactate and calcium citrate are free of lead. PMID:22338928

  15. Characterization of a Messer – The late-Medieval single-edged sword of Central Europe

    SciTech Connect

    Fajfar, Peter; Medved, Jožef; Klančnik, Grega; Lazar, Tomaž; Nečemer, Marijan; Mrvar, Primož

    2013-12-15

    Metallurgical characterization of a sword blade fragments dating from the second half of the 15th century found in central Slovenia was performed in order to determine its chemical composition, microstructure, microhardness, and to obtain insight into the methods of manufacture of a late-medieval Messer sword. As the artefact was broken, examinations were limited to six very small fragments that were allowed to be removed from the cutting edge, core and the back of the blade. Light optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, energy dispersive X-ray fluorescence spectrometry, differential scanning calorimetry, thermodynamics approach and Vickers micro-hardness tests were employed to analyze the microstructure and mechanical properties. The results show that the sword was manufactured from a single wrought iron billet. The surface of the sword was carburized. No evidence of quenching was found. The ferritic microstructure is concentrated in the core, and the pearlitic in the outer layer of the blade. All metal fragments contained non-metallic inclusions that were derived mostly from slag and some from hammer scale. - Highlights: • A metallurgical characterization of a medieval sword blade has been performed. • The carbon content decreased from the surface to the core of the blade. • The dominant microstructure in the outer layer is pearlite and in the core is ferrite. • The presence of lump shaped and elongated non-metallic inclusions was observed. • The sword was manufactured from a single wrought iron billet.

  16. Enzyme cofactors: Double-edged sword for catalysis

    NASA Astrophysics Data System (ADS)

    Ivanov, Ivaylo

    2013-01-01

    The metal cofactors responsible for the activity of CDK2 -- a representative member of the kinase superfamily of enzymes -- have now been shown to also have inhibitory effects during the catalytic cycle.

  17. Double-Edged Sword: Social Media Use in the Classroom

    ERIC Educational Resources Information Center

    Chromey, Kelli J.; Duchsherer, Amy; Pruett, Jennifer; Vareberg, Kyle

    2016-01-01

    The purpose of this research is to identify the students' perceptions of social media use in a classroom setting. Knowing students' perceptions of social media can help the instructor build a course that both student and teacher can find effective. Using focus groups this study found a model to determine if social media is an appropriate or…

  18. Transcendental meditation: a double-edged sword in epilepsy?

    PubMed

    Lansky, Ephraim Philip; St Louis, Erik K

    2006-11-01

    Transcendental Meditation (TM) is derived from ancient yogic teachings. Both short- and long-term physiological correlates of TM practice have been studied. EEG effects include increased alpha, theta, and gamma frequencies and increased coherence and synchrony. Neuronal hypersynchrony is also a cardinal feature of epilepsy, and subjective psychic symptoms, apnea, and myoclonic jerking are characteristic of both epileptic seizures and meditative states. Clinical vignettes have highlighted the potential risk of human kindling from repetitive meditation in persons practicing TM, but clinical studies of similar techniques suggest that meditation may also be a potential antiepileptic therapy. Future clinical studies of meditating subjects using video/EEG monitoring are warranted to determine whether behavioral phenomena have an underlying epileptic basis, and prospective clinical trials of TM in subjects with well-delineated epilepsy syndromes are necessary to establish the safety of this technique and its potential efficacy for seizure reduction and improvement of quality of life.

  19. The Double-Edged Sword: Fantasy and Censorship.

    ERIC Educational Resources Information Center

    Tunnell, Michael O.

    1994-01-01

    Notes that fantasy and fairy tales are frequent targets of censorship attempts. Provides a defense against such attacks, by offering an answer (perhaps a challenge) to each of the major objections to fantasy stories. (SR)

  20. The "Double-Edged Sword" of the Adult Learning Environment

    ERIC Educational Resources Information Center

    Murray, Sara; Mitchell, Jane

    2013-01-01

    The vocational education and training sector plays a critical role in the provision of educational opportunities for young adults who have left school prior to completing a qualification. Some research has found that a major factor that supports student re-engagement in formal education is the "adult learning environment" that characterises…

  1. Lymphopenia and autoimmunity: A double-edged sword.

    PubMed

    Merayo-Chalico, Javier; Rajme-López, Sandra; Barrera-Vargas, Ana; Alcocer-Varela, Jorge; Díaz-Zamudio, Mariana; Gómez-Martín, Diana

    2016-10-01

    Lymphopenia is strongly associated with autoimmune diseases. The molecular mechanisms that link both phenomena are still unclear, but certain key pathways have been described. Central tolerance is as important as peripheral. In the earlier, epithelial and dendritic cells play a crucial role in the selection of clones. In the latter, regulatory T cells (Tregs) rise as inductors of anergy in order to prevent the development of autoimmune pathology. In lymphopenic conditions, T cells develop the process of lymphopenia-induced proliferation (LIP). A complex interaction between the major histocompatibility complex (MHC) and the T cell receptor (TCR) makes this process possible. Furthermore, IL-7 can act synergistically or in an independent manner to promote LIP. A lack of Transforming Growth Factor-β (TGF-β) was recently described as the second hit needed to develop autoimmunity in a lymphopenic microenvironment, given its actions in Tregs and its interaction with CTLA-4. Regarding autoimmune clinical scenarios, lymphopenia is related to both, systemic and organ-specific diseases. Thus, the molecular study of such patients has been limited and needs to be widened to the pathways shown here to be involved in the development of lymphopenia and autoimmunity. PMID:27343993

  2. Parathyroid hormone: a double-edged sword for bone metabolism.

    PubMed

    Qin, Ling; Raggatt, Liza J; Partridge, Nicola C

    2004-03-01

    Parathyroid hormone (PTH) is the major hormone regulating calcium metabolism. It is also the only FDA-approved drug for osteoporosis treatment that stimulates bone formation when injected daily. However, continuous infusion of PTH causes severe bone loss in line with its known catabolic effects. Many studies to understand the dual effects of PTH have been carried out, and in recent years a growing number of molecular and cellular mechanisms underlying these effects have emerged. Here, we outline the present knowledge and conclude that the kinetics of administration and subsequent signaling probably account for the divergent actions of the hormone. PMID:15036251

  3. Neutrophil extracellular traps: double-edged swords of innate immunity.

    PubMed

    Kaplan, Mariana J; Radic, Marko

    2012-09-15

    Spectacular images of neutrophils ejecting nuclear chromatin and bactericidal proteins, in response to microbes, were first reported in 2004. As externalized chromatin could entangle bacteria, these structures were named neutrophil extracellular traps (NETs). Subsequent studies identified microorganisms and sterile conditions that stimulate NETs, as well as additional cell types that release extracellular chromatin. The release of NETs is the most dramatic stage in a cell death process called NETosis. Experimental evidence suggests that NETs participate in pathogenesis of autoimmune and inflammatory disorders, with proposed involvement in glomerulonephritis, chronic lung disease, sepsis, and vascular disorders. Exaggerated NETosis or diminished NET clearance likely increases risk of autoreactivity to NET components. The biological significance of NETs is just beginning to be explored. A more complete integration of NETosis within immunology and pathophysiology will require better understanding of NET properties associated with specific disease states and microbial infections. This may lead to the identification of important therapeutic targets.

  4. Manipulation of BCG vaccine: a double-edged sword.

    PubMed

    Singh, V K; Srivastava, R; Srivastava, B S

    2016-04-01

    Mycobacterium bovis Bacillus Calmette-Guérin (BCG), an attenuated vaccine derived from M. bovis, is the only licensed vaccine against tuberculosis (TB). Despite its protection against TB in children, the protective efficacy in pulmonary TB is variable in adolescents and adults. In spite of the current knowledge of molecular biology, immunology and cell biology, infectious diseases such as TB and HIV/AIDS are still challenges for the scientific community. Genetic manipulation facilitates the construction of recombinant BCG (rBCG) vaccine that can be used as a highly immunogenic vaccine against TB with an improved safety profile, but, still, the manipulation of BCG vaccine to improve efficacy should be carefully considered, as it can bring in both favourable and unfavourable effects. The purpose of this review is not to comprehensively review the interaction between microorganisms and host cells in order to use rBCG expressing M. tuberculosis (Mtb) immunodominant antigens that are available in the public domain, but, rather, to also discuss the limitations of rBCG vaccine, expressing heterologous antigens, during manipulation that pave the way for a promising new vaccine approach. PMID:26810060

  5. Opioids and Viral Infections: A Double-Edged Sword

    PubMed Central

    Tahamtan, Alireza; Tavakoli-Yaraki, Masoumeh; Mokhtari-Azad, Talat; Teymoori-Rad, Majid; Bont, Louis; Shokri, Fazel; Salimi, Vahid

    2016-01-01

    Opioids and their receptors have received remarkable attention because they have the ability to alter immune function, which affects disease progression. In vitro and in vivo findings as well as observations in humans indicate that opioids and their receptors positively or negatively affect viral replication and virus-mediated pathology. The present study reviews recent insights in the role of opioids and their receptors in viral infections and discusses possible therapeutic opportunities. This review supports the emerging concept that opioids and their receptors have both favorable and unfavorable effects on viral disease, depending on the type of virus. Targeting of the opioid system is a potential option for developing effective therapies; however caution is required in relation to the beneficial functions of opioid systems. PMID:27446011

  6. Playing with a double-edged sword: Analogies in biochemistry

    NASA Astrophysics Data System (ADS)

    Orgill, Marykay

    Analogy pervades our everyday reasoning. No situation we encounter is exactly like a situation we have encountered previously, and our ability to learn and survive in the world is based on our ability to find similarities between past and present situations and use the knowledge we have gained from past situations to manage current situations. Analogies can be powerful teaching tools because they can make new material intelligible to students by comparing it to material that is already familiar. It is clear, though, that not all analogies are good and that not all good analogies are useful to all students. In this study, I have used textbook analysis, classroom observations, student interviews and instructor interviews to determine the role that analogies play in biochemistry learning. Analogies are an important teaching technique in biochemistry classes, being used more often in both biochemistry classes and textbooks than they are in high school chemistry classes and textbooks. Most biochemistry students like, pay particular attention to, and remember the analogies their instructors provide; and they use these analogies to understand, visualize, and recall information from class. Even though students like and use analogies, they do not understand what analogies are or the mechanism by which they improve learning. For the students, analogies are simply any teaching technique that eases understanding, visualization, or recall. Instructors, on the other hand, have a good understanding of what analogies are and of how they should be presented in class; but they do not use analogies as effectively as they should. They do not plan, explain or identify the limitations of the analogies they use in class. However, regardless of how effectively instructors present analogies in class, this study indicates that, in general, analogies are useful in promoting understanding, visualization, recall, and motivation in biochemistry students at all levels. They would be even more useful if students understood what analogies are and how they can be used to improve understanding of biochemical concepts.

  7. Nodulation outer proteins: double-edged swords of symbiotic rhizobia

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rhizobia are nitrogen-fixing bacteria that establish a nodule symbiosis with legumes. Nodule formation is the result of a complex bacterial infection process, which depends on signals and surface determinants produced by both symbiotic partners. Among them, rhizobial nodulation outer proteins (Nops)...

  8. Reactive oxygen species a double-edged sword for mesothelioma

    PubMed Central

    Catalani, Simona; Galati, Rossella

    2015-01-01

    It is well known that oxidative stress can lead to chronic inflammation which, in turn, could mediate most chronic diseases including cancer. Oxidants have been implicated in the activity of crocidolite and amosite, the most powerful types of asbestos associated to the occurrence of mesothelioma. Currently rates of mesothelioma are rising and estimates indicate that the incidence of mesothelioma will peak within the next 10–15 years in the western world, while in Japan the peak is predicted not to occur until 40 years from now. Although the use of asbestos has been banned in many countries around the world, production of and the potentially hazardous exposure to asbestos is still present with locally high incidences of mesothelioma. Today a new man-made material, carbon nanotubes, has arisen as a concern; carbon nanotubes may display ‘asbestos-like’ pathogenicity with mesothelioma induction potential. Carbon nanotubes resulted in the greatest reactive oxygen species generation. How oxidative stress activates inflammatory pathways leading to the transformation of a normal cell to a tumor cell, to tumor cell survival, proliferation, invasion, angiogenesis, chemoresistance, and radioresistance, is the aim of this review. PMID:26078352

  9. Temperate bacterial viruses as double-edged swords in bacterial warfare.

    PubMed

    Gama, João Alves; Reis, Ana Maria; Domingues, Iolanda; Mendes-Soares, Helena; Matos, Ana Margarida; Dionisio, Francisco

    2013-01-01

    It has been argued that bacterial cells may use their temperate viruses as biological weapons. For instance, a few bacterial cells among a population of lysogenic cells could release the virus and kill susceptible non-lysogenic competitors, while their clone mates would be immune. Because viruses replicate inside their victims upon infection, this process would amplify their number in the arena. Sometimes, however, temperate viruses spare recipient cells from death by establishing themselves in a dormant state inside cells. This phenomenon is called lysogenization and, for some viruses such as the λ virus, the probability of lysogenization increases with the multiplicity of infection. Therefore, the amplification of viruses leads to conflicting predictions about the efficacy of temperate viruses as biological weapons: amplification can increase the relative advantage of clone mates of lysogens but also the likelihood of saving susceptible cells from death, because the probability of lysogenization is higher. To test the usefulness of viruses as biological weapons, we performed competition experiments between lysogenic Escherichia coli cells carrying the λ virus and susceptible λ-free E. coli cells, either in a structured or unstructured habitat. In structured and sometimes in unstructured habitats, the λ virus qualitatively behaved as a "replicating toxin". However, such toxic effect of λ viruses ceased after a few days of competition. This was due to the fact that many of initially susceptible cells became lysogenic. Massive lysogenization of susceptible cells occurred precisely under the conditions where the amplification of the virus was substantial. From then on, these cells and their descendants became immune to the λ virus. In conclusion, if at short term bacterial cells may use temperate viruses as biological weapons, after a few days only the classical view of temperate bacterial viruses as parasitic agents prevails.

  10. [Where are we going? The forced deinstitutionalization is a double-edged sword].

    PubMed

    Ferracuti, Stefano; Biondi, Massimo

    2015-01-01

    In Italy the deep crisis of the judicial system, and in particular of the jail system, has allowed the development of an intense deinstitutionalization. A set of rules implemented since 2008 are leading to the closure of the Judicial Psychiatric Hospitals and, simultaneously, to the release of a large number of detainees, mainly restricted for drug offenses. There is a lack of effective structures for the management of this population, plagued with mental disorders. Social policies are needed that allow the development of structures for this complex population, which otherwise will be left to itself. PMID:26156814

  11. The double-edged sword of pedagogy: Instruction limits spontaneous exploration and discovery.

    PubMed

    Bonawitz, Elizabeth; Shafto, Patrick; Gweon, Hyowon; Goodman, Noah D; Spelke, Elizabeth; Schulz, Laura

    2011-09-01

    Motivated by computational analyses, we look at how teaching affects exploration and discovery. In Experiment 1, we investigated children's exploratory play after an adult pedagogically demonstrated a function of a toy, after an interrupted pedagogical demonstration, after a naïve adult demonstrated the function, and at baseline. Preschoolers in the pedagogical condition focused almost exclusively on the target function; by contrast, children in the other conditions explored broadly. In Experiment 2, we show that children restrict their exploration both after direct instruction to themselves and after overhearing direct instruction given to another child; they do not show this constraint after observing direct instruction given to an adult or after observing a non-pedagogical intentional action. We discuss these findings as the result of rational inductive biases. In pedagogical contexts, a teacher's failure to provide evidence for additional functions provides evidence for their absence; such contexts generalize from child to child (because children are likely to have comparable states of knowledge) but not from adult to child. Thus, pedagogy promotes efficient learning but at a cost: children are less likely to perform potentially irrelevant actions but also less likely to discover novel information. PMID:21216395

  12. Inflammation and Inflammatory Cells in Myocardial Infarction and Reperfusion Injury: A Double-Edged Sword.

    PubMed

    Liu, Jiaqi; Wang, Haijuan; Li, Jun

    2016-01-01

    Myocardial infarction (MI) is the most common cause of cardiac injury, and subsequent reperfusion further enhances the activation of innate and adaptive immune responses and cell death programs. Therefore, inflammation and inflammatory cell infiltration are the hallmarks of MI and reperfusion injury. Ischemic cardiac injury activates the innate immune response via toll-like receptors and upregulates chemokine and cytokine expressions in the infarcted heart. The recruitment of inflammatory cells is a dynamic and superbly orchestrated process. Sequential infiltration of the injured myocardium with neutrophils, monocytes and their descendant macrophages, dendritic cells, and lymphocytes contributes to the initiation and resolution of inflammation, infarct healing, angiogenesis, and ventricular remodeling. Both detrimental effects and a beneficial role in the pathophysiology of MI and reperfusion injury may be attributed to the subset heterogeneity and functional diversity of these inflammatory cells. PMID:27279755

  13. The microbiota and chronic kidney diseases: a double-edged sword

    PubMed Central

    Felizardo, Raphael Jose Ferreira; Castoldi, Angela; Andrade-Oliveira, Vinicius; Câmara, Niels Olsen Saraiva

    2016-01-01

    Recent findings regarding the influence of the microbiota in many inflammatory processes have provided a new way to treat diseases. Now, one may hypothesize that the origin of a plethora of diseases is related to the health of the gut microbiota and its delicate, although complex, interface with the epithelial and immune systems. The ‘westernization' of diets, for example, is associated with alterations in the gut microbiota. Such alterations have been found to correlate directly with the increased incidence of diabetes and hypertension, the main causes of chronic kidney diseases (CKDs), which, in turn, have a high estimated prevalence. Indeed, data have arisen showing that the progression of kidney diseases is strictly related to the composition of the microbiota. Alterations in the gut microbiota diversity during CKDs do not only have the potential to exacerbate renal injury but may also contribute to the development of associated comorbidities, such as cardiovascular diseases and insulin resistance. In this review, we discuss how dysbiosis through alterations in the gut barrier and the consequent activation of immune system could intensify the progression of CKD and vice versa, how CKDs can modify the gut microbiota diversity and abundance. PMID:27757226

  14. The Sensitivity of Precocious Child Writers: More Evidence of the Double-Edged Sword

    ERIC Educational Resources Information Center

    Edmunds, Alan L.; Edmunds, Gail

    2014-01-01

    This article provides further evidence of the often observed sensitive nature displayed by children who are gifted. It also addresses the positive and negative effects that this sensitivity can have on these individuals. Earlier, the authors explored this concept through an analysis of the works and life experiences of Geoffrey, aged 9, a prolific…

  15. Protecting chemistry inventions: the double-edged sword of being an unpredictable art.

    PubMed

    Tostmann, Holger

    2015-04-01

    Recent decisions by the highest courts in the US in regard to written description and enablement as well as parallel restrictions previously established in Europe emphasize that applicants in the fields of chemistry/pharma/life sciences should strive to include as many examples, data, and guidance about how to extrapolate from the example(s) in the description. This holds in particular whenever a broad genus and/or functional features is/are to be protected. It is important to keep in mind that these data and this guidance must be disclosed in the application at the time of filing. Data collected at a later stage can only be used to further support data and evidence already present in the application as filed.

  16. Mitochondrial reactive oxygen species: A double edged sword in ischemia/reperfusion vs preconditioning

    PubMed Central

    Kalogeris, Theodore; Bao, Yimin; Korthuis, Ronald J.

    2014-01-01

    Reductions in the blood supply produce considerable injury if the duration of ischemia is prolonged. Paradoxically, restoration of perfusion to ischemic organs can exacerbate tissue damage and extend the size of an evolving infarct. Being highly metabolic organs, the heart and brain are particularly vulnerable to the deleterious effects of ischemia/reperfusion (I/R). While the pathogenetic mechanisms contributing to I/R-induced tissue injury and infarction are multifactorial, the relative importance of each contributing factor remains unclear. However, an emerging body of evidence indicates that the generation of reactive oxygen species (ROS) by mitochondria plays a critical role in damaging cellular components and initiating cell death. In this review, we summarize our current understanding of the mechanisms whereby mitochondrial ROS generation occurs in I/R and contributes to myocardial infarction and stroke. In addition, mitochondrial ROS have been shown to participate in preconditioning by several pharmacologic agents that target potassium channels (e.g., ATP-sensitive potassium (mKATP) channels or large conductance, calcium-activated potassium (mBKCa) channels) to activate cell survival programs that render tissues and organs more resistant to the deleterious effects of I/R. Finally, we review novel therapeutic approaches that selectively target mROS production to reduce postischemic tissue injury, which may prove efficacious in limiting myocardial dysfunction and infarction and abrogating neurocognitive deficits and neuronal cell death in stroke. PMID:24944913

  17. Chinese Sex-Role Conceptions: A Double Edged Sword for Women.

    ERIC Educational Resources Information Center

    Korabik, Karen

    Although Chinese government policies officially support the equality of the sexes, stereotyped views about the nature of men and women often serve to perpetuate discrimination and to keep women in inferior positions. Women are often segregated into lower paying jobs because of stereotypical views about what is natural for women to do. Despite…

  18. Wnt/β-catenin signaling in kidney injury and repair: a double-edged sword

    PubMed Central

    Zhou, Dong; Tan, Roderick J.; Fu, Haiyan; Liu, Youhua

    2015-01-01

    The Wnt/β-catenin signaling cascade is an evolutionarily conserved, highly complex pathway that is known to be involved in kidney injury and repair after a wide variety of insults. While the kidney displays an impressive ability to repair and recover after injury, these repair mechanisms can be overwhelmed, leading to maladaptive responses and eventual development of chronic kidney disease (CKD). Emerging evidence demonstrates that Wnt/β-catenin signaling possesses dual roles in promoting repair/regeneration or facilitating progression to CKD after acute kidney injury (AKI), depending on the magnitude and duration of its activation. In this review, we summarize the expression, intracellular modification, and secretion of Wnt family proteins and their regulation in a variety of kidney diseases. We also explore our current understanding of the potential mechanisms by which transient Wnt/β-catenin activation positively regulates adaptive responses of the kidney after AKI, and discuss how sustained activation of this signaling triggers maladaptive responses and causes destructive outcomes. A better understanding of these mechanisms may offer important opportunities for designing targeted therapy to promote adaptive kidney repair/recovery and prevent progression to CKD in patients. PMID:26692289

  19. The Effects of α-Tocopherol on Bone: A Double-Edged Sword?

    PubMed Central

    Chin, Kok-Yong; Ima-Nirwana, Soelaiman

    2014-01-01

    Recent studies have found conflicting evidence on the role of α-tocopherol (αTF) on bone health. This nonsystematic review aimed to summarize the current evidence on the effects of αTF on bone health from cell culture, animal, and human studies in order to clarify the role of αTF on bone health. Our review found that αTF exerted beneficial, harmful or null effects on bone formation cells. Animal studies generally showed positive effects of αTF supplementation on bone in various models of osteoporosis. However, high-dose αTF was possibly detrimental to bone in normal animals. Human studies mostly demonstrated a positive relationship between αTF, as assessed using high performance liquid chromatography and/or dietary questionnaire, and bone health, as assessed using bone mineral density and/or fracture incidence. Three possible reasons high dosage of αTF can be detrimental to bone include its interference with Vitamin K function on bone, the blocking of the entry of other Vitamin E isomers beneficial to bone, and the role of αTF as a prooxidant. However, these adverse effects have not been shown in human studies. In conclusion, αTF may have a dual role in bone health, whereby in the appropriate doses it is beneficial but in high doses it may be harmful to bone. PMID:24727433

  20. "My Past Is a Double Edge Sword": Temporality and Reflexivity in Mature Learners

    ERIC Educational Resources Information Center

    Stevenson, Jacqueline; Clegg, Sue

    2013-01-01

    This paper discusses the ways in which mature students orientate themselves towards the future in making decisions to access higher education (HE). Their narratives connect their past, often difficult, educational and personal lives to their future aspirations and to their current experiences in further education (FE) and HE. The research was part…

  1. Selenium: a double-edged sword for defense and offence in cancer.

    PubMed

    Brozmanová, Jela; Mániková, Dominika; Vlčková, Viera; Chovanec, Miroslav

    2010-12-01

    Selenium (Se) is an essential dietary component for animals including humans and is regarded as a protective agent against cancer. Although the mode of anticancer action of Se is not fully understood yet, several mechanisms, such as antioxidant protection by selenoenzymes, specific inhibition of tumor cell growth by Se metabolites, modulation of cell cycle and apoptosis, and effect on DNA repair have all been proposed. Despite the unsupported results of the last SELECT trial, the cancer-preventing activity of Se was demonstrated in majority of the epidemiological studies. Moreover, recent studies suggest that Se has a potential to be used not only in cancer prevention but also in cancer treatment where in combination with other anticancer drugs or radiation, it can increase efficacy of cancer therapy. In combating cancer cells, Se acts as pro-oxidant rather than antioxidant, inducing apoptosis through the generation of oxidative stress. Thus, the inorganic Se compound, sodium selenite (SeL), due to its prooxidant character, represents a promising alternative for cancer therapy. However, this Se compound is highly toxic compared to organic Se forms. Thus, the unregulated intake of dietary or pharmacological Se supplements mainly in the form of SeL has a potential to expose the body tissues to the toxic levels of Se with subsequent negative consequences on DNA integrity. Hence, due to a broad interest to exploit the positive effects of Se on human health and cancer therapy, studies investigating the negative effects such as toxicity and DNA damage induction resulting from high Se intake are also highly required. Here, we review a role of Se in cancer prevention and cancer therapy, as well as mechanisms underlying Se-induced toxicity and DNA injury. Since Saccharomyces cerevisiae has proven a powerful tool for addressing some important questions regarding Se biology, a part of this review is devoted to this model system.

  2. A double-edged sword: Benefits and pitfalls of heterogeneous punishment in evolutionary inspection games.

    PubMed

    Perc, Matjaž; Szolnoki, Attila

    2015-01-01

    As a simple model for criminal behavior, the traditional two-strategy inspection game yields counterintuitive results that fail to describe empirical data. The latter shows that crime is often recurrent, and that crime rates do not respond linearly to mitigation attempts. A more apt model entails ordinary people who neither commit nor sanction crime as the third strategy besides the criminals and punishers. Since ordinary people free-ride on the sanctioning efforts of punishers, they may introduce cyclic dominance that enables the coexistence of all three competing strategies. In this setup ordinary individuals become the biggest impediment to crime abatement. We therefore also consider heterogeneous punisher strategies, which seek to reduce their investment into fighting crime in order to attain a more competitive payoff. We show that this diversity of punishment leads to an explosion of complexity in the system, where the benefits and pitfalls of criminal behavior are revealed in the most unexpected ways. Due to the raise and fall of different alliances no less than six consecutive phase transitions occur in dependence on solely the temptation to succumb to criminal behavior, leading the population from ordinary people-dominated across punisher-dominated to crime-dominated phases, yet always failing to abolish crime completely. PMID:26046673

  3. A double-edged sword: Benefits and pitfalls of heterogeneous punishment in evolutionary inspection games.

    PubMed

    Perc, Matjaž; Szolnoki, Attila

    2015-01-01

    As a simple model for criminal behavior, the traditional two-strategy inspection game yields counterintuitive results that fail to describe empirical data. The latter shows that crime is often recurrent, and that crime rates do not respond linearly to mitigation attempts. A more apt model entails ordinary people who neither commit nor sanction crime as the third strategy besides the criminals and punishers. Since ordinary people free-ride on the sanctioning efforts of punishers, they may introduce cyclic dominance that enables the coexistence of all three competing strategies. In this setup ordinary individuals become the biggest impediment to crime abatement. We therefore also consider heterogeneous punisher strategies, which seek to reduce their investment into fighting crime in order to attain a more competitive payoff. We show that this diversity of punishment leads to an explosion of complexity in the system, where the benefits and pitfalls of criminal behavior are revealed in the most unexpected ways. Due to the raise and fall of different alliances no less than six consecutive phase transitions occur in dependence on solely the temptation to succumb to criminal behavior, leading the population from ordinary people-dominated across punisher-dominated to crime-dominated phases, yet always failing to abolish crime completely.

  4. Temperate bacterial viruses as double-edged swords in bacterial warfare.

    PubMed

    Gama, João Alves; Reis, Ana Maria; Domingues, Iolanda; Mendes-Soares, Helena; Matos, Ana Margarida; Dionisio, Francisco

    2013-01-01

    It has been argued that bacterial cells may use their temperate viruses as biological weapons. For instance, a few bacterial cells among a population of lysogenic cells could release the virus and kill susceptible non-lysogenic competitors, while their clone mates would be immune. Because viruses replicate inside their victims upon infection, this process would amplify their number in the arena. Sometimes, however, temperate viruses spare recipient cells from death by establishing themselves in a dormant state inside cells. This phenomenon is called lysogenization and, for some viruses such as the λ virus, the probability of lysogenization increases with the multiplicity of infection. Therefore, the amplification of viruses leads to conflicting predictions about the efficacy of temperate viruses as biological weapons: amplification can increase the relative advantage of clone mates of lysogens but also the likelihood of saving susceptible cells from death, because the probability of lysogenization is higher. To test the usefulness of viruses as biological weapons, we performed competition experiments between lysogenic Escherichia coli cells carrying the λ virus and susceptible λ-free E. coli cells, either in a structured or unstructured habitat. In structured and sometimes in unstructured habitats, the λ virus qualitatively behaved as a "replicating toxin". However, such toxic effect of λ viruses ceased after a few days of competition. This was due to the fact that many of initially susceptible cells became lysogenic. Massive lysogenization of susceptible cells occurred precisely under the conditions where the amplification of the virus was substantial. From then on, these cells and their descendants became immune to the λ virus. In conclusion, if at short term bacterial cells may use temperate viruses as biological weapons, after a few days only the classical view of temperate bacterial viruses as parasitic agents prevails. PMID:23536852

  5. Teaching Mathematics by Comparison: Analog Visibility as a Double-Edged Sword

    ERIC Educational Resources Information Center

    Begolli, Kreshnik Nasi; Richland, Lindsey Engle

    2016-01-01

    Comparing multiple solutions to a single problem is an important mode for developing flexible mathematical thinking, yet instructionally leading this activity is challenging (Stein, Engle, Smith, & Hughes, 2008). We test 1 decision teachers must make after having students solve a problem: whether to only verbally discuss students' solutions or…

  6. Regulatory T cells in central nervous system injury: a double-edged sword.

    PubMed

    Walsh, James T; Zheng, Jingjing; Smirnov, Igor; Lorenz, Ulrike; Tung, Kenneth; Kipnis, Jonathan

    2014-11-15

    Previous research investigating the roles of T effector (T(eff)) and T regulatory (T(reg)) cells after injury to the CNS has yielded contradictory conclusions, with both protective and destructive functions being ascribed to each of these T cell subpopulations. In this work, we study this dichotomy by examining how regulation of the immune system affects the response to CNS trauma. We show that, in response to CNS injury, T(eff) and T(reg) subsets in the CNS-draining deep cervical lymph nodes are activated, and surgical resection of these lymph nodes results in impaired neuronal survival. Depletion of T(reg), not surprisingly, induces a robust T(eff) response in the draining lymph nodes and is associated with impaired neuronal survival. Interestingly, however, injection of exogenous T(reg) cells, which limits the spontaneous beneficial immune response after CNS injury, also impairs neuronal survival. We found that no T(reg) accumulate at the site of CNS injury, and that changes in T(reg) numbers do not alter the amount of infiltration by other immune cells into the site of injury. The phenotype of macrophages at the site, however, is affected: both addition and removal of T(reg) negatively impact the numbers of macrophages with alternatively activated (tissue-building) phenotype. Our data demonstrate that neuronal survival after CNS injury is impaired when T(reg) cells are either removed or added. With this exacerbation of neurodegeneration seen with both addition and depletion of T(reg), we recommend exercising extreme caution when considering the therapeutic targeting of T(reg) cells after CNS injury, and possibly in chronic neurodegenerative conditions. PMID:25320276

  7. Hydrogen Peroxide and Polyamines Act as Double Edged Swords in Plant Abiotic Stress Responses.

    PubMed

    Gupta, Kamala; Sengupta, Atreyee; Chakraborty, Mayukh; Gupta, Bhaskar

    2016-01-01

    The specific genetic changes through which plants adapt to the multitude of environmental stresses are possible because of the molecular regulations in the system. These intricate regulatory mechanisms once unveiled will surely raise interesting questions. Polyamines and hydrogen peroxide have been suggested to be important signaling molecules during biotic and abiotic stresses. Hydrogen peroxide plays a versatile role from orchestrating physiological processes to stress response. It helps to achieve acclimatization and tolerance to stress by coordinating intra-cellular and systemic signaling systems. Polyamines, on the other hand, are low molecular weight polycationic aliphatic amines, which have been implicated in various stress responses. It is quite interesting to note that both hydrogen peroxide and polyamines have a fine line of inter-relation between them since the catabolic pathways of the latter releases hydrogen peroxide. In this review we have tried to illustrate the roles and their multifaceted functions of these two important signaling molecules based on current literature. This review also highlights the fact that over accumulation of hydrogen peroxide and polyamines can be detrimental for plant cells leading to toxicity and pre-mature cell death. PMID:27672389

  8. Dendritic Cells: A Double-Edged Sword in Immune Responses during Chagas Disease.

    PubMed

    Gil-Jaramillo, Natalia; Motta, Flávia N; Favali, Cecília B F; Bastos, Izabela M D; Santana, Jaime M

    2016-01-01

    Dendritic cells (DCs) are the most important member of the antigen presenting cells group due to their ability to recognize antigen at the infection site and their high specialized antigen internalization capacity. These cells have central role in connecting the innate and adaptive immune responses against Trypanosoma cruzi, the causative agent of Chagas disease. These first line defense cells modulate host immune response depending on type, maturation level, cytokine milieu and DC receptor involved in the interactions with T. cruzi, influencing the development of the disease clinic forms. Here, we present a review of DCs-T. cruzi interactions both in human and murine models, pointing out the parasite ability to manipulate DCs activity for the purpose of evading innate immune response and assuring its own survival and persistence. PMID:27471496

  9. The double-edged sword of pedagogy: Instruction limits spontaneous exploration and discovery.

    PubMed

    Bonawitz, Elizabeth; Shafto, Patrick; Gweon, Hyowon; Goodman, Noah D; Spelke, Elizabeth; Schulz, Laura

    2011-09-01

    Motivated by computational analyses, we look at how teaching affects exploration and discovery. In Experiment 1, we investigated children's exploratory play after an adult pedagogically demonstrated a function of a toy, after an interrupted pedagogical demonstration, after a naïve adult demonstrated the function, and at baseline. Preschoolers in the pedagogical condition focused almost exclusively on the target function; by contrast, children in the other conditions explored broadly. In Experiment 2, we show that children restrict their exploration both after direct instruction to themselves and after overhearing direct instruction given to another child; they do not show this constraint after observing direct instruction given to an adult or after observing a non-pedagogical intentional action. We discuss these findings as the result of rational inductive biases. In pedagogical contexts, a teacher's failure to provide evidence for additional functions provides evidence for their absence; such contexts generalize from child to child (because children are likely to have comparable states of knowledge) but not from adult to child. Thus, pedagogy promotes efficient learning but at a cost: children are less likely to perform potentially irrelevant actions but also less likely to discover novel information.

  10. The Double-Edged Sword of Pedagogy: Instruction Limits Spontaneous Exploration and Discovery

    ERIC Educational Resources Information Center

    Bonawitz, Elizabeth; Shafto, Patrick; Gweon, Hyowon; Goodman, Noah D.; Spelke, Elizabeth; Schulz, Laura

    2011-01-01

    Motivated by computational analyses, we look at how teaching affects exploration and discovery. In Experiment 1, we investigated children's exploratory play after an adult pedagogically demonstrated a function of a toy, after an interrupted pedagogical demonstration, after a naive adult demonstrated the function, and at baseline. Preschoolers in…

  11. Reading "the Word and the World": The Double-Edged Sword of Teaching Critical Literacy

    ERIC Educational Resources Information Center

    White, John Wesley

    2009-01-01

    White acknowledges that critical literacy is central to literacy instruction today, but warns that asking those untrained in critical literacy to "teach" critical literacy could have undesirable consequences. He suggests three potentially undesirable outcomes and offers advice for preventing them.

  12. Education Policy Reform in Sri Lanka: The Double-Edged Sword of Political Will

    ERIC Educational Resources Information Center

    Little, Angela W.

    2011-01-01

    In 1997, the Government of Sri Lanka launched a comprehensive set of education reforms designed to promote equitable access to basic education and improvements in learning outcomes. The package of reforms arose as a political response to widespread youth unrest in the late 1980s and attracted considerable "political will", a vague but much vaunted…

  13. Hydrogen Peroxide and Polyamines Act as Double Edged Swords in Plant Abiotic Stress Responses.

    PubMed

    Gupta, Kamala; Sengupta, Atreyee; Chakraborty, Mayukh; Gupta, Bhaskar

    2016-01-01

    The specific genetic changes through which plants adapt to the multitude of environmental stresses are possible because of the molecular regulations in the system. These intricate regulatory mechanisms once unveiled will surely raise interesting questions. Polyamines and hydrogen peroxide have been suggested to be important signaling molecules during biotic and abiotic stresses. Hydrogen peroxide plays a versatile role from orchestrating physiological processes to stress response. It helps to achieve acclimatization and tolerance to stress by coordinating intra-cellular and systemic signaling systems. Polyamines, on the other hand, are low molecular weight polycationic aliphatic amines, which have been implicated in various stress responses. It is quite interesting to note that both hydrogen peroxide and polyamines have a fine line of inter-relation between them since the catabolic pathways of the latter releases hydrogen peroxide. In this review we have tried to illustrate the roles and their multifaceted functions of these two important signaling molecules based on current literature. This review also highlights the fact that over accumulation of hydrogen peroxide and polyamines can be detrimental for plant cells leading to toxicity and pre-mature cell death.

  14. The DLK signalling pathway--a double-edged sword in neural development and regeneration.

    PubMed

    Tedeschi, Andrea; Bradke, Frank

    2013-07-01

    Dual leucine zipper kinase (DLK), a mitogen-activated protein kinase kinase kinase, controls axon growth, apoptosis and neuron degeneration during neural development, as well as neurodegeneration after various insults to the adult nervous system. Interestingly, recent studies have also highlighted a role of DLK in promoting axon regeneration in diverse model systems. Invertebrates and vertebrates, cold- and warm-blooded animals, as well as central and peripheral mammalian nervous systems all differ in their ability to regenerate injured axons. Here, we discuss how DLK-dependent signalling regulates apparently contradictory functions during neural development and regeneration in different species. In addition, we outline strategies to fine-tune DLK function, either alone or together with other approaches, to promote axon regeneration in the adult mammalian central nervous system. PMID:23681442

  15. Stabilizing versus destabilizing the microtubules: a double-edge sword for an effective cancer treatment option?

    PubMed

    Fanale, Daniele; Bronte, Giuseppe; Passiglia, Francesco; Calò, Valentina; Castiglia, Marta; Di Piazza, Florinda; Barraco, Nadia; Cangemi, Antonina; Catarella, Maria Teresa; Insalaco, Lavinia; Listì, Angela; Maragliano, Rossella; Massihnia, Daniela; Perez, Alessandro; Toia, Francesca; Cicero, Giuseppe; Bazan, Viviana

    2015-01-01

    Microtubules are dynamic and structural cellular components involved in several cell functions, including cell shape, motility, and intracellular trafficking. In proliferating cells, they are essential components in the division process through the formation of the mitotic spindle. As a result of these functions, tubulin and microtubules are targets for anticancer agents. Microtubule-targeting agents can be divided into two groups: microtubule-stabilizing, and microtubule-destabilizing agents. The former bind to the tubulin polymer and stabilize microtubules, while the latter bind to the tubulin dimers and destabilize microtubules. Alteration of tubulin-microtubule equilibrium determines the disruption of the mitotic spindle, halting the cell cycle at the metaphase-anaphase transition and, eventually, resulting in cell death. Clinical application of earlier microtubule inhibitors, however, unfortunately showed several limits, such as neurological and bone marrow toxicity and the emergence of drug-resistant tumor cells. Here we review several natural and synthetic microtubule-targeting agents, which showed antitumor activity and increased efficacy in comparison to traditional drugs in various preclinical and clinical studies. Cryptophycins, combretastatins, ombrabulin, soblidotin, D-24851, epothilones and discodermolide were used in clinical trials. Some of them showed antiangiogenic and antivascular activity and others showed the ability to overcome multidrug resistance, supporting their possible use in chemotherapy.

  16. Stabilizing versus Destabilizing the Microtubules: A Double-Edge Sword for an Effective Cancer Treatment Option?

    PubMed Central

    Fanale, Daniele; Bronte, Giuseppe; Passiglia, Francesco; Calò, Valentina; Castiglia, Marta; Di Piazza, Florinda; Barraco, Nadia; Cangemi, Antonina; Catarella, Maria Teresa; Insalaco, Lavinia; Listì, Angela; Maragliano, Rossella; Massihnia, Daniela; Perez, Alessandro; Toia, Francesca; Cicero, Giuseppe; Bazan, Viviana

    2015-01-01

    Microtubules are dynamic and structural cellular components involved in several cell functions, including cell shape, motility, and intracellular trafficking. In proliferating cells, they are essential components in the division process through the formation of the mitotic spindle. As a result of these functions, tubulin and microtubules are targets for anticancer agents. Microtubule-targeting agents can be divided into two groups: microtubule-stabilizing, and microtubule-destabilizing agents. The former bind to the tubulin polymer and stabilize microtubules, while the latter bind to the tubulin dimers and destabilize microtubules. Alteration of tubulin-microtubule equilibrium determines the disruption of the mitotic spindle, halting the cell cycle at the metaphase-anaphase transition and, eventually, resulting in cell death. Clinical application of earlier microtubule inhibitors, however, unfortunately showed several limits, such as neurological and bone marrow toxicity and the emergence of drug-resistant tumor cells. Here we review several natural and synthetic microtubule-targeting agents, which showed antitumor activity and increased efficacy in comparison to traditional drugs in various preclinical and clinical studies. Cryptophycins, combretastatins, ombrabulin, soblidotin, D-24851, epothilones and discodermolide were used in clinical trials. Some of them showed antiangiogenic and antivascular activity and others showed the ability to overcome multidrug resistance, supporting their possible use in chemotherapy. PMID:26484003

  17. MG53 is a double-edged sword for human diseases.

    PubMed

    Zhang, Yan; Wu, Hong-Kun; Lv, Feng-Xiang; Xiao, Rui-Ping

    2016-08-25

    Mitsugumin 53 (MG53), also named Trim72, is a multi-functional TRIM-family protein, which is abundantly expressed in cardiac and skeletal muscle. It has been shown that MG53 not only plays important physiological roles but also acts as a crucial pathogenic factor of various diseases. First, MG53 preserves cardiac and skeletal muscle integrity via facilitating plasma membrane repair. Second, MG53 is essentially involved in cardiac ischemic preconditioning and postconditioning by activating PI3K-Akt-GSK3β and ERK1/2 cell survival signaling pathways. Moreover, systemic delivery of recombinant MG53 is able to abolish mechanic or ischemia-reperfusion (I/R)-induced injury of multiple organs, including heart, skeletal muscle, lung, kidney and skin. Importantly, MG53 acts as an E3 ligase to mediate the degradation of insulin receptor and insulin receptor substrate-1, and subsequently induces insulin resistance and metabolic diseases such as type-2 diabetes and its cardiovascular complications. In addition, MG53 negatively regulates myogenesis. As a potential therapeutic target of human diseases, multiple facets of MG53 biological function and mechanisms of action should be taken into the consideration to maximize its beneficial effects and minimize potential side-effects. Here in this review, we intend to comprehensively summarize the current progresses on the biological functions of MG53, focusing on its clinical value as a therapeutic target. PMID:27546510

  18. Dendritic Cells: A Double-Edged Sword in Immune Responses during Chagas Disease

    PubMed Central

    Gil-Jaramillo, Natalia; Motta, Flávia N.; Favali, Cecília B. F.; Bastos, Izabela M. D.; Santana, Jaime M.

    2016-01-01

    Dendritic cells (DCs) are the most important member of the antigen presenting cells group due to their ability to recognize antigen at the infection site and their high specialized antigen internalization capacity. These cells have central role in connecting the innate and adaptive immune responses against Trypanosoma cruzi, the causative agent of Chagas disease. These first line defense cells modulate host immune response depending on type, maturation level, cytokine milieu and DC receptor involved in the interactions with T. cruzi, influencing the development of the disease clinic forms. Here, we present a review of DCs–T. cruzi interactions both in human and murine models, pointing out the parasite ability to manipulate DCs activity for the purpose of evading innate immune response and assuring its own survival and persistence. PMID:27471496

  19. Iron and copper in male reproduction: a double-edged sword.

    PubMed

    Tvrda, Eva; Peer, Rohan; Sikka, Suresh C; Agarwal, Ashok

    2015-01-01

    Iron and copper are essential trace nutrients playing important roles in general health and fertility. However, both elements are highly toxic when accumulating in large quantities. Their direct or indirect impact on the structure and function of male gonads and gametes is not completely understood yet. Excess or deficiency of either element may lead to defective spermatogenesis, reduced libido, and oxidative damage to the testicular tissue and spermatozoa, ultimately leading to fertility impairment. This review will detail the complex information currently available on the dual roles iron and copper play in male reproduction.

  20. Aural foreign body extraction in children: a double-edged sword

    PubMed Central

    Olajuyin, Oyebanji; Olatunya, Oladele Simeon

    2015-01-01

    Introduction Foreign body insertion into the ear in children is common world-wide. The goal of this work is to describe the procedural complications of aural foreign body extraction in children. Methods A retrospective analysis of records of children with aural foreign bodies was conducted. Patients’ bio data, type of foreign bodies, referrals, techniques of removal and complications were extracted from the case files. The foreign bodies were categorized into graspable and non-graspable objects. Patients with complications caused directly by the foreign body were excluded. Results There were 136 cases. Eighty-seven (64.0%) were males while forty-nine (36.0%) were females. Their age range from 5 days to 16 years with 109 (80.2%) aged below 8 years. Eighty-nine (65.4%) and 47 (34.6%) cases were treated by otolaryngologists and non-otolaryngologists with a complication rate of 15.7% and 68.1% respectively. One case suffered severe hearing loss following complicated attempt at removing foreign body in the only hearing ear. Overall, the complication rate was higher (44.4%) with removal of non-graspable than (28.6%) with graspable objects. Conclusion Procedural complication is an ever-present hazard of aural foreign body extraction in children. Its occurrence can be prevented or largely reduced if health care-givers know their limitation based on their clinical skills and acquaint themselves with established criteria for referral. As a rule, we suggest that, foreign body in the only hearing ear and failed attempted first removal should be considered criteria for otolaryngologic referral. PMID:26430483

  1. Tyrosine kinase inhibitors in pulmonary arterial hypertension: a double-edge sword?

    PubMed

    Godinas, Laurent; Guignabert, Christophe; Seferian, Andrei; Perros, Frederic; Bergot, Emmanuel; Sibille, Yves; Humbert, Marc; Montani, David

    2013-10-01

    New treatments for pulmonary arterial hypertension (PAH) are a crucial need. The increased proliferation, migration, and survival of pulmonary vascular cells within the pulmonary artery wall in PAH have allowed successful transposition of pathophysiological elements from oncologic researches. Next steps will require translation of these biological advances in PAH therapeutic arsenal and guidelines. This review synthesizes recent data concerning the role of receptor tyrosine kinases and their inhibitors in PAH, with implications in animal models and humans. Results of clinical trials are now accumulating to establish beneficial role of tyrosine kinase inhibitors (TKIs) in PAH and further findings are expected in the near future. Beside this curative approach, evidences of a possible TKI-induced cardiotoxicity are emerging. These safety issues raise concern about a potential amplified harmful effect in PAH, a pathology characterized by an underlying cardiac dysfunction. In addition, analyses of PAH registries shed light on a selective pulmonary vascular toxicity triggered by TKIs, especially dasatinib. These possible dual effects of the TKIs in PAH need to be taken in account for future pharmacological development of this therapeutic class in PAH. PMID:24037637

  2. A double-edged sword: Benefits and pitfalls of heterogeneous punishment in evolutionary inspection games

    NASA Astrophysics Data System (ADS)

    Perc, Matjaž; Szolnoki, Attila

    2015-06-01

    As a simple model for criminal behavior, the traditional two-strategy inspection game yields counterintuitive results that fail to describe empirical data. The latter shows that crime is often recurrent, and that crime rates do not respond linearly to mitigation attempts. A more apt model entails ordinary people who neither commit nor sanction crime as the third strategy besides the criminals and punishers. Since ordinary people free-ride on the sanctioning efforts of punishers, they may introduce cyclic dominance that enables the coexistence of all three competing strategies. In this setup ordinary individuals become the biggest impediment to crime abatement. We therefore also consider heterogeneous punisher strategies, which seek to reduce their investment into fighting crime in order to attain a more competitive payoff. We show that this diversity of punishment leads to an explosion of complexity in the system, where the benefits and pitfalls of criminal behavior are revealed in the most unexpected ways. Due to the raise and fall of different alliances no less than six consecutive phase transitions occur in dependence on solely the temptation to succumb to criminal behavior, leading the population from ordinary people-dominated across punisher-dominated to crime-dominated phases, yet always failing to abolish crime completely.

  3. Hydrogen Peroxide and Polyamines Act as Double Edged Swords in Plant Abiotic Stress Responses

    PubMed Central

    Gupta, Kamala; Sengupta, Atreyee; Chakraborty, Mayukh; Gupta, Bhaskar

    2016-01-01

    The specific genetic changes through which plants adapt to the multitude of environmental stresses are possible because of the molecular regulations in the system. These intricate regulatory mechanisms once unveiled will surely raise interesting questions. Polyamines and hydrogen peroxide have been suggested to be important signaling molecules during biotic and abiotic stresses. Hydrogen peroxide plays a versatile role from orchestrating physiological processes to stress response. It helps to achieve acclimatization and tolerance to stress by coordinating intra-cellular and systemic signaling systems. Polyamines, on the other hand, are low molecular weight polycationic aliphatic amines, which have been implicated in various stress responses. It is quite interesting to note that both hydrogen peroxide and polyamines have a fine line of inter-relation between them since the catabolic pathways of the latter releases hydrogen peroxide. In this review we have tried to illustrate the roles and their multifaceted functions of these two important signaling molecules based on current literature. This review also highlights the fact that over accumulation of hydrogen peroxide and polyamines can be detrimental for plant cells leading to toxicity and pre-mature cell death.

  4. The Double-edged Sword of Pedagogy: Instruction limits spontaneous exploration and discovery

    PubMed Central

    Shafto, Patrick; Gweon, Hyowon; Goodman, Noah D.; Spelke, Elizabeth; Schulz, Laura

    2012-01-01

    Motivated by computational analyses, we look at how teaching affects exploration and discovery. In Experiment 1, we investigated children’s exploratory play after an adult pedagogically demonstrated a function of a toy, after an interrupted pedagogical demonstration, after a naïve adult demonstrated the function, and at baseline. Preschoolers in the pedagogical condition focused almost exclusively on the target function; by contrast, children in the other conditions explored broadly. In Experiment 2, we show that children restrict their exploration both after direct instruction to themselves and after overhearing direct instruction given to another child; they do not show this constraint after observing direct instruction given to an adult or after observing a non-pedagogical intentional action. We discuss these findings as the result of rational inductive biases. In pedagogical contexts, a teacher’s failure to provide evidence for additional functions provides evidence for their absence; such contexts generalize from child to child (because children are likely to have comparable states of knowledge) but not from adult to child. Thus, pedagogy promotes efficient learning but at a cost: children are less likely to perform potentially irrelevant actions but also less likely to discover novel information. PMID:21216395

  5. NK Cells: A Double-Edged Sword in Chronic Hepatitis B Virus Infection

    PubMed Central

    Maini, Mala K.; Peppa, Dimitra

    2013-01-01

    There is natural enrichment of NK cells in the human liver and this intrahepatic predominance underscores their potential importance in the control of infections with hepatotropic viruses such as hepatitis B virus (HBV). The contribution of innate components during chronic HBV infection has been a relatively under-investigated area. However, recent data have highlighted that NK cells are capable of exerting antiviral and immunoregulatory functions whilst also contributing to the pathogenesis of liver injury via death receptor pathways. We will present an overview of current knowledge regarding the complex biology of NK cells in the context of their antiviral versus pathogenic role in chronic hepatitis B as a clinically relevant avenue for further investigation. PMID:23459859

  6. Increasing tomato fruit quality by enhancing fruit chloroplast function. A double-edged sword?

    PubMed

    Cocaliadis, Maria Florencia; Fernández-Muñoz, Rafael; Pons, Clara; Orzaez, Diego; Granell, Antonio

    2014-08-01

    Fruits are generally regarded as photosynthate sinks as they rely on energy provided by sugars transported from leaves to carry out the highly demanding processes of development and ripening; eventually these imported photosynthates also contribute to the fruit organoleptic properties. Three recent reports have revealed, however, that transcriptional factors enhancing chloroplast development in fruit may result in higher contents not only of tomato fruit-specialized metabolites but also of sugars. In addition to suggesting new ways to improve fruit quality by fortifying fruit chloroplasts and plastids, these results prompted us to re-evaluate the importance of the contribution of chloroplasts/photosynthesis to fruit development and ripening.

  7. A double-edged sword: Benefits and pitfalls of heterogeneous punishment in evolutionary inspection games

    PubMed Central

    Perc, Matjaž; Szolnoki, Attila

    2015-01-01

    As a simple model for criminal behavior, the traditional two-strategy inspection game yields counterintuitive results that fail to describe empirical data. The latter shows that crime is often recurrent, and that crime rates do not respond linearly to mitigation attempts. A more apt model entails ordinary people who neither commit nor sanction crime as the third strategy besides the criminals and punishers. Since ordinary people free-ride on the sanctioning efforts of punishers, they may introduce cyclic dominance that enables the coexistence of all three competing strategies. In this setup ordinary individuals become the biggest impediment to crime abatement. We therefore also consider heterogeneous punisher strategies, which seek to reduce their investment into fighting crime in order to attain a more competitive payoff. We show that this diversity of punishment leads to an explosion of complexity in the system, where the benefits and pitfalls of criminal behavior are revealed in the most unexpected ways. Due to the raise and fall of different alliances no less than six consecutive phase transitions occur in dependence on solely the temptation to succumb to criminal behavior, leading the population from ordinary people-dominated across punisher-dominated to crime-dominated phases, yet always failing to abolish crime completely. PMID:26046673

  8. Chloroquine in cancer therapy: a double-edged sword of autophagy.

    PubMed

    Kimura, Tomonori; Takabatake, Yoshitsugu; Takahashi, Atsushi; Isaka, Yoshitaka

    2013-01-01

    Autophagy is a homeostatic cellular recycling system that is responsible for degrading damaged or unnecessary cellular organelles and proteins. Cancer cells are thought to use autophagy as a source of energy in the unfavorable metastatic environment, and a number of clinical trials are now revealing the promising role of chloroquine, an autophagy inhibitor, as a novel antitumor drug. On the other hand, however, the kidneys are highly vulnerable to chemotherapeutic agents. Recent studies have shown that autophagy plays a protective role against acute kidney injury, including cisplatin-induced kidney injury, and thus, we suspect that the use of chloroquine in combination with anticancer drugs may exacerbate kidney damage. Moreover, organs in which autophagy also plays a homeostatic role, such as the neurons, liver, hematopoietic stem cells, and heart, may be sensitive to the combined use of chloroquine and anticancer drugs. Here, we summarize the functions of autophagy in cancer and kidney injury, especially focusing on the use of chloroquine to treat cancer, and address the possible side effects in the combined use of chloroquine and anticancer drugs. PMID:23288916

  9. Inflammation and Inflammatory Cells in Myocardial Infarction and Reperfusion Injury: A Double-Edged Sword

    PubMed Central

    Liu, Jiaqi; Wang, Haijuan; Li, Jun

    2016-01-01

    Myocardial infarction (MI) is the most common cause of cardiac injury, and subsequent reperfusion further enhances the activation of innate and adaptive immune responses and cell death programs. Therefore, inflammation and inflammatory cell infiltration are the hallmarks of MI and reperfusion injury. Ischemic cardiac injury activates the innate immune response via toll-like receptors and upregulates chemokine and cytokine expressions in the infarcted heart. The recruitment of inflammatory cells is a dynamic and superbly orchestrated process. Sequential infiltration of the injured myocardium with neutrophils, monocytes and their descendant macrophages, dendritic cells, and lymphocytes contributes to the initiation and resolution of inflammation, infarct healing, angiogenesis, and ventricular remodeling. Both detrimental effects and a beneficial role in the pathophysiology of MI and reperfusion injury may be attributed to the subset heterogeneity and functional diversity of these inflammatory cells. PMID:27279755

  10. The effects of α-tocopherol on bone: a double-edged sword?

    PubMed

    Chin, Kok-Yong; Ima-Nirwana, Soelaiman

    2014-04-01

    Recent studies have found conflicting evidence on the role of α-tocopherol (αTF) on bone health. This nonsystematic review aimed to summarize the current evidence on the effects of αTF on bone health from cell culture, animal, and human studies in order to clarify the role of αTF on bone health. Our review found that αTF exerted beneficial, harmful or null effects on bone formation cells. Animal studies generally showed positive effects of αTF supplementation on bone in various models of osteoporosis. However, high-dose αTF was possibly detrimental to bone in normal animals. Human studies mostly demonstrated a positive relationship between αTF, as assessed using high performance liquid chromatography and/or dietary questionnaire, and bone health, as assessed using bone mineral density and/or fracture incidence. Three possible reasons high dosage of αTF can be detrimental to bone include its interference with Vitamin K function on bone, the blocking of the entry of other Vitamin E isomers beneficial to bone, and the role of αTF as a prooxidant. However, these adverse effects have not been shown in human studies. In conclusion, αTF may have a dual role in bone health, whereby in the appropriate doses it is beneficial but in high doses it may be harmful to bone. PMID:24727433

  11. Angiopoietin-like 4: A double-edged sword in atherosclerosis and ischemic stroke?

    PubMed

    Xu, Liang; Guo, Zhen-Ni; Yang, Yi; Xu, Jun; Burchell, Sherrefa R; Tang, Jiping; Zhang, Jianmin; Xu, Jing; Zhang, John H

    2015-10-01

    Ischemic stroke is one of the leading causes of death in the world, and thus is a major public health concern. Atherosclerosis, also known as atherogenesis, is a crucial risk factor for cerebral ischemia, yet how it develops remains largely unknown. It has been found, however, that angiopoietin-like protein 4 (ANGPTL4), a protein expressed in vascular endothelial cells, plays a role in the pathophysiology of atherosclerosis and may therefore be involved in ischemic stroke. ANGPTL4 activity is associated with endothelial cell integrity, inflammation, oxidative stress, and lipid metabolism. ANGPTL4 also serves as a potent inhibitor of the lipoprotein lipase, and may inhibit atherogenesis via regulating inflammatory signaling and lipid metabolism. In addition, ANGPTL4 plays a role in the regulation of oxidative stress. However, there currently exists a controversy on the role of ANGPTL4 in endothelial cells. Some studies indicate that ANGPTL4 can protect the integrity of endothelial cells, while others have shown that it can be destructive to the endothelium, thereby leading to the initiation of atherosclerosis. Thus, the effects of ANGPTL4 on development of atherosclerosis and thereby ischemic stroke, are undefined. Further research is needed to better understand ANGPTL4-mediated signaling pathways in endothelial function and to determine its potentials as therapeutic target for atherosclerosis and ischemic stroke. PMID:26033474

  12. Protecting Chemistry Inventions: The Double-Edged Sword of Being an Unpredictable Art

    PubMed Central

    2015-01-01

    Recent decisions by the highest courts in the US in regard to written description and enablement as well as parallel restrictions previously established in Europe emphasize that applicants in the fields of chemistry/pharma/life sciences should strive to include as many examples, data, and guidance about how to extrapolate from the example(s) in the description. This holds in particular whenever a broad genus and/or functional features is/are to be protected. It is important to keep in mind that these data and this guidance must be disclosed in the application at the time of filing. Data collected at a later stage can only be used to further support data and evidence already present in the application as filed. PMID:25941548

  13. Levodopa-induced plasticity: a double-edged sword in Parkinson's disease?

    PubMed Central

    Calabresi, Paolo; Ghiglieri, Veronica; Mazzocchetti, Petra; Corbelli, Ilenia; Picconi, Barbara

    2015-01-01

    The long-term replacement therapy with the dopamine (DA) precursor 3,4-dihydroxy-l-phenylalanine (L-DOPA) is a milestone in the treatment of Parkinson's disease (PD). Although this drug precursor can be metabolized into the active neurotransmitter DA throughout the brain, its therapeutic benefit is due to restoring extracellular DA levels within the dorsal striatum, which lacks endogenous DA as a consequence of the neurodegenerative process induced by the disease. In the early phases of PD, L-DOPA treatment is able to restore both long-term depression (LTD) and long-term potentiation (LTP), two major forms of corticostriatal synaptic plasticity that are altered by dopaminergic denervation. However, unlike physiological DA transmission, this therapeutic approach in the advanced phase of the disease leads to abnormal peaks of DA, non-synaptically released, which are supposed to trigger behavioural sensitization, namely L-DOPA-induced dyskinesia. This condition is characterized by a loss of synaptic depotentiation, an inability to reverse previously induced LTP. In the advanced stages of PD, L-DOPA can also induce non-motor fluctuations with cognitive dysfunction and neuropsychiatric symptoms such as compulsive behaviours and impulse control disorders. Although the mechanisms underlying the role of L-DOPA in both motor and behavioural symptoms are still incompletely understood, recent data from electrophysiological and imaging studies have increased our understanding of the function of the brain areas involved and of the mechanisms implicated in both therapeutic and adverse actions of L-DOPA in PD patients. PMID:26009763

  14. Hydrogen Peroxide and Polyamines Act as Double Edged Swords in Plant Abiotic Stress Responses

    PubMed Central

    Gupta, Kamala; Sengupta, Atreyee; Chakraborty, Mayukh; Gupta, Bhaskar

    2016-01-01

    The specific genetic changes through which plants adapt to the multitude of environmental stresses are possible because of the molecular regulations in the system. These intricate regulatory mechanisms once unveiled will surely raise interesting questions. Polyamines and hydrogen peroxide have been suggested to be important signaling molecules during biotic and abiotic stresses. Hydrogen peroxide plays a versatile role from orchestrating physiological processes to stress response. It helps to achieve acclimatization and tolerance to stress by coordinating intra-cellular and systemic signaling systems. Polyamines, on the other hand, are low molecular weight polycationic aliphatic amines, which have been implicated in various stress responses. It is quite interesting to note that both hydrogen peroxide and polyamines have a fine line of inter-relation between them since the catabolic pathways of the latter releases hydrogen peroxide. In this review we have tried to illustrate the roles and their multifaceted functions of these two important signaling molecules based on current literature. This review also highlights the fact that over accumulation of hydrogen peroxide and polyamines can be detrimental for plant cells leading to toxicity and pre-mature cell death. PMID:27672389

  15. The Double-Edged Sword of "Disaster Volunteerism": A Study of New Orleans Rebirth Movement Participants

    ERIC Educational Resources Information Center

    Heldman, Caroline; Israel-Trummel, Mackenzie

    2012-01-01

    We examine the political and personal effects of disaster volunteerism with participants of the New Orleans Rebirth Movement (NORM) using four waves of pre- and postsurveys and qualitative analysis of participant journals. Significant increases are found in internal political efficacy, desire to be active in politics, and value placed on social…

  16. Regulatory T cells in central nervous system injury: A double-edged sword

    PubMed Central

    Walsh, James T.; Zheng, Jingjing; Smirnov, Igor; Lorenz, Ulrike; Tung, Kenneth; Kipnis, Jonathan

    2014-01-01

    Previous research investigating the roles of effector (Teff) and regulatory (Treg) T cells after injury to the central nervous system (CNS) has yielded contradictory conclusions, with both protective and destructive functions being ascribed to each of these T-cell subpopulations. Here we study this dichotomy by examining how regulation of the immune system affects the response to CNS trauma. We show that in response to CNS injury, Teff and Treg subsets in the CNS-draining deep cervical lymph nodes are activated, and surgical resection of these lymph nodes results in impaired neuronal survival. Depletion of Treg, not surprisingly, induces a robust Teff response in the draining lymph nodes and is associated with impaired neuronal survival. Interestingly, however, injection of exogenous Treg cells, which limits the spontaneous beneficial immune response after CNS injury, also impairs neuronal survival. We found that no Treg accumulate at the site of CNS injury, and that changes in Treg numbers do not alter the amount of infiltration by other immune cells into the site of injury. The phenotype of macrophages at the site, however, is affected: both addition and removal of Treg negatively impact the numbers of macrophages with alternatively activated (tissue-building) phenotype. Our data demonstrate that neuronal survival after CNS injury is impaired when Treg cells are either removed or added. With this exacerbation of neurodegeneration seen with both addition or depletion of Treg, we recommend exercising extreme caution when considering the therapeutic targeting Treg cells after CNS injury, and possibly in chronic neurodegenerative conditions. PMID:25320276

  17. "A double-edged sword"? The professionalisation of counselling in the United Kingdom.

    PubMed

    Bondi, Liz

    2004-12-01

    Drawing on interviews with practitioners involved in voluntary-sector counselling in Scotland, this paper explores contradictions associated with the professionalisation of counselling in the UK. Five meanings of the term "professional" are identified. Those in support of professionalisation aim to bring these different meanings into close alignment, whereas those with reservations point to tensions between at least some of these meanings and core values of counselling. In conclusion the paper reflects on the possibility that counselling might contribute to a reshaping of what it means to be a profession.

  18. The Double-Edged Sword of Goal Engagement: Consequences of Goal Pursuit in Bipolar Disorder

    PubMed Central

    Johnson, Sheri L.; Fulford, Daniel; Carver, Charles S.

    2012-01-01

    A series of studies suggest that bipolar disorder is related to high sensitivity to incentives and that incentive sensitivity (or sensitivity of the approach system) can predict the course of mania. Incentive sensitivity in bipolar disorder seems to be related to two processes: a tendency to invest in difficult-to-attain goals and an over-reactivity to cues of goal progress versus thwarting. Both of those processes appear relevant to symptom generation. Hence, bipolar disorder seems related to a greater emphasis on reaching goals and also a problematic reactivity to reaching those highly desired goals. We suggest directions for treatment development focused on these issues in goal regulation. PMID:22610999

  19. Pattern Recognition Receptors and Cytokines in Mycobacterium tuberculosis Infection—The Double-Edged Sword?

    PubMed Central

    Hossain, Md. Murad; Norazmi, Mohd-Nor

    2013-01-01

    Tuberculosis, an infectious disease caused by Mycobacterium tuberculosis (Mtb), remains a major cause of human death worldwide. Innate immunity provides host defense against Mtb. Phagocytosis, characterized by recognition of Mtb by macrophages and dendritic cells (DCs), is the first step of the innate immune defense mechanism. The recognition of Mtb is mediated by pattern recognition receptors (PRRs), expressed on innate immune cells, including toll-like receptors (TLRs), complement receptors, nucleotide oligomerization domain like receptors, dendritic cell-specific intercellular adhesion molecule grabbing nonintegrin (DC-SIGN), mannose receptors, CD14 receptors, scavenger receptors, and FCγ receptors. Interaction of mycobacterial ligands with PRRs leads macrophages and DCs to secrete selected cytokines, which in turn induce interferon-γ- (IFNγ-) dominated immunity. IFNγ and other cytokines like tumor necrosis factor-α (TNFα) regulate mycobacterial growth, granuloma formation, and initiation of the adaptive immune response to Mtb and finally provide protection to the host. However, Mtb can evade destruction by antimicrobial defense mechanisms of the innate immune system as some components of the system may promote survival of the bacteria in these cells and facilitate pathogenesis. Thus, although innate immunity components generally play a protective role against Mtb, they may also facilitate Mtb survival. The involvement of selected PRRs and cytokines on these seemingly contradictory roles is discussed. PMID:24350246

  20. Detail of double pole utility tower at the edge of ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail of double pole utility tower at the edge of the mesa. National Old Trails Road right-of-way crosses in foreground over a dry laid basaltic rock retaining wall. View south. - La Bajada Historic Trails and Roads, Approximately 1 mile East/Northeast of intersection of State Highway 16 and Indian Service Road 841, La Bajada, Santa Fe County, NM

  1. Immune Mechanism: A ‘Double-Edged Sword’

    PubMed Central

    Musa, Mustaffa

    2013-01-01

    Immunology has now developed into an independent discipline in medicine which covers not only germ infection which is related to immunity solely but also covers a lot of non-infectious diseases such as autoimmune disease, allergies, and others. Therefore, “The Immune Mechanism: “A Double-Edged Sword” means that the immune mechanism (consisted of antibody mediated mechanism and T cell mediated mechanism), just like one edge playing the role of giving benefit (immunity) as it destroys the agent of infection, and another one can be detrimental as it will cause tissue/cell damages and then give rise to immune diseases (immunopathology). Now, the prevalence of these immune diseases is on the rise and has become a new challenge to our country towards developed country in 2020. Therefore, we have to make ample preparation (laboratory facilities/services, main power, and research) from now on in order to face the problems and challenges. PMID:23966827

  2. Double-Edge Molecular Technique for Doppler Lidar Wind Measurement

    NASA Technical Reports Server (NTRS)

    Flesia, Cristina; Korb, C. Laurence

    1998-01-01

    The double-edge lidar technique for measuring the wind using molecular backscatter is described. Two high spectral resolution edge filters are located in the wings of the Rayleigh-Brillouin profile. This doubles the signal change per unit Doppler shift, the sensitivity, and gives nearly a factor of two improvement in measurement accuracy. The use of a crossover region is described where the sensitivity of a molecular and aerosol-based measurement are equal. This desensitizes the molecular measurement to the effects of aerosol scattering over a frequency range of +/- 100 m/s. We give methods for correcting for short-term frequency jitter and drift using a laser reference frequency measurement and methods for long-term frequency correction using a servo control system. The effects of Rayleigh-Brillouin scattering on the measurement are shown to be significant and are included in the analysis. Simulations for a conical scanning satellite-based lidar at 355 nm show an accuracy of 2-3 m/s for altitudes of 2 to 15 km for a 1 km vertical resolution, a satellite altitude of 400 km and a 200 km x 200 km spatial resolution. Results of ground based wind measurements are presented.

  3. Role of plant growth regulators as chemical signals in plant-microbe interactions: a double edged sword.

    PubMed

    Spence, Carla; Bais, Harsh

    2015-10-01

    Growth regulators act not only as chemicals that modulate plant growth but they also act as signal molecules under various biotic and abiotic stresses. Of all growth regulators, abscisic acid (ABA) is long known for its role in modulating plants response against both biotic and abiotic stress. Although the genetic information for ABA biosynthesis in plants is well documented, the knowledge about ABA biosynthesis in other organisms is still in its infancy. It is known that various microbes including bacteria produce and secrete ABA, but the overall functional significance of why ABA is synthesized by microbes is not known. Here we discuss the functional involvement of ABA biosynthesis by a pathogenic fungus. Furthermore, we propose that ABA biosynthesis in plant pathogenic fungi could be targeted for novel fungicidal discovery.

  4. Massing in high shear wet granulation can simultaneously improve powder flow and deteriorate powder compaction: a double-edged sword.

    PubMed

    Shi, Limin; Feng, Yushi; Sun, Changquan Calvin

    2011-05-18

    The influence of massing during high shear wet granulation (HSWG) process on granule properties and performance was investigated using microcrystalline cellulose (MCC). Massing time varied from 0 to 40 min while other factors were fixed. Granule physical properties, including morphology, size, porosity, and specific surface area (SSA), were characterized. Changes in powder properties were profound in the first 10 min of massing but negligible beyond 10 min. With 10 min of massing, granule tabletability decreased by 75% while flowability increased by 75%. The significantly deteriorated tabletability and improved flowability resulted from dramatic changes in granule morphology, porosity, and SSA. The results confirm that massing time is a key process parameter in HSWG, and it must be carefully evaluated and controlled during process development, scale up, and manufacturing.

  5. Unreacted PbI2 as a Double-Edged Sword for Enhancing the Performance of Perovskite Solar Cells.

    PubMed

    Jacobsson, T Jesper; Correa-Baena, Juan-Pablo; Halvani Anaraki, Elham; Philippe, Bertrand; Stranks, Samuel D; Bouduban, Marine E F; Tress, Wolfgang; Schenk, Kurt; Teuscher, Joël; Moser, Jacques-E; Rensmo, Håkan; Hagfeldt, Anders

    2016-08-17

    Lead halide perovskites have over the past few years attracted considerable interest as photo absorbers in PV applications with record efficiencies now reaching 22%. It has recently been found that not only the composition but also the precise stoichiometry is important for the device performance. Recent reports have, for example, demonstrated small amount of PbI2 in the perovskite films to be beneficial for the overall performance of both the standard perovskite, CH3NH3PbI3, as well as for the mixed perovskites (CH3NH3)x(CH(NH2)2)(1-x)PbBryI(3-y). In this work a broad range of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photo electron spectroscopy (PES), transient absorption spectroscopy (TAS), UV-vis, electroluminescence (EL), photoluminescence (PL), and confocal PL mapping have been used to further understand the importance of remnant PbI2 in perovskite solar cells. Our best devices were over 18% efficient, and had in line with previous results a small amount of excess PbI2. For the PbI2-deficient samples, the photocurrent dropped, which could be attributed to accumulation of organic species at the grain boundaries, low charge carrier mobility, and decreased electron injection into the TiO2. The PbI2-deficient compositions did, however, also have advantages. The record Voc was as high as 1.20 V and was found in PbI2-deficient samples. This was correlated with high crystal quality, longer charge carrier lifetimes, and high PL yields and was rationalized as a consequence of the dynamics of the perovskite formation. We further found the ion migration to be obstructed in the PbI2-deficient samples, which decreased the JV hysteresis and increased the photostability. PbI2-deficient synthesis conditions can thus be used to deposit perovskites with excellent crystal quality but with the downside of grain boundaries enriched in organic species, which act as a barrier toward current transport. Exploring ways to tune the synthesis conditions to give the high crystal quality obtained under PbI2-poor condition while maintaining the favorable grain boundary characteristics obtained under PbI2-rich conditions would thus be a strategy toward more efficiency devices. PMID:27437906

  6. Levodopa is a Double-Edged Sword for Balance and Gait in People with Parkinson’s Disease

    PubMed Central

    Curtze, Carolin; Nutt, John G.; Carlson-Kuhta, Patricia; Mancini, Martina; Horak, Fay B.

    2016-01-01

    Background The effects of levodopa on balance and gait function in people with Parkinson’s disease (PD) is controversial. This study compared the relative responsiveness to levodopa on six domains of balance and gait: postural sway in stance, gait pace, dynamic stability, gait initiation, arm swing, and turning in people with mild and severe PD, with and without dyskinesia. Methods We studied 104 subjects with idiopathic PD (Hohen & Yahr II (n=52) and III-IV (n=52)) and 64 age-matched controls. Subjects performed a mobility task in the practical OFF state and ON levodopa: standing quietly for 30 seconds, initiating gait, walking 7 meters, and turning 180 degrees. Thirty-four measures of mobility were computed from inertial sensors. Standardized response means were used to determine the relative responsiveness to levodopa. Results The largest improvements with levodopa were found for arm swing and pace-related gait measures. Gait dynamic stability was unaffected by PD and not responsive to levodopa. Levodopa reduced turning duration, but only in subjects with severe PD. In contrast to gait, postural sway in quiet standing increased with levodopa, especially in the more severely affected subjects. The increase in postural sway, as well as decrease in turning duration and exaggerated arm swing with levodopa was observed only for subjects with dyskinesia at the time of testing. Conclusions The observed spectrum of levodopa responsiveness in balance and gait measures suggests multiple neural circuits control balance and gait. Many of the negative effects of levodopa may be directly or indirectly caused by dyskinesia. PMID:26095928

  7. Von Willebrand factor in patients on mechanical circulatory support – a double-edged sword between bleeding and thrombosis

    PubMed Central

    Kaczmarski, Jacek; Pacholewicz, Jerzy; Zakliczynski, Michal; Gasior, Mariusz; Zembala, Marian

    2015-01-01

    Mechanical circulatory support (MCS) is an umbrella term describing the various technologies used in both short- and long-term management of patients with either end-stage chronic heart failure (HF) or acute HF. Most often, MCS has emerged as a bridge to transplantation, but more recently it is also used as a destination therapy. Mechanical circulatory support includes left ventricular assist device (LVAD) or bi-ventricular assist device (Bi-VAD). Currently, 2- to 3-year survival in carefully selected patients is much better than with medical therapy. However, MCS therapy is hampered by sometimes life-threatening complications including bleeding and device thrombosis. Von Willebrand factor (vWF) has two major functions in haemostasis. First, it plays a crucial role in platelet-subendothelium adhesion and platelet-platelet interactions (aggregation). Second, it is the carrier of factor VIII (FVIII) in plasma. Von Willebrand factor prolongs FVIII half-time by protecting it from proteolytic degradation. It delivers FVIII to the site of vascular injury thus enhancing haemostatic process. On one hand, high plasma levels of vWF have been associated with an increased risk of thrombosis. On the other, defects or deficiencies of vWF underlie the inherited von Willebrand disease or acquired von Willebrand syndrome. Here we review the pathophysiology of thrombosis and bleeding associated with vWF. PMID:26702279

  8. Work hours and work-family conflict: the double-edged sword of involvement in work and family.

    PubMed

    Matthews, Russell A; Swody, Cathleen A; Barnes-Farrell, Janet L

    2012-08-01

    In this study, we examine the role of work hours in a model that incorporates involvement in both work and family with experiences of work-family conflict and subjective well-being. Self-report data were collected from 383 full-time employees and analysed using structural equation modelling techniques. Results demonstrate that role salience was positively related to behavioural involvement with work and with family. In turn, behavioural family involvement was negatively related to work hours and family-to-work conflict, while behavioural work involvement was positively related to work hours. Behavioural family involvement was also positively related to life satisfaction. Finally, both family-to-work conflict and end-of-workday strain were negatively related to life satisfaction. Our results provide insight into unexpected problems that might arise when employees place overly high importance on work and work long hours. This study serves as a foundation for researchers to examine the interplay of time spent with work and family with other aspects of the work-family interface.

  9. The Regulatory Environment in Long Day Care: A "Double-Edged Sword" for Early Childhood Professional Practice

    ERIC Educational Resources Information Center

    Fenech, Marianne; Sumsion, Jennifer; Goodfellow, Joy

    2006-01-01

    While early childhood professionals in NSW are accountable to a substantial collection of regulatory requirements, little research has explored the outcomes of this regulatory environment, both intended and otherwise. This paper presents findings from a NSW study and shows how early childhood professionals working in long day care centres perceive…

  10. Can We Afford These Affordances? GarageBand and the Double-Edged Sword of the Digital Audio Workstation

    ERIC Educational Resources Information Center

    Bell, Adam Patrick

    2015-01-01

    The proliferation of computers, tablets, and smartphones has resulted in digital audio workstations (DAWs) such as GarageBand in being some of the most widely distributed musical instruments. Positing that software designers are dictating the music education of DAW-dependent music-makers, I examine the fallacy that music-making applications such…

  11. The nociceptive and anti-nociceptive effects of bee venom injection and therapy: A double-edged sword

    PubMed Central

    Chen, Jun; Lariviere, William R.

    2010-01-01

    Bee venom injection as a therapy, like many other complementary and alternative medicine approaches, has been used for thousands of years to attempt to alleviate a range of diseases including arthritis. More recently, additional theraupeutic goals have been added to the list of diseases making this a critical time to evaluate the evidence for the beneficial and adverse effects of bee venom injection. Although reports of pain reduction (analgesic and antinociceptive) and anti-inflammatory effects of bee venom injection are accumulating in the literature, it is common knowledge that bee venom stings are painful and produce inflammation. In addition, a significant number of studies have been performed in the past decade highlighting that injection of bee venom and components of bee venom produce significant signs of pain or nociception, inflammation and many effects at multiple levels of immediate, acute and prolonged pain processes. This report reviews the extensive new data regarding the deleterious effects of bee venom injection in people and animals, our current understanding of the responsible underlying mechanisms and critical venom components, and provides a critical evaluation of reports of the beneficial effects of bee venom injection in people and animals and the proposed underlying mechanisms. Although further studies are required to make firm conclusions, therapeutic bee venom injection may be beneficial for some patients, but may also be harmful. This report highlights key patterns of results, critical shortcomings, and essential areas requiring further study. PMID:20558236

  12. Microtubule-Targeting Agents Enter the Central Nervous System (CNS): Double-edged Swords for Treating CNS Injury and Disease

    PubMed Central

    2014-01-01

    Microtubules have been among the most successful targets in anticancer therapy and a large number of microtubule-targeting agents (MTAs) are in various stages of clinical development for the treatment of several malignancies. Given that injury and diseases in the central nervous system (CNS) are accompanied by acute or chronic disruption of the structural integrity of neurons and that microtubules provide structural support for the nervous system at cellular and intracellular levels, microtubules are emerging as potential therapeutic targets for treating CNS disorders. It has been postulated that exogenous application of MTAs might prevent the breakdown or degradation of microtubules after injury or during neurodegeneration, which will thereby aid in preserving the structural integrity and function of the nervous system. Here we review recent evidence that supports this notion and also discuss potential risks of targeting microtubules as a therapy for treating nerve injury and neurodegenerative diseases. PMID:25558415

  13. TLR ligand suppression or enhancement of Treg cells? A double-edged sword in immunity to tumours.

    PubMed

    Conroy, H; Marshall, N A; Mills, K H G

    2008-01-01

    Toll-like receptor (TLR) agonists are potent activators of innate immune responses, activating dendritic cell (DC) maturation and inflammatory cytokine secretion by innate immune cells and as a consequence they promote adaptive immune response when coadministered with foreign antigens. There is also some evidence from mouse models that TLR ligands can help to break tolerance to self-antigens and promote immune responses to tumour antigens. Therefore, they have been exploited as adjuvants for tumour vaccines or as immunotherapeutics against cancer. Clinical evaluation of TLR agonists has resulted in a licensed immunotherapeutic for basal cell carcinoma, but there have also been disappointing results from clinical trials, with one pharmaceutical company recently halting its clinical programme. A major obstacle to the development of any active immunotherapeutic approach to cancer is the immunosuppressive environment of the growing tumour, including the induction of tolerogenic DCs and regulatory T (Treg) cells, which suppress the development of protective effector T-cell responses. This can be compounded by the use of TLR ligands as immunotherapeutics. A problem with TLR agonists that has not been fully appreciated is that they can generate suppressive as well as inflammatory responses in innate immune cells and can promote the induction of regulatory as well as effector T cells. This is part of a normal mechanism for limiting collateral damage during infection or sterile inflammation, but can constrain their ability to induce protective antitumour immunity, especially in the immune suppressed environment of the tumour. Alternatively, manipulating the TLR-activated innate immune responses to selectively blocking immunosuppressive arm, as well as that induced by the tumour, may hold the key to enhancing their efficacy as tumour immunotherapeutics and as adjuvants for cancer vaccines.

  14. Unreacted PbI2 as a Double-Edged Sword for Enhancing the Performance of Perovskite Solar Cells.

    PubMed

    Jacobsson, T Jesper; Correa-Baena, Juan-Pablo; Halvani Anaraki, Elham; Philippe, Bertrand; Stranks, Samuel D; Bouduban, Marine E F; Tress, Wolfgang; Schenk, Kurt; Teuscher, Joël; Moser, Jacques-E; Rensmo, Håkan; Hagfeldt, Anders

    2016-08-17

    Lead halide perovskites have over the past few years attracted considerable interest as photo absorbers in PV applications with record efficiencies now reaching 22%. It has recently been found that not only the composition but also the precise stoichiometry is important for the device performance. Recent reports have, for example, demonstrated small amount of PbI2 in the perovskite films to be beneficial for the overall performance of both the standard perovskite, CH3NH3PbI3, as well as for the mixed perovskites (CH3NH3)x(CH(NH2)2)(1-x)PbBryI(3-y). In this work a broad range of characterization techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photo electron spectroscopy (PES), transient absorption spectroscopy (TAS), UV-vis, electroluminescence (EL), photoluminescence (PL), and confocal PL mapping have been used to further understand the importance of remnant PbI2 in perovskite solar cells. Our best devices were over 18% efficient, and had in line with previous results a small amount of excess PbI2. For the PbI2-deficient samples, the photocurrent dropped, which could be attributed to accumulation of organic species at the grain boundaries, low charge carrier mobility, and decreased electron injection into the TiO2. The PbI2-deficient compositions did, however, also have advantages. The record Voc was as high as 1.20 V and was found in PbI2-deficient samples. This was correlated with high crystal quality, longer charge carrier lifetimes, and high PL yields and was rationalized as a consequence of the dynamics of the perovskite formation. We further found the ion migration to be obstructed in the PbI2-deficient samples, which decreased the JV hysteresis and increased the photostability. PbI2-deficient synthesis conditions can thus be used to deposit perovskites with excellent crystal quality but with the downside of grain boundaries enriched in organic species, which act as a barrier toward current transport. Exploring ways to tune the synthesis conditions to give the high crystal quality obtained under PbI2-poor condition while maintaining the favorable grain boundary characteristics obtained under PbI2-rich conditions would thus be a strategy toward more efficiency devices.

  15. The Role of the Immune Response in Chlamydia trachomatis Infection of the Male Genital Tract: A Double-Edged Sword

    PubMed Central

    Redgrove, Kate A.; McLaughlin, Eileen A.

    2014-01-01

    Chlamydia trachomatis (CT) is the most prevalent bacterial sexually transmitted infection in the world, with more than 100 million cases reported annually. While there have been extensive studies into the adverse effects that CT infection has on the female genital tract, and on the subsequent ability of these women to conceive, studies into the consequences on male fertility have been limited and controversial. This is in part due to the asymptomatic nature of the infection, where it is estimated that 50% of men with Chlamydia fail to show any symptoms. It is accepted, however, that acute and/or persistent CT infection is the causative agent for conditions such as urethritis, epididymitis, epididymo-orchitis, and potentially prostatitis. As with most infections, the immune system plays a fundamental role in the body’s attempts to eradicate the infection. The first and most important immune response to Chlamydia infection is a local one, whereby immune cells such as leukocytes are recruited to the site of infections, and subsequently secrete pro-inflammatory cytokines and chemokines such as interferon gamma. Immune cells also work to initiate and potentiate chronic inflammation through the production of reactive oxygen species (ROS), and the release of molecules with degradative properties including defensins, elastase, collagenase, cathespins, and lysozyme. This long-term inflammation can lead to cell proliferation (a possible precursor to cancer), tissue remodeling, and scarring, as well as being linked to the onset of autoimmune responses in genetically disposed individuals. This review will focus on the ability of the immune system to recognize and clear acute and persistent chlamydial infections in the male genital tract, and on the paradoxical damage that chronic inflammation resulting from the infection can cause on the reproductive health of the individual. PMID:25386180

  16. Cooperative Learning--A Double-Edged Sword: A Cooperative Learning Model for Use with Diverse Student Groups

    ERIC Educational Resources Information Center

    Baker, Trish; Clark, Jill

    2010-01-01

    Although very little research has been done on cooperative learning (CL) in New Zealand, international research is positive about the educational benefits of working in culturally diverse groups. This paper presents the findings of a research project examining New Zealand experiences with CL in multicultural groups. Data were collected via surveys…

  17. A double-edged sword: the role of VEGF in wound repair and chemoattraction of opportunist pathogens.

    PubMed

    Birkenhauer, Eric; Neethirajan, Suresh

    2015-01-01

    Wound healing is a complex process essential to repairing damaged tissues and preventing infection. Skin is the first line of defense, a chief physical barrier to microbe entry. Wound healing is a physical rebuilding process, but at the same time it is an inflammatory event. In turn, molecules for wound repair are secreted by fibroblasts and others present at the wound site. Vascular endothelial growth factor (VEGF) is a critical cytokine that exhibits chemoattractant properties, recruiting other immune cells to the site. Although generally beneficial, VEGF may also act as a chemoattractant for invading microorganisms, such as Pseudomonas aeruginosa. P. aeruginosa is problematic during wound infection due to its propensity to form biofilms and exhibit heightened antimicrobial resistance. Here, we explored the influence of VEGF gradients (in a microfluidic device wound model) on the motility and chemotactic properties of P. aeruginosa. At lower concentrations, VEGF had little effect on motility, but as the maximal concentration within the gradient increased, P. aeruginosa cells exhibited directed movement along the gradient. Our data provide evidence that while beneficial, VEGF, in excess, may aid colonization by P. aeruginosa. This highlights the necessity for the efficient resolution of inflammation. Understanding the dynamics of wound colonization may lead to new/enhanced therapeutics to hasten recovery.

  18. A Double-Edged Sword: Lactation Consultants' Perceptions of the Impact of Breast Pumps on the Practice of Breastfeeding

    PubMed Central

    Buckley, Kathleen M

    2009-01-01

    This qualitative descriptive study examined the beliefs and experiences of 12 lactation consultants regarding the impact of breast pumps on breastfeeding practices. Interview topics on breast pumps included types and patterns of use, mothers' experiences, and advantages and risks. The lactation consultants reported an increase in the use of breast pumps due to improved marketing, a change in society's view of pumps as a necessity rather than a luxury, and the impact of birthing technology. Reasons given for this increased use were mothers' need to have greater control over the breastfeeding process and to quantify the amount of breastmilk. Concerns were expressed regarding an overdependency on breastfeeding technology by some lactation consultants and mothers. PMID:20190850

  19. A double-edged sword: CRISPR-Cas9 is emerging as a revolutionary technique for genome editing.

    PubMed

    Li, Chun-Xiao; Qian, Hai-Li

    2015-01-01

    In May 2015, Professor Xiao Yang authored a review on the development of CRISPR-Cas9 techniques in the journal of Military Medical Research. This review provided a valuable overview of this major scientific advance. It has been four years since the first publication of the CRISPR-Cas9 breakthrough (Science. 2012; 337: 816-21). The use of this technique has expanded into various scientific areas and is being developed into a systematic technical platform that may contribute to many bioengineering fields involving DNA sequence editing.

  20. Gendered Uncertainty and Variation in Physicians' Decisions for Coronary Heart Disease: The Double-Edged Sword of "Atypical Symptoms"

    ERIC Educational Resources Information Center

    Welch, Lisa C.; Lutfey, Karen E.; Gerstenberger, Eric; Grace, Matthew

    2012-01-01

    Nonmedical factors and diagnostic certainty contribute to variation in clinical decision making, but the process by which this occurs remains unclear. We examine how physicians' interpretations of patient sex-gender affect diagnostic certainty and, in turn, decision making for coronary heart disease. Data are from a factorial experiment of 256…

  1. Edge effects in vertically-oriented graphene based electric double-layer capacitors

    NASA Astrophysics Data System (ADS)

    Yang, Huachao; Yang, Jinyuan; Bo, Zheng; Zhang, Shuo; Yan, Jianhua; Cen, Kefa

    2016-08-01

    Vertically-oriented graphenes (VGs) have been demonstrated as a promising active material for electric double-layer capacitors (EDLCs), partially due to their edge-enriched structure. In this work, the 'edge effects', i.e., edges as the promoters of high capacitance, in VG based EDLCs are investigated with experimental research and numerical simulations. VGs with diverse heights (i.e., edge-to-basal ratios) and edge densities are prepared with varying the plasma-enabled growth time and employing different plasma sources. Electrochemical measurements show that the edges play a predominant role on the charge storage behavior of VGs. A simulation is further conducted to unveil the roles of the edges on the separation and adsorption of ions within VG channels. The initial charge distribution of a VG plane is obtained with density functional theory (DFT) calculations, which is subsequently applied to a molecular dynamics (MD) simulation system to gain the insights into the microscope EDLC structures. Compared with the basal planes, the edges present higher initial charge density (by 4.2 times), higher ion packing density (by 2.6 times), closer ion packing location (by 0.8 Å), and larger ion separation degree (by 14%). The as-obtained findings will be instructive in designing the morphology and structure of VGs for enhanced capacitive performances.

  2. Edge effects in vertically-oriented graphene based electric double-layer capacitors

    NASA Astrophysics Data System (ADS)

    Yang, Huachao; Yang, Jinyuan; Bo, Zheng; Zhang, Shuo; Yan, Jianhua; Cen, Kefa

    2016-08-01

    Vertically-oriented graphenes (VGs) have been demonstrated as a promising active material for electric double-layer capacitors (EDLCs), partially due to their edge-enriched structure. In this work, the 'edge effects', i.e., edges as the promoters of high capacitance, in VG based EDLCs are investigated with experimental research and numerical simulations. VGs with diverse heights (i.e., edge-to-basal ratios) and edge densities are prepared with varying the plasma-enabled growth time and employing different plasma sources. Electrochemical measurements show that the edges play a predominant role on the charge storage behavior of VGs. A simulation is further conducted to unveil the roles of the edges on the separation and adsorption of ions within VG channels. The initial charge distribution of a VG plane is obtained with density functional theory (DFT) calculations, which is subsequently applied to a molecular dynamics (MD) simulation system to gain the insights into the microscope EDLC structures. Compared with the basal planes, the edges present higher initial charge density (by 4.2 times), higher ion packing density (by 2.6 times), closer ion packing location (by 0.8 Å), and larger ion separation degree (by 14%). The as-obtained findings will be instructive in designing the morphology and structure of VGs for enhanced capacitive performances.

  3. Theory of the double-edge technique for Doppler lidar wind measurement.

    PubMed

    Korb, C L; Gentry, B M; Li, S X; Flesia, C

    1998-05-20

    The theory of the double-edge technique is described by a generalized formulation that substantially extends the capabilities of the edge technique. It uses two edges with opposite slopes located about the laser frequency. This doubles the signal change for a given Doppler shift and yields a factor of 1.6 improvement in the measurement accuracy compared with the single-edge technique. Use of two high-resolution edge filters reduces the effects of Rayleigh scattering on the measurement by as much as an order of magnitude and allows the signal-to-noise ratio to be substantially improved in areas of low aerosol backscatter. We describe a method that allows the Rayleigh and aerosol components of the signal to be independently determined. The effects of Rayleigh scattering are then subtracted from the measurement, and we show that the correction process does not significantly increase the measurement noise for Rayleigh-to-aerosol ratios as high as 10. We show that for small Doppler shifts a measurement accuracy of 0.4 m/s can be obtained for 5000 detected photons, 1.2 m/s for 1000 detected photons, and 3.7 m/s for 50 detected photons for a Rayleigh-to-aerosol ratio of 5. Methods for increasing the dynamic range to more than +/-100 m/s are given. PMID:18273256

  4. Doppler Lidar Measurements of Tropospheric Wind Profiles Using the Aerosol Double Edge Technique

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce M.; Li, Steven X.; Mathur, Savyasachee; Korb, C. Laurence; Chen, Huailin

    2000-01-01

    The development of a ground based direct detection Doppler lidar based on the recently described aerosol double edge technique is reported. A pulsed, injection seeded Nd:YAG laser operating at 1064 nm is used to make range resolved measurements of atmospheric winds in the free troposphere. The wind measurements are determined by measuring the Doppler shift of the laser signal backscattered from atmospheric aerosols. The lidar instrument and double edge method are described and initial tropospheric wind profile measurements are presented. Wind profiles are reported for both day and night operation. The measurements extend to altitudes as high as 14 km and are compared to rawinsonde wind profile data from Dulles airport in Virginia. Vertical resolution of the lidar measurements is 330 m and the rms precision of the measurements is a low as 0.6 m/s.

  5. A survey of the Saturnian ring edges: Results from double star occultations

    NASA Astrophysics Data System (ADS)

    Albers, Nicole

    2015-11-01

    The Cassini Ultraviolet Imaging Spectrograph (UVIS) High Speed Photometer (HSP) has recorded more than 150 stellar occultations of Saturn's rings. About one third are observations involving double stars, where each star contributes its own, independent light curve. For each light curve, its footprint, as projected into the ring plane and depending on observation geometry, samples a different region in the ring. Here, we focus on ring edges. Each occultation then yields two independent edge measurements at two different times and longitudes. We infer relative changes in optical depth and radial position over an azimuthal distance as short as 20 meters. These relative measurements require neither photometric nor geometric calibration and inform on the small-scale variability of structure/features with relative resolutions an order of magnitude higher than typically achieved.The Encke and Keeler gap edges as well as the outer B and A ring edges show radial excursions on the order of tens of meters. These radial variations are, in comparison to the common multi-mode analysis of edge kinematics, high-frequency components with corresponding m numbers of m>5000000. We note that spatial dimensions inferred here are 10-100 times smaller than those of features Region A and B at the B ring edge or "Peggy"-type objects at the A ring edge, and are comparable to individual self-gravity wakes or clumps/particles. The Titan and Huygens ringlets inner and outer edges, on the other hand, are, in comparison, highly regular and smooth with radial variations of only a few meters. Nevertheless they show changes in normal optical depth on the order of 0.4, well above the expected margin due to intrinsic stellar variability. We also identified three features in the C ring that show little radial variability and can thus be considered smooth. Interestingly, this irregularity or raggedness of the edges - manifestation of intrinsic small-scale structure of the ring - is stronger with

  6. The Sword of Orion

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] [figure removed for brevity, see original site] AnimationFigure 1

    This infrared image from NASA's Spitzer Space Telescope shows the Orion nebula, our closest massive star-making factory, 1,450 light-years from Earth. The nebula is close enough to appear to the naked eye as a fuzzy star in the sword of the popular hunter constellation.

    The nebula itself is located on the lower half of the image, surrounded by a ring of dust. It formed in a cold cloud of gas and dust and contains about 1,000 young stars. These stars illuminate the cloud, creating the beautiful nebulosity, or swirls of material, seen here in infrared.

    In the center of the nebula (bottom inset of figure 1) are four monstrously massive stars, up to 100,000 times as luminous as our sun, called the Trapezium (tiny yellow smudge to the lower left of green splotches. Radiation and winds from these stars are blasting gas and dust away, excavating a cavity walled in by the large ring of dust.

    Behind the Trapezium, still buried deeply in the cloud, a second generation of massive stars is forming (in the area with green splotches). The speckled green fuzz in this bright region is created when bullets of gas shoot out from the juvenile stars and ram into the surrounding cloud.

    Above this region of intense activity are networks of cold material that appear as dark veins against the pinkish nebulosity (upper inset pf figure 1). These dark veins contain embryonic stars. Some of the natal stars illuminate the cloud, creating small, aqua-colored wisps. In addition, jets of gas from the stars ram into the cloud, resulting in the green horseshoe-shaped globs.

    Spitzer surveyed a significant swath of the Orion constellation, beyond what is highlighted in this image. Within that region, called the Orion cloud complex, the telescope found 2,300 stars circled by disks of planet-forming dust and 200 stellar embryos too young to have developed

  7. Theory of the double-edge molecular technique for Doppler lidar wind measurement.

    PubMed

    Flesia, C; Korb, C L

    1999-01-20

    The theory of the double-edge lidar technique for measuring the wind with molecular backscatter is described. Two high-spectral-resolution edge filters are located in the wings of the Rayleigh-Brillouin profile. This doubles the signal change per unit Doppler shift, the sensitivity, and improves measurement accuracy relative to the single-edge technique by nearly a factor of 2. The use of a crossover region where the sensitivity of a molecular- and an aerosol-based measurement is equal is described. Use of this region desensitizes the molecular measurement to the effects of aerosol scattering over a velocity range of +/-100 m/s. We give methods for correcting short-term, shot-to-shot, frequency jitter and drift with a laser reference frequency measurement and methods for long-term frequency correction with a servo control system. The effects of Rayleigh-Brillouin scattering on the measurement are shown to be significant and are included in the analysis. Simulations for a conical scanning satellite-based lidar at 355 nm show an accuracy of 2-3 m/s for altitudes of 2-15 km for a 1-km vertical resolution, a satellite altitude of 400 km, and a 200 km x 200 km spatial resolution. PMID:18305631

  8. Empirical Determination of Optimal Parameters for Sodium Double-Edge Magneto-Optic Filters

    NASA Astrophysics Data System (ADS)

    Barry, Ian F.; Huang, Wentao; Smith, John A.; Chu, Xinzhao

    2016-06-01

    A method is proposed for determining the optimal temperature and magnetic field strength used to condition a sodium vapor cell for use in a sodium Double-Edge Magneto-Optic Filter (Na-DEMOF). The desirable characteristics of these filters are first defined and then analyzed over a range of temperatures and magnetic field strengths, using an IDL Faraday filter simulation adapted for the Na-DEMOF. This simulation is then compared to real behavior of a Na-DEMOF constructed for use with the Chu Research Group's STAR Na Doppler resonance-fluorescence lidar for lower atmospheric observations.

  9. Mutations for Worse or Better: Low-Fidelity DNA Synthesis by SOS DNA Polymerase V Is a Tightly Regulated Double-Edged Sword.

    PubMed

    Jaszczur, Malgorzata; Bertram, Jeffrey G; Robinson, Andrew; van Oijen, Antoine M; Woodgate, Roger; Cox, Michael M; Goodman, Myron F

    2016-04-26

    1953, the year of Watson and Crick, bore witness to a less acclaimed yet highly influential discovery. Jean Weigle demonstrated that upon infection of Escherichia coli, λ phage deactivated by UV radiation, and thus unable to form progeny, could be reactivated by irradiation of the bacterial host. Evelyn Witkin and Miroslav Radman later revealed the presence of the SOS regulon. The more than 40 regulon genes are repressed by LexA protein and induced by the coproteolytic cleavage of LexA, catalyzed by RecA protein bound to single-stranded DNA, the RecA* nucleoprotein filament. Several SOS-induced proteins are engaged in repairing both cellular and extracellular damaged DNA. There's no "free lunch", however, because error-free repair is accompanied by error-prone translesion DNA synthesis (TLS), involving E. coli DNA polymerase V (UmuD'2C) and RecA*. This review describes the biochemical mechanisms of pol V-mediated TLS. pol V is active only as a mutasomal complex, pol V Mut = UmuD'2C-RecA-ATP. RecA* donates a single RecA subunit to pol V. We highlight three recent insights. (1) pol V Mut has an intrinsic DNA-dependent ATPase activity that governs polymerase binding and dissociation from DNA. (2) Active and inactive states of pol V Mut are determined at least in part by the distinct interactions between RecA and UmuC. (3) pol V is activated by RecA*, not at a blocked replisome, but at the inner cell membrane.

  10. The Double Edged Sword: A Brief Comparison of IT and Internet Development in Malaysia and Some Few Neighboring Countries in the Context of Digital Divide.

    ERIC Educational Resources Information Center

    Samad, Ramli Abdul

    This paper shows that, although a digital divide exists between developed and developing countries, the development of information technology (IT) and the Internet has had a profound political, social, and economic impact on developing countries. IT and the Internet revolution are shaping the world into new polarized entities due to the uneven…

  11. The double-edged sword of long non-coding RNA: The role of human brain-specific BC200 RNA in translational control, neurodegenerative diseases, and cancer.

    PubMed

    Sosińska, Patrycja; Mikuła-Pietrasik, Justyna; Książek, Krzysztof

    2015-01-01

    The complexity of eukaryotic organisms involves the regulation of gene expression through DNA-protein, RNA-DNA, RNA-RNA, and RNA-protein interactions. The role of RNA molecules in the regulation of genes in higher species has become even more evident with the discovery that about 97% of transcription products are represented by non-protein coding RNAs (ncRNAs) including short ncRNAs and long ncRNAs (lncRNAs). In addition to the well-characterized role of ncRNAs in different physiological cellular processes, numerous studies have also indicated the crucial roles of ncRNAs in neurological diseases and cancer. Although involvement of short ncRNA in those pathologies has already been well documented, there is only scarce evidence to show the participation of lncRNAs. One of the examples of lncRNAs is BC200 RNA, which plays an important role in the regulation of dendritic protein expression. Mislocalization and overexpression of BC200 RNA leads to inadequate RNA delivery to the synapses and results in neurodegenerative processes of Alzheimer's disease and neoplastic changes in various groups of tissues. In this review, we summarize the current state of art in the field of the biological significance of lncRNAs, with particular attention paid to the physiological and pathophysiological role of BC200 RNA.

  12. Extracellular and Intracellular Polyphenol Oxidases Cause Opposite Effects on Sensitivity of Streptomyces to Phenolics: A Case of Double-Edged Sword

    PubMed Central

    Yang, Han-Yu; Chen, Carton W.

    2009-01-01

    Many but not all species of Streptomyces species harbour a bicistronic melC operon, in which melC2 encodes an extracellular tyrosinase (a polyphenol oxidase) and melC1 encodes a helper protein. On the other hand, a melC-homologous operon (melD) is present in all sequenced Streptomyces chromosomes and could be isolated by PCR from six other species tested. Bioinformatic analysis showed that melC and melD have divergently evolved toward different functions. MelD2, unlike tyrosinase (MelC2), is not secreted, and has a narrower substrate spectrum. Deletion of melD caused an increased sensitivity to several phenolics that are substrates of MelD2. Intracellularly, MelD2 presumably oxidizes the phenolics, thus bypassing spontaneous copper-dependent oxidation that generates DNA-damaging reactive oxygen species. Surprisingly, melC+ strains were more sensitive rather than less sensitive to phenolics than melC− strains. This appeared to be due to conversion of the phenolics by MelC2 to more hydrophobic and membrane-permeable quinones. We propose that the conserved melD operon is involved in defense against phenolics produced by plants, and the sporadically present melC operon probably plays an aggressive role in converting the phenolics to the more permeable quinones, thus fending off less tolerant competing microbes (lacking melD) in the phenolic-rich rhizosphere. PMID:19826489

  13. The double-edged sword of the mammalian oocyte--advantages, drawbacks and approaches for basic and clinical analysis at the single cell level.

    PubMed

    Brayboy, L M; Wessel, G M

    2016-03-01

    Oocytes are usually the largest cells in the body and as such offer unique opportunities for single-cell analysis. Unfortunately, these cells are also some of the rarest in the mammalian female, usually necessitating single-cell analysis. In cases of infertility in humans, determining the quality of the oocyte is often restricted to a morphological analysis or to the study of cellular behaviors in the developing embryo. Minimally invasive approaches could greatly assist the clinician to prioritize oocytes for fertilization or following fertilization, which embryo to transfer back into the woman. Transcriptomics of human and mouse oocytes may have great utility, and recently it was learned that the polar body faithfully reflects the transcript prevalence in the oocyte. The polar body may thus serve as a minimally invasive proxy for an oocyte in the clinic. In the mouse, the transcriptomes of oocytes from mice of the same strain are markedly similar; no significant differences are apparent in transcript prevalence or identity. In human oocytes however, the transcript pool is highly variable. This is likely the result of different histories of each oocyte, in the age of the donor woman, the different hormonal exposures and the prolonged time from specification of the primary oocyte to the fully grown and ovulated egg. This variability in human oocytes also emphasizes the need for cell-by-cell analysis of the oocytes in vitro; which oocytes have a better potential for fertilization and development? To this end, new imaging capabilities are being employed. For example, a single-cell analytical device for oocytes (the simple perfusion apparatus, or SPA) enables investigators to load multiple oocytes in individual wells, to visualize them on the microscope and to use controlled temperature and media flow by perfusion for optimal clinical applications. Recently, developed Raman microspectroscopy approaches suggest that this imaging modality may enable more in-depth analysis of the molecular characteristics of an oocyte that, in combination with the SPA and transcriptomic approaches, might assist the clinician to prioritize more effectively human oocytes and embryos for transfer into women. This review is intended to update the reader on the status of the examination of single oocytes from a variety of approaches and to emphasize areas that may be primed for advancement in the near future.

  14. Are Academic Discounting and Devaluing Double-Edged Swords? Their Relations to Global Self-Esteem, Achievement Goals, and Performance among Stigmatized Students

    ERIC Educational Resources Information Center

    Loose, Florence; Regner, Isabelle; Morin, Alexandre J. S.; Dumas, Florence

    2012-01-01

    Often taken for granted, the coexistence of benefits and costs of discounting and devaluing has never been tested. Yet, not only are there inconsistent findings about the relations between these processes and global self-esteem, but little is known about their relations to motivation and performance. Here we simultaneously examined how academic…

  15. The double-edged sword of the mammalian oocyte--advantages, drawbacks and approaches for basic and clinical analysis at the single cell level.

    PubMed

    Brayboy, L M; Wessel, G M

    2016-03-01

    Oocytes are usually the largest cells in the body and as such offer unique opportunities for single-cell analysis. Unfortunately, these cells are also some of the rarest in the mammalian female, usually necessitating single-cell analysis. In cases of infertility in humans, determining the quality of the oocyte is often restricted to a morphological analysis or to the study of cellular behaviors in the developing embryo. Minimally invasive approaches could greatly assist the clinician to prioritize oocytes for fertilization or following fertilization, which embryo to transfer back into the woman. Transcriptomics of human and mouse oocytes may have great utility, and recently it was learned that the polar body faithfully reflects the transcript prevalence in the oocyte. The polar body may thus serve as a minimally invasive proxy for an oocyte in the clinic. In the mouse, the transcriptomes of oocytes from mice of the same strain are markedly similar; no significant differences are apparent in transcript prevalence or identity. In human oocytes however, the transcript pool is highly variable. This is likely the result of different histories of each oocyte, in the age of the donor woman, the different hormonal exposures and the prolonged time from specification of the primary oocyte to the fully grown and ovulated egg. This variability in human oocytes also emphasizes the need for cell-by-cell analysis of the oocytes in vitro; which oocytes have a better potential for fertilization and development? To this end, new imaging capabilities are being employed. For example, a single-cell analytical device for oocytes (the simple perfusion apparatus, or SPA) enables investigators to load multiple oocytes in individual wells, to visualize them on the microscope and to use controlled temperature and media flow by perfusion for optimal clinical applications. Recently, developed Raman microspectroscopy approaches suggest that this imaging modality may enable more in-depth analysis of the molecular characteristics of an oocyte that, in combination with the SPA and transcriptomic approaches, might assist the clinician to prioritize more effectively human oocytes and embryos for transfer into women. This review is intended to update the reader on the status of the examination of single oocytes from a variety of approaches and to emphasize areas that may be primed for advancement in the near future. PMID:26590170

  16. Recent results on 3D double sided detectors with slim edges

    NASA Astrophysics Data System (ADS)

    Pellegrini, G.; Baselga, M.; Christophersen, M.; Ely, S.; Fadeyev, V.; Fleta, C.; Gimenez, A.; Grinstein, S.; Lopez, I.; Lozano, M.; Micelli, A.; Phlips, B. F.; Quirion, D.; Sadrozinski, H. F.-W.; Tsiskaridze, S.

    2013-12-01

    This paper reports on the first characterization of double sided 3D silicon radiation pixel detectors with slim edges. These detectors consist of a three-dimensional array of electrodes that penetrate into the detector bulk with the anode and cathode electrodes etched from opposite sides of the substrate. Different detectors were post-processed using the scribe-cleave-passivate (SCP) technology to make “slim edge” sensors. These sensors have only a minimal amount of inactive peripheral region, for the benefit of the construction of large-area tracker and imaging systems. The target application for this work is the use of 3D slim edge detectors for the ATLAS Forward Physics (AFP) CERN Project, where pixel detectors for position resolution and timing detectors for removal of pile up protons, will be placed as close as possible to the beam to detect diffractive protons at 220 m on either side of the ATLAS interaction point. For this reason the silicon areas should feature the narrowest possible insensitive zone on the sensor edge closest to the beam and withstand high nonuniform irradiation fluences.

  17. Double-peaked edge-bead in drying film of solvent-resin mixtures

    NASA Astrophysics Data System (ADS)

    Shiratori, Suguru; Kubokawa, Toru

    2015-10-01

    A thick ridge of a film arising along the periphery of a substrate, which is the so-called edge-bead, is investigated experimentally and numerically for the case where the bead becomes double-peaked shape in direction away from the periphery of the substrate. It is clarified, by the optical measurement of thickness variations, that the double-peaked bead is separated from a single bead during the drying process, and after the separation, the inner bead moves inward. This motion of the bead is modeled by a lubrication-approximated flow equation, where the Laplace pressure and the solutocapillary effect are taken into account, coupled with the convective and diffusive mass transfer. The numerically simulated motion of the bead shows a good agreement with that obtained by the experiment, and it is revealed that the mechanism how the double-peaked edge-bead is formed. At the early stage of the drying process, a single bead is formed by the Laplace pressure due to the curvature along the substrate periphery. Along this single bead, the concentration gradient is caused by both the spatial distribution of the evaporation rate and the thickness effect on the change rate of the concentration, due to the fact that the resin concentration increases at a faster rate in the thin region. Consequently, the concentration distribution has a local minimum in the middle of the single bead, which drives oppositely directed solutocapillary flows and separates the bead. After the separation, the inner bead moves inward by a kind of a feed-forward mechanism, until the viscosity of the film becomes large enough to suppress the flow.

  18. Double-Edge Molecular Measurement of Lidar Wind Profiles at 355 nm

    NASA Technical Reports Server (NTRS)

    Flesia, Cristina; Korb, C. Laurence; Hirt, Christian; Einaudi, Franco (Technical Monitor)

    2000-01-01

    We built a direct detection Doppler lidar based on the double-edge molecular technique and made the first molecular based wind measurements using the eyesafe 355 nm wavelength. Three etalon bandpasses are obtained with Step etalons on a single pair of etalon plates. Long-term frequency drift of the laser and the capacitively stabilized etalon is removed by locking the etalon to the laser frequency. We use a low angle design to avoid polarization effects. Wind measurements of 1 to 2 m/s accuracy are obtained to 10 km altitude with 5 mJ of laser energy, a 750s integration, and a 25 cm telescope. Good agreement is obtained between the lidar and rawinsonde measurements.

  19. Elastic-plastic finite-element analyses of thermally cycled double-edge wedge specimens

    NASA Technical Reports Server (NTRS)

    Kaufman, A.; Hunt, L. E.

    1982-01-01

    Elastic-plastic stress-strain analyses were performed for double-edge wedge specimens subjected to thermal cycling in fluidized beds at 316 and 1088 C. Four cases involving different nickel-base alloys (IN 100, Mar M-200, NASA TAZ-8A, and Rene 80) were analyzed by using the MARC nonlinear, finite element computer program. Elastic solutions from MARC showed good agreement with previously reported solutions obtained by using the NASTRAN and ISO3DQ computer programs. Equivalent total strain ranges at the critical locations calculated by elastic analyses agreed within 3 percent with those calculated from elastic-plastic analyses. The elastic analyses always resulted in compressive mean stresses at the critical locations. However, elastic-plastic analyses showed tensile mean stresses for two of the four alloys and an increase in the compressive mean stress for the highest plastic strain case.

  20. 0.6 GHz mapping of extended radio galaxies. II - Edge-darkened double sources

    NASA Astrophysics Data System (ADS)

    Jaegers, W. J.

    1987-10-01

    Radio observations made with the Westerbork telescope at 0.6 GHz are presented for 8 edge-darkened double sources: NGC 315, NGC 326, 3C 31, 3C 130, B 0915+320, HB 13, NGC 6251 and 3C 449. Previously observed Westerbork data at 1.4 GHz are convolved for comparison with the 0.6 GHz observational data. Besides maps of the total intensity and linear polarization structure, the distributions of the spectral index, the depolarization and the rotation of the polarization position angle between 0.6 GHz and 1.4 GHz have been derived. Integrated values for the total intensity and the polarization are also given.

  1. Double photoexcitation involving 2p and 4f electrons in L3 -edge x-ray absorption spectra of protactinium

    NASA Astrophysics Data System (ADS)

    Hennig, Christoph; Le Naour, Claire; Auwer, Christophe Den

    2008-06-01

    The L3 -edge x-ray absorption spectrum of Pa(V) fluoride in aqueous solution show clear evidence for the double photoexcitation involving 2p and 4f electrons. A comparison with the [2p4f] double-electron excitations observed in the L3 -edge x-ray absorption spectra of other actinides (thorium, uranium, neptunium, plutonium, and americium) indicates a monotonic increase in the excitation energy. The sharp edgelike structure of the multielectron excitation reveals the origin of a shake-up channel.

  2. Aharonov-Bohm and Aharonov-Casher tunneling effects and edge states in double-barrier structures

    SciTech Connect

    Bogachek, E.N.; Landman, U. )

    1994-07-15

    The simultaneous occurrence of Aharonov-Bohm (AB) and Aharonov-Casher (AC) effects due to edge states in double-barrier two-dimensional wires formed by an electrostatic confinement potential, in the quantum Hall effect regime, is discussed. The AC effect is manifested via a shift of the AB conductance oscillations, and a method for measurement of the effect is proposed.

  3. UEDGE simulation of edge plasmas in DIII-D double null configurations

    SciTech Connect

    Porter, G. D.; Rognlien, T. D.; Rensink, M. E.; Petrie, T. W.

    2010-11-15

    Analysis of plasma flow in the edge of double null hybrid mode DIII-D plasmas is reported. The two dimension fluid plasma code UEDGE [T. Rognlien et al., J. Nucl. Mater. 196-198, 347 (1992)] is used for the analysis. The effect of impurity radiation from intrinsic carbon sputtered from plasma facing surfaces is included as is the effect of plasma drifts. Two discharges in which the flux surfaces through the poloidal field nulls (X-points) are separated by 1 cm at the outer midplane are analyzed. The discharges differ only in the direction of the ion {nabla}B drift. It is shown that the flow of both primary ions and intrinsic impurities is dominated by the effect of plasma drifts. Variations in the recycling of deuterium ions, as seen in D{sub {alpha}} emission profiles, are qualitatively consistent with experiment and are driven by the effect of ExB drifts associated with radial gradients of the electron temperature at the secondary separatrix. Trace argon impurity is introduced to simulate the transport of argon used in the experiment to enhance divertor radiation power. Penetration of the trace argon to the closed field lines depends on the direction of the ion {nabla}B drift, consistent with experiment. The analysis described here includes the effect of a deuterium gas puff to establish the ''puff and pump'' configuration. The poloidal flow of impurities is a balance between the projection of the parallel flow and poloidal drifts, primarily from ExB. It is shown that the effect of the gas puff is primarily to alter the electron temperature profile and thus affects impurity flow via alteration of ExB drifts, not via entrainment in deuterium ion parallel flow.

  4. Rational behavior is a ‘double-edged sword’ when considering voluntary vaccination

    NASA Astrophysics Data System (ADS)

    Zhang, Haifeng; Fu, Feng; Zhang, Wenyao; Wang, Binghong

    2012-10-01

    behavior of individuals plays a ‘double-edged-sword’ role on the social effects.

  5. Specular Andreev reflection at the edge of an InAs/GaSb double quantum well with band inversion

    NASA Astrophysics Data System (ADS)

    Kononov, A.; Egorov, S. V.; Kostarev, V. A.; Semyagin, B. R.; Preobrazhenskii, V. V.; Putyato, M. A.; Emelyanov, E. A.; Deviatov, E. V.

    2016-07-01

    We experimentally investigate transport through the side junction between a niobium superconductor and the mesa edge of a two-dimensional system, realized in an InAs/GaSb double quantum well with band inversion. We demonstrate, that different transport regimes can be achieved by variation of the mesa step. We observe anomalous behavior of Andreev reflection within a finite low-bias interval, which is invariant for both transport regimes. We connect this behavior with the transition from retro- (at low biases) to specular (at high ones) Andreev reflection channels in an InAs/GaSb double quantum well with band inversion.

  6. Cancer: fundamentals behind pH targeting and the double-edged approach

    PubMed Central

    Koltai, Tomas

    2016-01-01

    targeting this vulnerable side of cancer development. It also analyzes the double-edged approach, which consists in pharmacologically increasing intracellular proton production and simultaneously decreasing proton extrusion creating intracellular acidity, acid stress, and eventual apoptosis. PMID:27799782

  7. Na double-edge magneto-optic filter for Na lidar profiling of wind and temperature in the lower atmosphere.

    PubMed

    Huang, Wentao; Chu, Xinzhao; Williams, B P; Harrell, S D; Wiig, Johannes; She, C-Y

    2009-01-15

    A Na double-edge magneto-optic filter is proposed for incorporation into the receiver of a three-frequency Na Doppler lidar to extend its wind and temperature measurements into the lower atmosphere. Two prototypes based on cold- and hot-cell designs were constructed and tested with laser scanning and quantum mechanics modeling. The hot-cell filter exhibits superior performances over the cold-cell filter containing buffer gas. Lidar simulations, metrics, and error analyses show that simultaneous wind and temperature measurements are feasible in the altitude range of 20-50 km using the hot-cell filter and reasonable Na lidar parameters. PMID:19148254

  8. Double surface effect causes a peak in band-edge photocurrent spectra: a quantitative model

    NASA Astrophysics Data System (ADS)

    Turkulets, Yury; Bick, Tamar; Shalish, Ilan

    2016-09-01

    Band-edge photocurrent spectra are typically observed in either of two shapes: a peak or a step. In this study, we show that the photocurrent band-edge response of a GaN layer forms a peak, while the same response in GaN nanowires takes the form of a step, and both are red-shifted to the actual band-edge energy. This apparent inconsistency is not limited to GaN. The physics of this phenomenon has been unclear. To understand the physics behind these observations, we propose a model that explains the apparent discrepancy as resulting from a structure-dependent surface effect. To test the model, we experiment with a GaAs layer, showing that we can deliberately switch between a step and a peak. We use GaAs because it is available at a semi-insulating doping level. We demonstrate that using this quantitative model one may obtain the exact band-edge transition energy, regardless of the red-shift variance, as well as the density of the surface state charges that cause the red shift. The model thus adds quantitative features to photocurrent spectroscopy.

  9. Nutritional therapy and infectious diseases: a two-edged sword.

    PubMed

    Donabedian, Haig

    2006-09-04

    The benefits and risks of nutritional therapies in the prevention and management of infectious diseases in the developed world are reviewed. There is strong evidence that early enteral feeding of patients prevents infections in a variety of traumatic and surgical illnesses. There is, however, little support for similar early feeding in medical illnesses. Parenteral nutrition increases the risk of infection when compared to enteral feeding or delayed nutrition. The use of gastric feedings appears to be as safe and effective as small bowel feedings. Dietary supplementation with glutamine appears to lower the risk of post-surgical infections and the ingestion of cranberry products has value in preventing urinary tract infections in women.

  10. Nutritional therapy and infectious diseases: a two-edged sword

    PubMed Central

    Donabedian, Haig

    2006-01-01

    The benefits and risks of nutritional therapies in the prevention and management of infectious diseases in the developed world are reviewed. There is strong evidence that early enteral feeding of patients prevents infections in a variety of traumatic and surgical illnesses. There is, however, little support for similar early feeding in medical illnesses. Parenteral nutrition increases the risk of infection when compared to enteral feeding or delayed nutrition. The use of gastric feedings appears to be as safe and effective as small bowel feedings. Dietary supplementation with glutamine appears to lower the risk of post-surgical infections and the ingestion of cranberry products has value in preventing urinary tract infections in women. PMID:16952310

  11. People vs. Collins: Statistics as a Two-Edged Sword

    ERIC Educational Resources Information Center

    McGivney-Burelle, Jean; McGivney, Katherine; McGivney, Ray

    2006-01-01

    Real-life applications of the use (and misuse) of mathematics invariably pique students' interest. This article describes a legal case in California that occurred in the 1960s in which a couple was convicted of robbery, in part, based on the expert testimony of a statistics instructor. On appeal, the judge noted several mathematical errors in this…

  12. The Pill vs. the Sword: Additional Considerations

    PubMed Central

    Lottes, Ilsa L.

    2015-01-01

    In this paper, I present additional information for policy-makers and researchers to consider in response to the view proposed by Potts et al that "the pill is mightier than the sword." I identify states with both high rates of terrorism and a youth bulge and discuss correlates of both these societal characteristics. The research examined supports the view that factors other than access to family planning are more important in facilitating terrorism. PMID:26673473

  13. Estimation of Neutral Density in Edge Plasma with Double Null Configuration in EAST

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Xu, Guosheng; Ding, Siye; Gao, Wei; Wu, Zhenwei; Chen, Yingjie; Huang, Juan; Liu, Xiaoju; Zang, Qing; Chang, Jiafeng; Zhang, Wei; Li, Yingying; Qian, Jinping

    2011-08-01

    In this work, population coefficients of hydrogen's n = 3 excited state from the hydrogen collisional-radiative (CR) model, from the data file of DEGAS 2, are used to calculate the photon emissivity coefficients (PECs) of hydrogen Balmer-α (n = 3 → n = 2) (Hα). The results are compared with the PECs from Atomic Data and Analysis Structure (ADAS) database, and a good agreement is found. A magnetic surface-averaged neutral density profile of typical double-null (DN) plasma in EAST is obtained by using FRANTIC, the 1.5-D fluid transport code. It is found that the sum of integral Dα and Hα emission intensity calculated via the neutral density agrees with the measured results obtained by using the absolutely calibrated multi-channel poloidal photodiode array systems viewing the lower divertor at the last closed flux surface (LCFS). It is revealed that the typical magnetic surface-averaged neutral density at LCFS is about 3.5 × 1016 m-3.

  14. CORE AND EDGE ASPECTS OF QUIESCENT DOUBLE BARRIER OPERATION ON DIII-D.WITH RELEVANCE TO CRITICAL ITB PHYSICS ISSUES

    SciTech Connect

    DOYLE,EJ; CASPER,TA; BURRELL,KH; GREENFIELD,CM; WEST,WP; BUDNY,RV; DeBOO,JC; GAROFALO,AM; GOHIL,P; GROEBNER,RJ; HYATT,AW; JACKSON,GL; JERINGAN,TC; KINSEY,JE; LAO,LL; LASNIER,CJ; LEBOEUF,JN; LUCE,TC; MAKOWSKI,MA; McKEE,GR

    2003-03-01

    OAK-B135 Recent results from DIII-D address critical internal transport barrier (ITB) research issues relating to sustainability, impurity accumulation and ITB control, and have also demonstrated successful application of general profile control tools. In addition, substantial progress has been made in understanding the physics of the Quiescent Double Barrier (QDB) regime, increasing the demonstrating operating space for the regime and improving performance. Highlights include: (1) a clear demonstration of q-profile modification using electron cyclotron current drive (ECCD); (2) successful use of localized profile control using electron cyclotron heating (ECH) or ECCD to reduce central high-Z impurity accumulation associated with density peaking; (3) theory-based modeling codes are now being used to design experiments; (4) the operating space for Quiescent H-mode (QH-mode) has been substantially broadened, in particular higher density operation has been achieved; (5) absolute ({beta} 3.8%, neutron rate S{sub n} {le} 5.5 x 10{sup 15} s{sup -1}) and relative ({beta}{sub N}H{sub 89} = 7 for 10 {tau}{sub E}) performance has been increased; (6) with regard to sustainment, QDB plasmas have been run for 3.8 s or 26 {tau}{sub E}. These results emphasize that it is possible to produce sustained high quality H-mode performance with an edge localized mode (ELM)-free edge, directly addressing a major issue in fusion research, of how to ameliorate or eliminate ELM induced pulsed divertor particle and heat loads.

  15. System Administration Support/SWORDS G2

    NASA Technical Reports Server (NTRS)

    Dito, Scott Joseph

    2014-01-01

    The Soldier-Warfighter Operationally Responsive Deployer for Space (SWORDS) rocket is a dedicated small satellite launcher that will minimize danger and complexity in order to allow soldiers in the field to put payloads of up to 25kg into orbit from the field. The SWORDSG2 project is the development of a model, simulation, and ultimately a working application that will control and monitor the cryogenic fluid delivery to the SWORDS rocket for testing purposes. To accomplish this, the project is using the programming language environment Gensym G2. The environment is an all-inclusive application that allows development, testing, modeling, and finally operation of the unique application through graphical and programmatic methods. In addition, observation of the current cryogenic fluid delivery system in the Kennedy Space Center Cry Lab has allowed me to gain valuable experience of fluid systems and propelant delivery that is valuable to our team when developing amd modeling our own system.The ultimate goal of having a test-ready application to show to the heads of the project, and demonstrating G2's capabilities, by late 2014 will require hard work and intense study and understanding of not only the programming aspect but also the physical phenomena we want to model, observe, and control.

  16. Double-edged-sword effect of IL-1β on the osteogenesis of periodontal ligament stem cells via crosstalk between the NF-κB, MAPK and BMP/Smad signaling pathways

    PubMed Central

    Mao, C-y; Wang, Y-g; Zhang, X; Zheng, X-y; Tang, T-t; Lu, E-y

    2016-01-01

    Microenvironmental conditions can interfere with the functional role and differentiation of mesenchymal stem cells (MSCs). Recent studies suggest that an inflammatory microenvironment can significantly impact the osteogenic potential of periodontal ligament stem cells (PDLSCs), but the precise effects and mechanisms involved remain unclear. Here, we show for the first time that interleukin-1β (IL-1β) has dual roles in the osteogenesis of PDLSCs at concentrations ranging from physiologically healthy levels to those found in chronic periodontitis. Low doses of IL-1β activate the BMP/Smad signaling pathway to promote the osteogenesis of PDLSCs, but higher doses of IL-1β inhibit BMP/Smad signaling through the activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) signaling, inhibiting osteogenesis. These results demonstrate that crosstalk between NF-κB, MAPK and BMP/Smad signaling mediates this dual effect of IL-1β on PDLSCs. We also show that the impaired osteogenesis of PDLSCs results in more inflammatory cytokines and chemokines being released, inducing the chemotaxis of macrophages, which further clarifies the role of PDLSCs in the pathogenesis of periodontitis. PMID:27415426

  17. Double conical crystal x-ray spectrometer for high resolution ultrafast x-ray absorption near-edge spectroscopy of Al K edge

    SciTech Connect

    Levy, A.; Dorchies, F.; Fourment, C.; Harmand, M.; Hulin, S.; Santos, J. J.; Descamps, D.; Petit, S.; Bouillaud, R.

    2010-06-15

    An x-ray spectrometer devoted to dynamical studies of transient systems using the x-ray absorption fine spectroscopy technique is presented in this article. Using an ultrafast laser-induced x-ray source, this optical device based on a set of two potassium acid phthalate conical crystals allows the extraction of x-ray absorption near-edge spectroscopy structures following the Al absorption K edge. The proposed experimental protocol leads to a measurement of the absorption spectra free from any crystal reflectivity defaults and shot-to-shot x-ray spectral fluctuation. According to the detailed analysis of the experimental results, a spectral resolution of 0.7 eV rms and relative fluctuation lower than 1% rms are achieved, demonstrated to be limited by the statistics of photon counting on the x-ray detector.

  18. Edward's sword? - A non-destructive study of a medieval king's sword

    SciTech Connect

    Segebade, Chr.

    2013-04-19

    Non-destructive and instrumental methods including photon activation analysis were applied in an examination of an ancient sword. It was tried to find indication of forgery or, if authentic, any later processing and alteration. Metal components of the hilt and the blade were analysed by instrumental photon activation. Non-destructive metallurgical studies (hardness measurements, microscopic microstructure analysis) are briefly described, too. The results of these investigations did not yield indication of non-authenticity. This stood in agreement with the results of stylistic and scientific studies by weapon experts.

  19. Crack growth behavior under creep-fatigue conditions using compact and double edge notch tension-compression specimens

    NASA Astrophysics Data System (ADS)

    Narasimha Chary, Santosh Balaji

    The American Society for Testing and Materials (ASTM) has recently developed a new standard for creep-fatigue crack growth testing, E 2760-10, that supports testing compact specimens, C(T), under load controlled conditions. C(T) specimens are commonly used for fatigue and creep-fatigue crack growth testing under constant-load-amplitude conditions. The use of these specimens is limited to positive load ratios. They are also limited in the amount of crack growth data that can be developed at high stress intensity values due to accumulation of plastic and/or creep strains leading to ratcheting in the specimen. Testing under displacement control can potentially address these shortcomings of the load-controlled tests for which the C(T) geometry is unsuitable. A double edge notch tension-compression, DEN(T-C), specimen to perform displacement controlled creep-fatigue crack growth testing is developed and optimized with the help of finite element and boundary element analyses. Accurate expressions for estimating the fracture mechanics crack tip parameters such as the stress intensity parameter, K, the crack mouth opening displacement (CMOD), and the load-line displacement (LLD) are developed over a wide range of crack sizes for the DEN(T-C) specimen. A new compliance relationship for use in experimental testing has been developed by using the compliance form available in ASTM E-647 standard. Experimentally determined compliance value compared well with the new relation for C15 steel (AISI 1015) and P91 steel tested at room and elevated temperature conditions respectively. Fatigue crack growth rate data generated using the DEN(T-C) specimens on the two metallic materials are in good agreement with the data generated using standard compact specimens; thus validating the stress-intensity factor and the compliance equation for the double edge notch tension-compression specimen. The testing has shown that the DEN(T-C) specimen is prone to crack asymmetry issues. Through

  20. Charge transfer in AuTa alloys: double resonance at the Au and Ta L 2, 3-edge

    NASA Astrophysics Data System (ADS)

    Sammynaiken, R.; Kuhn, M.; Sham, T. K.

    1995-02-01

    Charge redistribution in AuTa alloys has been studied with both Au and Ta L 2, 3-edge XANES for AuTa, AuTa 2 and AuTa 3. Emphasis is placed on the relative intensity of the whiteline which probes the change in d-hole count at both Au and Ta sites. It is found that all Au L 2, 3-edge XANES exhibit an appreciable whiteline of which the intensity increases as Au becomes more dilute in Ta while the Ta L 2, 3-edge whiteline intensity increases also as Ta becomes more dilute. These results are compared with core-level photoemission measurements.

  1. Covenants with Weak Swords: ISO 14001 and Facilities' Environmental Performance

    ERIC Educational Resources Information Center

    Potoski, Matthew; Prakash, Aseem

    2005-01-01

    Voluntary environmental programs are codes of progressive environmental conduct that firms pledge to adopt. This paper investigates whether ISO 14001, a voluntary program with a weak sword--a weak monitoring and sanctioning mechanism--can mitigate shirking and improve participants' environmental performance. Sponsored by the International…

  2. The turn of the sword: length increases male swimming costs in swordtails.

    PubMed Central

    Basolo, Alexandra L; Alcaraz, Guillermina

    2003-01-01

    Sexual selection via female mate choice can result in the evolution of elaborate male traits that incur substantial costs for males. Despite increased interest in how female mating preferences contribute to the evolution of male traits, few studies have directly quantified the locomotor costs of such traits. A sexually selected trait that could affect movement costs is the sword exhibited by male swordtail fishes: while longer swords may increase male mating success, they could negatively affect the hydrodynamic aspects of swimming activities. Here, we examine the energetic costs of the sword in Xiphophorus montezumae by experimentally manipulating sword length and measuring male aerobic metabolism during two types of activity, routine swimming and courtship swimming. Direct measurements of oxygen consumption indicate that males with longer swords expend more energy than males with shortened swords during both types of swimming. In addition, the sword increases the cost of male courtship. Thus, while sexual selection via female choice favours long swords, males with longer swords experience higher metabolic costs during swimming, suggesting that sexual and natural selection have opposing effects on sword evolution. This study demonstrates a hydrodynamic cost of a sexually selected trait. In addition, this study discriminates between the cost of a sexually selected trait used in courtship and other courtship costs. PMID:12908985

  3. Characterization of an Indian sword: classic and noninvasive methods of investigation in comparison

    NASA Astrophysics Data System (ADS)

    Barzagli, E.; Grazzi, F.; Williams, A.; Edge, D.; Scherillo, A.; Kelleher, J.; Zoppi, M.

    2015-04-01

    The evolution of metallurgy in history is one of the most interesting topics in Archaeometry. The production of steel and its forging methods to make tools and weapons are topics of great interest in the field of the history of metallurgy. In the production of weapons, we find almost always the highest level of technology. These were generally produced by skilled craftsmen who used the best quality materials available. Indian swords are an outstanding example in this field and one of the most interesting classes of objects for the study of the evolution of metallurgy. This work presents the study of a Shamsheer (a sword with a curved blade with single edge) made available by the Wallace Collection in London. The purpose of this study was to determine the composition, the microstructure, the level and the direction of residual strain and their distribution in the blade. We have used two different approaches: the classical one (metallography) and a nondestructive technique (neutron diffraction): In this way, we can test differences and complementarities of these two techniques. To obtain a good characterization of artifacts studied by traditional analytical methods, an invasive approach is required. However, the most ancient objects are scarce in number, and the most interesting ones are usually in an excellent state of conservation, so it is unthinkable to apply techniques with a destructive approach. The analysis of blades that has been performed by metallographic microscopy has demonstrated the specificity of the production of this type of steel. However, metallographic analysis can give only limited information about the structural characteristics of these artifacts of high quality, and it is limited to the sampled areas. The best approach for nondestructive analysis is therefore to use neutron techniques.

  4. Position and flux stabilization of X-ray beams produced by double-crystal monochromators for EXAFS scans at the titanium K-edge.

    PubMed

    van Silfhout, Roelof; Kachatkou, Anton; Groppo, Elena; Lamberti, Carlo; Bras, Wim

    2014-03-01

    The simultaneous and active feedback stabilization of X-ray beam position and monochromatic beam flux during EXAFS scans at the titanium K-edge as produced by a double-crystal monochromator beamline is reported. The feedback is generated using two independent feedback loops using separate beam flux and position measurements. The flux is stabilized using a fast extremum-searching algorithm that is insensitive to changes in the synchrotron ring current and energy-dependent monochromator output. Corrections of beam height are made using an innovative transmissive beam position monitor instrument. The efficacy of the feedback stabilization method is demonstrated by comparing the measurements of EXAFS spectra on inhomogeneous diluted Ti-containing samples with and without feedback applied.

  5. Fabrication of a Bronze Age Sword using Ancient Techniques

    NASA Astrophysics Data System (ADS)

    Sapiro, David; Webler, Bryan

    2016-09-01

    A khopesh was cast and forged for the TMS 2016 Bladesmithing Symposium. The khopesh was the first sword style, originating during the Bronze Age in the Near East. The manufacturing process used in this study closely followed Bronze Age techniques to determine the plausibility of open mold casting coupled with cold work and annealing cycles. Forging and annealing cycles substantially increased blade strength and diminished intergranular δ-phase inclusions. While a functional blade was not completed due to casting defects, the process gives valuable insight into the effort required to fabricate a khopesh during the Bronze Age. Forging and annealing cycles following casting were necessary to produce the mechanical properties desired in a sword.

  6. Casting Simulation of an Austrian Bronze Age Sword Hilt

    NASA Astrophysics Data System (ADS)

    Pola, Annalisa; Mödlinger, Marianne; Piccardo, Paolo; Montesano, Lorenzo

    2015-07-01

    Bronze Age swords with a metal hilt can be considered the peak of Bronze Age casting technologies. To reconstruct the casting techniques used more than 3000 years ago, a metal hilted sword of the Schalenknauf type from Lower Austria was studied with the aid of macroscopic analyses and simulation of mold filling and casting solidification. A three-dimensional model of the hilt was created based on optical scanner measurements performed on a hilt recently discovered during archaeological excavations. Three different configurations of the gating system were considered, two on the pommel disk and one on the knob, and the effect of its location on the formation of casting defects was investigated. Three-dimensional computed tomography was used to detect internal defects, such as gas and shrinkage porosity, which were then compared with those calculated by simulation. The best match between actual and predicted hilt quality demonstrated the location of the gating system, which turned out to be on the pommel disk.

  7. From the sword to Schindler: a saga of gastroscopy.

    PubMed

    Morgenstern, Leon

    2009-06-01

    Gastroscopy is an art as well as a science. The art is getting the instrument down; the science is the instrument itself. Rudolf Schindler was a master of both and is properly called "The Father Of Gastroscopy". He can also be called a renaissance man, so varied were his interests. Sword-swallowing played a minor but interesting role in the development of gastroscopy. It is still alive and well.

  8. Cutting Edge: DNase II deficiency prevents activation of autoreactive B cells by double-stranded DNA endogenous ligands.

    PubMed

    Pawaria, Sudesh; Moody, Krishna; Busto, Patricia; Nündel, Kerstin; Choi, Chee-Ho; Ghayur, Tariq; Marshak-Rothstein, Ann

    2015-02-15

    In mice that fail to express the phagolysosomal endonuclease DNase II and the type I IFN receptor, excessive accrual of undegraded DNA results in a STING-dependent, TLR-independent inflammatory arthritis. These double-knockout (DKO) mice develop additional indications of systemic autoimmunity, including anti-nuclear autoantibodies and splenomegaly, that are not found in Unc93b1(3d/3d) DKO mice and, therefore, are TLR dependent. The DKO autoantibodies predominantly detect RNA-associated autoantigens, which are commonly targeted in TLR7-dominated systemic erythematosus lupus-prone mice. To determine whether an inability of TLR9 to detect endogenous DNA could explain the absence of dsDNA-reactive autoantibodies in DKO mice, we used a novel class of bifunctional autoantibodies, IgM/DNA dual variable domain Ig molecules, to activate B cells through a BCR/TLR9-dependent mechanism. DKO B cells could not respond to the IgM/DNA dual variable domain Ig molecule, despite a normal response to both anti-IgM and CpG ODN 1826. Thus, DKO B cells only respond to RNA-associated ligands because DNase II-mediated degradation of self-DNA is required for TLR9 activation.

  9. Precipitation of sword bean proteins by heating and addition of magnesium chloride in a crude extract.

    PubMed

    Nishizawa, Kaho; Masuda, Tetsuya; Takenaka, Yasuyuki; Masui, Hironori; Tani, Fumito; Arii, Yasuhiro

    2016-08-01

    Sword bean (Canavalia gladiata) seeds are a traditional food in Asian countries. In this study, we aimed to determine the optimal methods for the precipitation of sword bean proteins useful for the food development. The soaking time for sword beans was determined by comparing it with that for soybeans. Sword bean proteins were extracted from dried seeds in distilled water using novel methods. We found that most proteins could be precipitated by heating the extract at more than 90 °C. Interestingly, adding magnesium chloride to the extract at lower temperatures induced specific precipitation of a single protein with a molecular weight of approximately 48 kDa. The molecular weight and N-terminal sequence of the precipitated protein was identical to that of canavalin. These data suggested that canavalin was precipitated by the addition of magnesium chloride to the extract. Our results provide important insights into the production of processed foods from sword bean.

  10. Role of disulfide linkage in action of bis(dialkylaminethiocarbonyl)disulfides as potent double-Edged microbicidal spermicide: Design, synthesis and biology.

    PubMed

    Lal, Nand; Jangir, Santosh; Bala, Veenu; Mandalapu, Dhanaraju; Sarswat, Amit; Kumar, Lalit; Jain, Ashish; Kumar, Lokesh; Kushwaha, Bhavana; Pandey, Atindra K; Krishna, Shagun; Rawat, Tara; Shukla, Praveen K; Maikhuri, Jagdamba P; Siddiqi, Mohammad I; Gupta, Gopal; Sharma, Vishnu L

    2016-06-10

    Trichomoniasis and candidiasis are amongst the most common morbidity-causing reproductive tract infections, generally treated by Metronidazole and Fluconazole respectively. Poor vaginal efficacy, drug-resistance and non-spermicidal nature limit their use as topical microbicidal contraceptives. Bis(dialkylaminethiocarbonyl)disulfides (4-38) were designed as dually active, non-surfactant molecules capable of eliminating Trichomonas vaginalis and Candida strains as well as irreversibly immobilizing 100% human sperm instantly, at doses non-cytotoxic to human cervical epithelial cells and vaginal microflora in vitro. Compounds 12, 16, 17 were fifty times more active than nonoxynol-9, OTC vaginal spermicide, and compounds 12 and 17 have shown remarkable in vivo activity in rabbit model. Most promising compound 17 has shown promise for further development as a double-edged vaginal microbicide due to their improved activity and safety along with notable in vivo trichomonicidal activity. Role of disulfide group was established by loss of spermicidal activity on chemical modifications (39-56). These disulfides might be targeting thiol groups present over cell membrane of human sperm and Trichomonas as shown by fluorescence labeling of free thiols. PMID:27084496

  11. Band edge tailoring of InGaAs/AlAsSb coupled double quantum wells for a monolithically integrated all-optical switch.

    PubMed

    Feng, Jijun; Akimoto, Ryoichi; Gozu, Shin-ichiro; Mozume, Teruo; Hasama, Toshifumi; Ishikawa, Hiroshi

    2013-07-01

    We demonstrate a compact all-optical Michelson interferometer (MI) gating switch with monolithic integration of two different bandgap energies. Based on the ion-induced intermixing in InGaAs/AlAsSb coupled double quantum wells, the blueshift of the band edge can be tailored. Through phosphorus ion implantation with a dose of 5 × 10(14) cm(-2) and subsequent annealing at 720 °C for 60 s, an implanted sample can acquire a high transmittance compared with the as-grown one. Meanwhile, the cross-phase modulation (XPM) efficiency of a non-implanted sample undergoing the same annealing process decreases little. An implanted part for signal propagation and a non-implanted section for XPM are thus monolithically integrated for an MI switch by an area-selective manner. Full switching of a π-rad nonlinear phase shift is achieved with pump pulse energy of 5.6 pJ at a 10-GHz repetition rate.

  12. Field demonstration of simultaneous wind and temperature measurements from 5 to 50 km with a Na double-edge magneto-optic filter in a multi-frequency Doppler lidar.

    PubMed

    Huang, Wentao; Chu, Xinzhao; Wiig, Johannes; Tan, Bo; Yamashita, Chihoko; Yuan, T; Yue, J; Harrell, S D; She, C-Y; Williams, B P; Friedman, J S; Hardesty, R M

    2009-05-15

    We report the first (to our knowledge) field demonstration of simultaneous wind and temperature measurements with a Na double-edge magneto-optic filter implemented in the receiver of a three-frequency Na Doppler lidar. Reliable winds and temperatures were obtained in the altitude range of 10-45 km with 1 km resolution and 60 min integration under the conditions of 0.4 W lidar power and 75 cm telescope aperture. This edge filter with a multi-frequency lidar concept can be applied to other direct-detection Doppler lidars for profiling both wind and temperature simultaneously from the lower to the upper atmosphere.

  13. External-RBS, PIXE and NRA analysis for ancient swords

    NASA Astrophysics Data System (ADS)

    Santos, Hellen C.; Added, Nemitala; Silva, Tiago F.; Rodrigues, C. L.

    2015-02-01

    Elemental composition of the steel of two ancient swords (Japanese and Damascus from a private collection) was characterized using in air IBA techniques. Our results contribute for the understanding the processes of manufacturing (hammering and quenching) and surface treatments applied in these swords. The Particle Induced X-ray Emission (PIXE) measurements along the Damascus blade allowed to identify and to trace a superficial concentration profile for the elements such Cr, Mn, Fe, Ni, Cu, Zn and As, while results for the Japanese blade showed only the presence of iron. The carbon content on the surface was also investigated using a resonant region in the Elastic Backscattering Spectrometry (EBS) measurements and the results have shown a slightly difference between the surfaces under investigation. In order to investigate the nitrogen content on surface, that could explain the hardening process, we used Nuclear Reaction Analysis (NRA) and the results shown that nitrogen content was under our detection limit for the technique (0.3% in mass). The measurements of PIXE, NRA and EBS were taken using the external beam setup installed at Lamfi - São Paulo/Brazil, the latter being successfully implemented for the first time in this facility.

  14. Double-Edged Roles of Nitric Oxide Signaling on APP Processing and Amyloid-β Production In Vitro: Preliminary Evidence from Sodium Nitroprusside.

    PubMed

    Cai, Zheng-Xu; Guo, Hui-Shu; Wang, Che; Wei, Min; Cheng, Cheng; Yang, Zhao-Fei; Chen, Yin-Wang; Le, Wei-Dong; Li, Song

    2016-01-01

    Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is thought to be caused in part by the age-related accumulation of amyloid-β (Aβ) in the brain. Recent findings have revealed that nitric oxide (NO) modulates the processing of amyloid-β precursor protein (APP) and alters Aβ production; however, the previously presented data are contradictory and the underlying molecular mechanisms are still incomplete. Here, using human SH-SY5Y neuroblastoma cells stably transfected with wild-type APPwt695, we found that NO, derived from NO donor sodium nitroprusside (SNP), bi-directionally modulates APP processing in vitro. The data from ELISA and Western blot (WB) tests indicated that SNP at lower concentrations (0.01 and 0.1 μM) inhibits BACE1 expression, thus consequently suppresses APP β-cleavage and decreases Aβ production. In contrast, SNP at higher concentrations (10 and 20 μM) biases the APP processing toward the amyloidogenic pathway as evidenced by an increased BACE1 but a decreased ADAM10 expression, together with an elevated Aβ secretion. This bi-directional modulating activity of SNP on APP processing was completely blocked by specific NO scavenger c-PTIO, indicating NO-dependent mechanisms. Moreover, the anti-amyloidogenic activity of SNP is sGC/cGMP/PKG-dependent as evidenced by its reversal by sGC/PKG inhibitions, whereas the amyloidogenic activity of SNP is peroxynitrite-related and can be reversed by peroxynitrite scavenger uric acid. In summary, these present findings predict a double-edged role of NO in APP processing in vitro. Low (physiological) levels of NO inhibit the amyloidogenic processing of APP, whereas extra-high (pathological) concentrations of NO favor the amyloidogenic pathway of APP processing. This preliminary study may provide further evidence to clarify the molecular roles of NO and NO-related signaling in AD and supply potential molecular targets for AD treatment.

  15. Simultaneous wind and temperature measurements in lower atmosphere by a 3-frequency Doppler lidar with a Na double-edge magneto-optic filter

    NASA Astrophysics Data System (ADS)

    Huang, W.; Chu, X.; Wang, Z.; Roberts, B.; Yuan, T.; Yue, J.; Harrell, S.; She, C.

    2009-12-01

    We have developed a new lidar technology to simultaneously profile wind and temperature from the lower to the middle atmosphere. This was to use a Na double-edge magneto-optic filter (Na-DEMOF) in the receiver of a 3-frequency Na Doppler lidar to analyze the Doppler shift and width of the Rayleigh/Mie scattering returns from 5 to 50 km altitude range. In last AGU meeting we reported our first field demonstration of this technology with the Colorado State University’s Na lidar running at 0.4 W power and 75 cm diameter telescope. Reliable winds and temperatures were measured in the altitude range of 10-45 km at 1 km and 60 min resolutions. Further tests reveal strong wavy structures in our short-time data set. In order to assess the capability of this technique in resolving the gravity waves and to understand the origin of the wavy structures, two PMTs were integrated to improve the temporal resolution and field tests were conducted covering an entire night. The preliminary data retrieval reveals the calibration regarding the different responses of the two PMTs being a critical issue for this new technique. A second-generation Na-DEMOF has been designed for reliable and stable performance. It is currently under construction and will soon be tested in the field. In this paper we will present these field test results and assess the usefulness of this new technology in the study of atmospheric thermal and dynamic structures, especially gravity wave properties.

  16. Extending 3-Frequency Na Doppler Lidar Wind and Temperature Measurements into Lower Atmosphere with Na Double-Edge Magneto-Optic Filters (Na-DEMOF)

    NASA Astrophysics Data System (ADS)

    Huang, W.; Chu, X.; Wiig, J.; Williams, B. P.; Harrell, S.; She, C.

    2008-12-01

    An important atmospheric process is the wave coupling among different layers. It is crucial to trace waves from their source regions in the lower atmosphere to their dissipation regions in the middle and upper atmosphere. This requires the profiling of wind and temperature simultaneously from the lower to the upper atmosphere. Utilizing Doppler shift and Doppler broadening effects, various types of Doppler lidars can measure wind and temperature in different atmospheric regions. However, none of the single lidars is able to profile both variables throughout the atmosphere. Resonance fluorescence Na Doppler lidars measure wind and temperature simultaneously in the mesosphere and lower thermosphere. They have made significant contributions to the study of wave dynamics. Unfortunately, their measurements are limited to 80-105 km where the trace gas Na atoms are available. We proposed to incorporate a Na double-edge magneto-optic filter (Na-DEMOF) into the receiver of a 3-frequency Na Doppler lidar to extend its wind and temperature measurements into the lower atmosphere. Two prototypes based on cold- and hot-cell designs were constructed and characterized with laboratory tests. The hot-cell filter showed superior performances than the cold-cell containing buffer gas. The hot-cell Na-DEMOF was also successfully modeled by quantum mechanics calculations. Lidar simulations were conducted for analysis of measurement errors in the altitude range of 15-50 km with the hot-cell filter developed. Field test using the hot-cell Na-DEMOF with the Colorado State University Na lidar is under its way and the initial results will be reported and compared to lidar simulation.

  17. Decoupling Edge Versus Bulk Conductance in the Trivial Regime of an InAs/GaSb Double Quantum Well Using Corbino Ring Geometry.

    PubMed

    Nguyen, Binh-Minh; Kiselev, Andrey A; Noah, Ramsey; Yi, Wei; Qu, Fanming; Beukman, Arjan J A; de Vries, Folkert K; van Veen, Jasper; Nadj-Perge, Stevan; Kouwenhoven, Leo P; Kjaergaard, Morten; Suominen, Henri J; Nichele, Fabrizio; Marcus, Charles M; Manfra, Michael J; Sokolich, Marko

    2016-08-12

    A Corbino ring geometry is utilized to analyze edge and bulk conductance of InAs/GaSb quantum well structures. We show that edge conductance exists in the trivial regime of this theoretically predicted topological system with a temperature-insensitive linear resistivity per unit length in the range of 2  kΩ/μm. A resistor network model of the device is developed to decouple the edge conductance from the bulk conductance, providing a quantitative technique to further investigate the nature of this trivial edge conductance, conclusively identified here as being of n type.

  18. Decoupling Edge Versus Bulk Conductance in the Trivial Regime of an InAs/GaSb Double Quantum Well Using Corbino Ring Geometry.

    PubMed

    Nguyen, Binh-Minh; Kiselev, Andrey A; Noah, Ramsey; Yi, Wei; Qu, Fanming; Beukman, Arjan J A; de Vries, Folkert K; van Veen, Jasper; Nadj-Perge, Stevan; Kouwenhoven, Leo P; Kjaergaard, Morten; Suominen, Henri J; Nichele, Fabrizio; Marcus, Charles M; Manfra, Michael J; Sokolich, Marko

    2016-08-12

    A Corbino ring geometry is utilized to analyze edge and bulk conductance of InAs/GaSb quantum well structures. We show that edge conductance exists in the trivial regime of this theoretically predicted topological system with a temperature-insensitive linear resistivity per unit length in the range of 2  kΩ/μm. A resistor network model of the device is developed to decouple the edge conductance from the bulk conductance, providing a quantitative technique to further investigate the nature of this trivial edge conductance, conclusively identified here as being of n type. PMID:27563999

  19. Decoupling Edge Versus Bulk Conductance in the Trivial Regime of an InAs /GaSb Double Quantum Well Using Corbino Ring Geometry

    NASA Astrophysics Data System (ADS)

    Nguyen, Binh-Minh; Kiselev, Andrey A.; Noah, Ramsey; Yi, Wei; Qu, Fanming; Beukman, Arjan J. A.; de Vries, Folkert K.; van Veen, Jasper; Nadj-Perge, Stevan; Kouwenhoven, Leo P.; Kjaergaard, Morten; Suominen, Henri J.; Nichele, Fabrizio; Marcus, Charles M.; Manfra, Michael J.; Sokolich, Marko

    2016-08-01

    A Corbino ring geometry is utilized to analyze edge and bulk conductance of InAs /GaSb quantum well structures. We show that edge conductance exists in the trivial regime of this theoretically predicted topological system with a temperature-insensitive linear resistivity per unit length in the range of 2 k Ω /μ m . A resistor network model of the device is developed to decouple the edge conductance from the bulk conductance, providing a quantitative technique to further investigate the nature of this trivial edge conductance, conclusively identified here as being of n type.

  20. Female preference for swords in Xiphophorus helleri reflects a bias for large apparent size

    PubMed Central

    Rosenthal, Gil G.; Evans, Christopher S.

    1998-01-01

    Swordtail fish (Poeciliidae: genus Xiphophorus) are a paradigmatic case of sexual selection by sensory exploitation. Female preference for males with a conspicuous “sword” ornament is ancestral, suggesting that male morphology has evolved in response to a preexisting bias. The perceptual mechanisms underlying female mate choice have not been identified, complicating efforts to understand the selection pressures acting on ornament design. We consider two alternative models of receiver behavior, each consistent with previous results. Females could respond either to specific characteristics of the sword or to more general cues, such as the apparent size of potential mates. We showed female swordtails a series of computer-altered video sequences depicting a courting male. Footage of an intact male was preferred strongly to otherwise identical sequences in which portions of the sword had been deleted selectively, but a disembodied courting sword was less attractive than an intact male. There was no difference between responses to an isolated sword and to a swordless male of comparable length, or between an isolated sword and a homogenous background. Female preference for a sworded male was abolished by enlarging the image of a swordless male to compensate for the reduction in length caused by removing the ornament. This pattern of results is consistent with mate choice being mediated by a general preference for large males rather than by specific characters. Similar processes may account for the evolution of exaggerated traits in other systems. PMID:9539754

  1. Microstructural Features in Corroded Celtic Iron Age Sword Blades

    NASA Astrophysics Data System (ADS)

    Ghiara, G.; Piccardo, P.; Campodonico, S.; Carnasciali, M. M.

    2014-05-01

    Archaeological artefacts made from iron and steel are often of critical importance for archaeometallurgical studies, which aim to understand the process of manufacturing, as the nearly complete alloy mineralization does not allow for any type of metallographic interpretation. In this study, three Iron Age sword blades dated from the second century BC (LaTène B2/D1) found in the archaeological site of Tintignac (Commune de Naves, Corrèze, France), were investigated. A multianalytical approach was employed to acquire a complete range of data from the partially or totally corroded objects. Analyses were carried out with the use of light optical microscopy, micro Raman spectroscopy, and scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy (EDXS). Remnants of metallographic features—ghost microstructure—in the corrosion layers of the blades were observed, allowing for a partial reconstruction of the manufacturing process.

  2. CHANG-ES. III. UGC 10288—An edge-on galaxy with a background double-lobed radio source

    SciTech Connect

    Irwin, Judith; Krause, Marita; Beck, Rainer; English, Jayanne; Murphy, Eric; Wiegert, Theresa; Heald, George; Walterbos, Rene; Rand, Richard J.; Porter, Troy E-mail: mkrause@mpifr-bonn.mpg.de E-mail: jayanne_english@umanitoba.ca E-mail: twiegert@astro.queensu.ca E-mail: rwalterb@nmsu.edu E-mail: tporter@stanford.edu

    2013-12-01

    This third paper in the Continuum Halos in Nearby Galaxies—an EVLA Survey (CHANG-ES) series shows the first results from our regular data taken with the Karl G. Jansky Very Large Array. The edge-on galaxy, UGC 10288, has been observed in the B, C, and D configurations at L band (1.5 GHz) and in the C and D configurations at C band (6 GHz) in all polarization products. We show the first spatially resolved images of this galaxy in these bands, the first polarization images, and the first composed image at an intermediate frequency (4.1 GHz) which has been formed from a combination of all data sets. A surprising new result is the presence of a strong, polarized, double-lobed extragalactic radio source (CHANG-ES A) almost immediately behind the galaxy and perpendicular to its disk. The core of CHANG-ES A has an optical counterpart (SDSS J161423.28–001211.8) at a photometric redshift of z {sub phot} = 0.39; the southern radio lobe is behind the disk of UGC 10288 and the northern lobe is behind the halo region. This background ''probe'' has allowed us to do a preliminary Faraday rotation analysis of the foreground galaxy, putting limits on the regular magnetic field and electron density in the halo of UGC 10288 in regions in which there is no direct detection of a radio continuum halo. We have revised the flux densities of the two sources individually as well as the star formation rate (SFR) for UGC 10288. The SFR is low (0.4-0.5 M {sub ☉} yr{sup –1}) and the galaxy has a high thermal fraction (44% at 6 GHz), as estimated using both the thermal and non-thermal SFR calibrations of Murphy et al. UGC 10288 would have fallen well below the CHANG-ES flux density cutoff, had it been considered without the brighter contribution of the background source. UGC 10288 shows discrete high-latitude radio continuum features, but it does not have a global radio continuum halo (exponential scale heights are typically ≈1 kpc averaged over regions with and without extensions

  3. A comparison of antioxidative and anti-inflammatory activities of sword beans and soybeans fermented with Bacillus subtilis.

    PubMed

    Han, Seon Su; Hur, Sun Jin; Lee, Si Kyung

    2015-08-01

    This study was conducted to determine the antioxidative and anti-inflammatory activities of non-fermented or Bacillus subtilis-fermented soybeans and sword beans (red and white). The total flavonoid content in both sword bean types was higher (1.9-2.5-fold) than that in soybeans. The total phenolic content in fermented red sword beans was 2.5-fold greater than that in non-fermented red sword beans. HPLC profiles revealed that gallic acid, methyl gallate, and ellagic acid were major phenolic components of non-fermented/fermented red sword beans. DPPH radical scavenging activity and ferric-reducing antioxidant power were higher in fermented red sword beans than in other beans. Non-fermented/fermented red sword beans had higher nitrite scavenging activity than butylated hydroxytoluene and non-fermented/fermented soybeans. The hyaluronidase inhibitory activity of non-fermented/fermented red sword beans was higher (1.5-2.6-fold) than that of non-fermented/fermented soybeans. These results suggest that B. subtilis-fermented sword beans are potential natural antioxidant sources and anti-inflammatory agents for the food industry.

  4. Thyroid hormones: a triple-edged sword for life history transitions.

    PubMed

    Holzer, Guillaume; Laudet, Vincent

    2015-04-20

    Thyroid hormones have long been known for their metabolic role in humans and for triggering amphibian metamorphosis. More recently they have been uncovered as an important effector mechanism in seasonality. A recent study of salmon smoltification relates these various biological roles. PMID:25898108

  5. Dual Identity as a Two-Edged Sword: Identity Threat and Minority School Performance

    ERIC Educational Resources Information Center

    Baysu, Gulseli; Phalet, Karen; Brown, Rupert

    2011-01-01

    Some members of ethnic minority groups respond to identity threat in ways that are detrimental to their school career, while others persist despite an unwelcoming school environment. It was hypothesized that ethnic and national identities, as combined in "separated," "assimilated," or "dual identity" strategies, moderate consequences of identity…

  6. Scavenger Receptor-A (CD204): A Two-Edged Sword in Health and Disease

    PubMed Central

    Kelley, Jim L.; Ozment, Tammy R.; Li, Chuanfu; Schweitzer, John B.; Williams, David L.

    2014-01-01

    Scavenger receptor A (SR-A), also known as the macrophage scavenger receptor and cluster of differentiation 204 (CD204), plays roles in lipid metabolism, atherogenesis, and a number of metabolic processes. However, recent evidence points to important roles for SR-A in inflammation, innate immunity, host defense, sepsis, and ischemic injury. Herein, we review the role of SR-A in inflammation, innate immunity, host defense, sepsis, cardiac and cerebral ischemic injury, Alzheimer’s disease, virus recognition and uptake, bone metabolism, and pulmonary injury. Interestingly, SR-A is reported to be host protective in some disease states, but there is also compelling evidence that SR-A plays a role in the pathophysiology of other diseases. These observations of both harmful and beneficial effects of SR-A are discussed here in the framework of inflammation, innate immunity, and endoplasmic reticulum stress. PMID:24941076

  7. The blunt-edged sword: genetic explanations of misbehavior neither mitigate nor aggravate punishment

    PubMed Central

    Scurich, Nicholas; Appelbaum, Paul

    2015-01-01

    Links between genetic variants and negatively valenced behaviors have stimulated intense commentary about the implications for responsibility and punishment. Previous research has suggested that behavioral genetic evidence of a predisposition to negative behaviors has modest to no impact on mitigation of punishment, at least for serious crimes. Data are presented on the effect of such evidence in a representative sample of the general population (n = 640) asked to consider three vignettes describing lesser offenses, dealt with in less formal adjudicatory settings and in everyday life. Genetic explanations of behavior had no effect on the severity of the punishment selected in any case, in contrast to the egregiousness of the behavior and respondents’ beliefs in free-will. Public views of genetic influences on behavior may be less deterministic and more nuanced than is often thought, or genetic explanations may simply not have the salience for decision makers that is frequently attributed to them. PMID:27239327

  8. My Patient, My Stalker Empathy as a Dual-Edged Sword: A Cautionary Tale.

    PubMed

    Farber, Sharon K

    2015-01-01

    Success in psychotherapy is correlated with the "fit" between patient and therapist, a factor related to attachment. For psychotherapists of any orientation, empathy and building the bond of attachment is our stock-in-trade. When empathy builds the bond of attachment with someone starved for connection, a therapist may inadvertently set him- or herself up to become a victim of a stalker. Because individuals who stalk others suffer from severe attachment disorders, their hunger for attachment motivates them to shadow psychotherapists, which makes being stalked a very real occupational hazard for psychotherapists. This was a painful discovery for me. I was stalked for 11 months, leaving me with post-traumatic stress disorder. After recovering, I deconstructed the experience to understand how and why it happened, and discovered that it was my empathy and compassion that contributed to and maintained the stalking. What I learned from the forensic literature provided the knowledge and confidence needed to end the stalking. In this paper recommendations are made about how to prevent stalking and to halt it if it does happens. PMID:26414313

  9. Exclusive contracts in the hospital setting: a two-edged sword, part 1: legal issues.

    PubMed

    Portman, Robert M

    2007-05-01

    Hospitals routinely enter into contracts with radiology groups for the right to be the exclusive provider of radiology services at the facility in exchange for the group agreeing to provide and manage all aspects of that service within the hospital. These "exclusive contracts" generally result in the radiology department and associated equipment being closed off to physicians who are not part of the contracting group. Exclusive contracts are generally considered to be good for physicians who have them and bad for those excluded by them. In fact, while exclusive contracts offer obvious benefits to the physicians who receive them and obvious disadvantages for those who are excluded, they also present pitfalls for physicians in the chosen group. Part I of this article discusses the legal issues raised by exclusive contracts. Although these agreements appear to be anti-competitive, most courts have rejected antitrust challenges to exclusive contracts. Excluded physicians have had much greater success in attacking exclusive contracting arrangements on breach of contract and procedural/due process grounds. Exclusive contracting arrangements can also raise concerns under the Medicare-Medicaid anti-kickback statute if the contracting physicians are required to pay consideration or accept less than fair market value compensation in exchange for exclusive contracts. These agreements can also raise issues under the Stark II physician self-referral law if the contracting physicians are in a position to refer Medicare or Medicaid patients to the hospital. Part II of this article will discuss the advantages and disadvantages of exclusive contracts for physicians covered and not covered by such contracts, as well as strategies for avoiding them or minimizing their potential adverse impact. It also will discuss specific provisions of exclusive contracts that should be included or avoided.

  10. Pro- and anti-inflammatory cytokines in tuberculosis: a two-edged sword in TB pathogenesis.

    PubMed

    Etna, Marilena Paola; Giacomini, Elena; Severa, Martina; Coccia, Eliana Marina

    2014-12-01

    A major challenge in tuberculosis (TB) is to improve current vaccination and therapeutic strategies and this requires a fine understanding of the mechanisms that mediate protection and pathogenesis. We need to discern how the host perceives Mycobacterium tuberculosis (Mtb) infection, what are the danger signals that activate the immune system and, in turn, how the immune response controls the life-cycle of Mtb. Cytokines, because of their nature of soluble mediators, represent key elements in mediating and tuning these complex processes. In this review, we provide an overview of recent studies on cytokines expression and function in active (mainly human) TB. Understanding of the balance between pro- and anti-inflammatory networks is crucial to refine our knowledge on the immune responses directed against Mtb.

  11. If SWORD Is the Answer, What Is the Question?: Use of the Simple Web-Service Offering Repository Deposit Protocol

    ERIC Educational Resources Information Center

    Lewis, Stuart; Hayes, Leonie; Newton-Wade, Vanessa; Corfield, Antony; Davis, Richard; Donohue, Tim; Wilson, Scott

    2009-01-01

    Purpose: The purpose of this paper is to describe the repository deposit protocol, Simple Web-service Offering Repository Deposit (SWORD), its development iteration, and some of its potential use cases. In addition, seven case studies of institutional use of SWORD are provided. Design/methodology/approach: The paper describes the recent…

  12. The Orion Nebula: The Jewel in the Sword

    NASA Astrophysics Data System (ADS)

    2001-01-01

    Orion the Hunter is perhaps the best known constellation in the sky, well placed in the evening at this time of the year for observers in both the northern and southern hemispheres, and instantly recognisable. And for astronomers, Orion is surely one of the most important constellations, as it contains one of the nearest and most active stellar nurseries in the Milky Way, the galaxy in which we live. Here tens of thousands of new stars have formed within the past ten million years or so - a very short span of time in astronomical terms. For comparison: our own Sun is now 4,600 million years old and has not yet reached half-age. Reduced to a human time-scale, star formation in Orion would have been going on for just one month as compared to the Sun's 40 years. Just below Orion's belt, the hilt of his sword holds a great jewel in the sky, the beautiful Orion Nebula . Bright enough to be seen with the naked eye, a small telescope or even binoculars show the nebula to be a few tens of light-years' wide complex of gas and dust, illuminated by several massive and hot stars at its core, the famous Trapezium stars . However, the heart of this nebula also conceals a secret from the casual observer. There are in fact about one thousand very young stars about one million years old within the so-called Trapezium Cluster , crowded into a space less than the distance between the Sun and its nearest neighbour stars. The cluster is very hard to observe in visible light, but is clearly seen in the above spectacular image of this area ( ESO PR 03a/01 ), obtained in December 1999 by Mark McCaughrean (Astrophysical Institute Potsdam, Germany) and his collaborators [1] with the infrared multi-mode ISAAC instrument on the ESO Very Large Telescope (VLT) at Paranal (Chile). Many details are seen in the new ISAAC image ESO PR Photo 03b/01 ESO PR Photo 03b/01 [Preview - JPEG: 400 x 589 pix - 62k] [Normal - JPEG: 800 x 1178 pix - 648k] [Hires - JPEG: 1957 x 2881 pix - 2.7M] ESO PR Photo 03c

  13. Study on the d state of platinum in Pt/SiO sub 2 and Na/Pt/SiO sub 2 catalysts under C double bond C hydrogenation conditions by X-ray absorption near-edge structure spectroscopy

    SciTech Connect

    Yoshitake, Hideaki; Iwasawa, Yasuhiro )

    1991-09-19

    The change in the d-electron density of platinum during D{sub 2} + CH{sub 2}{double bond}CHX reactions on Pt/SiO{sub 2} and Na/Pt/SiO{sub 2} catalysts and its influence on the catalysis were studied by X-ray absorption near-edge structure (XANES) spectroscopy, kinetics and FT-IR. It was demonstrated from the change of the white lines in XANES spectra at Pt L{sub 2} and L{sub 3} edges that CH{sub 2}{double bond}CHX (X = H, CH{sub 3}, COCH{sub 3}, CF{sub 3}, and CN) is adsorbed on the Pt surface and extracts the electrons of the d state. Hence, the deuterogenation rate is reduced as the value of Hammett's {sigma}{sub P} increases. The linear free energy relationship between the reaction rate and {sigma}{sub P} was observed for the deuterogenation of CH{sub 2}{double bond}CHX. The rate of ethene deuterogenation was promoted by Na{sub 2}O addition. The electron density of unoccupied d states of pt under vacuum decreased by Na{sub 2}O addition, indicating the electron donation from Na{sub 2}O addition. The electron density of unoccupied d states of Pt under vacuum decreased by Na{sub 2}O addition, indicating the electron donation from Na{sub 2}O addition. However, most of these additional electrons were observed to move to ethene under reaction conditions. The acceptor of the electrons was suggested by di-{sigma}-ethene by the shift of {upsilon}(C-H). The kinetic parameters are discussed in relation to the change in the d state of Pt as a function of {sigma}{sub P} and Na quantity.

  14. Is the sword moss (Bryoxiphium) a preglacial Tertiary relict?

    PubMed

    Patiño, Jairo; Goffinet, Bernard; Sim-Sim, Manuela; Vanderpoorten, Alain

    2016-03-01

    The disjunction of floras between East Asia, Southeast North America, West North America, and Southwest Eurasia has been interpreted in terms of the fragmentation of a once continuous mixed mesophytic forest that occurred throughout the Northern Hemisphere due to the climatic and geological changes during the late Tertiary. The sword moss, Bryoxiphium, exhibits a distribution that strikingly resembles that of the mesophytic forest elements such as Liriodendron and is considered as the only living member of an early Tertiary flora in Iceland. These hypotheses are tested here using molecular dating analyses and ancestral area estimations. The results suggest that the extant range of Bryoxiphium results from the fragmentation of a formerly wider range encompassing North America and Southeast Asia about 10 million years ago. The split of continental ancestral populations is too recent to match with a continental drift scenario but is spatially and temporally remarkably congruent with that observed in Tertiary angiosperm relict species. The timing of the colonization of Iceland from Macaronesian ancestors, about two million years ago, is, however, incompatible with the hypothesis that Bryoxiphium is the only living member of an early Tertiary flora of the island. Alaska was recurrently colonized from East Asia. The ability of Bryoxiphium to overcome large oceanic barriers is further evidenced by its occurrence on remote oceanic archipelagos. In particular, Madeira was colonized twice independently from American and East Asian ancestors, respectively. The striking range disjunction of Bryoxiphium is interpreted in terms of its mating system, as the taxon exhibits a very singular pattern of spatial segregation of the sexes. PMID:26708122

  15. Is the sword moss (Bryoxiphium) a preglacial Tertiary relict?

    PubMed

    Patiño, Jairo; Goffinet, Bernard; Sim-Sim, Manuela; Vanderpoorten, Alain

    2016-03-01

    The disjunction of floras between East Asia, Southeast North America, West North America, and Southwest Eurasia has been interpreted in terms of the fragmentation of a once continuous mixed mesophytic forest that occurred throughout the Northern Hemisphere due to the climatic and geological changes during the late Tertiary. The sword moss, Bryoxiphium, exhibits a distribution that strikingly resembles that of the mesophytic forest elements such as Liriodendron and is considered as the only living member of an early Tertiary flora in Iceland. These hypotheses are tested here using molecular dating analyses and ancestral area estimations. The results suggest that the extant range of Bryoxiphium results from the fragmentation of a formerly wider range encompassing North America and Southeast Asia about 10 million years ago. The split of continental ancestral populations is too recent to match with a continental drift scenario but is spatially and temporally remarkably congruent with that observed in Tertiary angiosperm relict species. The timing of the colonization of Iceland from Macaronesian ancestors, about two million years ago, is, however, incompatible with the hypothesis that Bryoxiphium is the only living member of an early Tertiary flora of the island. Alaska was recurrently colonized from East Asia. The ability of Bryoxiphium to overcome large oceanic barriers is further evidenced by its occurrence on remote oceanic archipelagos. In particular, Madeira was colonized twice independently from American and East Asian ancestors, respectively. The striking range disjunction of Bryoxiphium is interpreted in terms of its mating system, as the taxon exhibits a very singular pattern of spatial segregation of the sexes.

  16. The Effects of Negative Differential Resistance, Bipolar Spin-Filtering, and Spin-Rectifying on Step-Like Zigzag Graphene Nanoribbons Heterojunctions with Single or Double Edge-Saturated Hydrogen

    NASA Astrophysics Data System (ADS)

    Wang, Lihua; Zhao, Jianguo; Ding, Bingjun; Guo, Yong

    2016-09-01

    In this study, we investigated the spin-resolved transport aspects of step-like zigzag graphene ribbons (ZGNRs) with single or double edge-saturated hydrogen using a method that combined the density functional theory with the nonequilibrium Green's function method under the local spin density approximation. We found that, when the ZGNR-based heterojunctions were in a parallel or antiparallel layout, negative differential resistance, the maximum bipolar spin-filtering, and spin-rectifying effects occurred synchronously except for the case of spin-down electrons in the parallel magnetic layouts. Interestingly, these spin-resolved transport properties were almost unaffected by altering the widths of the two component ribbons. Therefore, step-like ZGNR heterojunctions are promising for use in designing high-performance multifunctional spintronic devices.

  17. Edge Bioinformatics

    SciTech Connect

    Lo, Chien-Chi

    2015-08-03

    Edge Bioinformatics is a developmental bioinformatics and data management platform which seeks to supply laboratories with bioinformatics pipelines for analyzing data associated with common samples case goals. Edge Bioinformatics enables sequencing as a solution and forward-deployed situations where human-resources, space, bandwidth, and time are limited. The Edge bioinformatics pipeline was designed based on following USE CASES and specific to illumina sequencing reads. 1. Assay performance adjudication (PCR): Analysis of an existing PCR assay in a genomic context, and automated design of a new assay to resolve conflicting results; 2. Clinical presentation with extreme symptoms: Characterization of a known pathogen or co-infection with a. Novel emerging disease outbreak or b. Environmental surveillance

  18. Edge Bioinformatics

    2015-08-03

    Edge Bioinformatics is a developmental bioinformatics and data management platform which seeks to supply laboratories with bioinformatics pipelines for analyzing data associated with common samples case goals. Edge Bioinformatics enables sequencing as a solution and forward-deployed situations where human-resources, space, bandwidth, and time are limited. The Edge bioinformatics pipeline was designed based on following USE CASES and specific to illumina sequencing reads. 1. Assay performance adjudication (PCR): Analysis of an existing PCR assay in amore » genomic context, and automated design of a new assay to resolve conflicting results; 2. Clinical presentation with extreme symptoms: Characterization of a known pathogen or co-infection with a. Novel emerging disease outbreak or b. Environmental surveillance« less

  19. Edge conduction in vacuum glazing

    SciTech Connect

    Simko, T.M.; Collins, R.E.; Beck, F.A.; Arasteh, D.

    1995-03-01

    Vacuum glazing is a form of low-conductance double glazing using in internal vacuum between the two glass sheets to eliminate heat transport by gas conduction and convection. An array of small support pillars separates the sheets; fused solder glass forms the edge seal. Heat transfer through the glazing occurs by radiation across the vacuum gap, conduction through the support pillars, and conduction through the bonded edge seal. Edge conduction is problematic because it affects stresses in the edge region, leading to possible failure of the glazing; in addition, excessive heat transfer because of thermal bridging in the edge region can lower overall window thermal performance and decrease resistance to condensation. Infrared thermography was used to analyze the thermal performance of prototype vacuum glazings, and, for comparison, atmospheric pressure superwindows. Research focused on mitigating the edge effects of vacuum glazings through the use of insulating trim, recessed edges, and framing materials. Experimentally validated finite-element and finite-difference modeling tools were used for thermal analysis of prototype vacuum glazing units and complete windows. Experimental measurements of edge conduction using infrared imaging were found to be in good agreement with finite-element modeling results for a given set of conditions. Finite-element modeling validates an analytic model developed for edge conduction.

  20. Sword-Like Trauma to the Shoulder with Open Head-Splitting Fracture of the Head

    PubMed Central

    Pantazis, Konstantinos; Iliopoulos, Ilias; Seferlis, Ioannis; Kokkalis, Zinon

    2016-01-01

    Head-splitting fractures occur as a result of violent compression of the head against the glenoid; the head splits and the tuberosities may remain attached to the fragments or split and separate. Isolated humeral head-splitting fractures are rare injuries. Favorable results with osteosynthesis can be difficult to achieve because of the very proximal location of the head fracture and associated poor vascularity. We present a case of a 67-year-old man who sustained a severe, sword-like trauma to his left shoulder after a road traffic accident with associated isolated open Gustilo-Anderson IIIA humeral head-splitting fracture. Bony union was achieved with minimal internal fixation but the clinical outcome deteriorated due to accompanying axillary nerve apraxia. To our knowledge, this type of sword-like injury with associated humeral head-split fracture has not previously been reported. PMID:27478665

  1. Sword-Like Trauma to the Shoulder with Open Head-Splitting Fracture of the Head.

    PubMed

    Panagopoulos, Andreas; Pantazis, Konstantinos; Iliopoulos, Ilias; Seferlis, Ioannis; Kokkalis, Zinon

    2016-01-01

    Head-splitting fractures occur as a result of violent compression of the head against the glenoid; the head splits and the tuberosities may remain attached to the fragments or split and separate. Isolated humeral head-splitting fractures are rare injuries. Favorable results with osteosynthesis can be difficult to achieve because of the very proximal location of the head fracture and associated poor vascularity. We present a case of a 67-year-old man who sustained a severe, sword-like trauma to his left shoulder after a road traffic accident with associated isolated open Gustilo-Anderson IIIA humeral head-splitting fracture. Bony union was achieved with minimal internal fixation but the clinical outcome deteriorated due to accompanying axillary nerve apraxia. To our knowledge, this type of sword-like injury with associated humeral head-split fracture has not previously been reported. PMID:27478665

  2. SoftWare for Optimization of Radiation Detectors, SWORD Version 5.0.

    SciTech Connect

    STRICKMAN, MARK S.

    2013-10-23

    Version 05 SoftWare for Optimization of Radiation Detectors (SWORD) is a framework to allow easy simulation and evaluation of radiation detection systems. It is targeted at system designers, who want to evaluate and optimize system parameters without actually building hardware first, at sponsors who need to evaluate proposed or actual system designs independent of the supplier, without having access to actual hardware, and at operators who want to use simulation to evaluate observed phenomena. SWORD is vertically integrated and modular. It allows users to define their own radiation detection instruments by building them from basic geometric “objects” and assigning those objects materials, detection, and/or radioactive emission properties. This process is accomplished by a CAD-like graphical user interface, in which objects may be defined, translated, rotated, grouped, arrayed, and/or nested to produce compound objects. In addition to providing the ability to build a detection system model from scratch, SWORD provides a library of “standard” detector design objects that can be used “as is” or modified by the user.

  3. Sulfur and iron accumulation in three marine-archaeological shipwrecks in the Baltic Sea: The Ghost, the Crown and the Sword

    PubMed Central

    Fors, Yvonne; Grudd, Håkan; Rindby, Anders; Jalilehvand, Farideh; Sandström, Magnus; Cato, Ingemar; Bornmalm, Lennart

    2014-01-01

    Sulfur and iron concentrations in wood from three 17th century shipwrecks in the Baltic Sea, the Ghost wreck, the Crown and the Sword, were obtained by X-ray fluorescence (XRF) scanning. In near anaerobic environments symbiotic microorganisms degrade waterlogged wood, reduce sulfate and promote accumulation of low-valent sulfur compounds, as previously found for the famous wrecks of the Vasa and Mary Rose. Sulfur K-edge X-ray absorption near-edge structure (XANES) analyses of Ghost wreck wood show that organic thiols and disulfides dominate, together with elemental sulfur probably generated by sulfur-oxidizing Beggiatoa bacteria. Iron sulfides were not detected, consistent with the relatively low iron concentration in the wood. In a museum climate with high atmospheric humidity oxidation processes, especially of iron sulfides formed in the presence of corroding iron, may induce post-conservation wood degradation. Subject to more general confirmation by further analyses no severe conservation concerns are expected for the Ghost wreck wood. PMID:24573214

  4. The Orion Nebula: The Jewel in the Sword

    NASA Astrophysics Data System (ADS)

    2001-01-01

    Orion the Hunter is perhaps the best known constellation in the sky, well placed in the evening at this time of the year for observers in both the northern and southern hemispheres, and instantly recognisable. And for astronomers, Orion is surely one of the most important constellations, as it contains one of the nearest and most active stellar nurseries in the Milky Way, the galaxy in which we live. Here tens of thousands of new stars have formed within the past ten million years or so - a very short span of time in astronomical terms. For comparison: our own Sun is now 4,600 million years old and has not yet reached half-age. Reduced to a human time-scale, star formation in Orion would have been going on for just one month as compared to the Sun's 40 years. Just below Orion's belt, the hilt of his sword holds a great jewel in the sky, the beautiful Orion Nebula . Bright enough to be seen with the naked eye, a small telescope or even binoculars show the nebula to be a few tens of light-years' wide complex of gas and dust, illuminated by several massive and hot stars at its core, the famous Trapezium stars . However, the heart of this nebula also conceals a secret from the casual observer. There are in fact about one thousand very young stars about one million years old within the so-called Trapezium Cluster , crowded into a space less than the distance between the Sun and its nearest neighbour stars. The cluster is very hard to observe in visible light, but is clearly seen in the above spectacular image of this area ( ESO PR 03a/01 ), obtained in December 1999 by Mark McCaughrean (Astrophysical Institute Potsdam, Germany) and his collaborators [1] with the infrared multi-mode ISAAC instrument on the ESO Very Large Telescope (VLT) at Paranal (Chile). Many details are seen in the new ISAAC image ESO PR Photo 03b/01 ESO PR Photo 03b/01 [Preview - JPEG: 400 x 589 pix - 62k] [Normal - JPEG: 800 x 1178 pix - 648k] [Hires - JPEG: 1957 x 2881 pix - 2.7M] ESO PR Photo 03c

  5. Edge detection

    NASA Astrophysics Data System (ADS)

    Hildreth, E. C.

    1985-09-01

    For both biological systems and machines, vision begins with a large and unwieldly array of measurements of the amount of light reflected from surfaces in the environment. The goal of vision is to recover physical properties of objects in the scene such as the location of object boundaries and the structure, color and texture of object surfaces, from the two-dimensional image that is projected onto the eye or camera. This goal is not achieved in a single step: vision proceeds in stages, with each stage producing increasingly more useful descriptions of the image and then the scene. The first clues about the physical properties of the scene are provided by the changes of intensity in the image. The importance of intensity changes and edges in early visual processing has led to extensive research on their detection, description and use, both in computer and biological vision systems. This article reviews some of the theory that underlies the detection of edges, and the methods used to carry out this analysis.

  6. The Pill Really Can Be Mightier Than the Sword: A Response to Recent Commentaries

    PubMed Central

    Potts, Malcolm; Graves, Alisha

    2016-01-01

    We appreciate the four commentaries that add new material and fresh perspectives to our article "The pill is mightier than the sword." In emphasizing the role of voluntary family planning and girls’ education as achievable strategies with a potential to make the world a more peaceable place, we did not mean to oversimplify or disregard the intrinsic complexity of human conflict. On the whole, the commentators support and add to our thesis, although we question Pillai and Ya-Chien Wang’s suggestion that we may have overstated the unique human predisposition to kill our own species. We present additional data on male team aggression. PMID:26927598

  7. The Pill Really Can Be Mightier Than the Sword: A Response to Recent Commentaries.

    PubMed

    Potts, Malcolm; Graves, Alisha

    2016-03-01

    We appreciate the four commentaries that add new material and fresh perspectives to our article "The pill is mightier than the sword." In emphasizing the role of voluntary family planning and girls' education as achievable strategies with a potential to make the world a more peaceable place, we did not mean to oversimplify or disregard the intrinsic complexity of human conflict. On the whole, the commentators support and add to our thesis, although we question Pillai and Ya-Chien Wang's suggestion that we may have overstated the unique human predisposition to kill our own species. We present additional data on male team aggression. PMID:26927598

  8. The Edge

    NASA Technical Reports Server (NTRS)

    2006-01-01

    6 April 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows the edge (running diagonally from the lower left to the upper right) of a trough, which is part of a large pit crater complex in Noachis Terra. This type of trough forms through the collapse of surface materials into the subsurface, and often begins as a series of individual pit craters. Over time, continued collapse increases the diameter of individual pits until finally, adjacent pits merge to form a trough such as the one captured in this image. The deep shadowed area is caused in part by an overhang; layered rock beneath this overhang is less resistant to erosion, and thus has retreated tens of meters backward, beneath the overhang. A person could walk up inside this 'cave' formed by the overhanging layered material.

    Location near: 47.0oS, 355.7oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  9. Hospital security's two-edged sword: over-reliance on automation, under-reliance on experienced personnel.

    PubMed

    Kelty, J

    The article explores the current trend in the healthcare industry of cutting not only personnel--security directors, managers, and security officers--but also training programs in the name of budget cuts. What are the dangers to patient protection? What changes can be made to operate more effectively in this economic climate? Why does over-reliance on automation create problems of its own?

  10. Hospital security's two-edged sword: over-reliance on automation, under-reliance on experienced personnel.

    PubMed

    Kelty, J

    The article explores the current trend in the healthcare industry of cutting not only personnel--security directors, managers, and security officers--but also training programs in the name of budget cuts. What are the dangers to patient protection? What changes can be made to operate more effectively in this economic climate? Why does over-reliance on automation create problems of its own? PMID:11382995

  11. Electronic and chemical state of aluminum from the single- (K) and double-electron excitation (KLII&III, KLI) x-ray absorption near-edge spectra of α-alumina, sodium aluminate, aqueous Al³⁺•(H₂O)₆, and aqueous Al(OH)₄⁻

    SciTech Connect

    Fulton, John L.; Govind, Niranjan; Huthwelker, Thomas; Bylaska, Eric J.; Vjunov, Aleksei; Pin, Sonia; Smurthwaite, Tricia D.

    2015-07-02

    We probe, at high energy resolution, the double electron excitation (KLII&II) x-ray absorption region that lies approximately 115 eV above the main Al K-edge (1566 eV) of α-alumina and sodium aluminate. The two solid standards, α-alumina (octahedral) and sodium aluminate (tetrahedral) are compared to aqueous species that have the same Al coordination symmetries, Al³⁺•6H₂O (octahedral) and Al(OH)₄⁻ (tetrahedral). For the octahedral species, the edge height of the KLII&III-edge is approximately 10% of the main K-edge however the edge height is much weaker (3% of K-edge height) for Al species with tetrahedral symmetry. For the α-alumina and aqueous Al³⁺•6H₂O the KLII&III spectra contain white line features and extended absorption fine structure (EXAFS) that mimics the K-edge spectra. The KLII&III-edge feature interferes with an important region of the extended-XAFS region of the spectra for the K-edge of the crystalline and aqueous standards. The K-edge spectra and K-edge positions are predicted using time-dependent density functional theory (TDDFT). The TDDFT calculations for the K-edge XANES spectra reproduce the observed transitions in the experimental spectra of the four Al species. The KLII&III and KLI onsets and their corresponding chemical shifts for the four standards are estimated using the delta self-consistent field (ΔSCF) method. Research by JLF, NG, EJB, AV, TDS was supported by U.S. Department of Energy’s (DOE), Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. NG thanks Amity Andersen for help with the α-Al₂O₃ and tetrahedral sodium aluminate (NaAlO₂) clusters. All the calculations were performed using the Molecular Science Computing Capability at EMSL, a national scientific user facility sponsored by the U.S. Department of Energy’s Office of Biological and Environmental Research and located at

  12. Unified EDGE

    SciTech Connect

    2007-06-18

    UEDGE is an interactive suite of physics packages using the Python or BASIS scripting systems. The plasma is described by time-dependent 2D plasma fluid equations that include equations for density, velocity, ion temperature, electron temperature, electrostatic potential, and gas density in the edge region of a magnetic fusion energy confinement device. Slab, cylindrical, and toroidal geometries are allowed, and closed and open magnetic field-line regions are included. Classical transport is assumed along magnetic field lines, and anomalous transport is assumed across field lines. Multi-charge state impurities can be included with the corresponding line-radiation energy loss. Although UEDGE is written in Fortran, for efficient execution and analysis of results, it utilizes either Python or BASIS scripting shells. Python is easily available for many platforms (http://www.Python.org/). The features and availability of BASIS are described in “Basis Manual Set” by P.F. Dubois, Z.C. Motteler, et al., Lawrence Livermore National Laboratory report UCRL-MA-1 18541, June, 2002 and http://basis.llnl.gov. BASIS has been reviewed and released by LLNL for unlimited distribution. The Python version utilizes PYBASIS scripts developed by D.P. Grote, LLNL. The Python version also uses MPPL code and MAC Perl script, available from the public-domain BASIS source above. The Forthon version of UEDGE uses the same source files, but utilizes Forthon to produce a Python-compatible source. Forthon has been developed by D.P. Grote at LBL (see http://hifweb.lbl.gov/Forthon/ and Grote et al. in the references below), and it is freely available. The graphics can be performed by any package importable to Python, such as PYGIST.

  13. Unified EDGE

    2007-06-18

    UEDGE is an interactive suite of physics packages using the Python or BASIS scripting systems. The plasma is described by time-dependent 2D plasma fluid equations that include equations for density, velocity, ion temperature, electron temperature, electrostatic potential, and gas density in the edge region of a magnetic fusion energy confinement device. Slab, cylindrical, and toroidal geometries are allowed, and closed and open magnetic field-line regions are included. Classical transport is assumed along magnetic field lines,more » and anomalous transport is assumed across field lines. Multi-charge state impurities can be included with the corresponding line-radiation energy loss. Although UEDGE is written in Fortran, for efficient execution and analysis of results, it utilizes either Python or BASIS scripting shells. Python is easily available for many platforms (http://www.Python.org/). The features and availability of BASIS are described in “Basis Manual Set” by P.F. Dubois, Z.C. Motteler, et al., Lawrence Livermore National Laboratory report UCRL-MA-1 18541, June, 2002 and http://basis.llnl.gov. BASIS has been reviewed and released by LLNL for unlimited distribution. The Python version utilizes PYBASIS scripts developed by D.P. Grote, LLNL. The Python version also uses MPPL code and MAC Perl script, available from the public-domain BASIS source above. The Forthon version of UEDGE uses the same source files, but utilizes Forthon to produce a Python-compatible source. Forthon has been developed by D.P. Grote at LBL (see http://hifweb.lbl.gov/Forthon/ and Grote et al. in the references below), and it is freely available. The graphics can be performed by any package importable to Python, such as PYGIST.« less

  14. SoftWare for Optimization of Radiation Detectors, SWORD Version 5.0.

    2013-10-23

    Version 05 SoftWare for Optimization of Radiation Detectors (SWORD) is a framework to allow easy simulation and evaluation of radiation detection systems. It is targeted at system designers, who want to evaluate and optimize system parameters without actually building hardware first, at sponsors who need to evaluate proposed or actual system designs independent of the supplier, without having access to actual hardware, and at operators who want to use simulation to evaluate observed phenomena. SWORDmore » is vertically integrated and modular. It allows users to define their own radiation detection instruments by building them from basic geometric “objects” and assigning those objects materials, detection, and/or radioactive emission properties. This process is accomplished by a CAD-like graphical user interface, in which objects may be defined, translated, rotated, grouped, arrayed, and/or nested to produce compound objects. In addition to providing the ability to build a detection system model from scratch, SWORD provides a library of “standard” detector design objects that can be used “as is” or modified by the user.« less

  15. Hippocratic ideal, Faustian bargain and Damocles' sword: erosion of patient autonomy in obstetrics.

    PubMed

    Rybak, E A

    2009-11-01

    Respect for patient autonomy remains a foundational principle guiding the ethical practice of medicine-a mission first articulated by Hippocrates. Damocles, another figure from ancient Greece, provides a useful parable for describing performance under distress: Damocles loses his desire for opulence and power when he notices a sword dangling precariously above his head. Contemporary obstetricians deciding whether to forestall or impose major abdominal surgery on parturients entrusted to their care struggle valiantly in the chasm dividing Hippocratic idealism from the economic realism driven by the medicolegal sword of Damocles. Given the inherent risk of unforeseeable and unsalvageable fetal catastrophe during labor and vaginal delivery, and the often unsubstantiated, yet automatic, allegation of negligence that follows a labor-associated adversity, obstetricians-and their liability insurance carriers-have recalibrated obstetric practice in alignment with the increasingly risk-averse preferences of most patients. Indeed, less intrapartum risk for patients and less corresponding medicolegal exposure for obstetricians help explain the rising cesarean delivery rate and, more importantly, the steady disappearance of higher-risk interventions such as vaginal birth after cesarean (VBAC). Is this increasing reluctance to offer VBAC supervision ethically defensible? This paper argues that it is. Fiduciary professionalism mandates physician self-sacrifice, not self-destruction; a VBAC gone awry without negligence or substandard care may, nevertheless, render future affordable liability coverage unattainable. Yet, the unavailability of VBAC infringes on the autonomy of women who want to assume the intrapartum risks of a VBAC in lieu of a repeat cesarean delivery. The proposed solution is the regionalization of VBAC care provision in designated medical centers and/or the implementation of binding arbitration in an ethical trade-off to enhance patient autonomy regarding the

  16. Quality Coaching Counts

    ERIC Educational Resources Information Center

    Gould, Daniel

    2016-01-01

    Scholastic sport is a double-edged sword that can have positive or negative effects. Whether those effects are positive or negative depends on those who wield that sword--chiefly, the school's sports coach. While it is clear that coaches make a difference in ensuring that educational athletics lead to beneficial outcomes for student-athletes, a…

  17. James Sowerby: meteorites and his meteoritic sword made for the Emperor of Russia, Alexander I, in 1814

    PubMed Central

    Henderson, Paul

    2013-01-01

    James Sowerby included meteorites in his publications of British and exotic natural history and so raised interest in their nature and origins at a time of much debate and involving the President of the Royal Society, Sir Joseph Banks. The celebrations over the defeat of France in 1814 prompted Sowerby to make a sword from the Cape of Good Hope iron meteorite to present to the Russian Emperor, Alexander I, at the time of his state visit to London in June 1814 and in recognition of his achievements in bringing peace to Europe. The story of its attempted presentation, its final reception and the following response, including publications, all helped to increase interest in meteorites and their properties. The rediscovery of the sword after a lengthy disappearance probably brings an unusual saga to a fitting close.

  18. The edges of graphene.

    PubMed

    Zhang, Xiuyun; Xin, John; Ding, Feng

    2013-04-01

    The edge of two dimensional (2D) graphene, as the surface of a three dimensional (3D) crystal, plays a crucial role in the determination of its physical, electronic and chemical properties and thus has been extensively studied recently. In this review, we summarize the recent advances in the study of graphene edges, including edge formation energy, edge reconstruction, method of graphene edge synthesis and the recent progress on metal-passivated graphene edges and the role of edges in graphene CVD growth. We expect this review to provide a guideline for readers to gain a clear picture of graphene edges from several aspects, especially the catalyst-passivated graphene edges and their role in graphene CVD growth.

  19. Leather material found on a 6th B.C. Chinese bronze sword: A technical study

    NASA Astrophysics Data System (ADS)

    Luo, Wugan; Si, Yi; Wang, Hongmin; Qin, Ying; Huang, Fengchun; Wang, Changsui

    2011-09-01

    During July to November, 2006, an important archaeological excavation was conducted in Yun country, Hubei province, southern China. Chinese archaeologists found some remnant of leather materials, covered with red pigments, on a 6th century B.C. Chinese bronze sword. To understand the technology/ies that may have been utilized for manufacturing the leathers, a combined of Raman spectroscopy, FT-IR and XRF was thus applied to the remnant of leather materials. Raman analyses showed that red pigment on the leather was cinnabar (HgS). FT-IR and XRF analyses indicated that the content of some elements, such as Ca (existing as CaCO 3) and Fe (existing as Fe 2O 3), were much higher than those in the surrounding grave soil. The results inferred an application of lime depilation and retting, and the Fe-Al compound salt as tanning agent. And it was furthermore implicated that the Fe-Al salt tanning technique had been developed in the middle and late Spring and Autumn Period of China.

  20. SWORD '99: surveillance of work-related and occupational respiratory disease in the UK.

    PubMed

    Meyer, J D; Holt, D L; Chen, Y; Cherry, N M; McDonald, J C

    2001-05-01

    Systematic reports from chest and occupational physicians under the SWORD and OPRA (Occupational Physicians Reporting Activity) surveillance schemes continue to provide a picture of the incidence of occupational respiratory disease in the UK. An estimated total of 4393 incident cases (comprising 4530 diagnoses) were reported during the 1999 calendar year, an increase of 1427 cases over the previous year. Benign pleural disease was the single most frequently reported condition (28% of all diagnoses reported). Occupational asthma cases (1168; 26%) remained high, as did mesothelioma (1032; 23%). Analysis of trends over the past 8 years shows an increase in mesothelioma cases, but little change in asthma. The annual incidence per 100,000 employed people, 1996-1999, for mesothelioma, lung cancer and pneumoconiosis was high amongst construction workers (28.7), miners and quarrymen (26.5), woodworkers (18.9) and gas, coal and chemical workers (15.2). Trends in mesothelioma incidence by birth cohort continue to show an increase in construction workers and a continuing decline in shipyard and insulation workers. The relative proportion of pneumoconiosis cases attributed to coal mining has fallen steadily in workers born since approximately 1920 and most cases are now in men who have been employed in quarrying and rock drilling. PMID:11385125

  1. Canavanine content in sword beans (Canavalia gladiata): analysis and effect of processing.

    PubMed

    Ekanayake, S; Skog, K; Asp, N-G

    2007-05-01

    The amino acid canavanine is a potentially toxic constituent of leguminous seeds. The aim of the present study was to determine the ability of different processing methods to reduce canavanine in sword beans (Canavalia gladiata). For this purpose a method for the detection and quantification of canavanine was developed using reversed-phase high-performance liquid chromatography of the dabsylated derivatives. The recovery of canavanine using this method was 88-91%. Optimum extraction of canavanine from raw and processed beans was obtained by addition of hot water prior to overnight soaking. The results obtained with this method agree well with previously published values for raw seeds. The method is sensitive, specific and can successfully be applied to the detection of canavanine in legumes. Overnight soaking and boiling in excess water followed by decanting gave the most pronounced reduction in canavanine content (around 50%), followed by boiling and decanting excess water (34%). Roasting as used in this study and autoclaving were less effective in reducing the canavanine content.

  2. More a plowshare than a sword: the legacy of US Cold War agricultural diplomacy.

    PubMed

    McGlade, Jacqueline

    2009-01-01

    Recently, agriculture has assumed an elevated role in world diplomacy due to pressing issues like international poverty relief, changing environmental conditions, farm trade imbalances, rising food prices, and the diversion of crops into bio-fuel production. Consequently, agricultural interests and production have become increasingly entwined with the politics of national protectionism and identity, domestic security, and the preservation of trading advantage in developed and developing countries alike. This study examines the current impasse in world agricultural negotiations as an outgrowth of US foreign aid and trade policymaking as it evolved during the Cold War. In particular, it chronicles the historic shift in US foreign policy away from "give-away" food aid and surplus sales and toward the championing of global agricultural redevelopment under such programs as the Marshall Plan and PL 480, the Food for Peace program. As more a plowshare than a sword, the American Cold War push for worldwide agricultural modernization led many countries to experience new levels of food self-efficiency and export capabilities. Along with production parity, however, has come escalating levels of trade competition and national protectionism, which challenges again the achievement of world agricultural stability and prosperity.

  3. SWORD '99: surveillance of work-related and occupational respiratory disease in the UK.

    PubMed

    Meyer, J D; Holt, D L; Chen, Y; Cherry, N M; McDonald, J C

    2001-05-01

    Systematic reports from chest and occupational physicians under the SWORD and OPRA (Occupational Physicians Reporting Activity) surveillance schemes continue to provide a picture of the incidence of occupational respiratory disease in the UK. An estimated total of 4393 incident cases (comprising 4530 diagnoses) were reported during the 1999 calendar year, an increase of 1427 cases over the previous year. Benign pleural disease was the single most frequently reported condition (28% of all diagnoses reported). Occupational asthma cases (1168; 26%) remained high, as did mesothelioma (1032; 23%). Analysis of trends over the past 8 years shows an increase in mesothelioma cases, but little change in asthma. The annual incidence per 100,000 employed people, 1996-1999, for mesothelioma, lung cancer and pneumoconiosis was high amongst construction workers (28.7), miners and quarrymen (26.5), woodworkers (18.9) and gas, coal and chemical workers (15.2). Trends in mesothelioma incidence by birth cohort continue to show an increase in construction workers and a continuing decline in shipyard and insulation workers. The relative proportion of pneumoconiosis cases attributed to coal mining has fallen steadily in workers born since approximately 1920 and most cases are now in men who have been employed in quarrying and rock drilling.

  4. More a plowshare than a sword: the legacy of US Cold War agricultural diplomacy.

    PubMed

    McGlade, Jacqueline

    2009-01-01

    Recently, agriculture has assumed an elevated role in world diplomacy due to pressing issues like international poverty relief, changing environmental conditions, farm trade imbalances, rising food prices, and the diversion of crops into bio-fuel production. Consequently, agricultural interests and production have become increasingly entwined with the politics of national protectionism and identity, domestic security, and the preservation of trading advantage in developed and developing countries alike. This study examines the current impasse in world agricultural negotiations as an outgrowth of US foreign aid and trade policymaking as it evolved during the Cold War. In particular, it chronicles the historic shift in US foreign policy away from "give-away" food aid and surplus sales and toward the championing of global agricultural redevelopment under such programs as the Marshall Plan and PL 480, the Food for Peace program. As more a plowshare than a sword, the American Cold War push for worldwide agricultural modernization led many countries to experience new levels of food self-efficiency and export capabilities. Along with production parity, however, has come escalating levels of trade competition and national protectionism, which challenges again the achievement of world agricultural stability and prosperity. PMID:19618529

  5. Historical and Metallurgical Characterization of a "Falchion" Sword Manufactured in Caino (Brescia, Italy) in the Early 17th Century A.D.

    NASA Astrophysics Data System (ADS)

    Tonelli, G.; Faccoli, M.; Gotti, R.; Roberti, R.; Cornacchia, G.

    2016-08-01

    A historical and metallurgical characterization of a "falchion" sword manufactured in Caino (Brescia, northern Italy) and dating from the early 17th century was performed to understand the manufacture methods of a Renaissance sword. At first, a set of size measurements was carried out to look for the existence of constant and/or recurring macroscopic sizes, which would indicate a standardized production, or of any type of proportionality between different parts of a sword, which would prove an intentional design activity. Light optical microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, quantometer analyses, and Vickers microhardness tests were then employed to analyze the microstructure and obtain the mechanical properties. All the metallurgical work is supported by an accurate study on the chemical composition of both metal-matrix and nonmetallic inclusions, which allowed for rebuilding and evaluating the efficiency of the whole production process.

  6. Historical and Metallurgical Characterization of a "Falchion" Sword Manufactured in Caino (Brescia, Italy) in the Early 17th Century A.D.

    NASA Astrophysics Data System (ADS)

    Tonelli, G.; Faccoli, M.; Gotti, R.; Roberti, R.; Cornacchia, G.

    2016-04-01

    A historical and metallurgical characterization of a "falchion" sword manufactured in Caino (Brescia, northern Italy) and dating from the early 17th century was performed to understand the manufacture methods of a Renaissance sword. At first, a set of size measurements was carried out to look for the existence of constant and/or recurring macroscopic sizes, which would indicate a standardized production, or of any type of proportionality between different parts of a sword, which would prove an intentional design activity. Light optical microscopy, scanning electron microscopy, energy-dispersive x-ray spectroscopy, quantometer analyses, and Vickers microhardness tests were then employed to analyze the microstructure and obtain the mechanical properties. All the metallurgical work is supported by an accurate study on the chemical composition of both metal-matrix and nonmetallic inclusions, which allowed for rebuilding and evaluating the efficiency of the whole production process.

  7. The Edge, Fall 1999.

    ERIC Educational Resources Information Center

    Edge, 1999

    1999-01-01

    "The Edge" is a Canadian publication for youth. The mandate of the Edge is to support and celebrate all career journeys embraced by youth. This issue contains career profile articles covering three jobs: crane operator, indoor climbing instructor, and product certification tester. Career trends and the state of today's workplace are also…

  8. Supersonic Leading Edge Receptivity

    NASA Technical Reports Server (NTRS)

    Maslov, Anatoly A.

    1998-01-01

    This paper describes experimental studies of leading edge boundary layer receptivity for imposed stream disturbances. Studies were conducted in the supersonic T-325 facility at ITAM and include data for both sharp and blunt leading edges. The data are in agreement with existing theory and should provide guidance for the development of more complete theories and numerical computations of this phenomena.

  9. Escape from extreme specialization: passionflowers, bats and the sword-billed hummingbird.

    PubMed

    Abrahamczyk, S; Souto-Vilarós, D; Renner, S S

    2014-11-22

    A striking example of plant/pollinator trait matching is found between Andean species of Passiflora with 6-14-cm-long nectar tubes and the sword-billed hummingbird, Ensifera ensifera, with up to 11-cm-long bills. Because of the position of their anthers and stigmas, and self-incompatibility, these passionflower species depend on E. ensifera for pollination. Field observations show that the bird and plant distribution match completely and that scarcity of Ensifera results in reduced passionflower seed set. We here use nuclear and plastid DNA sequences to investigate how often and when these mutualisms evolved and under which conditions, if ever, they were lost. The phylogeny includes 26 (70%) of the 37 extremely long-tubed species, 13 (68%) of the 19 species with tubes too short for Ensifera and four of the seven bat-pollinated species for a total of 43 (69%) of all species in Passiflora supersection Tacsonia (plus 11 outgroups). We time-calibrated the phylogeny to infer the speed of any pollinator switching. Results show that Tacsonia is monophyletic and that its stem group dates to 10.7 Ma, matching the divergence at 11.6 Ma of E. ensifera from its short-billed sister species. Whether pollination by short-billed hummingbirds or by Ensifera is the ancestral condition cannot be securely inferred, but extremely long-tubed flowers exclusively pollinated by Ensifera evolved early during the radiation of the Tacsonia clade. There is also evidence of several losses of Ensifera dependence, involving shifts to bat pollination and shorter billed birds. Besides being extremely asymmetric-a single bird species coevolving with a speciose plant clade-the Ensifera/Passiflora system is a prime example of a specialized pollinator not driving plant speciation, but instead being the precondition for the maintenance of isolated populations (through reliable seed set) that then underwent allopatric speciation. PMID:25274372

  10. The digital step edge

    NASA Technical Reports Server (NTRS)

    Haralick, R. M.

    1982-01-01

    The facet model was used to accomplish step edge detection. The essence of the facet model is that any analysis made on the basis of the pixel values in some neighborhood has its final authoritative interpretation relative to the underlying grey tone intensity surface of which the neighborhood pixel values are observed noisy samples. Pixels which are part of regions have simple grey tone intensity surfaces over their areas. Pixels which have an edge in them have complex grey tone intensity surfaces over their areas. Specially, an edge moves through a pixel only if there is some point in the pixel's area having a zero crossing of the second directional derivative taken in the direction of a non-zero gradient at the pixel's center. To determine whether or not a pixel should be marked as a step edge pixel, its underlying grey tone intensity surface was estimated on the basis of the pixels in its neighborhood.

  11. Hierarchy in a double braneworld

    SciTech Connect

    Guerrero, Rommel; Rodriguez, R. Omar; Melfo, Alejandra; Pantoja, Nelson

    2006-10-15

    We show that the hierarchy between the Planck and the weak scales can follow from the tendency of gravitons and fermions to localize at different edges of a thick double wall embedded in an AdS{sub 5} spacetime without reflection symmetry. This double wall is a stable BPS thick-wall solution with two subwalls located at its edges; fermions are coupled to the scalar field through Yukawa interactions, but the lack of reflection symmetry forces them to be localized in one of the subwalls. We show that the graviton zero-mode wave function is suppressed in the fermion edge by an exponential function of the distance between the subwalls, and that the massive modes decouple so that Newtonian gravity is recuperated.

  12. Universal edge information from wavefunction deformation

    NASA Astrophysics Data System (ADS)

    Ho, Wen Wei; Cincio, Lukasz; Moradi, Heidar; Vidal, Guifre

    It is well known that the bulk physics of a topological phase constrains its possible edge physics through the bulk-edge correspondence. Therefore, the different types of edge theories that a topological phase can host is a universal piece of data which can be used to characterize topological order. Here, we argue that beginning from only the fixed point wavefunction (FPW) of a nonchiral topological phase and by locally deforming it, all possible edge theories can be extracted from its entanglement Hamiltonian (EH). We illustrate our claim by deforming the FPW of the Wen-plaquette model, the quantum double of ℤ2. We show that the possible EHs of the deformed FPWs reflect the known possible types of edge theories, which are generically gapped, but gapless if translational symmetry is preserved. We stress that our results do not require an underlying Hamiltonian - thus, this lends support to the notion that a topological phase is indeed characterized by only a set of quantum states and can be studied through its FPWs. Also affiliated to Perimeter Inst for Theo Phys.

  13. The Edge supersonic transport

    NASA Technical Reports Server (NTRS)

    Agosta, Roxana; Bilbija, Dushan; Deutsch, Marc; Gallant, David; Rose, Don; Shreve, Gene; Smario, David; Suffredini, Brian

    1992-01-01

    As intercontinental business and tourism volumes continue their rapid expansion, the need to reduce travel times becomes increasingly acute. The Edge Supersonic Transport Aircraft is designed to meet this demand by the year 2015. With a maximum range of 5750 nm, a payload of 294 passengers and a cruising speed of M = 2.4, The Edge will cut current international flight durations in half, while maintaining competitive first class, business class, and economy class comfort levels. Moreover, this transport will render a minimal impact upon the environment, and will meet all Federal Aviation Administration Part 36, Stage III noise requirements. The cornerstone of The Edge's superior flight performance is its aerodynamically efficient, dual-configuration design incorporating variable-geometry wingtips. This arrangement combines the benefits of a high aspect ratio wing at takeoff and low cruising speeds with the high performance of an arrow-wing in supersonic cruise. And while the structural weight concerns relating to swinging wingtips are substantial, The Edge looks to ever-advancing material technologies to further increase its viability. Heeding well the lessons of the past, The Edge design holds economic feasibility as its primary focus. Therefore, in addition to its inherently superior aerodynamic performance, The Edge uses a lightweight, largely windowless configuration, relying on a synthetic vision system for outside viewing by both pilot and passengers. Additionally, a fly-by-light flight control system is incorporated to address aircraft supersonic cruise instability. The Edge will be produced at an estimated volume of 400 aircraft and will be offered to airlines in 2015 at $167 million per transport (1992 dollars).

  14. Double space with double line

    SciTech Connect

    Cheltsov, I A

    2004-10-31

    For a singular double cover of P{sup 3} ramified in a sextic with double line, its birational maps into Fano 3-folds with canonical singularities, elliptic fibrations, and fibrations on surfaces of Kodaira dimension zero are described.

  15. Double space with double line

    NASA Astrophysics Data System (ADS)

    Cheltsov, I. A.

    2004-10-01

    For a singular double cover of \\mathbb P^3 ramified in a sextic with double line, its birational maps into Fano 3-folds with canonical singularities, elliptic fibrations, and fibrations on surfaces of Kodaira dimension zero are described.

  16. [Double teeth].

    PubMed

    Schuurs, A H B; van Loveren, C

    2002-04-01

    Double teeth are not really rare, but it is still enigmatic why and how they develop. Based upon the clinical, morphological and anatomical appearance and the number of teeth in mouths with double teeth, the double teeth are labelled as products of 'fusion' and 'clefting', but the criteria to attach such etiological names are lacking. It is assumed that heredity is involved in the development of double teeth. Therefore it is attempted to explain why only one of a homozygotic twin had a double tooth. PMID:11982209

  17. Extended Klein edges in graphene.

    PubMed

    He, Kuang; Robertson, Alex W; Lee, Sungwoo; Yoon, Euijoon; Lee, Gun-Do; Warner, Jamie H

    2014-12-23

    Graphene has three experimentally confirmed periodic edge terminations, zigzag, reconstructed 5-7, and arm-chair. Theory predicts a fourth periodic edge of graphene called the extended Klein (EK) edge, which consists of a series of single C atoms protruding from a zigzag edge. Here, we confirm the existence of EK edges in both graphene nanoribbons and on the edge of bulk graphene using atomic resolution imaging by aberration-corrected transmission electron microscopy. The formation of the EK edge stems from sputtering and reconstruction of the zigzag edge. Density functional theory reveals minimal energy for EK edge reconstruction and bond distortion both in and out of plane, supporting our TEM observations. The EK edge can now be included as the fourth member of observed periodic edge structures in graphene.

  18. Properties on the edge: graphene edge energies, edge stresses, edge warping, and the Wulff shape of graphene flakes

    NASA Astrophysics Data System (ADS)

    Branicio, Paulo S.; Jhon, Mark H.; Gan, Chee Kwan; Srolovitz, David J.

    2011-07-01

    It has been shown that the broken bonds of an unreconstructed graphene edge generate compressive edge stresses leading to edge warping. Here, we investigate edge energies and edge stresses of graphene nanoribbons with arbitrary orientations from armchair to zigzag, considering both flat and warped edge shapes in the presence and absence of hydrogen. We use the second generation reactive empirical bond order potential to calculate the edge energies and stresses for clean and hydrogenated edges. Using these energies, we perform a Wulff construction to determine the equilibrium shapes of flat graphene flakes as a function of hydrogen chemical potential. While edge stresses for clean, flat edges are compressive, they become tensile if allowed to warp. Conversely, we find that edge energies change little (~1%) with edge warping. Hydrogenation of the edges virtually eliminates both the edge energy and edge stresses. For warped edges an approximately linear relationship is found between amplitudes and wavelengths. The equilibrium shape of a graphene flake is determined by the value of the hydrogen chemical potential. For very small (and large) values of it the flakes have a nearly hexagonal (dodecagon) shape with zigzag oriented edges, while for intermediate values graphene flakes are found with complex shapes.

  19. High Speed Edge Detection

    NASA Technical Reports Server (NTRS)

    Prokop, Norman F (Inventor)

    2015-01-01

    Analog circuits for detecting edges in pixel arrays are disclosed. A comparator may be configured to receive an all pass signal and a low pass signal for a pixel intensity in an array of pixels. A latch may be configured to receive a counter signal and a latching signal from the comparator. The comparator may be configured to send the latching signal to the latch when the all pass signal is below the low pass signal minus an offset. The latch may be configured to hold a last negative edge location when the latching signal is received from the comparator.

  20. High Speed Edge Detection

    NASA Technical Reports Server (NTRS)

    Prokop, Norman F (Inventor)

    2016-01-01

    Analog circuits for detecting edges in pixel arrays are disclosed. A comparator may be configured to receive an all pass signal and a low pass signal for a pixel intensity in an array of pixels. A latch may be configured to receive a counter signal and a latching signal from the comparator. The comparator may be configured to send the latching signal to the latch when the all pass signal is below the low pass signal minus an offset. The latch may be configured to hold a last negative edge location when the latching signal is received from the comparator.

  1. Commentary: Hyperbaric oxygen treatment for wounds - evidence and the Sword of Damocles.

    PubMed

    Laden, Gerard

    2015-12-01

    Increased access to any treatment sensibly follows the clinical and cost benefit being established. For many treatments this requires multiple, high-quality clinical trials and supporting cost analysis. Cost analysis may be applied to a single treatment or used to compare two or more treatments. Clinical efficacy and cost benefit are best scrutinised and validated by publication in the peer-reviewed literature. True peer review is most effectively achieved 'after publication' by the wider scientific community, i.e., the journal readers. However, initially an editor, usually advised by referees, is asked to make a judgment on a paper's suitability for publication. It follows that medical journals are in a position of power and responsibility. Researchers and editors know publications are currency; effectively they are the equivalent of academic bitcoins. Regarding the paper in this issue by Santema et al., the same authors, in designing a prospective randomised controlled trial (RCT) of the role of hyperbaric oxygen treatment (HBOT) in diabetic wounds, included the name "Damocles" in that trial's title. Readers will perhaps appreciate from my comments below as a referee for the Santema et al. paper, that behind the scenes "the Sword of Damocles" (an allusion to the imminent and ever-present peril faced by those in positions of power) hangs over researchers, treating physician, journal editors and referees alike. Whilst positive about its content, upon reflection, my concern was the anticipated reception of this paper by the journal readership. This is, of course, a matter for the Editor; however, herewith is my reasoning. Further to the body of published work by Bennett et al., and others that has focused attention on the lack of good quality evidence for the use of HBOT for most indications, I think this regrettable state of affairs is now both known and accepted by mainstream healthcare purchasers and providers. I speculate that all these bodies already

  2. Oscillating edge-flames

    NASA Astrophysics Data System (ADS)

    Buckmaster, J.; Zhang, Yi

    1999-09-01

    It has been known for some years that when a near-limit flame spreads over a liquid pool of fuel, the edge of the flame can oscillate. It is also known that when a near-asphyxiated candle-flame burns in zero gravity, the edge of the (hemispherical) flame can oscillate violently prior to extinction. We propose that these oscillations are nothing more than a manifestation of the large Lewis number instability well known in chemical reactor studies and in combustion studies, one that is exacerbated by heat losses. As evidence of this we examine an edge-flame confined within a fuel-supply boundary and an oxygen-supply boundary, anchored by a discontinuity in data at the fuel-supply boundary. We show that when the Lewis number of the fuel is 2, and the Lewis number of the oxidizer is 1, oscillations of the edge occur when the Damköhler number is reduced below a critical value. During a single oscillation period there is a short premixed propagation stage and a long diffusion stage, behaviour that has been observed in flame spread experiments. Oscillations do not occur when both Lewis numbers are equal to 1.

  3. Exclusive contracts in the hospital setting: a two-edged sword: part 2: pros and cons, avoidance strategies, and negotiating tips.

    PubMed

    Portman, Robert M

    2007-06-01

    Hospitals routinely enter into contracts with radiology groups for the right to be the exclusive providers of radiologic services at the facilities in exchange for the groups' agreeing to provide and manage all aspects of those services within the hospitals. These exclusive contracts generally result in radiology departments and associated equipment being closed off to physicians who are not part of the contracting groups. Although exclusive contracts offer obvious benefits to the physicians who receive them and obvious disadvantages for those who are excluded, they also present pitfalls for physicians in the chosen group. Part 1 of this article discussed the legal issues raised by exclusive contracts. Part 2 weighs the practical advantages and disadvantages of exclusive contracts for physicians covered and not covered by such contracts and strategies for avoiding them, as well as provisions that can be included in medical staff bylaws to protect physicians from the automatic termination of privileges when a hospital enters into or terminates an exclusive contract. The remainder of the article provides tips on specific provisions of exclusive contracts that should be included or avoided.

  4. Superpixel edges for boundary detection

    DOEpatents

    Moya, Mary M.; Koch, Mark W.

    2016-07-12

    Various embodiments presented herein relate to identifying one or more edges in a synthetic aperture radar (SAR) image comprising a plurality of superpixels. Superpixels sharing an edge (or boundary) can be identified and one or more properties of the shared superpixels can be compared to determine whether the superpixels form the same or two different features. Where the superpixels form the same feature the edge is identified as an internal edge. Where the superpixels form two different features, the edge is identified as an external edge. Based upon classification of the superpixels, the external edge can be further determined to form part of a roof, wall, etc. The superpixels can be formed from a speckle-reduced SAR image product formed from a registered stack of SAR images, which is further segmented into a plurality of superpixels. The edge identification process is applied to the SAR image comprising the superpixels and edges.

  5. Edge magnetoplasmons in graphene

    NASA Astrophysics Data System (ADS)

    Petković, Ivana; Williams, F. I. B.; Glattli, D. Christian

    2014-03-01

    We have observed propagation of edge magnetoplasmon (EMP) modes in graphene in the quantum Hall regime by performing picosecond time-of-flight measurements between narrow contacts on the perimeter of micrometric exfoliated graphene. We find the propagation to be chiral with low attenuation and to have a velocity which is quantized on Hall plateaus. The velocity has two contributions, one arising from the Hall conductivity and the other from carrier drift along the edge, which we were able to separate by their different filling factor dependence. The drift component is found to be slightly less than the Fermi velocity as expected for graphene dynamics in an abrupt edge potential. The Hall conduction contribution is slower than expected and indicates a characteristic length in the Coulomb potential from the Hall charge of about 500 nm. The experiment illustrates how EMP can be coupled to the electromagnetic field, opening the perspective of GHz to THz chiral plasmonics applications to devices such as voltage controlled phase shifters, circulators, switches and compact, tunable ring resonators.

  6. The edges of understanding

    PubMed Central

    2010-01-01

    A culture's icons are a window onto its soul. Few would disagree that, in the culture of molecular biology that dominated much of the life sciences for the last third of the 20th century, the dominant icon was the double helix. In the present, post-modern, 'systems biology' era, however, it is, arguably, the hairball. PMID:20385033

  7. Along Freedom's Double Edge: The Arab Press Under Israeli Occupation.

    ERIC Educational Resources Information Center

    Nasser, Munir K.

    This paper examines the Arab press under Israeli occupation and presents two hypotheses: freedom of the press under occupation serves both Israeli interests and the Arab population, and freedom of the Arab press under occupation is "relative" and "controlled." By allowing freedom of expression, the Israelis achieve several aims: a free press will…

  8. Bulgaria: The Double Edge of Economy and Demography

    ERIC Educational Resources Information Center

    Georgieva, Patricia

    2004-01-01

    The higher education and research sector in Bulgaria is undergoing a gradual change. Whether this transformation will bring success or failure depends on how prepared stakeholders are to meet associated challenges and opportunities. The mobility of academics and the related phenomenon of brain drain need careful investigation. Academic teachers…

  9. Electrochemistry of folded graphene edges.

    PubMed

    Ambrosi, Adriano; Bonanni, Alessandra; Pumera, Martin

    2011-05-01

    There is enormous interest in the investigation of electron transfer rates at the edges of graphene due to possible energy storage and sensing applications. While electrochemistry at the edges and the basal plane of graphene has been studied in the past, the new frontier is the electrochemistry of folded graphene edges. Here we describe the electrochemistry of folded graphene edges and compare it to that of open graphene edges. The materials were characterized in detail by high-resolution transmission electron microscopy, Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry. We found that the heterogeneous electron transfer rate is significantly lower on folded graphene edges compared to open edge sites for ferro/ferricyanide, and that electrochemical properties of open edges offer lower potential detection of biomarkers than the folded ones. It is apparent, therefore, that for sensing and biosensing applications the folded edges are less active than open edges, which should then be preferred for such applications. As folded edges are the product of thermal treatment of multilayer graphene, such thermal procedures should be avoided when fabricating graphene for electrochemical applications.

  10. Edge remap for solids

    SciTech Connect

    Kamm, James R.; Love, Edward; Robinson, Allen C.; Young, Joseph G.; Ridzal, Denis

    2013-12-01

    We review the edge element formulation for describing the kinematics of hyperelastic solids. This approach is used to frame the problem of remapping the inverse deformation gradient for Arbitrary Lagrangian-Eulerian (ALE) simulations of solid dynamics. For hyperelastic materials, the stress state is completely determined by the deformation gradient, so remapping this quantity effectively updates the stress state of the material. A method, inspired by the constrained transport remap in electromagnetics, is reviewed, according to which the zero-curl constraint on the inverse deformation gradient is implicitly satisfied. Open issues related to the accuracy of this approach are identified. An optimization-based approach is implemented to enforce positivity of the determinant of the deformation gradient. The efficacy of this approach is illustrated with numerical examples.

  11. Edge-on!

    NASA Astrophysics Data System (ADS)

    2007-08-01

    Peering at Uranus's Rings as they Swing Edge-on to Earth for the First Time Since their Discovery in 1977 As Uranus coasts through a brief window of time when its rings are edge-on to Earth - a view of the planet we get only once every 42 years - astronomers peering at the rings with ESO's Very Large Telescope and other space or ground-based telescopes are getting an unprecedented view of the fine dust in the system, free from the glare of the bright rocky rings. They may even find a new moon or two. ESO PR Photo 37/07 ESO PR Photo 37/07 The Uranus System "ESO's VLT took data at the precise moment when the rings were edge-on to Earth," said Imke de Pater, of University of California, Berkeley who coordinated the worldwide campaign. She worked with two team members observing in Chile: Daphne Stam of the Technical University Delft in the Netherlands and Markus Hartung of ESO. The observations were done with NACO, one of the adaptive optics instruments installed at the VLT. With adaptive optics, it is possible to obtain images almost free from the blurring effect of the atmosphere. It is as if the 8.2-m telescope were observing from space. Observations were also done with the Keck telescope in Hawaii, the Hubble Space Telescope, and at the Palomar Observatory. "Using different telescopes around the world allows us to observe as much of the changes during the ring-plane crossing as possible: when Uranus sets as seen from the VLT, it can still be observed by the Keck," emphasised Stam. Uranus orbits the Sun in 84 years. Twice during a Uranian year, the rings appear edge-on to Earth for a brief period. The rings were discovered in 1977, so this is the first time for a Uranus ring-crossing to be observed from Earth. The advantage of observations at a ring-plane crossing is that it becomes possible to look at the rings from the shadowed or dark side. From that vantage point, the normally bright outer rings grow fainter because their centimetre- to metre-sized rocks obscure

  12. Double layers above the aurora

    NASA Technical Reports Server (NTRS)

    Temerin, M.; Mozer, F. S.

    1987-01-01

    Two different kinds of double layers were found in association with auroral precipitation. One of these is the so-called electrostatic shock, which is oriented at an oblique angle to the magnetic field in such a way that the perpendicular electric field is much larger than the parallel electric field. This type of double layer is often found at the edges of regions of upflowing ion beams and the direction of the electric fields in the shock points toward the ion beam. The potential drop through the shock can be several kV and is comparable to the total potential needed to produce auroral acceleration. Instabilities associated with the shock may generate obliquely propagating Alfven waves, which may accelerate electrons to produce flickering auroras. The flickering aurora provides evidence that the electrostatic shock may have large temporal fluctuations. The other kind of double layer is the small-amplitude double layer found in regions of upward flowing in beams, often in association with electrostatic ion cyclotron waves. The parallel and perpendicular electric fields in these structures are comparable in magnitude. The associated potentials are a few eV. Since many such double layers are found in regions of upward flowing ion beams, the combined potential drop through a set of these double layers can be substantial.

  13. Edge phonons in black phosphorus

    NASA Astrophysics Data System (ADS)

    Ribeiro, H. B.; Villegas, C. E. P.; Bahamon, D. A.; Muraca, D.; Castro Neto, A. H.; de Souza, E. A. T.; Rocha, A. R.; Pimenta, M. A.; de Matos, C. J. S.

    2016-07-01

    Black phosphorus has recently emerged as a new layered crystal that, due to its peculiar and anisotropic crystalline and electronic band structures, may have important applications in electronics, optoelectronics and photonics. Despite the fact that the edges of layered crystals host a range of singular properties whose characterization and exploitation are of utmost importance for device development, the edges of black phosphorus remain poorly characterized. In this work, the atomic structure and behaviour of phonons near different black phosphorus edges are experimentally and theoretically studied using Raman spectroscopy and density functional theory calculations. Polarized Raman results show the appearance of new modes at the edges of the sample, and their spectra depend on the atomic structure of the edges (zigzag or armchair). Theoretical simulations confirm that the new modes are due to edge phonon states that are forbidden in the bulk, and originated from the lattice termination rearrangements.

  14. Edge phonons in black phosphorus.

    PubMed

    Ribeiro, H B; Villegas, C E P; Bahamon, D A; Muraca, D; Castro Neto, A H; de Souza, E A T; Rocha, A R; Pimenta, M A; de Matos, C J S

    2016-01-01

    Black phosphorus has recently emerged as a new layered crystal that, due to its peculiar and anisotropic crystalline and electronic band structures, may have important applications in electronics, optoelectronics and photonics. Despite the fact that the edges of layered crystals host a range of singular properties whose characterization and exploitation are of utmost importance for device development, the edges of black phosphorus remain poorly characterized. In this work, the atomic structure and behaviour of phonons near different black phosphorus edges are experimentally and theoretically studied using Raman spectroscopy and density functional theory calculations. Polarized Raman results show the appearance of new modes at the edges of the sample, and their spectra depend on the atomic structure of the edges (zigzag or armchair). Theoretical simulations confirm that the new modes are due to edge phonon states that are forbidden in the bulk, and originated from the lattice termination rearrangements. PMID:27412813

  15. Edge phonons in black phosphorus

    PubMed Central

    Ribeiro, H. B.; Villegas, C. E. P.; Bahamon, D. A.; Muraca, D.; Castro Neto, A. H.; de Souza, E. A. T.; Rocha, A. R.; Pimenta, M. A.; de Matos, C. J. S.

    2016-01-01

    Black phosphorus has recently emerged as a new layered crystal that, due to its peculiar and anisotropic crystalline and electronic band structures, may have important applications in electronics, optoelectronics and photonics. Despite the fact that the edges of layered crystals host a range of singular properties whose characterization and exploitation are of utmost importance for device development, the edges of black phosphorus remain poorly characterized. In this work, the atomic structure and behaviour of phonons near different black phosphorus edges are experimentally and theoretically studied using Raman spectroscopy and density functional theory calculations. Polarized Raman results show the appearance of new modes at the edges of the sample, and their spectra depend on the atomic structure of the edges (zigzag or armchair). Theoretical simulations confirm that the new modes are due to edge phonon states that are forbidden in the bulk, and originated from the lattice termination rearrangements. PMID:27412813

  16. The Facilitator's Edge: Group Sessions for Edge-ucators.

    ERIC Educational Resources Information Center

    Handcock, Helen

    The Facilitator's Edge is a workshop series based on the life/work messages of The Edge magazine. The workshops are deigned to help educators, youth workers, and their career practitioners facilitate conscious career building. This manual consists of five group sessions, each focusing on a different career-building theme. "Megatrends and Making it…

  17. Edge-edge interactions in stacked graphene nanoplatelets

    SciTech Connect

    Cruz Silva, Eduardo; Terrones Maldonado, Humberto; Terrones Maldonado, Mauricio; Jia, Xiaoting; Sumpter, Bobby G; Dresselhaus, M; Meunier, V.

    2013-01-01

    High-resolution transmission electron microscopy (HRTEM) studies show the dynamics of small graphene platelets on larger graphene layers. The platelets move nearly freely to eventually lock in at well-defined positions close to the edges of the larger underlying graphene sheet. While such movement is driven by a shallow potential energy surface described by an interplane interaction, the lock-in position occurs by via edge-edge interactions of the platelet and the graphene surface located underneath. Here we quantitatively study this behavior using van der Waals density functional calculations. Local interactions at the open edges are found to dictate stacking configurations that are different from Bernal (AB) stacking. These stacking configurations are known to be otherwise absent in edge-free two-dimensional (2D) graphene. The results explain the experimentally observed platelet dynamics and provide a detailed account of the new electronic properties of these combined systems.

  18. Giant edge state splitting at atomically precise graphene zigzag edges

    PubMed Central

    Wang, Shiyong; Talirz, Leopold; Pignedoli, Carlo A.; Feng, Xinliang; Müllen, Klaus; Fasel, Roman; Ruffieux, Pascal

    2016-01-01

    Zigzag edges of graphene nanostructures host localized electronic states that are predicted to be spin-polarized. However, these edge states are highly susceptible to edge roughness and interaction with a supporting substrate, complicating the study of their intrinsic electronic and magnetic structure. Here, we focus on atomically precise graphene nanoribbons whose two short zigzag edges host exactly one localized electron each. Using the tip of a scanning tunnelling microscope, the graphene nanoribbons are transferred from the metallic growth substrate onto insulating islands of NaCl in order to decouple their electronic structure from the metal. The absence of charge transfer and hybridization with the substrate is confirmed by scanning tunnelling spectroscopy, which reveals a pair of occupied/unoccupied edge states. Their large energy splitting of 1.9 eV is in accordance with ab initio many-body perturbation theory calculations and reflects the dominant role of electron–electron interactions in these localized states. PMID:27181701

  19. Giant edge state splitting at atomically precise graphene zigzag edges.

    PubMed

    Wang, Shiyong; Talirz, Leopold; Pignedoli, Carlo A; Feng, Xinliang; Müllen, Klaus; Fasel, Roman; Ruffieux, Pascal

    2016-05-16

    Zigzag edges of graphene nanostructures host localized electronic states that are predicted to be spin-polarized. However, these edge states are highly susceptible to edge roughness and interaction with a supporting substrate, complicating the study of their intrinsic electronic and magnetic structure. Here, we focus on atomically precise graphene nanoribbons whose two short zigzag edges host exactly one localized electron each. Using the tip of a scanning tunnelling microscope, the graphene nanoribbons are transferred from the metallic growth substrate onto insulating islands of NaCl in order to decouple their electronic structure from the metal. The absence of charge transfer and hybridization with the substrate is confirmed by scanning tunnelling spectroscopy, which reveals a pair of occupied/unoccupied edge states. Their large energy splitting of 1.9 eV is in accordance with ab initio many-body perturbation theory calculations and reflects the dominant role of electron-electron interactions in these localized states.

  20. Assessment of imaging with extended depth-of-field by means of the light sword lens in terms of visual acuity scale

    PubMed Central

    Kakarenko, Karol; Ducin, Izabela; Grabowiecki, Krzysztof; Jaroszewicz, Zbigniew; Kolodziejczyk, Andrzej; Mira-Agudelo, Alejandro; Petelczyc, Krzysztof; Składowska, Aleksandra; Sypek, Maciej

    2015-01-01

    We present outcomes of an imaging experiment using the refractive light sword lens (LSL) as a contact lens in an optical system that serves as a simplified model of the presbyopic eye. The results show that the LSL produces significant improvements in visual acuity of the simplified presbyopic eye model over a wide range of defocus. Therefore, this element can be an interesting alternative for the multifocal contact and intraocular lenses currently used in ophthalmology. The second part of the article discusses possible modifications of the LSL profile in order to render it more suitable for fabrication and ophthalmological applications. PMID:26137376

  1. Assessment of imaging with extended depth-of-field by means of the light sword lens in terms of visual acuity scale.

    PubMed

    Kakarenko, Karol; Ducin, Izabela; Grabowiecki, Krzysztof; Jaroszewicz, Zbigniew; Kolodziejczyk, Andrzej; Mira-Agudelo, Alejandro; Petelczyc, Krzysztof; Składowska, Aleksandra; Sypek, Maciej

    2015-05-01

    We present outcomes of an imaging experiment using the refractive light sword lens (LSL) as a contact lens in an optical system that serves as a simplified model of the presbyopic eye. The results show that the LSL produces significant improvements in visual acuity of the simplified presbyopic eye model over a wide range of defocus. Therefore, this element can be an interesting alternative for the multifocal contact and intraocular lenses currently used in ophthalmology. The second part of the article discusses possible modifications of the LSL profile in order to render it more suitable for fabrication and ophthalmological applications.

  2. Double Layers in Astrophysics

    NASA Technical Reports Server (NTRS)

    Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)

    1987-01-01

    Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

  3. Rock Segmentation through Edge Regrouping

    NASA Technical Reports Server (NTRS)

    Burl, Michael

    2008-01-01

    Rockster is an algorithm that automatically identifies the locations and boundaries of rocks imaged by the rover hazard cameras (hazcams), navigation cameras (navcams), or panoramic cameras (pancams). The software uses edge detection and edge regrouping to identify closed contours that separate the rocks from the background.

  4. Computer Methods in EDG Education.

    ERIC Educational Resources Information Center

    Mabrey, Robert L.

    1999-01-01

    Presents several computer-related techniques that encourage engineering design graphics (EDG) students to develop knowledge at levels 4 and 5 of Bloom's taxonomy. Contrasts this approach to extend the educational process with the development of training skills at knowledge levels 2 and 3, which are often the sole basis for EDG instruction.…

  5. The Robotic Edge Finishing Laboratory

    SciTech Connect

    Loucks, C.S.; Selleck, C.B.

    1990-08-01

    The Robotic Edge Finishing Laboratory at Sandia National Laboratories is developing four areas of technology required for automated deburring, chamfering, and blending of machined edges: (1) the automatic programming of robot trajectories and deburring processes using information derived from a CAD database, (2) the use of machine vision for locating the workpiece coupled with force control to ensure proper tool contact, (3) robotic deburring, blending, and machining of precision chamfered edges, and (4) in-process automated inspection of the formed edge. The Laboratory, its components, integration, and results from edge finishing experiments to date are described here. Also included is a discussion of the issues regarding implementation of the technology in a production environment. 24 refs., 17 figs.

  6. Edge-on Galaxy

    NASA Technical Reports Server (NTRS)

    1999-01-01

    NASA's Hubble Space Telescope has imaged an unusual edge-on galaxy, revealing remarkable details of its warped dusty disc and showing how colliding galaxies trigger the birth of new stars.

    The image, taken by Hubble's Wide Field and Planetary Camera 2 (WFPC2), is online at http://heritage.stsci.edu and http://www.jpl.nasa.gov/images/wfpc. The camera was designed and built by NASA's Jet Propulsion Laboratory, Pasadena, Calif. During observations of the galaxy, the camera passed a milestone, taking its 100,000th image since shuttle astronauts installed it in Hubble in 1993.

    The dust and spiral arms of normal spiral galaxies, like our Milky Way, look flat when seen edge- on. The new image of the galaxy ESO 510-G13 shows an unusual twisted disc structure, first seen in ground-based photographs taken at the European Southern Observatory in Chile. ESO 510-G13 lies in the southern constellation Hydra, some 150 million light-years from Earth. Details of the galaxy's structure are visible because interstellar dust clouds that trace its disc are silhouetted from behind by light from the galaxy's bright, smooth central bulge.

    The strong warping of the disc indicates that ESO 510-G13 has recently collided with a nearby galaxy and is in the process of swallowing it. Gravitational forces distort galaxies as their stars, gas, and dust merge over millions of years. When the disturbances die out, ESO 510-G13 will be a single galaxy.

    The galaxy's outer regions, especially on the right side of the image, show dark dust and bright clouds of blue stars. This indicates that hot, young stars are forming in the twisted disc. Astronomers believe star formation may be triggered when galaxies collide and their interstellar clouds are compressed.

    The Hubble Heritage Team used WFPC2 to observe ESO 510-G13 in April 2001. Pictures obtained through blue, green, and red filters were combined to make this color-composite image, which emphasizes the contrast between the dusty

  7. Theory of edge detection.

    PubMed

    Marr, D; Hildreth, E

    1980-02-29

    A theory of edge detection is presented. The analysis proceeds in two parts. (1) Intensity changes, which occur in a natural image over a wide range of scales, are detected separately at different scales. An appropriate filter for this purpose at a given scale is found to be the second derivative of a Gaussian, and it is shown that, provided some simple conditions are satisfied, these primary filters need not be orientation-dependent. Thus, intensity changes at a given scale are best detected by finding the zero values of delta 2G(x,y)*I(x,y) for image I, where G(x,y) is a two-dimensional Gaussian distribution and delta 2 is the Laplacian. The intensity changes thus discovered in each of the channels are then represented by oriented primitives called zero-crossing segments, and evidence is given that this representation is complete. (2) Intensity changes in images arise from surface discontinuities or from reflectance or illumination boundaries, and these all have the property that they are spatially. Because of this, the zero-crossing segments from the different channels are not independent, and rules are deduced for combining them into a description of the image. This description is called the raw primal sketch. The theory explains several basic psychophysical findings, and the operation of forming oriented zero-crossing segments from the output of centre-surround delta 2G filters acting on the image forms the basis for a physiological model of simple cells (see Marr & Ullman 1979).

  8. Edge of a cliff

    NASA Astrophysics Data System (ADS)

    Shimizu, Yusuke; Tatsuta, Yoshiyuki

    2016-10-01

    We discuss the neutrino flavor structures in the Occam's razor approach for the Dirac neutrino mass matrices. We assume that the charged lepton mass matrix takes a diagonal base, while the right-handed Majorana neutrino mass matrix is also diagonal and we consider nine patterns of the four zero textures for the Dirac neutrinos mass matrices. We numerically analyze the left-handed Majorana neutrino mass matrices for nine patterns of the Dirac neutrino mass matrices and we find two interesting patterns where both normal and inverted neutrino mass hierarchies can be realized. We also find if the neutrino mass is normal hierarchy, this scenario will be likely to be excluded by the measurements of the Dirac CP violating phase in the T2K and NO νA neutrino experiments, for instance. On the other hand, if the neutrino mass is inverted hierarchy, this scenario will be also likely to be excluded by the measurements of neutrinoless double beta decay experiments, e.g., K amLAND-Zen experiment.

  9. Hydrogen-free graphene edges

    NASA Astrophysics Data System (ADS)

    He, Kuang; Lee, Gun-Do; Robertson, Alex W.; Yoon, Euijoon; Warner, Jamie H.

    2014-01-01

    Graphene edges and their functionalization influence the electronic and magnetic properties of graphene nanoribbons. Theoretical calculations predict saturating graphene edges with hydrogen lower its energy and form a more stable structure. Despite the importance, experimental investigations of whether graphene edges are always hydrogen-terminated are limited. Here we study graphene edges produced by sputtering in vacuum and direct measurements of the C-C bond lengths at the edge show ~86% contraction relative to the bulk. Density functional theory reveals the contraction is attributed to the formation of a triple bond and the absence of hydrogen functionalization. Time-dependent images reveal temporary attachment of a single atom to the arm-chair C-C bond in a triangular configuration, causing expansion of the bond length, which then returns back to the contracted value once the extra atom moves on and the arm-chair edge is returned. Our results provide confirmation that non-functionalized graphene edges can exist in vacuum.

  10. Hydrogen-free graphene edges.

    PubMed

    He, Kuang; Lee, Gun-Do; Robertson, Alex W; Yoon, Euijoon; Warner, Jamie H

    2014-01-01

    Graphene edges and their functionalization influence the electronic and magnetic properties of graphene nanoribbons. Theoretical calculations predict saturating graphene edges with hydrogen lower its energy and form a more stable structure. Despite the importance, experimental investigations of whether graphene edges are always hydrogen-terminated are limited. Here we study graphene edges produced by sputtering in vacuum and direct measurements of the C-C bond lengths at the edge show ~86% contraction relative to the bulk. Density functional theory reveals the contraction is attributed to the formation of a triple bond and the absence of hydrogen functionalization. Time-dependent images reveal temporary attachment of a single atom to the arm-chair C-C bond in a triangular configuration, causing expansion of the bond length, which then returns back to the contracted value once the extra atom moves on and the arm-chair edge is returned. Our results provide confirmation that non-functionalized graphene edges can exist in vacuum.

  11. Double aortic arch

    MedlinePlus

    Aortic arch anomaly; Double arch; Congenital heart defect - double aortic arch; Birth defect heart - double aortic arch ... aorta is a single arch that leaves the heart and moves leftward. In double aortic arch, some ...

  12. Reduction of airfoil trailing edge noise by trailing edge blowing

    NASA Astrophysics Data System (ADS)

    Gerhard, T.; Erbslöh, S.; Carolus, T.

    2014-06-01

    The paper deals with airfoil trailing edge noise and its reduction by trailing edge blowing. A Somers S834 airfoil section which originally was designed for small wind turbines is investigated. To mimic realistic Reynolds numbers the boundary layer is tripped on pressure and suction side. The chordwise position of the blowing slot is varied. The acoustic sources, i.e. the unsteady flow quantities in the turbulent boundary layer in the vicinity of the trailing edge, are quantified for the airfoil without and with trailing edge blowing by means of a large eddy simulation and complementary measurements. Eventually the far field airfoil noise is measured by a two-microphone filtering and correlation and a 40 microphone array technique. Both, LES-prediction and measurements showed that a suitable blowing jet on the airfoil suction side is able to reduce significantly the turbulence intensity and the induced surface pressure fluctuations in the trailing edge region. As a consequence, trailing edge noise associated with a spectral hump around 500 Hz could be reduced by 3 dB. For that a jet velocity of 50% of the free field velocity was sufficient. The most favourable slot position was at 90% chord length.

  13. Glucocorticoids and inflammation: a double-headed sword in depression? How do neuroendocrine and inflammatory pathways interact during stress to contribute to the pathogenesis of depression?

    PubMed

    Horowitz, M A; Zunszain, P A; Anacker, C; Musaelyan, K; Pariante, C M

    2013-01-01

    Both glucocorticoids and inflammation have been implicated in the pathogenesis of depression. There is a large body of literature indicating that hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis and glucocorticoid receptor (GR) dysfunction are present in a significant proportion of depressed patients. There is also evidence of increased inflammatory processes in depressed populations, with higher levels of cytokines being a prominent finding - including raised levels of IL-6, and IL-1. These findings appear difficult to reconcile given the well-recognised property of glucocorticoids as prominent anti-inflammatory molecules. There are three potential solutions posed to this dilemma. Firstly, it has been argued that the glucocorticoid system and the inflammatory system exist in balance with one another and chronic stress can disrupt this balance in favour of inflammatory processes at the expense of glucocorticoid signalling. It has also been suggested that glucocorticoids have more complex actions than typically thought, and, in low levels can actually be pro-inflammatory, rather than universally anti-inflammatory. Lastly, it is possible that inflammation and glucocorticoid signalling may act on the same processes and structures without direct interaction to give rise to cumulative damage. Improved understanding of this interaction will allow further progress in determining targets for treatment.

  14. Fast tracking using edge histograms

    NASA Astrophysics Data System (ADS)

    Rokita, Przemyslaw

    1997-04-01

    This paper proposes a new algorithm for tracking objects and objects boundaries. This algorithm was developed and applied in a system used for compositing computer generated images and real world video sequences, but can be applied in general in all tracking systems where accuracy and high processing speed are required. The algorithm is based on analysis of histograms obtained by summing along chosen axles pixels of edge segmented images. Edge segmentation is done by spatial convolution using gradient operator. The advantage of such an approach is that it can be performed in real-time using available on the market hardware convolution filters. After edge extraction and histograms computation, respective positions of maximums in edge intensity histograms, in current and previous frame, are compared and matched. Obtained this way information about displacement of histograms maximums, can be directly converted into information about changes of target boundaries positions along chosen axles.

  15. Edge equilibrium code for tokamaks

    SciTech Connect

    Li, Xujing; Drozdov, Vladimir V.

    2014-01-15

    The edge equilibrium code (EEC) described in this paper is developed for simulations of the near edge plasma using the finite element method. It solves the Grad-Shafranov equation in toroidal coordinate and uses adaptive grids aligned with magnetic field lines. Hermite finite elements are chosen for the numerical scheme. A fast Newton scheme which is the same as implemented in the equilibrium and stability code (ESC) is applied here to adjust the grids.

  16. Edge instabilities of topological superconductors

    NASA Astrophysics Data System (ADS)

    Hofmann, Johannes S.; Assaad, Fakher F.; Schnyder, Andreas P.

    2016-05-01

    Nodal topological superconductors display zero-energy Majorana flat bands at generic edges. The flatness of these edge bands, which is protected by time-reversal and translation symmetry, gives rise to an extensive ground-state degeneracy. Therefore, even arbitrarily weak interactions lead to an instability of the flat-band edge states towards time-reversal and translation-symmetry-broken phases, which lift the ground-state degeneracy. We examine the instabilities of the flat-band edge states of dx y-wave superconductors by performing a mean-field analysis in the Majorana basis of the edge states. The leading instabilities are Majorana mass terms, which correspond to coherent superpositions of particle-particle and particle-hole channels in the fermionic language. We find that attractive interactions induce three different mass terms. One is a coherent superposition of imaginary s -wave pairing and current order, and another combines a charge-density-wave and finite-momentum singlet pairing. Repulsive interactions, on the other hand, lead to ferromagnetism together with spin-triplet pairing at the edge. Our quantum Monte Carlo simulations confirm these findings and demonstrate that these instabilities occur even in the presence of strong quantum fluctuations. We discuss the implications of our results for experiments on cuprate high-temperature superconductors.

  17. Edge of polar cap patches

    NASA Astrophysics Data System (ADS)

    Hosokawa, K.; Taguchi, S.; Ogawa, Y.

    2016-04-01

    On the night of 4 December 2013, a sequence of polar cap patches was captured by an all-sky airglow imager (ASI) in Longyearbyen, Norway (78.1°N, 15.5°E). The 630.0 nm airglow images from the ASI of 4 second exposure time, oversampled the emission of natural lifetime (with quenching) of at least ˜30 sec, introduce no observational blurring effects. By using such high-quality ASI images, we succeeded in visualizing an asymmetry in the gradients between the leading/trailing edges of the patches in a 2-D fashion. The gradient in the leading edge was found to be 2-3 times steeper than that in the trailing edge. We also identified fingerlike structures, appearing only along the trailing edge of the patches, whose horizontal scale size ranged from 55 to 210 km. These fingers are considered to be manifestations of plasma structuring through the gradient-drift instability (GDI), which is known to occur only along the trailing edge of patches. That is, the current 2-D observations visualized, for the first time, how GDI stirs the patch plasma and such a mixing process makes the trailing edge more gradual. This result strongly implies a close connection between the GDI-driven plasma stirring and the asymmetry in the large-scale shape of patches and then suggests that the fingerlike structures can be used as markers to estimate the fine-scale structure in the plasma flow within patches.

  18. Flap-Edge Blowing Experiments

    NASA Technical Reports Server (NTRS)

    Gaeta, R. J.; Englar, R. J.; Ahuja, K. K.

    2003-01-01

    This Appendix documents the salient results from an effort to mitigate the so-called flap-edge noise generated at the split between a flap edge that is deployed and the undeployed flap. Utilizing a Coanda surface installed at the flap edge, steady blowing was used in an attempt to diminish the vortex strength resulting from the uneven lift distribution. The strength of this lifting vortex was augmented by steady blowing over the deployed flap. The test article for this study was the same 2D airfoil used in the steady blowing program reported earlier (also used in pulsed blowing tests, see Appendix G), however its trailing edge geometry was modified. An exact duplicate of the airfoil shape was made out of fiberglass with no flap, and in the clean configuration. It was attached to the existing airfoil to make an airfoil that has half of its flap deployed and half un-deployed. Figure 1 shows a schematic of the planform showing the two areas where steady blowing was introduced. The flap-edge blowing or the auxiliary blowing was in the direction normal to the freestream velocity vector. Slot heights for the blowing chambers were on the order of 0.0 14 inches.

  19. Edge-Aware BMA Filters.

    PubMed

    Guang Deng

    2016-01-01

    There has been continuous research in edge-aware filters which have found many applications in computer vision and image processing. In this paper, we propose a principled-approach for the development of edge-aware filters. The proposed approach is based on two well-established principles: 1) optimal parameter estimation and 2) Bayesian model averaging (BMA). Using this approach, we formulate the problem of filtering a pixel in a local pixel patch as an optimal estimation problem. Since a pixel belongs to multiple local patches, there are multiple estimates of the same pixel. We combine these estimates into a final estimate using BMA. We demonstrate the versatility of this approach by developing a family of BMA filters based on different settings of cost functions and log-likelihood and log-prior functions. We also present a new interpretation of the guided filter and develop a BMA guided filter which includes the guided filter as a special case. We show that BMA filters can produce similar smoothing results as those of the state-of-the-art edge-aware filters. Two BMA filters are computationally as efficient as the guided filter which is one of the fastest edge-aware filters. We also demonstrate that the BMA guided filter is better than the guided filter in preserving sharp edges. A new feature of the BMA guided filter is that the filtered image is similar to that produced by a clustering process.

  20. Reduction of wing rock amplitudes using leading-edge vortex manipulations

    NASA Technical Reports Server (NTRS)

    Walton, James; Katz, Joseph

    1992-01-01

    A mechanically operated leading edge flap system was used to perturb leading edge vortex position on a free-to-roll double-delta wing. The motion of the flaps was synchronized with the wing rolling oscillations and the effect of the phase shift between the oscillations of the wing and the flaps was investigated. Experimental results indicated that this simple approach was effective in reducing the amplitude of the unintended rolling motion and its implementation to actual airplane configurations is rather simple.

  1. Image recovery from edge primitives

    NASA Technical Reports Server (NTRS)

    Alter-Gartenberg, Rachel; Huck, Friedrich O.; Narayanswamy, Ramkumar

    1990-01-01

    A method for extracting edge primitives from Mach-band patterns is presented together with a method for recovering image representations of features outlined by the edge boundaries. The accuracy, stability, and resolution of these representations are assessed. Since these representations are most commonly used in characterizing targets, this method of low-level processing offers new opportunities for computer vision and high data-compressing coding. Two bandpass filters are considered, the spatially invariant Laplacian of Gaussian filter and spatially variant intensity-dependent spatial (IDS) summation. It is shown that the recovery from the IDS bandpass data is particularly advantageous in applications for which robustness to local and temporal variations in illumination is important. It is concluded that the edge primitives extracted from bandpassed images can be an efficient way to store, transmit, and represent images.

  2. A Little Bit of Sugar Helps the Pill Go Down: Resilience, Peace, and Family Planning: Comment on "The Pill Is Mightier Than the Sword".

    PubMed

    De Souza, Roger-Mark

    2016-02-01

    The article by Potts et al, "The Pill is Mightier than the Sword," points out that family planning has an important role to play in building peace by increasing women's empowerment and their agency, ultimately helping peacebuilding efforts. Evidence has demonstrated that family planning programs are cost effective, produce quick results, help women and couples meet their desired fertility levels, and produce a multitude of benefits around economic productivity, community engagement, conservation, resilience, and peacebuilding. In order for policy audiences from a variety of sectors, including conflict and peacebuilding, to appreciate these benefits, it is important to find common ground and articulate co-benefits that will help them appreciate and value the role of family planning, as it were, give them sugar to help the pill go down. This commentary examines how resilience, peacebuilding and family planning efforts need to focus on co-benefits in order to build on the successful interventions and opportunities that Potts et al highlight. PMID:26927398

  3. Seeing Double

    NASA Astrophysics Data System (ADS)

    Pesic, Peter

    2003-10-01

    The separateness and connection of individuals is perhaps the central question of human life: What, exactly, is my individuality? To what degree is it unique? To what degree can it be shared, and how? To the many philosophical and literary speculations about these topics over time, modern science has added the curious twist of quantum theory, which requires that the elementary particles of which everything consists have no individuality at all. All aspects of chemistry depend on this lack of individuality, as do many branches of physics. From where, then, does our individuality come? In Seeing Double, Peter Pesic invites readers to explore this intriguing set of questions. He draws on literary and historical examples that open the mind (from Homer to Martin Guerre to Kafka), philosophical analyses that have helped to make our thinking and speech more precise, and scientific work that has enabled us to characterize the phenomena of nature. Though he does not try to be all-inclusive, Pesic presents a broad range of ideas, building toward a specific point of view: that the crux of modern quantum theory is its clash with our ordinary concept of individuality. This represents a departure from the usual understanding of quantum theory. Pesic argues that what is bizarre about quantum theory becomes more intelligible as we reconsider what we mean by individuality and identity in ordinary experience. In turn, quantum identity opens a new perspective on us. Peter Pesic is a Tutor and Musician-in-Residence at St. John's College, Santa Fe, New Mexico. He has a Ph.D. in physics from Stanford University.

  4. Double inflation

    SciTech Connect

    Silk, J.; Turner, M.S.

    1986-04-01

    The Zel'dovich spectrum of adiabatic density perturbations is a generic prediction of inflation. There is increasing evidence that when the spectrum is normalized by observational data on small scales, there is not enough power on large scales to account for the observed large-scale structure in the Universe. Decoupling the spectrum on large and small scales could solve this problem. As a means of decoupling the large and small scales we propose double inflation (i.e., two episodes of inflation). In this scenario the spectrum on large scales is determined by the first episode of inflation and those on small scales by a second episode of inflation. We present three models for such a scenario. By nearly saturating the large angular-scale cosmic microwave anisotropy bound, we can easily account for the observed large-scale structure. We take the perturbations on small scales to be very large, deltarho/rho approx. = 0.1 to 0.01, which results in the production of primordial black holes (PBHs), early formation of structure, reionization of the Universe, and a rich array of astrophysical events. The ..cap omega..-problem is also addressed by our scenario. Allowing the density perturbations produced by the second episode of inflation to be large also lessens the fine-tuning required in the scalar potential and makes reheating much easier. We briefly speculate on the possibility that the second episode of inflation proceeds through the nucleation of bubbles, which today manifest themselves as empty bubbles whose surfaces are covered with galaxies. 37 refs., 1 fig.

  5. Edge shape and comfort of rigid lenses.

    PubMed

    La Hood, D

    1988-08-01

    One of the main factors determining the comfort of a rigid contact lens is the shape of the edge. The comfort of four different contact lens edge shapes was assessed with four unadapted subjects in a randomized masked trial. Lenses with well rounded anterior edge profiles were found to be significantly more comfortable than lenses with square anterior edges. There was no significant difference in subjective comfort between a rounded and square posterior edge profile. The results suggest that the interaction of the edge with the eyelid is more important in determining comfort than edge effects on the cornea, when lenses are fitted according to a corneal alignment philosophy. PMID:3177585

  6. Shape-dependent canny edge detector

    NASA Astrophysics Data System (ADS)

    Panetta, Karen A.; Agaian, Sos S.; Nercessian, Shahan C.; Almunstashri, Ali A.

    2011-08-01

    Edges characterize the boundaries of objects in images and are informative structural cues for computer vision and target/object detection and recognition systems. The Canny edge detector is widely regarded as the edge detection standard. It is fairly adaptable to different environments, as its parametric nature attempts to tailor the detection of edges based on image-dependent characteristics or the particular requirements of a given implementation. Though it has been used in a myriad of image processing tasks, the Canny edge detector is still vulnerable to edge losses, localization errors, and noise sensitivity. These issues are largely due to the key tradeoff made in the scale and size of the edge detection filters used by the algorithm. Small-scaled filters are sensitive to edges but also to noise, whereas large-scaled filters are robust to noise but could filter out fine details. In this paper, novel edge detection kernel generalizations and a shape-dependent edge detector are introduced to alleviate these shortcomings. While most standard edge detection algorithms are based on convolving the input image with fixed size square kernels, this paper will illustrate the benefits of different filter sizes, and more importantly, different kernel shapes for edge detection. Moreover, new edge fusion methods are introduced to more effectively combine the individual edge responses. Existing edge detectors, including the Canny edge detector, can be obtained from the generalized edge detector by specifying corresponding parameters and kernel shapes. The proposed representations and edge detector have been qualitatively and quantitatively evaluated on several different types of image data. Computer simulations demonstrate that nonsquare kernel approaches can outperform square kernel approaches such as Canny, Sobel, Prewitt, Roberts, and others, providing better tradeoffs between noise rejection, accurate edge localization, and resolution. Where possible, Pratt's figure of

  7. Edge transport in the trivial phase of InAs/GaSb

    NASA Astrophysics Data System (ADS)

    Nichele, Fabrizio; Suominen, Henri J.; Kjaergaard, Morten; Marcus, Charles M.; Sajadi, Ebrahim; Folk, Joshua A.; Qu, Fanming; Beukman, Arjan J. A.; de Vries, Folkert K.; van Veen, Jasper; Nadj-Perge, Stevan; Kouwenhoven, Leo P.; Nguyen, Binh-Minh; Kiselev, Andrey A.; Yi, Wei; Sokolich, Marko; Manfra, Michael J.; Spanton, Eric M.; Moler, Kathryn A.

    2016-08-01

    We present transport and scanning SQUID measurements on InAs/GaSb double quantum wells, a system predicted to be a two-dimensional topological insulator. Top and back gates allow independent control of density and band offset, allowing tuning from the trivial to the topological regime. In the trivial regime, bulk conductivity is quenched but transport persists along the edges, superficially resembling the predicted helical edge-channels in the topological regime. We characterize edge conduction in the trivial regime in a wide variety of sample geometries and measurement configurations, as a function of temperature, magnetic field, and edge length. Despite similarities to studies claiming measurements of helical edge channels, our characterization points to a non-topological origin for these observations.

  8. On detection of the Fermi edge in in situ grown thin films of high- Tc oxides

    NASA Astrophysics Data System (ADS)

    Abrecht, M.; Ariosa, D.; Saleh, S. A.; Rast, S.; Margaritondo, G.; Onellion, M.; Pavuna, D.

    2001-11-01

    We discuss our systematic series of experiments on the photoelectric detection of the Fermi edge using a cylindrical mirror analyser on films of high- Tc oxides, grown in situ by pulsed laser ablation. The Fermi edge (comparable to the edge of the reference Ag) is very easily observed even in the two-phase BSCCO-2212 film that exhibits onsets of superconducting transitions, at 85 and 45 K. In contrast, the Fermi edge is weaker and more difficult to observe even in the state-of-the-art, highly epitaxial, monophase YBa 2Cu 3O 7- y (YBCO) and NdBa 2Cu 3O 7- y (NBCO-123) films (both with Tc=92 K). So far we could not detect the Fermi edge in the films of the double-`chain' YBCO-124.

  9. The Problem of the Edge.

    ERIC Educational Resources Information Center

    Faatz, Judith A.

    1998-01-01

    Describes a field study in a local ecosystem which allows high school students to investigate the edge effect, where a meadow and a forest meet. Students measure soil moisture content, soil temperature, air temperature, relative humidity, wind intensity, and illumination level. Teachers can help students apply their findings to understand problems…

  10. Development of edge effects around experimental ecosystem hotspots is affected by edge density and matrix type

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ecological edge effects are sensitive to landscape context. In particular, edge effects can be altered by matrix type and by the presence of other nearby edges. We experimentally altered patch configurations in an African savanna to determine how edge density and matrix type influence edge effect de...

  11. Edge absorption and circular photogalvanic effect in 2D topological insulator edges

    NASA Astrophysics Data System (ADS)

    Entin, M. V.; Magarill, L. I.

    2016-06-01

    The electron absorption on the edge states and the edge photocurrent of a 2D topological insulator (TI) are studied. We consider the optical transitions within linear edge branches of the energy spectrum. The interaction with impurities is taken into account. The circular polarization is found to produce the edge photocurrent, the direction of which is determined by light polarization and edge orientation.

  12. Beating Swords into . . . Chips?

    ERIC Educational Resources Information Center

    Marshall, Eliot

    1991-01-01

    Discussed are the efforts of the Pentagon to help U.S. companies remain competitive in high-tech civilian markets. The tug-of-war for these companies between Congress, which has come to view them as a vehicle for pork-barrel funding, and the administration, which is trying to rein them in, is described. (KR)

  13. Assessment of transmitral flow after mitral valve edge-to-edge repair using High-speed particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Jeyhani, Morteza; Shahriari, Shahrokh; Labrosse, Michel; Kadem, Lyes

    2013-11-01

    Approximately 500,000 people in North America suffer from mitral valve regurgitation (MR). MR is a disorder of the heart in which the mitral valve (MV) leaflets do not close securely during systole. Edge-to-edge repair (EtER) technique can be used to surgically treat MR. This technique produces a double-orifice configuration for the MV. Under these un-physiological conditions, flow downstream of the MV forms a double jet structure that may disturb the intraventricular hemodynamics. Abnormal flow patterns following EtER are mainly characterized by high-shear stress and stagnation zones in the left ventricle (LV), which increase the potential of blood component damage. In this study, a custom-made prosthetic bicuspid MV was used to analyze the LV flow patterns after EtER by means of digital particle image velocimetry (PIV). Although the repair of a MV using EtER technique is an effective approach, this study confirms that EtER leads to changes in the LV flow field, including the generation of a double mitral jet flow and high shear stress regions.

  14. Language at a Distance: Sharpening a Communication Tool in the Online Classroom

    ERIC Educational Resources Information Center

    Hannan, Annika

    2009-01-01

    Both immensely powerful and entirely fickle, language in online instruction is a double-edged sword. A potent intermediary between instructor and students, and among students themselves, language is a key tool in online learning. It carries and cultivates information. It builds knowledge and self-awareness. It brings learners together in a…

  15. Are Plush Dorms and Fancy Food Plans Important Drivers of College Cost?

    ERIC Educational Resources Information Center

    Archibald, Robert B.; Feldman, David H.

    2011-01-01

    Like most schools, College of William and Mary is not shy about touting its amenities. The Webpage that advertises the college's housing and dining options begins with, "Wireless and Starbucks? Thomas Jefferson never had it this good." Advertising of this sort is a double-edged public-relations sword. Colleges and universities clearly want to…

  16. Factors Contributed by Community Organizations to the Motivation of Teachers in Rural Punjab, Pakistan, and Implications for the Quality of Teaching

    ERIC Educational Resources Information Center

    Barrs, J.

    2005-01-01

    The double-edged sword of Jomtien (1990), which emphasized access to education, and of Dakar (2000), which placed additional emphasis on the quality of education, the Holy Grail, provides the context for the expansion of education in developing countries. One of the most frequently espoused ingredients for success is good governance. The…

  17. Human Flesh Search Engine and Online Privacy.

    PubMed

    Zhang, Yang; Gao, Hong

    2016-04-01

    Human flesh search engine can be a double-edged sword, bringing convenience on the one hand and leading to infringement of personal privacy on the other hand. This paper discusses the ethical problems brought about by the human flesh search engine, as well as possible solutions.

  18. Whose Lingua Franca? The Politics of Language in Transnational Medical Education

    ERIC Educational Resources Information Center

    Kane, Tanya

    2014-01-01

    The lingua franca promoted at Weill Cornell Medical College in Qatar belongs to few as a first language. The implementation of an English-medium curriculum at Qatar's only medical school has proved a double-edged sword. Despite English being deployed out of necessity as part of a strategy geared to improve health care provision and medical…

  19. Analyzing the Cognitive Skills and Inquiry

    ERIC Educational Resources Information Center

    Stafford, Tish

    2011-01-01

    The Common Core Standards (CCS) movement represents a double-edged sword for school librarians. On the one hand, it gives prominence to inquiry skills and interdisciplinary collaboration, reinforcing the profession's efforts to infuse inquiry into the curriculum through collaborative planning and co-instruction between classroom teachers and…

  20. Co-Ethnic Network, Social Class, and Heritage Language Maintenance among Chinese Immigrant Families

    ERIC Educational Resources Information Center

    Zhang, Donghui

    2012-01-01

    This ethnographic study investigated heritage language maintenance among two distinct groups of Chinese immigrant families (Mandarin and Fujianese) from the social network perspective. The results indicated that a co-ethnic network could be a double-edged sword, which works differently on children from different social classes. While the Mandarin…

  1. Postmodernity or High Modernity? Emerging Approaches in the New History of Education.

    ERIC Educational Resources Information Center

    Escolano, Agustin

    1996-01-01

    Compares and contrasts two emerging approaches to educational historical research. Reveals a double-edged sword in that while these approaches open up the field to a wide array of subject matter and styles of inquiry, they also may weaken the epistemological stature of the discipline. (MJP)

  2. The Social Validation of Institutional Indicators to Promote System-Wide Web Accessibility in Postsecondary Institutions

    ERIC Educational Resources Information Center

    Mariger, Heather Ann

    2011-01-01

    The Internet is an integral part of higher education today. Students, faculty, and staff must have access to the institutional web for essential activities. For persons with disabilities, the web is a double-edged sword. While an accessibly designed website can mitigate or remove barriers, an inaccessible one can make access impossible. If…

  3. Saddle-node dynamics for edge detection

    SciTech Connect

    Wong, Y.F.

    1994-09-01

    The author demonstrates how the formulation of a nonlinear scale-space filter can be used for edge detection and junction analysis. By casting edge-preserving filtering in terms of maximizing information content subject to an average cost function, the computed cost at each pixel location becomes a local measure of edgeness. This computation depends on a single scale parameter and the given image data. Unlike previous approaches which require careful tuning of the filter kernels for various types of edges, this scheme is general enough to be able to handle different edges, such as lines, step edges, corners and junctions. Anisotropy in the data is handled automatically by the nonlinear dynamics.

  4. Edge-on thick discs

    NASA Astrophysics Data System (ADS)

    Kasparova, A.; Katkov, I.; Chilingarian, I.; Silchenko, O.; Moiseev, A.; Borisov, S.

    2016-06-01

    Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations. Using the Russian 6-m telescope BTA we collected deep spectra of thick discs in three edge-on early-type disc galaxies located in different environments: NGC4111 in a dense group, NGC4710 in the Virgo cluster, and NGC5422 in a sparse group. We see intermediate age (4 ‑ 5 Gyr) metal rich ([Fe/H] ~ ‑0.2 ‑ 0.0 dex) stellar populations in NGC4111 and NGC4710. On the other hand, NGC5422 does not harbour young stars, its only disc is thick and old (10 Gyr) and its α-element abundance suggests a long formation epoch implying its formation at high redshift. Our results prove the diversity of thick disc formation scenarios.

  5. Linear array optical edge sensor

    NASA Technical Reports Server (NTRS)

    Bejczy, Antal K. (Inventor); Primus, Howard C. (Inventor)

    1987-01-01

    A series of independent parallel pairs of light emitting and detecting diodes for a linear pixel array, which is laterally positioned over an edge-like discontinuity in a workpiece to be scanned, is disclosed. These independent pairs of light emitters and detectors sense along intersecting pairs of separate optical axes. A discontinuity, such as an edge in the sensed workpiece, reflects a detectable difference in the amount of light from that discontinuity in comparison to the amount of light that is reflected on either side of the discontinuity. A sequentially sychronized clamping and sampling circuit detects that difference as an electrical signal which is recovered by circuitry that exhibits an improved signal-to-noise capability for the system.

  6. Gyrosheath near the tokamak edge

    SciTech Connect

    Hazeltine, R.D.; Xiao, H. . Inst. for Fusion Studies); Valanju, P.M. . Fusion Research Center)

    1993-03-01

    A new model for the structure of the radial electric field profile in the edge during the H-mode is proposed. Charge separation caused by the difference between electron and ion gyromotion, or more importantly in a tokamak, the banana motion (halo effect) can self-consistently produce an electric dipole moment that causes the sheared radial electric field. The calculated results based on the model are consistent with D-III D and TEXTOR experimental results.

  7. Edge-driven microplate kinematics

    USGS Publications Warehouse

    Schouten, Hans; Klitgord, Kim D.; Gallo, David G.

    1993-01-01

    It is known from plate tectonic reconstructions that oceanic microplates undergo rapid rotation about a vertical axis and that the instantaneous rotation axes describing the microplate's motion relative to the bounding major plates are frequently located close to its margins with those plates, close to the tips of propagating rifts. We propose a class of edge-driven block models to illustrate how slip across the microplate margins, block rotation, and propagation of rifting may be related to the relative motion of the plates on either side. An important feature of these edge-driven models is that the instantaneous rotation axes are always located on the margins between block and two bounding plates. According to those models the pseudofaults or traces of disrupted seafloor resulting from the propagation of rifting between microplate and major plates may be used independently to approximately trace the continuous kinematic evolution of the microplate back in time. Pseudofault geometries and matching rotations of the Easter microplate show that for most of its 5 m.y. history, block rotation could be driven by the drag of the Nazca and Pacific plates on the microplate's edges rather than by a shear flow of mantle underneath.

  8. Chemistry at the Edge of Graphene.

    PubMed

    Bellunato, Amedeo; Arjmandi Tash, Hadi; Cesa, Yanina; Schneider, Grégory F

    2016-03-16

    The selective functionalization of graphene edges is driven by the chemical reactivity of its carbon atoms. The chemical reactivity of an edge, as an interruption of the honeycomb lattice of graphene, differs from the relative inertness of the basal plane. In fact, the unsaturation of the pz orbitals and the break of the π conjugation on an edge increase the energy of the electrons at the edge sites, leading to specific chemical reactivity and electronic properties. Given the relevance of the chemistry at the edges in many aspects of graphene, the present Review investigates the processes and mechanisms that drive the chemical functionalization of graphene at the edges. Emphasis is given to the selective chemical functionalization of graphene edges from theoretical and experimental perspectives, with a particular focus on the characterization tools available to investigate the chemistry of graphene at the edge.

  9. Edge localized mode control with an edge resonant magnetic perturbation

    SciTech Connect

    Moyer, R.A.; Boedo, J.A.; Rudakov, D.L.; Evans, T.E.; Osborne, T.H.; Gohil, P.; Groebner, R.J.; Jackson, G.L.; La Haye, R.J.; Leonard, A.W.; Schaffer, M.J.; Snyder, P.B.; West, W.P.; Thomas, P.R.; Becoulet, M.; Harris, J.; Finken, K.-H.; Doyle, E.J.; Rhodes, T.L.; Wang, G.

    2005-05-15

    A low amplitude ({delta}b{sub r}/B{sub T}=1 part in 5000) edge resonant magnetic field perturbation with toroidal mode number n=3 and poloidal mode numbers between 8 and 15 has been used to suppress most large type I edge localized modes (ELMs) without degrading core plasma confinement. ELMs have been suppressed for periods of up to 8.6 energy confinement times when the edge safety factor q{sub 95} is between 3.5 and 4. The large ELMs are replaced by packets of events (possibly type II ELMs) with small amplitude, narrow radial extent, and a higher level of magnetic field and density fluctuations, creating a duty cycle with long 'active' intervals of high transport and short 'quiet' intervals of low transport. The increased transport associated with these events is less impulsive and slows the recovery of the pedestal profiles to the values reached just before the large ELMs without the n=3 perturbation. Changing the toroidal phase of the perturbation by 60 deg. with respect to the best ELM suppression case reduces the ELM amplitude and frequency by factors of 2-3 in the divertor, produces a more stochastic response in the H-mode pedestal profiles, and displays similar increases in small scale events, although significant numbers of large ELMs survive. In contrast to the best ELM suppression case where the type I ELMs are also suppressed on the outboard midplane, the midplane recycling increases until individual ELMs are no longer discernable. The ELM response depends on the toroidal phase of the applied perturbation because intrinsic error fields make the target plasma nonaxisymmetric, and suggests that at least some of the variation in ELM behavior in a single device or among different devices is due to differences in the intrinsic error fields in these devices. These results indicate that ELMs can be suppressed by small edge resonant magnetic field perturbations. Extrapolation to next-step burning plasma devices will require extending the regime of operation to

  10. Impact of edge current density and pressure gradient on the stability of DIII-D high performance discharges

    SciTech Connect

    Lao, L.L.; Ferron, J.R.; Strait, E.J.

    1997-06-01

    One of the major goals of advanced tokamak research is to develop plasma configurations with good confinement and improved stability at high {beta}. In DIII-D, various high performance configurations with H- and VH-mode edges have been produced. These include discharges with poloidal cross sections in the forms of dee and crecent shapes, single- and double-null divertors, and with various central magnetic shear profiles and current profile peakedness. All these discharges exhibit confinement in the outer plasma region which leads to a large edge pressure gradient and a large edge bootstrap current driven by this steep pressure gradient. These edge conditions often drive an instability near the edge region which can severely degrade the discharge performance. An understanding of this edge instability is essential to sustain an enhance discharge performance.

  11. RECENT EXPERIMENTAL STUDIES OF EDGE AND INTERNAL TRANSPORT BARRIERS IN THE DIII-D TOKAMAK

    SciTech Connect

    P. GOHIL; L.R. BAYLOR; K.H. BURRELL; T.A. CASPER; E.J. DOYLE; C.M. GREENFIELD; T.C. JERNIGAN; J.E. KINSEY; C.J LASNIER; R.A. MOYER; M. MURAKAMI; T.L. RHODES; D.L. RUDAKOV; G.M. STAEBLER; G. WANG; J.G. WATKINS; W.P. WEST; L.ZENG

    2002-08-01

    Results from recent experiments on the DIII-D tokamak have revealed many important details on transport barriers at the plasma edge and in the plasma core. These experiments include: (a) the formation of the H-mode edge barrier directly by pellet injection; (b) the formation of a quiescent H-mode edge barrier (QH-mode) which is free from edge localized modes (ELMs), but which still exhibits good density and radiative power control; (c) the formation of multiple transport barriers, such as the quiescent double barrier (QDB) which combines a internal transport barrier with the quiescent H-mode edge barrier. Results from the pellet-induced H-mode experiments indicate that: (a) the edge temperature (electron or ion) is not a critical parameter for the formation of the H-mode barrier, (b) pellet injection leads to an increased gradient in the radial electric field, E{sub r}, at the plasma edge; (c) the experimentally determined edge parameters at barrier transition are well below the predictions of several theories on the formation of the H-mode barrier, (d) pellet injection can lower the threshold power required to form the H-mode barrier. The quiescent H-mode barrier exhibits good density control as the result of continuous magnetohydrodynamic (MHD) activity at the plasma edge called the edge harmonic oscillation (EHO). The EHO enhances the edge particle transport while maintaining a good energy transport barrier. The ability to produce multiple barriers in the QDB regime has led to long duration, high performance plasmas with {beta}{sub NH{sub 89}} values of 7 for up to 10 times the confinement time. Density profile control in the plasma core of QDB plasmas has been demonstrated using on-axis ECH.

  12. Ultrasonicated double wall carbon nanotubes for enhanced electric double layer capacitance

    NASA Astrophysics Data System (ADS)

    Pandey, Srikrishna; Maiti, Uday N.; Palanisamy, Kowsalya; Nikolaev, Pavel; Arepalli, Sivaram

    2014-06-01

    An intense ultrasonication of the double wall carbon nanotubes (DWCNTs) causes fractures and splitting of the individual tubes. This not only generates open tips and edges in DWCNTs but also incorporates defects in the tube walls. The electric double layer capacitor (EDLC) electrodes of intensively ultrasonicated DWCNTs (U-DWCNTs) form organized layered-porous structures. The EDLC behavior of U-DWCNTs electrodes shows dramatic improvements (specific capacitance 10 times and 222 times larger than the pristine DWCNTs at scan rates 5 mV s-1 and 500 mV s-1, respectively) due to the increased wettability of electrodes and accessibility of the electrolyte ions.

  13. Densified edge seals for fuel cell components

    DOEpatents

    DeCasperis, Anthony J.; Roethlein, Richard J.; Breault, Richard D.

    1982-01-01

    A porous fuel cell component, such as an electrode substrate, has a densified edge which forms an improved gas seal during operation when soaked with electrolyte. The edges are made from the same composition as the rest of the component and are made by compressing an increased thickness of this material along the edges during the fabrication process.

  14. K-edge densitometer (KED)

    SciTech Connect

    Sprinkle, J.K.; Hansen, W.J.

    1993-02-11

    In 1979, a K-edge densitometer (KED) was installed by the Safeguards Assay group from Los Alamos National Laboratory in the PNC reprocessing plant at Tokai-mura, Japan. It uses an active nondestructive assay technique, KED, to measure the plutonium concentration of the product solution. The measurement uncertainty of an assay depends on the count time chosen, but can be 0.5% or better. The computer hardware and software were upgraded in 1992. This manual describes the operation of the instrument, with an emphasis on the user interface to the software.

  15. A double-double/double-single computation package

    2004-12-01

    The DDFUNIDSFUN software permits a new or existing Fortran-90 program to utilize double-double precision (approx. 31 digits) or double-single precision (approx. 14 digits) arithmetic. Double-double precision is required by a rapidly expandirtg body of scientific computations in physics and mathematics, for which the conventional 64-bit IEEE computer arithmetic (about 16 decimal digit accuracy) is not sufficient. Double-single precision permits users of systems that do not have hardware 64-bit IEEE arithmetic (such as some game systems)more » to perform arithmetic at a precision nearly as high as that of systems that do. Both packages run significantly faster Than using multiple precision or arbitrary precision software for this purpose. The package includes an extensive set of low-level routines to perform high-precision arithmetic, including routines to calculate various algebraic and transcendental functions, such as square roots, sin, ccc, exp, log and others. In addition, the package includes high-level translation facilities, so that Fortran programs can utilize these facilities by making only a few changes to conventional Fortran programs. In most cases, the only changes that are required are to change the type statements of variables that one wishes to be treated as multiple precision, plus a few other minor changes. The DDFUN package is similar in functionality to the double-double part of the GD package, which was previously written at LBNL. However, the DDFUN package is written exclusively in Fortran-90, thus avoidIng difficulties that some users experience when using GD, which includes both Fortran-90 and C++ code.« less

  16. An Efficient Ant-Based Edge Detector

    NASA Astrophysics Data System (ADS)

    Aydın, Doğan

    An efficient ant-based edge detector is presented. It is based on the distribution of ants on an image, ants try to find possible edges by using a state transition function based on 5x5 edge structures. Visual comparisons show that the proposed method gives finer details and thinner edges at lesser computational times when compared to earlier ant-based approaches. When compared to standard edge detectors, it shows robustness to Gaussian and Salt & Pepper noise and provides finer details than others with same parameter set in both clear and noisy images.

  17. Tunable skewed edges in puckered structures

    NASA Astrophysics Data System (ADS)

    Grujić, Marko M.; Ezawa, Motohiko; Tadić, Milan Ž.; Peeters, François M.

    2016-06-01

    We propose a type of edges arising due to the anisotropy inherent in the puckered structure of a honeycomb system such as in phosphorene. Skewed-zigzag and skewed-armchair nanoribbons are semiconducting and metallic, respectively, in contrast to their normal edge counterparts. Their band structures are tunable, and a metal-insulator transition is induced by an electric field. We predict a field-effect transistor based on the edge states in skewed-armchair nanoribbons, where the edge state is gapped by applying arbitrary small electric field Ez. A topological argument is presented, revealing the condition for the emergence of such edge states.

  18. Optimal edge filters explain human blur detection.

    PubMed

    McIlhagga, William H; May, Keith A

    2012-01-01

    Edges are important visual features, providing many cues to the three-dimensional structure of the world. One of these cues is edge blur. Sharp edges tend to be caused by object boundaries, while blurred edges indicate shadows, surface curvature, or defocus due to relative depth. Edge blur also drives accommodation and may be implicated in the correct development of the eye's optical power. Here we use classification image techniques to reveal the mechanisms underlying blur detection in human vision. Observers were shown a sharp and a blurred edge in white noise and had to identify the blurred edge. The resultant smoothed classification image derived from these experiments was similar to a derivative of a Gaussian filter. We also fitted a number of edge detection models (MIRAGE, N(1), and N(3)(+)) and the ideal observer to observer responses, but none performed as well as the classification image. However, observer responses were well fitted by a recently developed optimal edge detector model, coupled with a Bayesian prior on the expected blurs in the stimulus. This model outperformed the classification image when performance was measured by the Akaike Information Criterion. This result strongly suggests that humans use optimal edge detection filters to detect edges and encode their blur. PMID:22984222

  19. The Cambridge Double Star Atlas

    NASA Astrophysics Data System (ADS)

    MacEvoy, Bruce; Tirion, Wil

    2015-12-01

    Preface; What are double stars?; The binary orbit; Double star dynamics; Stellar mass and the binary life cycle; The double star population; Detecting double stars; Double star catalogs; Telescope optics; Preparing to observe; Helpful accessories; Viewing challenges; Next steps; Appendices: target list; Useful formulas; Double star orbits; Double star catalogs; The Greek alphabet.

  20. Measuring edge importance to improve immunization performance

    NASA Astrophysics Data System (ADS)

    Huang, He; Yan, Zhijun; Pan, Yaohui

    2014-12-01

    The edge heterogeneity has a remarkable influence on disease spreading, but it has seldom been considered in the disease-controlling policies. Based on the gravity model, we propose the edge importance index to describe the influence of edge heterogeneity on immunization strategies. Then the edge importance and contact weight are combined to calculate the infection rates on the I-S (Infected-Susceptible) edges in the complex network, and the difference of the infection rates on strong and weak ties is analyzed. Simulation results show that edge heterogeneity has a significant influence on the performance of immunization strategies, and better immunization efficiency is derived when the vaccination rate of the nodes in the weak I-S edges is increased.

  1. Haptic Edge Detection Through Shear

    PubMed Central

    Platkiewicz, Jonathan; Lipson, Hod; Hayward, Vincent

    2016-01-01

    Most tactile sensors are based on the assumption that touch depends on measuring pressure. However, the pressure distribution at the surface of a tactile sensor cannot be acquired directly and must be inferred from the deformation field induced by the touched object in the sensor medium. Currently, there is no consensus as to which components of strain are most informative for tactile sensing. Here, we propose that shape-related tactile information is more suitably recovered from shear strain than normal strain. Based on a contact mechanics analysis, we demonstrate that the elastic behavior of a haptic probe provides a robust edge detection mechanism when shear strain is sensed. We used a jamming-based robot gripper as a tactile sensor to empirically validate that shear strain processing gives accurate edge information that is invariant to changes in pressure, as predicted by the contact mechanics study. This result has implications for the design of effective tactile sensors as well as for the understanding of the early somatosensory processing in mammals. PMID:27009331

  2. Haptic Edge Detection Through Shear.

    PubMed

    Platkiewicz, Jonathan; Lipson, Hod; Hayward, Vincent

    2016-01-01

    Most tactile sensors are based on the assumption that touch depends on measuring pressure. However, the pressure distribution at the surface of a tactile sensor cannot be acquired directly and must be inferred from the deformation field induced by the touched object in the sensor medium. Currently, there is no consensus as to which components of strain are most informative for tactile sensing. Here, we propose that shape-related tactile information is more suitably recovered from shear strain than normal strain. Based on a contact mechanics analysis, we demonstrate that the elastic behavior of a haptic probe provides a robust edge detection mechanism when shear strain is sensed. We used a jamming-based robot gripper as a tactile sensor to empirically validate that shear strain processing gives accurate edge information that is invariant to changes in pressure, as predicted by the contact mechanics study. This result has implications for the design of effective tactile sensors as well as for the understanding of the early somatosensory processing in mammals. PMID:27009331

  3. Double outlet right ventricle

    MedlinePlus

    ... medlineplus.gov/ency/article/007328.htm Double outlet right ventricle To use the sharing features on this page, please enable JavaScript. Double outlet right ventricle (DORV) is a heart disease that is ...

  4. Chromosome doubling method

    DOEpatents

    Kato, Akio

    2006-11-14

    The invention provides methods for chromosome doubling in plants. The technique overcomes the low yields of doubled progeny associated with the use of prior techniques for doubling chromosomes in plants such as grasses. The technique can be used in large scale applications and has been demonstrated to be highly effective in maize. Following treatment in accordance with the invention, plants remain amenable to self fertilization, thereby allowing the efficient isolation of doubled progeny plants.

  5. Distributed-element circuit model of edge magnetoplasmon transport

    NASA Astrophysics Data System (ADS)

    Hashisaka, Masayuki; Kamata, Hiroshi; Kumada, Norio; Washio, Kazuhisa; Murata, Ryuji; Muraki, Koji; Fujisawa, Toshimasa

    2013-12-01

    We report experimental and theoretical studies of edge magnetoplasmon (EMP) transport in quantum Hall (QH) devices. We develop a model that allows us to calculate the transport coefficients of EMPs in QH devices with various geometries. In our model, a QH system is described as a chiral distributed-element (CDE) circuit, where the effects of Coulomb interaction are represented by an electrochemical capacitance distributed along unidirectional transmission lines. We measure the EMP transport coefficients through single- and coupled-edge channels, a quantum point contact, and single- and double-cavity structures. These measured transmission spectra can be reproduced well by simulations using the corresponding CDE circuits. By fitting the experimental results with the simulations, we deduce the circuit parameters that characterize the electrostatic environment around the edge channels in a realistic QH system. The observed gate-voltage dependences of the EMP transport properties in gate-defined structures are explained in terms of the gate tuning of the circuit parameters in CDE circuits.

  6. Operation Dominic, Shot Sword Fish. Project Officer's report - Project 1. 3b. Effects of an underwater nuclear explosion on hydroacoustic systems

    SciTech Connect

    McMillan, T.; La Houssaye, W.P.; Johnson, C.T.

    1985-09-01

    The objectives of Project 1.2 were to determine and evaluate the effects of an underwater nuclear explosion on the operational capabilities of shipboard sonar and other types of hydroacoustic systems. Project 1.3b included all measurements at ranges greater than 10 nautical miles and the results of these measurements constitute the subject of this report. This report concerns the effects of the underwater nuclear explosion, Sword Fish, on: (a) Long-range active detection systems at the first convergence zone (25 to 30 miles); (b) Passive shipboard or submarine sonars at a few hundred miles; and (c) Long-range passive detection and surveillance at Sound Surveillance System (SOSUS) and Missile Impact Locating System (MILS) stations at several hundred to several thousand miles. A submarine station at the first convergence zone and five shipboard stations at ranges from 200 miles to 5,000 miles recorded signals from hydrophones suspended at various depths to approximately 2,000 feet. Submarines on other assignments recorded signals on standard submarine sonar equipment on a not-to interfere basis. SOSUS and MILS stations operated normally during the period and also made special magnetic-tape and strip-chart recordings of signals from single hydrophones from before burst time to several hours after burst.

  7. Age and growth of the sword razor clam Ensis arcuatus in the Ría de Pontevedra (NW Spain): Influence of environmental parameters

    NASA Astrophysics Data System (ADS)

    Hernández-Otero, A.; Gaspar, M. B.; Macho, G.; Vázquez, E.

    2014-01-01

    The sword razor clam Ensis arcuatus is the most important commercial species of razor clam in Spain, and its fishery in the Ría de Pontevedra (Galicia, NW Spain) is the most productive. Despite the economic importance of this species, information on its biology is scarce. This study reports shell morphometric relationships, age, and growth rates of E. arcuatus in three fishing beds in the Ría de Pontevedra (Brensa, Bueu and Ons, located in respectively the inner, middle and outer zones of the ria), providing the first estimates of growth parameters for the species in the Iberian Peninsula. Growth was estimated by examination of surface growth rings and internal shell microgrowth patterns (acetate peel technique) that proved to be the most suitable method for growth estimate. Growth of E. arcuatus was slower in Bueu (L∞ = 140.4, k = 0.40) followed by Brensa (L∞ = 151.91, k = 0.40) and Ons (L∞ = 172.7, k = 0.33), and the clams reached commercial size in 1.7, 2.3 and 2.8 years in Ons, Brensa and Bueu, respectively. The differences in growth between sites in relation to environmental parameters are evaluated and the implications for the razor clam fishery are discussed.

  8. Occupational respiratory disease in the United Kingdom 1989: a report to the British Thoracic Society and the Society of Occupational Medicine by the SWORD project group.

    PubMed Central

    Meredith, S K; Taylor, V M; McDonald, J C

    1991-01-01

    A voluntary scheme for the surveillance of work related and occupational respiratory disease (SWORD) was established in January 1989 with help from the British Thoracic Society and the Society of Occupational Medicine and support from the Health and Safety Executive. Three hundred and fifty four chest physicians representing 90% of the chest clinics in the United Kingdom and 361 occupational physicians submit reports regularly of newly diagnosed cases of work related respiratory illness with information on age, sex, residence, occupation, and suspected causal agent. In 1989 2101 cases were notified, of which frequent diagnoses were asthma (26%), mesothelioma (16%), pneumoconiosis (15%), benign pleural disease (11%), and allergic alveolitis (6%). Incidence rates calculated against denominators from the Labour Force Survey showed very large differences between occupational groups, especially for asthma and asbestos related diseases. Substantial regional variation in the incidence of asthma was not explained by the geographical distribution of high risk industries and was probably due to differing levels of ascertainment. The results imply that the true frequency of acute occupational respiratory disease in the United Kingdom may have been three times greater than that reported. PMID:2039741

  9. On the edge energy of lipid membranes and the thermodynamic stability of pores

    SciTech Connect

    Pera, H.; Kleijn, J. M.; Leermakers, F. A. M.

    2015-01-21

    To perform its barrier function, the lipid bilayer membrane requires a robust resistance against pore formation. Using a self-consistent field (SCF) theory and a molecularly detailed model for membranes composed of charged or zwitterionic lipids, it is possible to predict structural, mechanical, and thermodynamical parameters for relevant lipid bilayer membranes. We argue that the edge energy in membranes is a function of the spontaneous lipid monolayer curvature, the mean bending modulus, and the membrane thickness. An analytical Helfrich-like model suggests that most bilayers should have a positive edge energy. This means that there is a natural resistance against pore formation. Edge energies evaluated explicitly in a two-gradient SCF model are consistent with this. Remarkably, the edge energy can become negative for phosphatidylglycerol (e.g., dioleoylphosphoglycerol) bilayers at a sufficiently low ionic strength. Such bilayers become unstable against the formation of pores or the formation of lipid disks. In the weakly curved limit, we study the curvature dependence of the edge energy and evaluate the preferred edge curvature and the edge bending modulus. The latter is always positive, and the former increases with increasing ionic strength. These results point to a small window of ionic strengths for which stable pores can form as too low ionic strengths give rise to lipid disks. Higher order curvature terms are necessary to accurately predict relevant pore sizes in bilayers. The electric double layer overlap across a small pore widens the window of ionic strengths for which pores are stable.

  10. Fusion Of Edge Maps In Color Images

    NASA Astrophysics Data System (ADS)

    Delcroix, C. J.; Abidi, M. A.

    1988-10-01

    In this paper, a new analytic method for the detection, of edges in color images is presented. This method focuses on the integration of three edge maps in order to increase one's confidence about the presence/absence of edges in a depicted scene. The integration process utilizes an algorithm developed by the authors under a broader research topic: The integration of registered multisensory data. It is based on the interaction between the following two constraints: the principle of existence, which tends to maximize the value of the output edge map at a given location if one input edge map features an edge, and the principle of confirmability, which adjusts this value according to the edge contents in the other input edge map at the same location by maximiz-ing the similarity between them. The latter two maximizations are achieved using the Euler-Language Calculus of Variations equations. This algorithm, which fuses optimally two correlated edge maps with regard to the above principles is extended to the simultaneous fusion of three edge maps. Experiments were conducted using not only the red, green, and blue representation of color information but also other bases.

  11. Edge detection in microscopy images using curvelets

    PubMed Central

    Gebäck, Tobias; Koumoutsakos, Petros

    2009-01-01

    Background Despite significant progress in imaging technologies, the efficient detection of edges and elongated features in images of intracellular and multicellular structures acquired using light or electron microscopy is a challenging and time consuming task in many laboratories. Results We present a novel method, based on the discrete curvelet transform, to extract a directional field from the image that indicates the location and direction of the edges. This directional field is then processed using the non-maximal suppression and thresholding steps of the Canny algorithm to trace along the edges and mark them. Optionally, the edges may then be extended along the directions given by the curvelets to provide a more connected edge map. We compare our scheme to the Canny edge detector and an edge detector based on Gabor filters, and show that our scheme performs better in detecting larger, elongated structures possibly composed of several step or ridge edges. Conclusion The proposed curvelet based edge detection is a novel and competitive approach for imaging problems. We expect that the methodology and the accompanying software will facilitate and improve edge detection in images available using light or electron microscopy. PMID:19257905

  12. Jet formation at the sea ice edge

    NASA Astrophysics Data System (ADS)

    Feltham, D. L.; Heorton, H. D.

    2014-12-01

    The sea ice edge presents a region of many feedback processes between the atmosphere, ocean and sea ice, which are inadequately represented in current climate models. Here we focus on on-ice atmospheric and oceanic flows at the sea ice edge. Mesoscale jet formation due to the Coriolis effect is well understood over sharp changes in surface roughness such as coastlines. This sharp change in surface roughness is experienced by the atmosphere flowing over, and ocean flowing under, a compacted sea ice edge. We have studied a dynamic sea ice edge responding to atmospheric and oceanic jet formation. The shape and strength of atmospheric and oceanic jets during on-ice flows is calculated from existing studies of the sea ice edge and prescribed to idealised models of the sea ice edge. An idealised analytical model of sea ice drift is developed and compared to a sea ice climate model (the CICE model) run on an idealised domain. The response of the CICE model to jet formation is tested at various resolutions. We find that the formation of atmospheric jets during on-ice winds at the sea ice edge increases the wind speed parallel to the sea ice edge and results in the formation of a sea ice edge jet. The modelled sea ice edge jet is in agreement with an observed jet although more observations are needed for validation. The increase in ice drift speed is dependent upon the angle between the ice edge and wind and can result in a 40% increase in ice transport along the sea ice edge. The possibility of oceanic jet formation during on-ice currents and the resultant effect upon the sea ice edge is less conclusive. Observations and climate model data of the polar oceans has been analysed to show areas of likely atmospheric jet formation, with the Fram Strait being of particular interest.

  13. Edge adaptive intra field de-interlacing of video images

    NASA Astrophysics Data System (ADS)

    Lachine, Vladimir; Smith, Gregory; Lee, Louie

    2013-02-01

    Expanding image by an arbitrary scale factor and thereby creating an enlarged image is a crucial image processing operation. De-interlacing is an example of such operation where a video field is enlarged in vertical direction with 1 to 2 scale factor. The most advanced de-interlacing algorithms use a few consequent input fields to generate one output frame. In order to save hardware resources in video processors, missing lines in each field may be generated without reference to the other fields. Line doubling, known as "bobbing", is the simplest intra field de-interlacing method. However, it may generate visual artifacts. For example, interpolation of an inserted line from a few neighboring lines by vertical filter may produce such visual artifacts as "jaggies." In this work we present edge adaptive image up-scaling and/or enhancement algorithm, which can produce "jaggies" free video output frames. As a first step, an edge and its parameters in each interpolated pixel are detected from gradient squared tensor based on local signal variances. Then, according to the edge parameters including orientation, anisotropy and variance strength, the algorithm determines footprint and frequency response of two-dimensional interpolation filter for the output pixel. Filter's coefficients are defined by edge parameters, so that quality of the output frame is controlled by local content. The proposed method may be used for image enlargement or enhancement (for example, anti-aliasing without resampling). It has been hardware implemented in video display processor for intra field de-interlacing of video images.

  14. Edge Magnon Excitation in Spin Dimer Systems

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Ryo; Matsumoto, Masashige

    2016-10-01

    Magnetic excitation in a spin dimer system on a bilayer honeycomb lattice is investigated in the presence of a zigzag edge, where disordered and ordered phases can be controlled by a quantum phase transition. In analogy with the case of graphene with a zigzag edge, a flat edge magnon mode appears in the disordered phase. In an ordered phase, a finite magnetic moment generates a mean-field potential to the magnon. Since the potential is nonuniform on the edge and bulk sites, it affects the excitation, and the dispersion of the edge mode deviates from the flat shape. We investigate how the edge magnon mode evolves when the phase changes through the quantum phase transition and discuss the similarities to ordered spin systems on a monolayer honeycomb lattice.

  15. Moveable Leading Edge Device for a Wing

    NASA Technical Reports Server (NTRS)

    Pitt, Dale M. (Inventor); Eckstein, Nicholas Stephen (Inventor)

    2013-01-01

    A method and apparatus for managing a flight control surface system. A leading edge section on a wing of an aircraft is extended into a deployed position. A deformable section connects the leading edge section to a trailing section. The deformable section changes from a deformed shape to an original shape when the leading edge section is moved into the deployed position. The leading edge section on the wing is moved from the deployed position to an undeployed position. The deformable section changes to the deformed shape inside of the wing.

  16. An edge index for topological insulators

    NASA Astrophysics Data System (ADS)

    Prodan, Emil

    2009-03-01

    Topological insulators display dissipationless currents flowing at the edges of the samples. These currents are associated to chiral edge modes, whose existence is intrinsically linked to the topology of the electronic states of the bulk. The edge modes can be easily investigated when the edges are smooth and have a periodicity, but as soon as the periodicity is absent, the problem becomes un-traceable by purely theoretical means. In my talk I will exemplify the use of non-commutative calculus to explore the properties, especially the stability of the edge modes. For example, using such techniques one can give a fairly elementary proof that the edge modes in Chern insulators survive even for a rough (random) edge. Similarly, for the Spin-Hall effect, one can define an observable and its associated current whose conductance remains quantized during various deformations of the Hamiltonian system. It turns out that in all cases, the edge conductance is given by the index of a Fredholm operator, which provides a new topological invariant linked directly to the edge rather than the bulk.

  17. Visible imaging of edge turbulence in NSTX

    SciTech Connect

    S. Zweben; R. Maqueda; K. Hill; D. Johnson; et al

    2000-06-13

    Edge plasma turbulence in tokamaks and stellarators is believed to cause the radical heat and particle flux across the separatrix and into the scrape-off-layers of these devices. This paper describes initial measurements of 2-D space-time structure of the edge density turbulence made using a visible imaging diagnostic in the National Spherical Torus Experiment (NSTX). The structure of the edge turbulence is most clearly visible using a method of gas puff imaging to locally illuminate the edge density turbulence.

  18. BHZ model edge states on Mobius strip

    NASA Astrophysics Data System (ADS)

    Mogni, Christopher; Vakaryuk, Victor; Tchernyshyov, Oleg

    2014-03-01

    We present analytical edge state solutions to the Bernevig-Hughes-Zhang (BHZ) model of a quantum spin hall topological insulator with Mobius geometry. The edge state solutions are obtained by solving the differential equations governing the BHZ model. The edge states satisfy both inverted periodic boundary conditions and single-valuedness boundary conditions. Furthermore, we develop a classification of boundary conditions compatible with the BHZ model insulator with Mobius geometry. We demonstrate that in the limit of large strip length that there exists a finite energy gap between the edge states. This energy gap does not exist for strips with periodic boundary conditions.

  19. Efficient edge-guided full-waveform inversion by Canny edge detection and bilateral filtering algorithms

    NASA Astrophysics Data System (ADS)

    Xiang, Shiming; Zhang, Haijiang

    2016-11-01

    It is known full-waveform inversion (FWI) is generally ill-conditioned and various strategies including pre-conditioning and regularizing the inversion system have been proposed to obtain a reliable estimation of the velocity model. Here, we propose a new edge-guided strategy for FWI in frequency domain to efficiently and reliably estimate velocity models with structures of the size similar to the seismic wavelength. The edges of the velocity model at the current iteration are first detected by the Canny edge detection algorithm that is widely used in image processing. Then, the detected edges are used for guiding the calculation of FWI gradient as well as enforcing edge-preserving total variation (TV) regularization for next iteration of FWI. Bilateral filtering is further applied to remove noise but keep edges of the FWI gradient. The proposed edge-guided FWI in the frequency domain with edge-guided TV regularization and bilateral filtering is designed to preserve model edges that are recovered from previous iterations as well as from lower frequency waveforms when FWI is conducted from lower to higher frequencies. The new FWI method is validated using the complex Marmousi model that contains several steeply dipping fault zones and hundreds of horizons. Compared to FWI without edge guidance, our proposed edge-guided FWI recovers velocity model anomalies and edges much better. Unlike previous image-guided FWI or edge-guided TV regularization strategies, our method does not require migrating seismic data, thus is more efficient for real applications.

  20. Saturn's Rings Edge-on

    NASA Technical Reports Server (NTRS)

    1995-01-01

    In one of nature's most dramatic examples of 'now-you see-them, now-you-don't', NASA's Hubble Space Telescope captured Saturn on May 22, 1995 as the planet's magnificent ring system turned edge-on. This ring-plane crossing occurs approximately every 15 years when the Earth passes through Saturn's ring plane.

    For comparison, the top picture was taken by Hubble on December 1, 1994 and shows the rings in a more familiar configuration for Earth observers.

    The bottom picture was taken shortly before the ring plane crossing. The rings do not disappear completely because the edge of the rings reflects sunlight. The dark band across the middle of Saturn is the shadow of the rings cast on the planet (the Sun is almost 3 degrees above the ring plane.) The bright stripe directly above the ring shadow is caused by sunlight reflected off the rings onto Saturn's atmosphere. Two of Saturn's icy moons are visible as tiny starlike objects in or near the ring plane. They are, from left to right, Tethys (slightly above the ring plane) and Dione.

    This observation will be used to determine the time of ring-plane crossing and the thickness of the main rings and to search for as yet undiscovered satellites. Knowledge of the exact time of ring-plane crossing will lead to an improved determination of the rate at which Saturn 'wobbles' about its axis (polar precession).

    Both pictures were taken with Hubble's Wide Field Planetary Camera 2. The top image was taken in visible light. Saturn's disk appears different in the bottom image because a narrowband filter (which only lets through light that is not absorbed by methane gas in Saturn's atmosphere) was used to reduce the bright glare of the planet. Though Saturn is approximately 900 million miles away, Hubble can see details as small as 450 miles across.

    The Wide Field/Planetary Camera 2 was developed by the Jet Propulsion Laboratory and managed by the Goddard Spaced Flight Center for NASA's Office of Space Science

  1. Double exchange model for magnetic hexaborides.

    PubMed

    Pereira, Vitor M; Lopes dos Santos, J M B; Castro, Eduardo V; Neto, A H Castro

    2004-10-01

    A microscopic theory for rare-earth ferromagnetic hexaborides, such as Eu1-xCaxB6, is proposed on the basis of the double-exchange Hamiltonian. In these systems, the reduced carrier concentrations place the Fermi level near the mobility edge, introduced in the spectral density by the disordered spin background. We show that the transport properties such as the Hall effect, magnetoresistance, frequency dependent conductivity, and dc resistivity can be quantitatively described within the model. We also make specific predictions for the behavior of the Curie temperature T(C) as a function of the plasma frequency omega(p).

  2. The reconstructed edges of the hexagonal BN

    NASA Astrophysics Data System (ADS)

    Zhao, Ruiqi; Gao, Junfeng; Liu, Zhongfan; Ding, Feng

    2015-05-01

    As an important two-dimensional material which shows exceptional mechanical and chemical stability, superior electronic properties, along with broad applications, the hexagonal-BN (h-BN) has drawn great attention recently. Here we report a systematic study on the structural stability, electronic and magnetic properties of various h-BN edges, including both bare and hydrogen-terminated ones. It is found that along the armchair (AC) direction, the pristine edge is the most stable one because of the formation of a triple B\\z.tbd N bond, while, along the zigzag (ZZ) directions, the reconstructed ones, ZZB + N and ZZN57 are more stable. The pristine edges are more stable in bare BN in most cases if saturated with hydrogen. By applying the theory of Wulff construction, we predicted that an unpassivated BN domain prefers the hexagonal shape enclosed with bare AC edges i.e., AC-Ns, AC, AC-Bs if the feedstock varies from N-rich to B-rich. However, the evolution from ZZN edged triangular domain, to hexagonal domain enclosed with AC edges, and ZZB edged triangle may occur if the edges are terminated by hydrogen atoms. Further calculation shows that these edges present rich type-dependent properties and thus are important for various applications. This theoretical study showed that controlling the morphologies of BN domains and BN edges is crucial for various applications.As an important two-dimensional material which shows exceptional mechanical and chemical stability, superior electronic properties, along with broad applications, the hexagonal-BN (h-BN) has drawn great attention recently. Here we report a systematic study on the structural stability, electronic and magnetic properties of various h-BN edges, including both bare and hydrogen-terminated ones. It is found that along the armchair (AC) direction, the pristine edge is the most stable one because of the formation of a triple B\\z.tbd N bond, while, along the zigzag (ZZ) directions, the reconstructed ones, ZZB + N

  3. Double bowl piston

    DOEpatents

    Meffert, Darrel Henry; Urven, Jr., Roger Leroy; Brown, Cory Andrew; Runge, Mark Harold

    2007-03-06

    A piston for an internal combustion engine is disclosed. The piston has a piston crown with a face having an interior annular edge. The piston also has first piston bowl recessed within the face of the piston crown. The first piston bowl has a bottom surface and an outer wall. A line extending from the interior annular edge of the face and tangent with the outer wall forms an interior angle greater than 90 degrees with the face of the piston. The piston also has a second piston bowl that is centrally located and has an upper edge located below a face of the piston crown.

  4. A Mesh Refinement Study on the Impact Response of a Shuttle Leading-Edge Panel Finite Element Simulation

    NASA Technical Reports Server (NTRS)

    Fasanella, Edwin L.; Jackson, Karen E.; Lyle, Karen H.; Spellman, Regina L.

    2006-01-01

    A study was performed to examine the influence of varying mesh density on an LS-DYNA simulation of a rectangular-shaped foam projectile impacting the space shuttle leading edge Panel 6. The shuttle leading-edge panels are fabricated of reinforced carbon-carbon (RCC) material. During the study, nine cases were executed with all possible combinations of coarse, baseline, and fine meshes of the foam and panel. For each simulation, the same material properties and impact conditions were specified and only the mesh density was varied. In the baseline model, the shell elements representing the RCC panel are approximately 0.2-in. on edge, whereas the foam elements are about 0.5-in. on edge. The element nominal edge-length for the baseline panel was halved to create a fine panel (0.1-in. edge length) mesh and doubled to create a coarse panel (0.4-in. edge length) mesh. In addition, the element nominal edge-length of the baseline foam projectile was halved (0.25-in. edge length) to create a fine foam mesh and doubled (1.0-in. edge length) to create a coarse foam mesh. The initial impact velocity of the foam was 775 ft/s. The simulations were executed in LS-DYNA for 6 ms of simulation time. Contour plots of resultant panel displacement and effective stress in the foam were compared at four discrete time intervals. Also, time-history responses of internal and kinetic energy of the panel, kinetic and hourglass energy of the foam, and resultant contact force were plotted to determine the influence of mesh density.

  5. Absence of edge states in covalently bonded zigzag edges of graphene on Ir(111).

    PubMed

    Li, Yan; Subramaniam, Dinesh; Atodiresei, Nicolae; Lazić, Predrag; Caciuc, Vasile; Pauly, Christian; Georgi, Alexander; Busse, Carsten; Liebmann, Marcus; Blügel, Stefan; Pratzer, Marco; Morgenstern, Markus; Mazzarello, Riccardo

    2013-04-11

    The zigzag edges of graphene on Ir(111) are studied by ab initio simulations and low-temperature scanning tunneling spectroscopy, providing information about their structural, electronic, and magnetic properties. No edge state is found to exist, which is explained in terms of the interplay between a strong geometrical relaxation at the edge and a hybridization of the d orbitals of Ir atoms with the graphene orbitals at the edge.

  6. Observing Double Stars

    NASA Astrophysics Data System (ADS)

    Genet, Russell M.; Fulton, B. J.; Bianco, Federica B.; Martinez, John; Baxter, John; Brewer, Mark; Carro, Joseph; Collins, Sarah; Estrada, Chris; Johnson, Jolyon; Salam, Akash; Wallen, Vera; Warren, Naomi; Smith, Thomas C.; Armstrong, James D.; McGaughey, Steve; Pye, John; Mohanan, Kakkala; Church, Rebecca

    2012-05-01

    Double stars have been systematically observed since William Herschel initiated his program in 1779. In 1803 he reported that, to his surprise, many of the systems he had been observing for a quarter century were gravitationally bound binary stars. In 1830 the first binary orbital solution was obtained, leading eventually to the determination of stellar masses. Double star observations have been a prolific field, with observations and discoveries - often made by students and amateurs - routinely published in a number of specialized journals such as the Journal of Double Star Observations. All published double star observations from Herschel's to the present have been incorporated in the Washington Double Star Catalog. In addition to reviewing the history of visual double stars, we discuss four observational technologies and illustrate these with our own observational results from both California and Hawaii on telescopes ranging from small SCTs to the 2-meter Faulkes Telescope North on Haleakala. Two of these technologies are visual observations aimed primarily at published "hands-on" student science education, and CCD observations of both bright and very faint doubles. The other two are recent technologies that have launched a double star renaissance. These are lucky imaging and speckle interferometry, both of which can use electron-multiplying CCD cameras to allow short (30 ms or less) exposures that are read out at high speed with very low noise. Analysis of thousands of high speed exposures allows normal seeing limitations to be overcome so very close doubles can be accurately measured.

  7. Eliminating Unbonded Edges In Explosive Bonding

    NASA Technical Reports Server (NTRS)

    Bement, Laurence J.; Kushnick, Anne C.

    1991-01-01

    Explosive-bonding technique elminates sharp unbonded notch normally occurring between flyer plate and baseplate. Makes it possible to simply break away unbonded outer extremity of flyer plate; no longer necessary to grind away unbonded edge to prevent collection of corrosive contaminants in edge voids. Method not limited to flat surfaces.

  8. How Forest Inhomogeneities Affect the Edge Flow

    NASA Astrophysics Data System (ADS)

    Boudreault, Louis-Étienne; Dupont, Sylvain; Bechmann, Andreas; Dellwik, Ebba

    2016-09-01

    Most of our knowledge on forest-edge flows comes from numerical and wind-tunnel experiments where canopies are horizontally homogeneous. To investigate the impact of tree-scale heterogeneities ({>}1 m) on the edge-flow dynamics, the flow in an inhomogeneous forest edge on Falster island in Denmark is investigated using large-eddy simulation. The three-dimensional forest structure is prescribed in the model using high resolution helicopter-based lidar scans. After evaluating the simulation against wind measurements upwind and downwind of the forest leading edge, the flow dynamics are compared between the scanned forest and an equivalent homogeneous forest. The simulations reveal that forest inhomogeneities facilitate flow penetration into the canopy from the edge, inducing important dispersive fluxes in the edge region as a consequence of the flow spatial variability. Further downstream from the edge, the forest inhomogeneities accentuate the canopy-top turbulence and the skewness of the wind-velocity components while the momentum flux remains unchanged. This leads to a lower efficiency in the turbulent transport of momentum within the canopy. Dispersive fluxes are only significant in the upper canopy. Above the canopy, the mean flow is less affected by the forest inhomogeneities. The inhomogeneities induce an increase in the mean wind speed that was found to be equivalent to a decrease in the aerodynamic height of the canopy. Overall, these results highlight the importance of forest inhomogeneities when looking at canopy-atmosphere exchanges in forest-edge regions.

  9. Cutting a Tapered Edge on Padding Material

    NASA Technical Reports Server (NTRS)

    Mitchell, M. J.

    1982-01-01

    Resilience and flexibility of felt, rubber, or other padding materials allow them to be clamped in form block, cut straight down, and then released to produce straight clean tapered edge. With material held in slanted position, edge can be cut straight down; hence cut depth is minimum.

  10. More results on oscillating edge-flames

    NASA Astrophysics Data System (ADS)

    Buckmaster, J.; Hegab, A.; Jackson, T. L.

    2000-06-01

    We examine a simple model of a side-anchored non-premixed edge-flame in order to gain insights into the oscillations that are sometimes observed in microgravity candle burning, flame-spread over liquids, etc. Previous results describe the role played by the Lewis number of the fuel, and the Damköhler number, and here we examine both the effects of an on-edge and off-edge convective flow, and the effects of a heat sink. The on-edge flow and the heat sink tend to destabilize and the off-edge flow tends to stabilize, results consistent with our hypothesis regarding the genesis of the oscillations.

  11. Magnetism of zigzag edge phosphorene nanoribbons

    SciTech Connect

    Zhu, Zhili E-mail: jiayu@zzu.edu.cn; Li, Chong; Yu, Weiyang; Chang, Dahu; Sun, Qiang; Jia, Yu E-mail: jiayu@zzu.edu.cn

    2014-09-15

    We have investigated, by means of ab initio calculations, the electronic and magnetic structures of zigzag edge phosphorene nanoribbons (ZPNRs) with various widths. The stable magnetic state was found in pristine ZPNRs by allowing the systems to be spin-polarized. The ground state of pristine ZPNRs prefers ferromagnetic order in the same edge but antiferromagnetic order between two opposite edges. The magnetism arises from the dangling bond states as well as edge localized π-orbital states. The presence of a dangling bond is crucial to the formation of the magnetism of ZPNRs. The hydrogenated ZPNRs get nonmagnetic semiconductors with a direct band gap. While, the O-saturated ZPNRs show magnetic ground states due to the weak P-O bond in the ribbon plane between the p{sub z}-orbitals of the edge O and P atoms.

  12. Particle and heat flux measurements in PDX edge plasmas

    NASA Astrophysics Data System (ADS)

    Budny, R.; Manos, D.

    1984-05-01

    This paper describes the use of novel combined Langmuir-calorimeter probes to measure edge plasma conditions near the midplane in PDX. The probes consisted of up to five Langmuir probes and up to two calorimeters. Single and double probe characteristics yield ne and Tc which are compared with results derived from a triple probe analysis. The calorimeters measure heat flux in the electron and ion drift directions. This paper presents time-resolved radial profiles of ne, Te, VF (floating potential),and P (heat flux) during high power neutral beam-heated, single-null discharges and circular scoop limiter discharges. The temporal dependence of these quantities displays the previously observed behavior with respect to gross discharge characteristics; however, an additional dependence on confinement mode has been observed. During the H-mode of energy confinement, a transient depression of ne, Te, and P occur in the scrape-off plasma.

  13. Elastically Deformable Side-Edge Link for Trailing-Edge Flap Aeroacoustic Noise Reduction

    NASA Technical Reports Server (NTRS)

    Khorrami, Mehdi R. (Inventor); Lockard, David P. (Inventor); Moore, James B. (Inventor); Su, Ji (Inventor); Turner, Travis L. (Inventor); Lin, John C. (Inventor); Taminger, Karen M. (Inventor); Kahng, Seun K. (Inventor); Verden, Scott A. (Inventor)

    2014-01-01

    A system is provided for reducing aeroacoustic noise generated by an aircraft having wings equipped with trailing-edge flaps. The system includes a plurality of elastically deformable structures. Each structure is coupled to and along one of the side edges of one of the trailing-edge flaps, and is coupled to a portion of one of the wings that is adjacent to the one of the side edges. The structures elastically deform when the trailing-edge flaps are deployed away from the wings.

  14. Multidimensional period doubling structures.

    PubMed

    Lee, Jeong Yup; Flom, Dvir; Ben-Abraham, Shelomo I

    2016-05-01

    This paper develops the formalism necessary to generalize the period doubling sequence to arbitrary dimension by straightforward extension of the substitution and recursion rules. It is shown that the period doubling structures of arbitrary dimension are pure point diffractive. The symmetries of the structures are pointed out. PMID:27126116

  15. The effects of plasma shape control on the edge collisionless ion orbit loss

    SciTech Connect

    Wu, G. J.; Zhang, X. D.; Li, Y. D.; Sun, P. J.; Cao, G. M.

    2013-10-15

    Double null magnetic configurations with different elongation κ and triangularity δ are constructed by using an analytical solution of the Grad–Shafranov equation. The ion orbit losses in plasma edge region are calculated by solving the ion guiding center orbit equation for different values of κ and δ. It is found that the ion orbit loss is larger for a smaller value of κ or δ. The variation of the ion orbit loss fraction on the magnetic surface is also studied.

  16. TCT measurements with slim edge strip detectors

    NASA Astrophysics Data System (ADS)

    Mandić, Igor; Cindro, Vladimir; Gorišek, Andrej; Kramberger, Gregor; Mikuž, Marko; Zavrtanik, Marko; Fadeyev, Vitaliy; Sadrozinski, Hartmut F.-W.; Christophersen, Marc; Phlips, Bernard

    2014-07-01

    Transient current technique (TCT) measurements with focused laser light on miniature silicon strip detectors (n+-type strips on p-type bulk) with one inactive edge thinned to about 100 μm using the Scribe-Cleave-Passivate (SCP) method are presented. Pulses of focused IR (λ=1064 nm) laser light were directed to the surface of the detector and charge collection properties near the slim edge were investigated. Measurements before and after irradiation with reactor neutrons up to 1 MeV equivalent fluence of 1.5×1015 neq/cm2 showed that SCP thinning of detector edge does not influence its charge collection properties. TCT measurements were done also with focused red laser beam (λ=640 nm) directed to the SCP processed side of the detector. The absorption length of red light in silicon is about 3 μm so with this measurement information about the electric field at the edge can be obtained. Observations of laser induced signals indicate that the electric field distribution along the depth of the detector at the detector edge is different than in the detector bulk: electric field is higher near the strip side and lower at the back side. This is a consequence of negative surface charge caused by passivation of the cleaved edge with Al2O3. The difference between bulk and edge electric field distributions gets smaller after irradiation.

  17. Technidilaton at the conformal edge

    SciTech Connect

    Hashimoto, Michio; Yamawaki, Koichi

    2011-01-01

    Technidilaton (TD) was proposed long ago in the technicolor near criticality/conformality. To reveal the critical behavior of TD, we explicitly compute the nonperturbative contributions to the scale anomaly <{theta}{sub {mu}}{sup {mu}>} and to the technigluon condensate <{alpha}G{sub {mu}{nu}}{sup 2}>, which are generated by the dynamical mass m of the technifermions. Our computation is based on the (improved) ladder Schwinger-Dyson equation, with the gauge coupling {alpha} replaced by the two-loop running coupling {alpha}({mu}) having the Caswell-Banks-Zaks infrared fixed point {alpha}{sub *}: {alpha}({mu}){approx_equal}{alpha}={alpha}{sub *} for the infrared region m<{mu}<{Lambda}{sub TC}, where {Lambda}{sub TC} is the intrinsic scale (analogue of {Lambda}{sub QCD} of QCD) relevant to the perturbative scale anomaly. We find that -<{theta}{sub {mu}}{sup {mu}}>/m{sup 4}{yields}const{ne}0 and <{alpha}G{sub {mu}}{nu}{sup 2}>/m{sup 4}{yields}({alpha}/{alpha}{sub cr}-1){sup -3/2}{yields}{infinity} in the criticality limit m/{Lambda}{sub TC}{approx}exp(-{pi}/({alpha}/{alpha}{sub cr}-1){sup 1/2}){yields}0 ({alpha}={alpha}{sub *}=>{alpha}{sub cr}, or N{sub f} approaches N{sub f}{sup cr}) ('conformal edge'). Our result precisely reproduces the formal identity <{theta}{sub {mu}}{sup {mu}>}=({beta}({alpha})/4{alpha}{sup 2})<{alpha}G{sub {mu}{nu}}{sup 2}>, where {beta}({alpha})={Lambda}{sub TC}({partial_derivative}{alpha}/{partial_derivative}{Lambda}{sub TC})=-(2{alpha}{sub cr}/{pi}){center_dot}({alpha}/{alpha}{sub cr}-1){sup 3/2} is the nonperturbative beta function corresponding to the above essential singularity scaling of m/{Lambda}{sub TC}. Accordingly, the partially conserved dilatation current implies (M{sub TD}/m){sup 2}(F{sub TD}/m){sup 2}=-4<{theta}{sub {mu}}{sup {mu}}>/m{sup 4}{yields}const{ne}0 at criticality limit, where M{sub TD} is the mass of TD and F{sub TD} the decay constant of TD. We thus conclude that at criticality limit the TD could become a ''true

  18. Formation of Klein Edge Doublets from Graphene Monolayers.

    PubMed

    Kim, Judy S; Warner, Jamie H; Robertson, Alex W; Kirkland, Angus I

    2015-09-22

    With increasing possibilities for applications of graphene, it is essential to fully characterize the rich topological variations in graphene edge structures. Using aberration-corrected transmission electron microscopy, dangling carbon doublets at the edge of monolayer graphene crystals have been observed. Unlike the single-atom Klein edge often found at zigzag edges, these carbon dimers were observed in various edge structure environments, but most frequently on the more stable armchair edges. Observation of this Klein edge doublet over time reveals that its existence enhances the stability of armchair edges and is a route to atom abstraction on zigzag edges.

  19. An edge preserving differential image coding scheme

    NASA Technical Reports Server (NTRS)

    Rost, Martin C.; Sayood, Khalid

    1992-01-01

    Differential encoding techniques are fast and easy to implement. However, a major problem with the use of differential encoding for images is the rapid edge degradation encountered when using such systems. This makes differential encoding techniques of limited utility, especially when coding medical or scientific images, where edge preservation is of utmost importance. A simple, easy to implement differential image coding system with excellent edge preservation properties is presented. The coding system can be used over variable rate channels, which makes it especially attractive for use in the packet network environment.

  20. Image Edge Extraction via Fuzzy Reasoning

    NASA Technical Reports Server (NTRS)

    Dominquez, Jesus A. (Inventor); Klinko, Steve (Inventor)

    2008-01-01

    A computer-based technique for detecting edges in gray level digital images employs fuzzy reasoning to analyze whether each pixel in an image is likely on an edge. The image is analyzed on a pixel-by-pixel basis by analyzing gradient levels of pixels in a square window surrounding the pixel being analyzed. An edge path passing through the pixel having the greatest intensity gradient is used as input to a fuzzy membership function, which employs fuzzy singletons and inference rules to assigns a new gray level value to the pixel that is related to the pixel's edginess degree.

  1. Electrostatic analysis of the tokamak edge plasma

    SciTech Connect

    Motley, R.W.

    1981-07-01

    The intrusion of an equipotential poloidal limiter into the edge plasma of a circular tokamak discharge distorts the axisymmetry in two ways: (1) it (partially) shorts out the top-to-bottom Pfirsch-Schlueter driving potentials, and (2) it creates zones of back current flow into the limiter. The resulting boundary mismatch between the outer layers and the inner axisymmetric Pfirsch-Schlueter layer provides free energy to drive the edge plasma unstable. Special limiters are proposed to symmetrize the edge plasma and thereby reduce the electrical and MHD activity in the boundary layer.

  2. Differential Search Algorithm Based Edge Detection

    NASA Astrophysics Data System (ADS)

    Gunen, M. A.; Civicioglu, P.; Beşdok, E.

    2016-06-01

    In this paper, a new method has been presented for the extraction of edge information by using Differential Search Optimization Algorithm. The proposed method is based on using a new heuristic image thresholding method for edge detection. The success of the proposed method has been examined on fusion of two remote sensed images. The applicability of the proposed method on edge detection and image fusion problems have been analysed in detail and the empirical results exposed that the proposed method is useful for solving the mentioned problems.

  3. Cavitation on hydrofoils with sinusoidal leading edge

    NASA Astrophysics Data System (ADS)

    Johari, H.

    2015-12-01

    Cavitation characteristics of hydrofoils with sinusoidal leading edge were examined experimentally at a Reynolds number of 7.2 × 105. The hydrofoils had an underlying NACA 634-021 profile and an aspect ratio of 4.3. The sinusoidal leading edge geometries included three amplitudes of 2.5%, 5%, and 12% and two wavelengths of 25% and 50% of the mean chord length. Results revealed that cavitation on the leading edge-modified hydrofoils existed in pockets behind the troughs whereas the baseline hydrofoil produced cavitation along its entire span. Moreover, cavitation on the modified hydrofoils appeared at consistently lower angles of attack than on the baseline hydrofoil.

  4. Stresses in edge stiffened anisotropic sandwich plate

    NASA Astrophysics Data System (ADS)

    Rao, Koganti M.; Rao, Y. U. M.

    Hybrid-stress finite elements are used to study the static behavior of an edge stiffened anisotropic sandwich plate subjected to cylindrical bending. The stress concentration factors at the interface of core and stiffener are evaluated. The analysis of the simply-supported sandwich indicates that the state of stress at the interface of core and stiffener is increased and that the edge stiffener induces clamping conditions. The faces and stiffener at the edge are, respectively, subjected to negative and positive transverse shear, causing considerable bending action in faces about their own centroidal axis.

  5. An edge preserving differential image coding scheme

    NASA Technical Reports Server (NTRS)

    Rost, Martin C.; Sayood, Khalid

    1991-01-01

    Differential encoding techniques are fast and easy to implement. However, a major problem with the use of differential encoding for images is the rapid edge degradation encountered when using such systems. This makes differential encoding techniques of limited utility especially when coding medical or scientific images, where edge preservation is of utmost importance. We present a simple, easy to implement differential image coding system with excellent edge preservation properties. The coding system can be used over variable rate channels which makes it especially attractive for use in the packet network environment.

  6. Edge of chaos and genesis of turbulence.

    PubMed

    Chian, Abraham C-L; Muñoz, Pablo R; Rempel, Erico L

    2013-11-01

    The edge of chaos is analyzed in a spatially extended system, modeled by the regularized long-wave equation, prior to the transition to permanent spatiotemporal chaos. In the presence of coexisting attractors, a chaotic saddle is born at the basin boundary due to a smooth-fractal metamorphosis. As a control parameter is varied, the chaotic transient evolves to well-developed transient turbulence via a cascade of fractal-fractal metamorphoses. The edge state responsible for the edge of chaos and the genesis of turbulence is an unstable traveling wave in the laboratory frame, corresponding to a saddle point lying at the basin boundary in the Fourier space. PMID:24329334

  7. Composite laminate free edge reinforcement concepts

    NASA Technical Reports Server (NTRS)

    Howard, W. E.; Gossard, T., Jr.; Jones, R. M.

    1985-01-01

    The presence of a free edge in a laminated composite structure can result in delamination of the composite under certain loading conditions. Linear finite element analysis predicts large or even singular interlaminar stresses near the free edge. Edge reinforcements which will reduce these interlaminar stresses, prevent or delay the onset of delaminations, and thereby increase the strength and life of the structure were studied. Finite element models are used to analyze reinforced laminates which were subsequently fabricated and loaded to failure in order to verify the analysis results.

  8. Double diameter boring tool

    DOEpatents

    Ashbaugh, Fred N.; Murry, Kenneth R.

    1988-12-27

    A boring tool and a method of operation are provided for boring two concentric holes of precision diameters and depths in a single operation. The boring tool includes an elongated tool body, a shank for attachment to a standard adjustable boring head which is used on a manual or numerical control milling machine and first and second diametrically opposed cutting edges formed for cutting in opposite directions. The diameter of the elongated tool body is substantially equal to the distance from the first cutting edge tip to the axis of rotation plus the distance from the second cutting edge tip to the axis of rotation. The axis of rotation of the tool is spaced from the tool centerline a distance substantially equal to one-half the distance from the second cutting edge tip to the axis of rotation minus one-half the distance from the first cutting edge tip to the axis of rotation. The method includes the step of inserting the boring tool into the boring head, adjusting the distance between the tool centerline and the tool axis of rotation as described above and boring the two concentric holes.

  9. Comprehensive phylogenetic analysis of all species of swordtails and platies (Pisces: Genus Xiphophorus) uncovers a hybrid origin of a swordtail fish, Xiphophorus monticolus, and demonstrates that the sexually selected sword originated in the ancestral lineage of the genus, but was lost again secondarily

    PubMed Central

    2013-01-01

    Background Males in some species of the genus Xiphophorus, small freshwater fishes from Meso-America, have an extended caudal fin, or sword – hence their common name “swordtails”. Longer swords are preferred by females from both sworded and – surprisingly also, non-sworded (platyfish) species that belong to the same genus. Swordtails have been studied widely as models in research on sexual selection. Specifically, the pre-existing bias hypothesis was interpreted to best explain the observed bias of females in presumed ancestral lineages of swordless species that show a preference for assumed derived males with swords over their conspecific swordless males. However, many of the phylogenetic relationships within this genus still remained unresolved. Here we construct a comprehensive molecular phylogeny of all 26 known Xiphophorus species, including the four recently described species (X. kallmani, X. mayae, X. mixei and X. monticolus). We use two mitochondrial and six new nuclear markers in an effort to increase the understanding of the evolutionary relationships among the species in this genus. Based on the phylogeny, the evolutionary history and character state evolution of the sword was reconstructed and found to have originated in the common ancestral lineage of the genus Xiphophorus and that it was lost again secondarily. Results We estimated the evolutionary relationships among all known species of the genus Xiphophorus based on the largest set of DNA markers so far. The phylogeny indicates that one of the newly described swordtail species, Xiphophorus monticolus, is likely to have arisen through hybridization since it is placed with the southern platyfish in the mitochondrial phylogeny, but with the southern swordtails in the nuclear phylogeny. Such discordance between these two types of markers is a strong indication for a hybrid origin. Additionally, by using a maximum likelihood approach the possession of the sexually selected sword trait is shown

  10. Edge states in a honeycomb lattice: effects of anisotropic hopping and mixed edges

    SciTech Connect

    Dahal, Hari P; Balatsky, Alexander V; Sinistsyn, N A; Hu, Zi - Xiang; Yang, Kun

    2008-01-01

    We study the edge states in graphene in the presence of a magnetic field perpendicular to the plane of the lattice. Most of the work done so far discusses the edge states in either zigzag or armchair edge graphene considering an isotropic electron hopping. In practice, graphene can have a mixture of armchair and zigzag edges and the electron hopping can be anisotropic, which is the subject of this article. We predict that the mixed edges smear the enhanced local density of states (LDOS) at E=0 of the zigzag edge and, on the other hand, the anisotropic hopping gives rise to the enhanced LDOS at E=0 in the armchair edge. The behavior of the LDOS can be studied using scanning tunneling microscopy (STM) experiments. We suggest that care must be taken while interpreting the STM data, because the clear distinction between the zigzag edge (enhanced LDOS at E=0) and armchair edge (suppressed LDOS at E=0) can be lost if the hopping is not isotropic and if the edges are mixed.

  11. Probing the sorption reactivity of the edge surfaces in birnessite nanoparticles using nickel(II)

    NASA Astrophysics Data System (ADS)

    Simanova, Anna A.; Kwon, Kideok D.; Bone, Sharon E.; Bargar, John R.; Refson, Keith; Sposito, Garrison; Peña, Jasquelin

    2015-09-01

    Birnessite minerals are layer-type manganese oxides characterized by large surface areas, the presence of cation vacancy sites and varying amounts of structural and adsorbed Mn(III). In this study, we identify the conditions that favor trace metal adsorption on the edge surfaces of birnessite nanoparticles by using Ni as a probe ion for Ni K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy and geometry optimizations based on density function theory (DFT). In δ-MnO2 nanoparticles free of Mn(II,III) at pH 6.6, Ni was adsorbed primarily at vacancy sites, with a minor fraction of Ni present as a double-edge sharing (DES) or a double-corner sharing (DCS) complex at surface loadings exceeding the vacancy content. In Mn(III)-rich δ-MnO2 nanoparticles, about 80% of the adsorbed Ni formed a mixture of DES and DCS complexes at particle edges in samples with loadings ranging from 0.01 to 0.08 mol Ni mol-1 Mn, with only a small fraction of vacancy sites available to adsorb Ni. The presence of Mn(III) at the nanoparticle edges also changed the architecture of the DES complex, causing the Ni octahedra to adsorb onto the cavity formed between two Mn(III) octahedra at the particle edges. The EXAFS-derived Ni-Mn interatomic distances of 3.01-3.05 Å for this "flipped" Ni-DES complex were in excellent agreement with those obtained by DFT geometry optimization. Edge surfaces on birnessite nanoparticles have a lower affinity for trace metals than vacancy sites, but have a moderate sorption capacity (ca. 0.14 mol Ni mol-1 Mn at vacancies vs. 0.06 mol Ni mol-1 Mn at edge surfaces). Finally, although Mn(III) increases the relative proportion of Ni adsorbed at particle edges by blocking sorption sites on the basal surface, the overall sorption capacity of the mineral diminishes significantly.

  12. Survey of atomic processes in edge plasmas

    SciTech Connect

    Janev, R.K.; Post, D.E.; Langer, W.D.; Evans, K.; Heifetz, D.B.; Weisheit, J.C.

    1983-11-01

    A review of the most important reactions of atomic and molecular hydrogen with the fusion edge plasma electrons and ions is presented. An appropriate characterization of the considered collision processes, useful in plasma edge studies (evaluated cross sections, reaction rates, energy gain/loss per collision, etc.) has been performed. While a complete survey of atomic physics of fusion edge plasmas will be given elsewhere shortly, we demonstrate here the relevance of the atomic collision processes for describing the physical state of edge plasmas and understanding the energy balance in cool divertor plasmas. It is found that the excited neutral species play an important role in the low-temperature, high-density plasmas.

  13. Miniature Trailing Edge Effector for Aerodynamic Control

    NASA Technical Reports Server (NTRS)

    Lee, Hak-Tae (Inventor); Bieniawski, Stefan R. (Inventor); Kroo, Ilan M. (Inventor)

    2008-01-01

    Improved miniature trailing edge effectors for aerodynamic control are provided. Three types of devices having aerodynamic housings integrated to the trailing edge of an aerodynamic shape are presented, which vary in details of how the control surface can move. A bucket type device has a control surface which is the back part of a C-shaped member having two arms connected by the back section. The C-shaped section is attached to a housing at the ends of the arms, and is rotatable about an axis parallel to the wing trailing edge to provide up, down and neutral states. A flip-up type device has a control surface which rotates about an axis parallel to the wing trailing edge to provide up, down, neutral and brake states. A rotating type device has a control surface which rotates about an axis parallel to the chord line to provide up, down and neutral states.

  14. Folded membrane dialyzer with mechanically sealed edges

    DOEpatents

    Markley, Finley W.

    1976-01-01

    A semipermeable membrane is folded in accordion fashion to form a stack of pleats and the edges are sealed so as to isolate the opposite surfaces of the membrane. The stack is contained within a case that provides ports for flow of blood in contact with one surface of the membrane through channels formed by the pleats and also provides ports for flow of a dialysate through channels formed by the pleats in contact with the other surface of the membrane. The serpentine side edges of the membrane are sealed by a solidified plastic material, whereas effective mechanical means are provided to seal the end edges of the folded membrane. The mechanical means include a clamping strip which biases case sealing flanges into a sealed relationship with end portions of the membrane near the end edges, which portions extend from the stack and between the sealing flanges.

  15. Overview of Edge Simulation Laboratory (ESL)

    NASA Astrophysics Data System (ADS)

    Cohen, R. H.; Dorr, M.; Hittinger, J.; Rognlien, T.; Umansky, M.; Xiong, A.; Xu, X.; Belli, E.; Candy, J.; Snyder, P.; Colella, P.; Martin, D.; Sternberg, T.; van Straalen, B.; Bodi, K.; Krasheninnikov, S.

    2006-10-01

    The ESL is a new collaboration to build a full-f electromagnetic gyrokinetic code for tokamak edge plasmas using continuum methods. Target applications are edge turbulence and transport (neoclassical and anomalous), and edge-localized modes. Initially the project has three major threads: (i) verification and validation of TEMPEST, the project's initial (electrostatic) edge code which can be run in 4D (neoclassical and transport-timescale applications) or 5D (turbulence); (ii) design of the next generation code, which will include more complete physics (electromagnetics, fluid equation option, improved collisions) and advanced numerics (fully conservative, high-order discretization, mapped multiblock grids, adaptivity), and (iii) rapid-prototype codes to explore the issues attached to solving fully nonlinear gyrokinetics with steep radial gradiens. We present a brief summary of the status of each of these activities.

  16. Edge energies and shapes of nanoprecipitates.

    SciTech Connect

    Hamilton, John C.

    2006-01-01

    In this report we present a model to explain the size-dependent shapes of lead nano-precipitates in aluminum. Size-dependent shape transitions, frequently observed at nanolength scales, are commonly attributed to edge energy effects. This report resolves an ambiguity in the definition and calculation of edge energies and presents an atomistic calculation of edge energies for free clusters. We also present a theory for size-dependent shapes of Pb nanoprecipitates in Al, introducing the concept of ''magic-shapes'' defined as precipitate shapes having near zero elastic strains when inserted into similarly shaped voids in the Al matrix. An algorithm for constructing a complete set of magic-shapes is presented. The experimental observations are explained by elastic strain energies and interfacial energies; edge energies play a negligible role. We replicate the experimental observations by selecting precipitates having magic-shapes and interfacial energies less than a cutoff value.

  17. Leading edge protection for composite blades

    NASA Technical Reports Server (NTRS)

    Brantley, J. W.; Irwin, T. P. (Inventor)

    1977-01-01

    A laminated filament composite structure, such as an airfoil for use in an environment in which it is subjected to both foreign object impact and bending is provided with improved leading edge protection. At least one fine wire mesh layer is partially bonded within the composite structure along its neutral bending axis. A portion of the wire mesh layer extends beyond the neutral bending axis and partially around the leading edge where it is bonded to the outer periphery of the primary composite structure. The wire mesh is clad with a metal such as nickel to provide an improved leading edge protective device which is firmly anchored within the composite structure. Also described is a novel method of constructing a composite airfoil so as to further minimize the possibility of losing the leading edge protective device due to delamination caused by impact and bending.

  18. Mechanotunable monatomic metal structures at graphene edges.

    PubMed

    Wei, Ning; Chang, Cheng; Zhu, Hongwei; Xu, Zhiping

    2014-06-14

    Monatomic metal (e.g. silver) structures could form preferably at graphene edges. We explore their structural and electronic properties by performing density functional theory based first-principles calculations. The results show that cohesion between metal atoms, as well as electronic coupling between metal atoms and graphene edges offer remarkable structural stability of the hybrid. We find that the outstanding mechanical properties of graphene allow tunable properties of the metal monatomic structures by straining the structure. The concept is extended to metal rings and helices that form at open ends of carbon nanotubes and edges of twisted graphene ribbons. These findings demonstrate the role of graphene edges as an efficient one-dimensional template for low-dimensional metal structures that are mechanotunable.

  19. Imaging The Leading Edge Of A Weld

    NASA Technical Reports Server (NTRS)

    Mcgee, William F.; Rybicki, Daniel J.

    1994-01-01

    Proposed optical system integrated into plasma arc welding torch provides image of leading edge of weld pool and welding-arc-initiation point. Welding torch aligned better with joint. System includes coherent bundle of optical fibers and transparent cup.

  20. Edge Equilibrium Code (EEC) For Tokamaks

    SciTech Connect

    Li, Xujling

    2014-02-24

    The edge equilibrium code (EEC) described in this paper is developed for simulations of the near edge plasma using the finite element method. It solves the Grad-Shafranov equation in toroidal coordinate and uses adaptive grids aligned with magnetic field lines. Hermite finite elements are chosen for the numerical scheme. A fast Newton scheme which is the same as implemented in the equilibrium and stability code (ESC) is applied here to adjust the grids

  1. Galilean invariance at quantum Hall edge

    NASA Astrophysics Data System (ADS)

    Moroz, Sergej; Hoyos, Carlos; Radzihovsky, Leo

    2015-05-01

    We construct the theory of a chiral Luttinger liquid that lives on the boundary of a Galilean invariant quantum Hall fluid. In contrast to previous studies, Galilean invariance of the total (bulk plus edge) theory is guaranteed. We consider electromagnetic response at the edge and calculate momentum- and frequency-dependent electric conductivity and argue that its experimental measurement can provide a new means to determine the "shift" and bulk Hall viscosity.

  2. Edge states in polariton honeycomb lattices

    NASA Astrophysics Data System (ADS)

    Milićević, M.; Ozawa, T.; Andreakou, P.; Carusotto, I.; Jacqmin, T.; Galopin, E.; Lemaître, A.; Le Gratiet, L.; Sagnes, I.; Bloch, J.; Amo, A.

    2015-09-01

    The experimental study of edge states in atomically thin layered materials remains a challenge due to the difficult control of the geometry of the sample terminations, the stability of dangling bonds, and the need to measure local properties. In the case of graphene, localized edge modes have been predicted in zigzag and bearded edges, characterized by flat dispersions connecting the Dirac points. Polaritons in semiconductor microcavities have recently emerged as an extraordinary photonic platform to emulate 1D and 2D Hamiltonians, allowing the direct visualization of the wavefunctions in both real- and momentum-space as well as of the energy dispersion of eigenstates via photoluminescence experiments. Here we report on the observation of edge states in a honeycomb lattice of coupled micropillars. The lowest two bands of this structure arise from the coupling of the lowest energy modes of the micropillars, and emulate the π and π* bands of graphene. We show the momentum-space dispersion of the edge states associated with the zigzag and bearded edges, holding unidimensional quasi-flat bands. Additionally, we evaluate polarization effects characteristic of polaritons on the properties of these states.

  3. Aircraft wing trailing-edge noise

    NASA Technical Reports Server (NTRS)

    Underwood, R. L.; Hodgson, T. H.

    1981-01-01

    The mechanism and sound pressure level of the trailing-edge noise for two-dimensional turbulent boundary layer flow was examined. Experiment is compared with current theory. A NACA 0012 airfoil of 0.61 m chord and 0.46 m span was immersed in the laminar flow of a low turbulence open jet. A 2.54 cm width roughness strip was placed at 15 percent chord from the leading edge on both sides of the airfoil as a boundary layer trip so that two separate but statistically equivalent turbulent boundary layers were formed. Tests were performed with several trailing-edge geometries with the upstream velocity U sub infinity ranging from a value of 30.9 m/s up to 73.4 m/s. Properties of the boundary layer for the airfoil and pressure fluctuations in the vicinity of the trailing-edge were examined. A scattered pressure field due to the presence of the trailing-edge was observed and is suggested as a possible sound producing mechanism for the trailing-edge noise.

  4. Double Degenerate Binary Systems

    SciTech Connect

    Yakut, K.

    2011-09-21

    In this study, angular momentum loss via gravitational radiation in double degenerate binary (DDB)systems (NS + NS, NS + WD, WD + WD, and AM CVn) is studied. Energy loss by gravitational waves has been estimated for each type of systems.

  5. On the generation of side-edge flap noise. [part span trailing edge flaps

    NASA Technical Reports Server (NTRS)

    Howe, M. S.

    1981-01-01

    A theory is proposed for estimating the noise generated at the side edges of part span trailing edge flaps in terms of pressure fluctuations measured just in-board of the side edge of the upper surface of the flap. Asymptotic formulae are developed in the opposite extremes of Lorentz contracted acoustic wavelength large/small compared with the chord of the flap. Interpolation between these limiting results enables the field shape and its dependence on subsonic forward flight speed to be predicted over the whole frequency range. It is shown that the mean width of the side edge gap between the flap and the undeflected portion of the airfoil has a significant influence on the intensity of the radiated sound. It is estimated that the noise generated at a single side edge of a full scale part span flap can exceed that produced along the whole of the trailing edge of the flap by 3 dB or more.

  6. Edge-to-Edge Oriented Self-Assembly of ReS2 Nanoflakes.

    PubMed

    Zhang, Qin; Wang, Wenjie; Kong, Xin; Mendes, Rafael G; Fang, Liwen; Xue, Yinghui; Xiao, Yao; Rümmeli, Mark H; Chen, Shengli; Fu, Lei

    2016-09-01

    The self-assembly of two-dimensional (2D) nanomaterials, an emerging research area, still remains largely unexplored. The strong interlayer attraction between 2D nanosheets leads to face-to-face stacking rather than edge-to-edge coupling. We demonstrate, for the first time, how one can induce and control an edge-to-edge self-assembly process for 2D nanomaterials. The extremely weak van der Waals coupling and strong anisotropy of ReS2 allow us to realize an oriented self-assembly (OSA) process. The aspect ratio of the resulting ReS2 nanoscrolls can be well controlled. In addition, we perform simulations to further explain and confirm the OSA process, demonstrating its great potential to be expanded as a general edge-to-edge self-assembly process suitable for other 2D nanomaterials.

  7. Edge-to-Edge Oriented Self-Assembly of ReS2 Nanoflakes.

    PubMed

    Zhang, Qin; Wang, Wenjie; Kong, Xin; Mendes, Rafael G; Fang, Liwen; Xue, Yinghui; Xiao, Yao; Rümmeli, Mark H; Chen, Shengli; Fu, Lei

    2016-09-01

    The self-assembly of two-dimensional (2D) nanomaterials, an emerging research area, still remains largely unexplored. The strong interlayer attraction between 2D nanosheets leads to face-to-face stacking rather than edge-to-edge coupling. We demonstrate, for the first time, how one can induce and control an edge-to-edge self-assembly process for 2D nanomaterials. The extremely weak van der Waals coupling and strong anisotropy of ReS2 allow us to realize an oriented self-assembly (OSA) process. The aspect ratio of the resulting ReS2 nanoscrolls can be well controlled. In addition, we perform simulations to further explain and confirm the OSA process, demonstrating its great potential to be expanded as a general edge-to-edge self-assembly process suitable for other 2D nanomaterials. PMID:27547983

  8. Nonlinear fitting of absorption edges in K-edge densitometry spectra

    SciTech Connect

    Collins, M.; Hsue, Sin-Tao

    1997-11-01

    A new method for analyzing absorption edges in K-Edge Densitometry (KED) spectra is introduced. This technique features a nonlinear function that specifies the empirical form of a broadened K-absorption edge. Nonlinear fitting of the absorption edge can be used to remove broadening effects from the KED spectrum. This allows more data near the edge to be included in the conventional KED fitting procedure. One possible benefit is enhanced precision of measured uranium and plutonium concentrations. Because no additional hardware is required, several facilities that use KED may eventually benefit from this approach. Applications of nonlinear KED fitting in the development of the Los Alamos National Laboratory (LANL) hybrid K-edge/x-ray fluorescence (XRF) densitometer system are described.

  9. The dependence of edge displacement thresholds on edge blur, contrast, and displacement distance.

    PubMed

    Mather, G

    1987-01-01

    Two experiments measured thresholds for discriminating the movement direction of an isolated intensity edge. The luminance profile of the edge took the form of an integrated Gaussian. In the first experiment, displacement thresholds were measured as a function of edge blur width and contrast. In the second experiment, contrast thresholds were measured as a function of edge blur width and displacement. Using the estimated retinal profile of the edge (given the LSF of the display and of the optics of the eye), the data were found to collapse onto a single function relating the maximum spatial luminance gradient defined by the edge to the maximum temporal change in luminance generated by its displacement. There was a direct relationship between the two gradients at threshold, so that lower spatial gradients were paired with smaller temporal changes. Implications for current models of motion detection are examined.

  10. Double-Stranded Water on Stepped Platinum Surfaces

    NASA Astrophysics Data System (ADS)

    Kolb, Manuel J.; Farber, Rachael G.; Derouin, Jonathan; Badan, Cansin; Calle-Vallejo, Federico; Juurlink, Ludo B. F.; Killelea, Daniel R.; Koper, Marc T. M.

    2016-04-01

    The interaction of platinum with water plays a key role in (electro)catalysis. Herein, we describe a combined theoretical and experimental study that resolves the preferred adsorption structure of water wetting the Pt(111)-step type with adjacent (111) terraces. Double stranded lines wet the step edge forming water tetragons with dissimilar hydrogen bonds within and between the lines. Our results qualitatively explain experimental observations of water desorption and impact our thinking of solvation at the Pt electrochemical interface.

  11. Effects of increased leading-edge thickness on performance of a transonic rotor blade. [in single stage transonic compressor

    NASA Technical Reports Server (NTRS)

    Reid, L.; Urasek, D. C.

    1972-01-01

    A single-stage transonic compressor was tested with two rotor blade leading-edge configurations to investigate the effect of increased leading-edge thickness on the performance of a transonic blade row. The original rotor blade configuration was modified by cutting back the leading edge sufficiently to double the blade leading-edge thickness and thus the blade gap blockage in the tip region. At design speed this modification resulted in a decrease in rotor overall peak efficiency of four points. The major portion of this decrement in rotor overall peak efficienty was attributed to the flow conditions in the outer 30 percent of the blade span. At 70 and 90 percent of design speed, the modification had very little effect on rotor overall performance.

  12. Access to a New Plasma Edge State with High Density and Pressures using Quiescent H-mode

    SciTech Connect

    Solomon, Wayne M.; Snyder, P. B.; Burrell, K. H.; Fenstermacher, M. E.; Garofalo, A. M.; Grierson, B. A.; Loarte, A.; McKee, G. R.; Nazikian, R; Osborne, T. H.

    2014-07-01

    A path to a new high performance regime has been discovered in tokamaks that could improve the attractiveness of a fusion reactor. Experiments on DIII-D using a quiescent H-mode edge have navigated a valley of improved edge peeling-ballooning stability that opens up with strong plasma shaping at high density, leading to a doubling of the edge pressure over standard edge localized mode (ELM)ing H-mode at these parameters. The thermal energy confinement time increases both as a result of the increased pedestal height and improvements in the core transport and reduced low-k turbulence. Calculations of the pedestal height and width as a function of density using constraints imposed by peeling-ballooning and kinetic-ballooning theory are in quantitative agreement with the measurements.

  13. Joint distribution of the first and second eigenvalues at the soft edge of unitary ensembles

    NASA Astrophysics Data System (ADS)

    Witte, N. S.; Bornemann, F.; Forrester, P. J.

    2013-06-01

    The density function for the joint distribution of the first and second eigenvalues at the soft edge of unitary ensembles is found in terms of a Painlevé II transcendent and its associated isomonodromic system. As a corollary, the density function for the spacing between these two eigenvalues is similarly characterized.The particular solution of Painlevé II that arises is a double shifted Bäcklund transformation of the Hastings-McLeod solution, which applies in the case of the distribution of the largest eigenvalue at the soft edge. Our deductions are made by employing the hard-to-soft edge transition, involving the limit as the repulsion strength at the hard edge a → ∞, to existing results for the joint distribution of the first and second eigenvalue at the hard edge (Forrester and Witte 2007 Kyushu J. Math. 61 457-526). In addition recursions under a ↦ a + 1 of quantities specifying the latter are obtained. A Fredholm determinant type characterization is used to provide accurate numerics for the distribution of the spacing between the two largest eigenvalues.

  14. Losing your edge: climate change and the conservation value of range-edge populations.

    PubMed

    Rehm, Evan M; Olivas, Paulo; Stroud, James; Feeley, Kenneth J

    2015-10-01

    Populations occurring at species' range edges can be locally adapted to unique environmental conditions. From a species' perspective, range-edge environments generally have higher severity and frequency of extreme climatic events relative to the range core. Under future climates, extreme climatic events are predicted to become increasingly important in defining species' distributions. Therefore, range-edge genotypes that are better adapted to extreme climates relative to core populations may be essential to species' persistence during periods of rapid climate change. We use relatively simple conceptual models to highlight the importance of locally adapted range-edge populations (leading and trailing edges) for determining the ability of species to persist under future climates. Using trees as an example, we show how locally adapted populations at species' range edges may expand under future climate change and become more common relative to range-core populations. We also highlight how large-scale habitat destruction occurring in some geographic areas where many species range edge converge, such as biome boundaries and ecotones (e.g., the arc of deforestation along the rainforest-cerrado ecotone in the southern Amazonia), can have major implications for global biodiversity. As climate changes, range-edge populations will play key roles in helping species to maintain or expand their geographic distributions. The loss of these locally adapted range-edge populations through anthropogenic disturbance is therefore hypothesized to reduce the ability of species to persist in the face of rapid future climate change.

  15. Losing your edge: climate change and the conservation value of range-edge populations.

    PubMed

    Rehm, Evan M; Olivas, Paulo; Stroud, James; Feeley, Kenneth J

    2015-10-01

    Populations occurring at species' range edges can be locally adapted to unique environmental conditions. From a species' perspective, range-edge environments generally have higher severity and frequency of extreme climatic events relative to the range core. Under future climates, extreme climatic events are predicted to become increasingly important in defining species' distributions. Therefore, range-edge genotypes that are better adapted to extreme climates relative to core populations may be essential to species' persistence during periods of rapid climate change. We use relatively simple conceptual models to highlight the importance of locally adapted range-edge populations (leading and trailing edges) for determining the ability of species to persist under future climates. Using trees as an example, we show how locally adapted populations at species' range edges may expand under future climate change and become more common relative to range-core populations. We also highlight how large-scale habitat destruction occurring in some geographic areas where many species range edge converge, such as biome boundaries and ecotones (e.g., the arc of deforestation along the rainforest-cerrado ecotone in the southern Amazonia), can have major implications for global biodiversity. As climate changes, range-edge populations will play key roles in helping species to maintain or expand their geographic distributions. The loss of these locally adapted range-edge populations through anthropogenic disturbance is therefore hypothesized to reduce the ability of species to persist in the face of rapid future climate change. PMID:26664681

  16. The double-lobed blazar 3C 371

    NASA Astrophysics Data System (ADS)

    Wrobel, J. M.; Lind, K. R.

    1990-01-01

    High dynamic range VLA imaging reveals, for the first time, that the blazar 3C 371 exhibits very low surface brightness twin radio lobes. These lobes straddle the dominant compact core and have a projected extent of about 42/h kpc. A weak component located in the western lobe shares the morphology, size, and inferred magnetic field configuration of radio source hot spots. A continuous wiggling jet connects this hot spot with the compact core. Double lobes, hot spots, and one-sided jets are traits of extended, edge-brightened radio sources. The discovery of corresponding components in 3C 371's extended emission suggests that this emission is an edge-brightened double, viewed at a large enough angle to the line of sight that the radio lobes do not overlap. A moderate viewing angle is consistent with 3C 371's low bolometric luminosity for a blazar. The diffuse radio halo that surrounds the twin lobes may be related to the fat bridges or bridge distortions shown by edge-brightened doubles with similar radio powers.

  17. Computation of leading-edge vortex flows

    NASA Technical Reports Server (NTRS)

    Newsome, R. W.; Thomas, J. L.

    1986-01-01

    The simulation of the leading edge vortex flow about a series of conical delta wings through solution of the Navier-Stokes and Euler equations is studied. The occurrence, the validity, and the usefulness of separated flow solutions to the Euler equations of particular interest. Central and upwind difference solutions to the governing equations are compared for a series of cross sectional shapes, including both rounded and sharp tip geometries. For the rounded leading edge and the flight condition considered, viscous solutions obtained with either central or upwind difference methods predict the classic structure of vortical flow over a highly swept delta wing. Predicted features include the primary vortex due to leading edge separation and the secondary vortex due to crossflow separation. Central difference solutions to the Euler equations show a marked sensitivity to grid refinement. On a coarse grid, the flow separates due to numerical error and a primary vortex which resembles that of the viscous solution is predicted. In contrast, the upwind difference solutions to the Euler equations predict attached flow even for first-order solutions on coarse grids. On a sufficiently fine grid, both methods agree closely and correctly predict a shock-curvature-induced inviscid separation near the leeward plane of symmetry. Upwind difference solutions to the Navier-Stokes and Euler equations are presented for two sharp leading edge geometries. The viscous solutions are quite similar to the rounded leading edge results with vortices of similar shape and size. The upwind Euler solutions predict attached flow with no separation for both geometries. However, with sufficient grid refinement near the tip or through the use of more accurate spatial differencing, leading edge separation results. Once the leading edge separation is established, the upwind solution agrees with recently published central difference solutions to the Euler equations.

  18. Cloud deposition to a spruce forest edge

    NASA Astrophysics Data System (ADS)

    Weathers, K. C.; Lovett, G. M.; Likens, G. E.

    Deposition from clouds to a spruce (Picea rubens Sarg.) forest edge on Hunter Mt. in the Catskill Mts of New York State was measured during 1987 and 1988 to determine whether the windward edge of forest floor receives greater deposition of water and ions via cloud water than the interior of a forest. Throughfall was used as a measure of deposition and was collected during cloud-only and mixed cloud-and-rain events along five windward-to-leeward transects in a 30 x 30 m forested area. Ambient cloud water was also collected in a passive collector and chemically analyzed. Trees at the edge of the forest received on average three times, and up to 15 times, greater deposition of ions than those in the interior of the forest. Lead content in samples from Hunter Mt. forest floor at the windward edge, relative to the interior, was enhanced as well. Using a regression of distance vs deposition, the deposition "half-distance", (i.e. the point at which the rate of cloud water deposition is 50% of the rate at the windward edge of the forest) was found to be 28 m. The cloud deposition data from this study are compared to other studies of Na particle deposition to low-elevation forest edges, which show similar deposition "half distances", ranging from ˜ 2 to 36 m into the forest. Most models of cloud deposition currently in use assume landscape homogeneity. Montane forest landscapes, however, are often highly heterogeneous, consisting of many "edges", and thus current models may seriously underestimate cloud deposition.

  19. LT-STM/STS studies of clean armchair edge

    NASA Astrophysics Data System (ADS)

    Ju, Zheng; Zhang, Wenhan; Wu, Weida; Weida Wu Team

    It was predicted and observed that the passivated zigzag edges of graphene host highly localized edge state. This edge state is predicted to be spin-polarized, which is appealing for spintronic applications. In contrast, no edge state was expected at passivated armchair graphene edge. Here we report low temperature scanning tunneling microscopy and spectroscopy (STM/STS) studies of electronic properties of clean monoatomic step edges on cleaved surface of HOPG. Most of step edges are armchair edges, in agreement with previous STM results. We observed only (√{ 3} ×√{ 3}) R30° superstructure near armchair edges, which has been reported in previous STM studies. On the other hand, no honeycomb superstructure was observed in our STM data. In addition, our STM results reveal an intriguing localized electronic state at clean armchair edges. Spectroscopic and spatial evolution of this edge state will be presented. This work is supported by NSF DMR-1506618.

  20. Power spectrum weighted edge analysis for straight edge detection in images

    NASA Astrophysics Data System (ADS)

    Karvir, Hrishikesh V.; Skipper, Julie A.

    2007-04-01

    Most man-made objects provide characteristic straight line edges and, therefore, edge extraction is a commonly used target detection tool. However, noisy images often yield broken edges that lead to missed detections, and extraneous edges that may contribute to false target detections. We present a sliding-block approach for target detection using weighted power spectral analysis. In general, straight line edges appearing at a given frequency are represented as a peak in the Fourier domain at a radius corresponding to that frequency, and a direction corresponding to the orientation of the edges in the spatial domain. Knowing the edge width and spacing between the edges, a band-pass filter is designed to extract the Fourier peaks corresponding to the target edges and suppress image noise. These peaks are then detected by amplitude thresholding. The frequency band width and the subsequent spatial filter mask size are variable parameters to facilitate detection of target objects of different sizes under known imaging geometries. Many military objects, such as trucks, tanks and missile launchers, produce definite signatures with parallel lines and the algorithm proves to be ideal for detecting such objects. Moreover, shadow-casting objects generally provide sharp edges and are readily detected. The block operation procedure offers advantages of significant reduction in noise influence, improved edge detection, faster processing speed and versatility to detect diverse objects of different sizes in the image. With Scud missile launcher replicas as target objects, the method has been successfully tested on terrain board test images under different backgrounds, illumination and imaging geometries with cameras of differing spatial resolution and bit-depth.

  1. Partnership for Edge Physics Simulation (EPSI)

    SciTech Connect

    Schroder, Peter

    2015-02-11

    We propose to develop advanced simulation codes, based upon an extreme parallelism, first principles kinetic approach, to address the challenges associated with the edge region of magnetically confined plasmas. This work is relevant to both existing magnetic fusion facilities and essential for next-generation burning plasma experiments, such as ITER where success is critically dependent upon H-mode operation achieving an edge pedestal of sufficient height for good core plasma performance without producing deleterious large scale edge localized instabilities. The plasma edge presents a well-known set of multi-physics, multi-scale problems involving complex 3D magnetic geometry. Perhaps the greatest computational challenge is the lack of scale separation – temporal scales for drift waves, Alfven waves, ELM dynamics for example have strong overlap. Similar overlap occurs on the spatial scales for the ion poloidal gyro-radius, drift wave and pedestal width. The traditional approach of separating fusion problems into weakly interacting spatial or temporal domains clearly breaks down in the edge. A full kinetic model (full-f model) must be solved to understand and predict the edge physics including non-equilibrium thermodynamic issues arising from the magnetic topology (the open field lines producing a spatially sensitive velocity hole), plasma wall interactions, neutral and atomic physics. The plan here is to model these phenomena within a comprehensive first principles set of equations without the need for the insurmountable multiple-codes coupling issues by building on the XGC1 code developed under the SciDAC Proto-FSP Center for Plasma Edge Simulation (CPES). This proposal includes the critical participants in the XGC1 development. We propose enhancing the capability of XGC1 by including all the important turbulence physics contained in kinetic ion and electron electromagnetic dynamics, by extending the PIC technology to incorporate several positive features found

  2. Flap Edge Aeroacoustic Measurements and Predictions

    NASA Technical Reports Server (NTRS)

    Brooks, Thomas F.; Humphreys, William M., Jr.

    2000-01-01

    An aeroacoustic model test has been conducted to investigate the mechanisms of sound generation on high-lift wing configurations. This paper presents an analysis of flap side-edge noise, which is often the most dominant source. A model of a main element wing section with a half-span flap was tested at low speeds of up to a Mach number of 0.17, corresponding to a wing chord Reynolds number of approximately 1.7 million. Results are presented for flat (or blunt), flanged, and round flap-edge geometries, with and without boundary-layer tripping, deployed at both moderate and high flap angles. The acoustic database is obtained from a Small Aperture Directional Array (SADA) of microphones, which was constructed to electronically steer to different regions of the model and to obtain farfield noise spectra and directivity from these regions. The basic flap-edge aerodynamics is established by static surface pressure data, as well as by Computational Fluid Dynamics (CFD) calculations and simplified edge flow analyses. Distributions of unsteady pressure sensors over the flap allow the noise source regions to be defined and quantified via cross-spectral diagnostics using the SADA output. It is found that shear layer instability and related pressure scatter is the primary noise mechanism. For the flat edge flap, two noise prediction methods based on unsteady-surface-pressure measurements are evaluated and compared to measured noise. One is a new causality spectral approach developed here. The other is a new application of an edge-noise scatter prediction method. The good comparisons for both approaches suggest that much of the physics is captured by the prediction models. Areas of disagreement appear to reveal when the assumed edge noise mechanism does not fully define, the noise production. For the different edge conditions, extensive spectra and directivity are presented. Significantly, for each edge configuration, the spectra for different flow speeds, flap angles, and

  3. Image sharpness function based on edge feature

    NASA Astrophysics Data System (ADS)

    Jun, Ni

    2009-11-01

    Autofocus technique has been widely used in optical tracking and measure system, but it has problem that when the autofocus device should to work. So, no-reference image sharpness assessment has become an important issue. A new Sharpness Function that can estimate current frame image be in focus or not is proposed in this paper. According to current image whether in focus or not and choose the time of auto focus automatism. The algorithm measures object typical edge and edge direction, and then get image local kurtosis information to determine the degree of image sharpness. It firstly select several grads points cross the edge line, secondly calculates edge sharpness value and get the cure of the kurtosis, according the measure precision of optical-equipment, a threshold value will be set beforehand. If edge kurtosis value is more than threshold, it can conclude current frame image is in focus. Otherwise, it is out of focus. If image is out of focus, optics system then takes autofocus program. This algorithm test several thousands of digital images captured from optical tracking and measure system. The results show high correlation with subjective sharpness assessment for s images of sky object.

  4. Trailing edge modifications for flatback airfoils.

    SciTech Connect

    Kahn, Daniel L.; van Dam, C.P.; Berg, Dale E.

    2008-03-01

    The adoption of blunt trailing edge airfoils (also called flatback airfoils) for the inboard region of large wind turbine blades has been proposed. Blunt trailing edge airfoils would not only provide a number of structural benefits, such as increased structural volume and ease of fabrication and handling, but they have also been found to improve the lift characteristics of thick airfoils. Therefore, the incorporation of blunt trailing edge airfoils would allow blade designers to more freely address the structural demands without having to sacrifice aerodynamic performance. These airfoils do have the disadvantage of generating high levels of drag as a result of the low-pressure steady or periodic flow in the near-wake of the blunt trailing edge. Although for rotors, the drag penalty appears secondary to the lift enhancement produced by the blunt trailing edge, high drag levels are of concern in terms of the negative effect on the torque and power generated by the rotor. Hence, devices are sought that mitigate the drag of these airfoils. This report summarizes the literature on bluff body vortex shedding and bluff body drag reduction devices and proposes four devices for further study in the wind tunnel.

  5. New analytic formula for edge bootstrap current

    NASA Astrophysics Data System (ADS)

    Chang, C. S.; Koh, S.; Menard, J.; Weitzner, H.; Choe, W.

    2012-10-01

    The edge bootstrap current plays a critical role in the equilibrium and stability of the steep edge pedestal plasma. The pedestal plasma has an unconventional and difficult neoclassical property, as compared with the core plasma. A drift-kinetic particle code XGC0, equipped with a mass-momentum-energy conserving collision operator, is used to study the edge bootstrap current in a realistic diverted magnetic field geometry with a self-consistent radial electric field. When the edge electrons are in the low collisionality banana regime, surprisingly, the present kinetic simulation confirms that the existing analytic expressions (represented by O. Sauter, et. al., Phys. Plasmas 6, 1999) are still valid in this unconventional region, except in a thin radial layer in contact with the magnetic separatrix. However, when the pedestal electrons are in plateau-collisional regime, there is a significant deviation of numerical results from the existing analytic formulas. The deviation occurs in different ways between a conventional aspect ratio tokamak and a tight aspect ratio tokamak. A new analytic fitting formula, as a simple modification to the Sauter formula, is obtained to bring the analytic expression to a better agreement with the edge kinetic simulation results.

  6. Image enhancement based on edge boosting algorithm

    NASA Astrophysics Data System (ADS)

    Ngernplubpla, Jaturon; Chitsobhuk, Orachat

    2015-12-01

    In this paper, a technique for image enhancement based on proposed edge boosting algorithm to reconstruct high quality image from a single low resolution image is described. The difficulty in single-image super-resolution is that the generic image priors resided in the low resolution input image may not be sufficient to generate the effective solutions. In order to achieve a success in super-resolution reconstruction, efficient prior knowledge should be estimated. The statistics of gradient priors in terms of priority map based on separable gradient estimation, maximum likelihood edge estimation, and local variance are introduced. The proposed edge boosting algorithm takes advantages of these gradient statistics to select the appropriate enhancement weights. The larger weights are applied to the higher frequency details while the low frequency details are smoothed. From the experimental results, the significant performance improvement quantitatively and perceptually is illustrated. It can be seen that the proposed edge boosting algorithm demonstrates high quality results with fewer artifacts, sharper edges, superior texture areas, and finer detail with low noise.

  7. Numerical simulation of the edge tone phenomenon

    NASA Technical Reports Server (NTRS)

    Dougherty, N. S.; Liu, B. L.; Ofarrell, J. M.

    1994-01-01

    Time accurate Navier-Stokes computations were performed to study a class 2 (acoustic) whistle, the edge tone, and to gain knowledge of the vortex-acoustic coupling mechanisms driving production of these tones. Results were obtained by solving the full Navier-Stokes equations for laminar compressible air flow of a two dimensional jet issuing from a slit interacting with a wedge. Cases considered were determined by varying the distance from the slit to the wedge. Flow speed was kept constant at 1,750 cm/s as was the slit thickness of 0.1 cm, corresponding to conditions in the experiments of Brown. The analytical computations revealed edge tones to be present in four harmonic stages of jet flow instability over the wedge as the jet length was varied from 0.3 to 1.6 cm. Excellent agreement was obtained in all four edge tone stage cases between the present computational results and the experimentally obtained frequencies and flow visualization results of Brown. Specific edge tone generation phenomena and further confirmation of certain theories and empirical formulas concerning these phenomena were brought to light in this analytical simulation of edge tones.

  8. Edge printability: techniques used to evaluate and improve extreme wafer edge printability

    NASA Astrophysics Data System (ADS)

    Roberts, Bill; Demmert, Cort; Jekauc, Igor; Tiffany, Jason P.

    2004-05-01

    The economics of semiconductor manufacturing have forced process engineers to develop techniques to increase wafer yield. Improvements in process controls and uniformities in all areas of the fab have reduced film thickness variations at the very edge of the wafer surface. This improved uniformity has provided the opportunity to consider decreasing edge exclusions, and now the outermost extents of the wafer must be considered in the yield model and expectations. These changes have increased the requirements on lithography to improve wafer edge printability in areas that previously were not even coated. This has taxed all software and hardware components used in defining the optical focal plane at the wafer edge. We have explored techniques to determine the capabilities of extreme wafer edge printability and the components of the systems that influence this printability. We will present current capabilities and new detection techniques and the influence that the individual hardware and software components have on edge printability. We will show effects of focus sensor designs, wafer layout, utilization of dummy edge fields, the use of non-zero overlay targets and chemical/optical edge bead optimization.

  9. General-purpose adaptive edge detector based on an empirical edge model

    SciTech Connect

    Breedlove, J.R. Jr.; Cantoni, V.

    1982-01-01

    We present a new approach to computer edge detection for image mensuration. Our technique uses data from the actual image to build an edge-detector template for a matched filtering algorithm. We show that the procedure is superior to classical, template matching techniques for a computer-generated image and for a very noisy x-ray image.

  10. Diagnosing Topological Edge States via Entanglement Monogamy.

    PubMed

    Meichanetzidis, K; Eisert, J; Cirio, M; Lahtinen, V; Pachos, J K

    2016-04-01

    Topological phases of matter possess intricate correlation patterns typically probed by entanglement entropies or entanglement spectra. In this Letter, we propose an alternative approach to assessing topologically induced edge states in free and interacting fermionic systems. We do so by focussing on the fermionic covariance matrix. This matrix is often tractable either analytically or numerically, and it precisely captures the relevant correlations of the system. By invoking the concept of monogamy of entanglement, we show that highly entangled states supported across a system bipartition are largely disentangled from the rest of the system, thus, usually appearing as gapless edge states. We then define an entanglement qualifier that identifies the presence of topological edge states based purely on correlations present in the ground states. We demonstrate the versatility of this qualifier by applying it to various free and interacting fermionic topological systems.

  11. Preparation of edge states by shaking boundaries

    NASA Astrophysics Data System (ADS)

    Shi, Z. C.; Hou, S. C.; Wang, L. C.; Yi, X. X.

    2016-10-01

    Preparing topological states of quantum matter, such as edge states, is one of the most important directions in condensed matter physics. In this work, we present a proposal to prepare edge states in Aubry-André-Harper (AAH) model with open boundaries, which takes advantage of Lyapunov control to design operations. We show that edge states can be obtained with almost arbitrary initial states. A numerical optimalization for the control is performed and the dependence of control process on the system size is discussed. The merit of this proposal is that the shaking exerts only on the boundaries of the model. As a by-product, a topological entangled state is achieved by elaborately designing the shaking scheme.

  12. Acoustic metamaterial for subwavelength edge detection

    PubMed Central

    Molerón, Miguel; Daraio, Chiara

    2015-01-01

    Metamaterials have demonstrated the possibility to produce super-resolved images by restoring propagative and evanescent waves. However, for efficient information transfer, for example, in compressed sensing, it is often desirable to visualize only the fast spatial variations of the wave field (carried by evanescent waves), as the one created by edges or small details. Image processing edge detection algorithms perform such operation, but they add time and complexity to the imaging process. Here we present an acoustic metamaterial that transmits only components of the acoustic field that are approximately equal to or smaller than the operating wavelength. The metamaterial converts evanescent waves into propagative waves exciting trapped resonances, and it uses periodicity to attenuate the propagative components. This approach achieves resolutions ∼5 times smaller than the operating wavelength and makes it possible to visualize independently edges aligned along different directions. PMID:26304739

  13. Floquet edge states in germanene nanoribbons

    PubMed Central

    Tahir, M.; Zhang, Q. Y.; Schwingenschlögl, U.

    2016-01-01

    We theoretically demonstrate versatile electronic properties of germanene monolayers under circularly, linearly, and elliptically polarized light. We show for the high frequency regime that the edge states can be controlled by tuning the amplitude of the light and by applying a static electric field. For circularly polarized light the band gap in one valley is reduced and in the other enhanced, enabling single valley edge states. For linearly polarized light spin-split states are found for both valleys, being connected by time reversal symmetry. The effects of elliptically polarized light are similar to those of circularly polarized light. The transport properties of zigzag nanoribbons in the presence of disorder confirm a nontrivial nature of the edge states under circularly and elliptically polarized light. PMID:27550632

  14. Floquet edge states in germanene nanoribbons.

    PubMed

    Tahir, M; Zhang, Q Y; Schwingenschlögl, U

    2016-01-01

    We theoretically demonstrate versatile electronic properties of germanene monolayers under circularly, linearly, and elliptically polarized light. We show for the high frequency regime that the edge states can be controlled by tuning the amplitude of the light and by applying a static electric field. For circularly polarized light the band gap in one valley is reduced and in the other enhanced, enabling single valley edge states. For linearly polarized light spin-split states are found for both valleys, being connected by time reversal symmetry. The effects of elliptically polarized light are similar to those of circularly polarized light. The transport properties of zigzag nanoribbons in the presence of disorder confirm a nontrivial nature of the edge states under circularly and elliptically polarized light. PMID:27550632

  15. Development of Columbia Leading Edge Reconstruction System

    NASA Technical Reports Server (NTRS)

    Trautwein, John; Wegerif, Dan

    2004-01-01

    After the loss of Columbia in 2003, the Columbia Accident Investigation Board and NASA KSC directed personnel at the Launch Equipment Test Facility (LETF) to design and build high fidelity mock-ups of Columbia's left wing leading edges. These leading edge segments, constructed of reinforced carbon-carbon, were a major point of inquiry by the investigation team. The LETF engineers developed a concept of building a clear Lexan panel with an aluminum support structure ten percent larger than the original panel. The leading edge debris are attached to the Lexan panels and both the front and back side of each panel are visible for inspection. The entire assembly can be rotated, to provide visual access to the entire panel. Six carts were fabricated to support the thirteen panels. These carts could be set up in order, next to each other, to provide the desired inspection access. The carts and attached debris are currently located in the Vehicle Assembly Building at KSC.

  16. Edge Detection By Differences Of Gaussians

    NASA Astrophysics Data System (ADS)

    Marthon, Ph.; Thiesse, B.; Bruel, A.

    1986-06-01

    The Differences of Gaussians (DOGs) are of fundamental importance in edge detection. They belong to the human vision system as shown by Enroth-Cugell and Robson [ENR66]. The zero-crossings of their outputs mark the loci of the intensity changes. The set of descriptions from different operator sizes forms the input for later visual processes, such as stereopsis and motion analysis. We show that DOGs uniformly converge to the Laplacian of a Gaussian (ΔG2,σ) when both the inhibitory and excitatory variables converge to σ. Spatial and spectral properties of DOGs and ΔGs are compared: width and height of their central positive regions, bandiwidths... Finally, DOGs' responses to some features such as ideal edge, right angle corner, general corner..., are presented and magnitudes of error on edge position are given.

  17. Heuristic edge detector for noisy range images

    NASA Astrophysics Data System (ADS)

    Wu, Kung C.

    1994-10-01

    This paper presents a heuristic edge detector for extracting wireframe representations of objects from noisy range data. Jump and roof edges were detected successfully from range images containing additive white Gaussian noise with a standard deviation equal to as high as 1.2% of the measured range values. This represents an appreciable amount of noise since approximately 5% of the errors are greater than 12 cm and 32% of errors are greater than 6 cm at a distance of 5 meters. The noise insensitive characteristic of the heuristic edge detector enables low cost range scanners to be used for practical industrial applications. The availability of low cost active vision systems greatly broadens the horizon of integrating robotics vision systems to manufacturing automation.

  18. Edge excitations in fractional Chern insulators

    NASA Astrophysics Data System (ADS)

    Luo, Wei-Wei; Chen, Wen-Chao; Wang, Yi-Fei; Gong, Chang-De

    2013-10-01

    Recent theoretical papers have demonstrated the realization of fractional quantum anomalous Hall states (also called fractional Chern insulators) in topological flat band lattice models without an external magnetic field. Such newly proposed lattice systems play a vital role in obtaining a large class of fractional topological phases. Here we report the exact numerical studies of edge excitations for such systems in a disk geometry loaded with hard-core bosons, which will serve as a more viable experimental probe for such topologically ordered states. We find convincing numerical evidence of a series of edge excitations characterized by the chiral Luttinger liquid theory for the bosonic fractional Chern insulators in both the honeycomb disk Haldane model and the kagome-lattice disk model. We further verify these current-carrying chiral edge states by inserting a central flux to test their compressibility.

  19. Black phosphorus edges: a polarized Raman study

    NASA Astrophysics Data System (ADS)

    Ribeiro, H.; Villegas, C.; Bahamon, D.; Castro Neto, A.; de Souza, E.; Rocha, A.; Pimenta, M.; de Matos, C.

    Black phosphorus (BP) has been recently exfoliated down to few-layer thicknesses revealing numerous interesting features such as a tunable direct bandgap. Ever since, demonstrations of BP electronic devices have bloomed, as well as studies of the electric, optical, mechanical and thermal properties of its bulk and few-layer forms. However, the edges of BP crystals have, so far, been poorly characterized, even though the terminations of layered crystals are known to possess a range of interesting properties. In this work, the edges of exfoliated BP flakes are characterized by polarized confocal Raman spectroscopy. We will present experimental Raman spectra at zigzag and armchair edges, as well as density functional theory calculations that explain the peculiarities of the experimental data. Fapesp, INCT/Nanocarbono, Fapemig, CNPq, MackPesquisa, Grid-Unesp, CENAPAD-SP, and NRF.

  20. Floquet edge states in germanene nanoribbons

    NASA Astrophysics Data System (ADS)

    Tahir, M.; Zhang, Q. Y.; Schwingenschlögl, U.

    2016-08-01

    We theoretically demonstrate versatile electronic properties of germanene monolayers under circularly, linearly, and elliptically polarized light. We show for the high frequency regime that the edge states can be controlled by tuning the amplitude of the light and by applying a static electric field. For circularly polarized light the band gap in one valley is reduced and in the other enhanced, enabling single valley edge states. For linearly polarized light spin-split states are found for both valleys, being connected by time reversal symmetry. The effects of elliptically polarized light are similar to those of circularly polarized light. The transport properties of zigzag nanoribbons in the presence of disorder confirm a nontrivial nature of the edge states under circularly and elliptically polarized light.

  1. Dynamics of Double Stochastic Operators

    NASA Astrophysics Data System (ADS)

    Saburov, Mansoor

    2016-03-01

    A double stochastic operator is a generalization of a double stochastic matrix. In this paper, we study the dynamics of double stochastic operators. We give a criterion for a regularity of a double stochastic operator in terms of absences of its periodic points. We provide some examples to insure that, in general, a trajectory of a double stochastic operator may converge to any interior point of the simplex.

  2. Double Helical Fluid Containment

    NASA Astrophysics Data System (ADS)

    Lowry, Brian

    2003-11-01

    In the absence of gravity or at micro-scales, helical wires can support cylindrical volumes of fluid of infinite length, making them convenient as conduits. However, fixed contact line double helical fluid volumes have the additional property that they can be drained to zero volume without loss of stability to constant pressure disturbances. Thus the two-wire support is a convenient microgravity or micro-scale container as well as conduit. For evenly spaced wires, continuous draining of a cylindrical volume to zero is possible for double helices ranging from moderate pitch to the parallel wire case. Double helices of steeper pitch are stable as cylinders and at zero volume, but are unstable for some range of intermediate volumes. This unstable zone is very strongly dependent on the offset between the helical wires, varying rapidly for offsets other than 180 degrees. Preliminary experimental results validate the theoretical predictions.

  3. Double face sealing device

    NASA Technical Reports Server (NTRS)

    Weddendorf, Bruce C. (Inventor)

    1991-01-01

    A double face sealing device for mounting between two surfaces to provide an airtight and fluid-tight seal between a closure member bearing one of the surfaces and a structure or housing bearing the other surface which extends around the opening or hatchway to be closed. The double face sealing device includes a plurality of sections or segments mounted to one of the surfaces, each having a main body portion, a pair of outwardly extending and diverging, cantilever, spring arms, and a pair of inwardly extending and diverging, cantilever, spring arms, an elastomeric cover on the distal, free, ends of the outwardly extending and diverging spring arms, and an elastomeric cover on the distal, free, ends of the inwardly extending and diverging spring arms. The double face sealing device has application or use in all environments requiring a seal, but is particularly useful to seal openings or hatchways between compartments of spacecraft or aircraft.

  4. Double Emulsion Templated Celloidosomes

    NASA Astrophysics Data System (ADS)

    Arriaga, Laura R.; Marquez, Samantha M.; Kim, Shin-Hyun; Chang, Connie; Wilking, Jim; Monroy, Francisco; Marquez, Manuel; Weitz, David A.

    2012-02-01

    We present a novel approach for fabricating celloidosomes, which represent a hollow and spherical three-dimensional self-assembly of living cells encapsulating an aqueous core. Glass- capillary microfluidics is used to generate monodisperse water-in-oil-in-water double emulsion templates using lipids as stabilizers. Such templates allow for obtaining single but also double concentric celloidosomes. In addition, after a solvent removal step the double emulsion templates turn into monodisperse lipid vesicles, whose membrane spontaneously phase separates when choosing the adequate lipid composition, providing the adequate scaffold for fabricating Janus-celloidosomes. These structures may find applications in the development of bioreactors in which the synergistic effects of two different types of cells selectively adsorbed on one of the vesicle hemispheres may be exploited.

  5. Revisting the Double Helix

    SciTech Connect

    Ha, Taekjip

    2010-12-08

    Properties of DNA double helix have been studied for over 60 years. Yet as more sensitive tools become available, fundamental assumptions in our understanding of these properties are being challenged. One such question is over the flexibility of DNA. Looping or bending of DNA on short length scales is essential for many cellular processes but it is highly controversial exactly how flexible the DNA is. Using a new, single-molecule based method, we found that DNA of lengths as short as 50 base pairs can form a circle more than 108 times faster than theoretical predictions. Another question concerns the physical principles governing the reversible, helix-coil transitions of DNA between the double helix and single strands. Using porous nanocontainers, we found that the rate of double helix formation shows an abrupt 100 fold change depending on whether there are 7 or more contiguous base pairs or not.

  6. Tracking The Double Eagle

    NASA Technical Reports Server (NTRS)

    1979-01-01

    Last summer a trio of aeronauts made aviation history. Ben Abruzzo, Maxie Anderson and Larry Newman, all of Albuquerque, New Mexico, piloted their balloon Double Eagle I1 from Presque Isle, Maine to Miserey, France, some 50 miles from Paris. They were the first to negotiate a successful Atlantic crossing in a freeflying balloon after a score of attempts over a span of more than a century. A year earlier, Abruzzo and Anderson had made an unsuccessful try in their predecessor balloon Double Eagle. On that occasion, a NASA-developed satellite beacon helped save their lives. Carried aboard the balloon, the simple, seven-pound beacon continuously transmitted signals to NASA's Nimbus-6 satellite. Nimbus relayed the signals to monitors at Goddard Space Flight Center, enabling Goddard to compute the balloon's position. Position reports were then telephoned regularly to Double Eagle's control center at Bedford, Massachusetts. This monitoring system proved invaluable when the balloon encountered trouble several days after liftoff.

  7. Design friendly double patterning

    NASA Astrophysics Data System (ADS)

    Yesilada, Emek

    2012-03-01

    Double patterning using 193nm immersion has been adapted as the solution to enable 2x nm technology nodes until the arrival of EUV tools. As a result the past few years have seen a huge effort in creating double patterning friendly design flows. These flows have so far proposed a combination of decomposition rules at cell level and/or at placement level as well as sophisticated decomposition tools with varying density, design iteration and decomposition complexity penalties. What is more, designers have to familiarize themselves with double patterning challenges and decomposition tools. In this paper an alternative approach is presented that allows the development of dense standard cells with minimal impact on design flow due to double patterning. A real case study is done on 20nm node first metal layer where standard cells are designed without considering decomposition restrictions. The resulting layout is carefully studied in order to establish decomposition or color rules that can map the layout into two masks required for double patterning but without the need of complex coloring algorithms. Since the rules are derived from a decomposition unaware design they do not in return impose heavy restrictions on the design at the cell or placement level and show substantial density gains compared to previously proposed methods. Other key advantages are a simplified design flow without complex decomposition tools that can generate a faster time to market solution all at the same time keeping designers isolated from the challenges of the double patterning. The derived design rules highlight process development path required for design driven manufacturing.

  8. Double checking: a second look

    PubMed Central

    Chreim, Samia; Forster, Alan

    2015-01-01

    Abstract Rationale, aims and objectives Double checking is a standard practice in many areas of health care, notwithstanding the lack of evidence supporting its efficacy. We ask in this study: ‘How do front line practitioners conceptualize double checking? What are the weaknesses of double checking? What alternate views of double checking could render it a more robust process?’ Method This is part of a larger qualitative study based on 85 semi‐structured interviews of health care practitioners in general internal medicine and obstetrics and neonatology; thematic analysis of the transcribed interviews was undertaken. Inductive and deductive themes are reported. Results Weaknesses in the double checking process include inconsistent conceptualization of double checking, double (or more) checking as a costly and time‐consuming procedure, double checking trusted as an accepted and stand‐alone process, and double checking as preventing reporting of near misses. Alternate views of double checking that would render it a more robust process include recognizing that double checking requires training and a dedicated environment, Introducing automated double checking, and expanding double checking beyond error detection. These results are linked with the concepts of collective efficiency thoroughness trade off (ETTO), an in‐family approach, and resilience. Conclusion(s) Double checking deserves more questioning, as there are limitations to the process. Practitioners could view double checking through alternate lenses, and thus help strengthen this ubiquitous practice that is rarely challenged. PMID:26568537

  9. Airplane wing leading edge variable camber flap

    NASA Technical Reports Server (NTRS)

    Cole, J. B.

    1980-01-01

    The invention and design of an aerodynamic high lift device which provided a solution to an aircraft performance problem are described. The performance problem of converting a high speed cruise airfoil into a low speed aerodynamic shape that would provide landing and take-off characteristics superior to those available with contemporary high lift devices are addressed. The need for an improved wing leading edge device that would complement the high lift performance of a triple slotted trailing edge flap is examined. The mechanical and structural aspects of the variable camber flap are discussed and the aerodynamic performance aspects only as they relate to the invention and design of the device are presented.

  10. Edge Mode Coupling within a Plasmonic Nanoparticle

    PubMed Central

    2016-01-01

    The coupling of plasmonic nanoparticles can strongly modify their optical properties. Here, we show that the coupling of the edges within a single rectangular particle leads to mode splitting and the formation of bonding and antibonding edge modes. We are able to unambiguously designate the modes due to the high spatial resolution of electron microscopy-based electron energy loss spectroscopy and the comparison with numerical simulations. Our results provide simple guidelines for the interpretation and the design of plasmonic mode spectra. PMID:27427962

  11. Edge detection techniques for iris recognition system

    NASA Astrophysics Data System (ADS)

    Tania, U. T.; Motakabber, S. M. A.; Ibrahimy, M. I.

    2013-12-01

    Nowadays security and authentication are the major parts of our daily life. Iris is one of the most reliable organ or part of human body which can be used for identification and authentication purpose. To develop an iris authentication algorithm for personal identification, this paper examines two edge detection techniques for iris recognition system. Between the Sobel and the Canny edge detection techniques, the experimental result shows that the Canny's technique has better ability to detect points in a digital image where image gray level changes even at slow rate.

  12. Edge states of periodically kicked quantum rotors.

    PubMed

    Floss, Johannes; Averbukh, Ilya Sh

    2015-05-01

    We present a quantum localization phenomenon that exists in periodically kicked three-dimensional rotors, but is absent in the commonly studied two-dimensional ones: edge localization. We show that under the condition of a fractional quantum resonance there are states of the kicked rotor that are strongly localized near the edge of the angular momentum space at J=0. These states are analogs of surface states in crystalline solids, and they significantly affect resonant excitation of molecular rotation by laser pulse trains.

  13. Near Field Trailing Edge Tone Noise Computation

    NASA Technical Reports Server (NTRS)

    Loh, Ching Y.

    2002-01-01

    Blunt trailing edges in a flow often generate tone noise due to wall-jet shear layer and vortex shedding. In this paper, the space-time conservation element (CE/SE) method is employed to numerically study the near-field noise of blunt trailing edges. Two typical cases, namely, flow past a circular cylinder (aeolian noise problem) and flow past a flat plate of finite thickness are considered. The computed frequencies compare well with experimental data. For the aeolian noise problem, comparisons with the results of other numerical approaches are also presented.

  14. Wing Leading Edge Concepts for Noise Reduction

    NASA Technical Reports Server (NTRS)

    Shmilovich, Arvin; Yadlin, Yoram; Pitera, David M.

    2010-01-01

    This study focuses on the development of wing leading edge concepts for noise reduction during high-lift operations, without compromising landing stall speeds, stall characteristics or cruise performance. High-lift geometries, which can be obtained by conventional mechanical systems or morphing structures have been considered. A systematic aerodynamic analysis procedure was used to arrive at several promising configurations. The aerodynamic design of new wing leading edge shapes is obtained from a robust Computational Fluid Dynamics procedure. Acoustic benefits are qualitatively established through the evaluation of the computed flow fields.

  15. Double Bragg Interferometry.

    PubMed

    Ahlers, H; Müntinga, H; Wenzlawski, A; Krutzik, M; Tackmann, G; Abend, S; Gaaloul, N; Giese, E; Roura, A; Kuhl, R; Lämmerzahl, C; Peters, A; Windpassinger, P; Sengstock, K; Schleich, W P; Ertmer, W; Rasel, E M

    2016-04-29

    We employ light-induced double Bragg diffraction of delta-kick collimated Bose-Einstein condensates to create three symmetric Mach-Zehnder interferometers. They rely on (i) first-order, (ii) two successive first-order, and (iii) second-order processes which demonstrate the scalability of the corresponding momentum transfer. With respect to devices based on conventional Bragg scattering, these symmetric interferometers double the scale factor and feature a better suppression of noise and systematic uncertainties intrinsic to the diffraction process. Moreover, we utilize these interferometers as tiltmeters for monitoring their inclination with respect to gravity. PMID:27176520

  16. Double arch mirror study

    NASA Technical Reports Server (NTRS)

    Vukobratovich, D.; Hillman, D.

    1983-01-01

    The development of a method of mounting light weight glass mirrors for astronomical telescopes compatible with the goals of the Shuttle Infrared Telescope Facility (SIRTF) was investigated. A 20 in. diameter double arch lightweight mirror previously fabricated was modified to use a new mount configuration. This mount concept was developed and fabricated. The mounting concept of the double mounting mirror is outlined. The modifications made to the mirror, fabrication of the mirror mount, and room temperature testing of the mirror and mount and the extension of the mirror and mount concept to a full size (40 in. diameter) primary mirror for SIRTF are discussed.

  17. ? - ? Double twinning in magnesium

    NASA Astrophysics Data System (ADS)

    Jäger, Aleš; Ostapovets, Andriy; Molnár, Peter; Lejček, Pavel

    2011-08-01

    It is demonstrated that metalworking processes performed at different temperatures can lead to the ? - ? double twinning. This twinning mode has been observed during direct extrusion of the coarse-grained Mg-0.3at.%Al alloy at 433 K and analysed in detail on room-temperature rolled magnesium single crystal with the c-axis parallel to transverse direction and the a-axis parallel to rolling direction. The ? - ? double twins originated during initial stage of the formation on coarse-grained and single-crystalline structure.

  18. Double Photoionization Near Threshold

    NASA Technical Reports Server (NTRS)

    Wehlitz, Ralf

    2007-01-01

    The threshold region of the double-photoionization cross section is of particular interest because both ejected electrons move slowly in the Coulomb field of the residual ion. Near threshold both electrons have time to interact with each other and with the residual ion. Also, different theoretical models compete to describe the double-photoionization cross section in the threshold region. We have investigated that cross section for lithium and beryllium and have analyzed our data with respect to the latest results in the Coulomb-dipole theory. We find that our data support the idea of a Coulomb-dipole interaction.

  19. A new method of edge detection for object recognition

    USGS Publications Warehouse

    Maddox, Brian G.; Rhew, Benjamin

    2004-01-01

    Traditional edge detection systems function by returning every edge in an input image. This can result in a large amount of clutter and make certain vectorization algorithms less accurate. Accuracy problems can then have a large impact on automated object recognition systems that depend on edge information. A new method of directed edge detection can be used to limit the number of edges returned based on a particular feature. This results in a cleaner image that is easier for vectorization. Vectorized edges from this process could then feed an object recognition system where the edge data would also contain information as to what type of feature it bordered.

  20. Acoustic Pulse Diffraction by Curved and Planar Structures with Edges

    NASA Astrophysics Data System (ADS)

    Zhang, Qin

    1990-01-01

    Efficient and accurate solutions of acoustic wave diffraction by a rigid step discontinuity and a curved half-plane are derived by the uniform geometrical theory of diffraction. These solutions can be used in seismic data processing to evaluate and, eventually, to improve the existing data processing procedures. They can also find applications in electromagnetics, microwave antenna design, acoustic design and sound engineering. The rigid step discontinuity solution given in this thesis is more accurate than the existing solutions which are based on Kirchhoff theory of diffraction. This solution removes the previous restriction on the source and the receiver arrangement. It also provides high efficiency by the use of ray theory. This solution is further generalized to two offset half-planes and an inclined wedge. Solutions for more complicated structures can be obtained by superposition of these solutions with added interactions. The complex source position method is used to extend the omnidirectional point source solution to a beam source solution. The effect of changes of the directivity and orientation of the beam source is studied. Time-domain single and double diffraction coefficients are determined through direct Fourier transforming and convolution. An infinite impulse response filter is applied to the time-domain direct computation of single diffraction. This combination achieves a total saving of 75% of computing time over the frequency-domain approach. Diffraction by a curved half-plane is analyzed with the inclusion of creeping wave diffraction and second order edge diffraction. An acoustic model of a curved half-plane is designed to verify the theory. The experimental results obtained by Mellema have verified the existence of the creeping wave diffraction and weak traces of the second order edge diffraction.

  1. Green autofluorescence, a double edged monitoring tool for bacterial growth and activity in micro-plates

    NASA Astrophysics Data System (ADS)

    Mihalcescu, Irina; Van-Melle Gateau, Mathilde; Chelli, Bernard; Pinel, Corinne; Ravanat, Jean-Luc

    2015-12-01

    The intrinsic green autofluorescence of an Escherichia coli culture has long been overlooked and empirically corrected in green fluorescent protein (GFP) reporter experiments. We show here, by using complementary methods of fluorescence analysis and HPLC, that this autofluorescence, principally arise from the secreted flavins in the external media. The cells secrete roughly 10 times more than what they keep inside. We show next that the secreted flavin fluorescence can be used as a complementary method in measuring the cell concentration particularly when the classical method, based on optical density measure, starts to fail. We also demonstrate that the same external flavins limit the dynamical range of GFP quantification and can lead to a false interpretation of lower global dynamic range of expression than what really happens. In the end we evaluate different autofluorescence correction methods to extract the real GFP signal.

  2. Double-edged effects of arsenic compounds: anticancer and carcinogenic effects.

    PubMed

    Rehman, Kanwal; Naranmandura, Hua

    2013-12-01

    Although arsenic is known to cause cancers of lung, skin and kidney, arsenic trioxide (As2O3) has been recently recognized as one of the most effective novel anticancer agent for the treatment of acute promyelocytic leukemia (APL). These paradoxical effects of arsenic may be dose-dependent, associated with its distinctive metabolism, or correlated with its direct or indirect effects on different cellular pathways which may result in altered cellular functions. The basic mechanism through which As2O3 induces molecular remission in APL patients include direct targeting of PML and retinoic acid receptor alpha fusion protein (PML-RARα) by arsenic resulting in oncoprotein degradation leading to partial differentiation. Many in vitro studies have also indicated that the anticancer properties of As2O3 against non-APL blood cancers predominantly occur through induction of apoptotic pathway. Especially, release of cytochrome c or activation of the caspase cascades and apoptosis-related proteins by arsenic is thought to occur by directly targeting mitochondria. The mechanisms and the selective target sites that have been usually associated with the cytotoxic effects of arsenicals are discussed here with reference to their contribution towards the anticancer properties of arsenic. In this review we have particularly explained the in vivo or in vitro arsenic toxicity based on arsenic metabolic pathway and its different metabolites. These multiple effects and different selective target sites for arsenic and its metabolites emphasize the need for better understanding of paradoxical effects of arsenic which may provide the appropriate use of this agent in the treatment of various malignancies. PMID:24164099

  3. Double-edged effects of arsenic compounds: anticancer and carcinogenic effects.

    PubMed

    Rehman, Kanwal; Naranmandura, Hua

    2013-12-01

    Although arsenic is known to cause cancers of lung, skin and kidney, arsenic trioxide (As2O3) has been recently recognized as one of the most effective novel anticancer agent for the treatment of acute promyelocytic leukemia (APL). These paradoxical effects of arsenic may be dose-dependent, associated with its distinctive metabolism, or correlated with its direct or indirect effects on different cellular pathways which may result in altered cellular functions. The basic mechanism through which As2O3 induces molecular remission in APL patients include direct targeting of PML and retinoic acid receptor alpha fusion protein (PML-RARα) by arsenic resulting in oncoprotein degradation leading to partial differentiation. Many in vitro studies have also indicated that the anticancer properties of As2O3 against non-APL blood cancers predominantly occur through induction of apoptotic pathway. Especially, release of cytochrome c or activation of the caspase cascades and apoptosis-related proteins by arsenic is thought to occur by directly targeting mitochondria. The mechanisms and the selective target sites that have been usually associated with the cytotoxic effects of arsenicals are discussed here with reference to their contribution towards the anticancer properties of arsenic. In this review we have particularly explained the in vivo or in vitro arsenic toxicity based on arsenic metabolic pathway and its different metabolites. These multiple effects and different selective target sites for arsenic and its metabolites emphasize the need for better understanding of paradoxical effects of arsenic which may provide the appropriate use of this agent in the treatment of various malignancies.

  4. DYRK1A: the double-edged kinase as a protagonist in cell growth and tumorigenesis

    PubMed Central

    Fernández-Martínez, P; Zahonero, C; Sánchez-Gómez, P

    2015-01-01

    DYRK1A (dual-specificity tyrosine-regulated kinase 1A) is a kinase with multiple implications for embryonic development, especially in the nervous system where it regulates the balance between proliferation and differentiation of neural progenitors. The DYRK1A gene is located in the Down syndrome critical region and may play a significant role in the developmental brain defects, early neurodegeneration, and cancer susceptibility of individuals with this syndrome. DYRK1A is also expressed in adults, where it might participate in the regulation of cell cycle, survival, and tumorigenesis, thus representing a potential therapeutic target for certain types of cancer. However, the final readout of DYRK1A overexpression or inhibition depends strongly on the cellular context, as it has both tumor suppressor and oncogenic activities. Here, we will discuss the functions and substrates of DYRK1A associated with the control of cell growth and tumorigenesis with a focus on the potential use of DYRK1A inhibitors in cancer therapy. PMID:27308401

  5. DYRK1A: the double-edged kinase as a protagonist in cell growth and tumorigenesis.

    PubMed

    Fernández-Martínez, P; Zahonero, C; Sánchez-Gómez, P

    2015-01-01

    DYRK1A (dual-specificity tyrosine-regulated kinase 1A) is a kinase with multiple implications for embryonic development, especially in the nervous system where it regulates the balance between proliferation and differentiation of neural progenitors. The DYRK1A gene is located in the Down syndrome critical region and may play a significant role in the developmental brain defects, early neurodegeneration, and cancer susceptibility of individuals with this syndrome. DYRK1A is also expressed in adults, where it might participate in the regulation of cell cycle, survival, and tumorigenesis, thus representing a potential therapeutic target for certain types of cancer. However, the final readout of DYRK1A overexpression or inhibition depends strongly on the cellular context, as it has both tumor suppressor and oncogenic activities. Here, we will discuss the functions and substrates of DYRK1A associated with the control of cell growth and tumorigenesis with a focus on the potential use of DYRK1A inhibitors in cancer therapy. PMID:27308401

  6. The Double Edge of Common Interest: Ethnic Segregation as an Unintended Byproduct of Opinion Homophily

    ERIC Educational Resources Information Center

    Stark, Tobias H.; Flache, Andreas

    2012-01-01

    How can we reduce ethnic friendship segregation in ethnically heterogeneous schools? The Common Ingroup Identity Model suggests that interethnic friendships are promoted by those intervention programs that focus on the interests students have in common. The authors argue that the outcome of these common interest interventions may crucially depend…

  7. CD26/dipeptidylpeptidase IV-chemokine interactions: double-edged regulation of inflammation and tumor biology.

    PubMed

    Mortier, Anneleen; Gouwy, Mieke; Van Damme, Jo; Proost, Paul; Struyf, Sofie

    2016-06-01

    Post-translational modification of chemokines is an essential regulatory mechanism to enhance or dampen the inflammatory response. CD26/dipeptidylpeptidase IV, ubiquitously expressed in tissues and blood, removes NH2-terminal dipeptides from proteins with a penultimate Pro or Ala. A large number of human chemokines, including CXCL2, CXCL6, CXCL9, CXCL10, CXCL11, CXCL12, CCL3L1, CCL4, CCL5, CCL11, CCL14, and CCL22, are cleaved by CD26; however, the efficiency is clearly influenced by the amino acids surrounding the cleavage site and although not yet proven, potentially affected by the chemokine concentration and interactions with third molecules. NH2-terminal cleavage of chemokines by CD26 has prominent effects on their receptor binding, signaling, and hence, in vitro and in vivo biologic activities. However, rather than having a similar result, the outcome of NH2-terminal truncation is highly diverse. Either no difference in activity or drastic alterations in receptor recognition/specificity and hence, chemotactic activity are observed. Analogously, chemokine-dependent inhibition of HIV infection is enhanced (for CCL3L1 and CCL5) or decreased (for CXCL12) by CD26 cleavage. The occurrence of CD26-processed chemokine isoforms in plasma underscores the importance of the in vitro-observed CD26 cleavages. Through modulation of chemokine activity, CD26 regulates leukocyte/tumor cell migration and progenitor cell release from the bone marrow, as shown by use of mice treated with CD26 inhibitors or CD26 knockout mice. As chemokine processing by CD26 has a significant impact on physiologic and pathologic processes, application of CD26 inhibitors to affect chemokine function is currently explored, e.g., as add-on therapy in viral infection and cancer. PMID:26744452

  8. A bio-inspired CMOS vision chip for edge detection using an offset-free column readout circuit

    NASA Astrophysics Data System (ADS)

    Shin, Jang-Kyoo; Suh, Sung-Ho; Kong, Jae-Sung; Kim, Jung-Hwan; Lee, Minho

    2005-06-01

    The noise problem, such as the fixed pattern noise (FPN) due to the process variation, should be considered when designing a vision chip. In this paper, we proposed an edge detection circuit based on biological retina using an offset-free column readout circuit (OFCRC) to reduce the FPN occurring in the photo-detector. The OFCRC consists of one source follower, one capacitor and five transmission gates. Thus, it is simpler than a conventional correlated double sampling (CDS) circuit. A vision chip for edge detection has been designed and fabricated using a 0.35μm 2-poly 4-metal CMOS process and its output characteristics have been investigated.

  9. First principles calculation of oxygen K edge absorption spectrum of acetic acid: Relationship between the spectrum and molecular dynamics

    NASA Astrophysics Data System (ADS)

    Matsui, Yoshiki; Mizoguchi, Teruyasu

    2016-04-01

    First principles calculation of the oxygen K-edge absorption near-edge structure of liquid acetic acid was performed to investigate the relationship between the spectrum and the molecular dynamics in a liquid. The single and double bonded oxygens gave strong peaks at different energies. A liquid model constructed using a molecular dynamics simulation reproduced the experimental spectrum. We revealed that the effect of the dynamic behavior of molecules in a liquid clearly appears in the particular peak from a single-bond oxygen. The relationship between the bonding nature and the dynamic information of a molecule in a spectrum was determined and presented.

  10. Properties of the edge plasma in the rebuilt Extrap-T2R reversed field pinch experiment

    NASA Astrophysics Data System (ADS)

    Vianello, N.; Spolaore, M.; Serianni, G.; Bergsåker, H.; Antoni, V.; Drake, J. R.

    2002-12-01

    The edge region of the rebuilt Extrap-T2R reversed field pinch experiment has been investigated using Langmuir probes. Radial profiles of main plasma parameters are obtained and compared with those of the previous device Extrap-T2. The spontaneous setting up of a double shear layer of E×B toroidal velocity is confirmed. The particle flux induced by electrostatic fluctuations is calculated and the resulting effective diffusion coefficient is consistent with the Bohm estimate. A close relationship between electrostatic fluctuations at the edge and non-linear coupling of MHD modes in the core is found.

  11. Liquid-Crystal Light Valve Enhances Edges In Images

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin; Liu, Hua-Kuang

    1991-01-01

    Experiments show liquid-crystal light valve (LCLV) exhibits operating mode in which it enhances edges in images projected on it. Operates in edge-enhancing mode (or in combination of edge-enhancing and normal modes) by suitably adjusting bias voltage and frequency. Enhancement of edges one of most important preprocessing steps in optical pattern-recognition systems. Incorporated into image-processing system to enhance edges without introducing excessive optical noise.

  12. Development of a Double Crystal Monochromator

    SciTech Connect

    Kupp, Tom; Blank, Basil; Deyhim, Alex; Benson, Curtis; Robinson, Ian; Fuoss, Paul

    2004-05-12

    A high-precision water-cooled, small offset, double crystal monochromator has been developed for the Advanced Photon Source (APS) UNICAT Sector 34 beamline. The design incorporates the supports and gravity feed water cooling of two diamond or silicon crystals correctly positioned about a common rotation axis so that the incident and diffracted beam do not walk off the edges of the crystals within the energy range 6-15KeV (30 deg.

  13. Development of a Double Crystal Monochromator

    SciTech Connect

    Kupp, T.; Blank, B.; Deyhim, A.; Fuoss, P.H.; Benson, C.A.; Robinson, I.K.

    2010-11-16

    A high-precision water-cooled, small offset, double crystal monochromator has been developed for the Advanced Photon Source (APS) UNICAT Sector 34 beamline. The design incorporates the supports and gravity feed water cooling of two diamond or silicon crystals correctly positioned about a common rotation axis so that the incident and diffracted beam do not walk off the edges of the crystals within the energy range 6-15KeV (30{sup o} < q < 11.6{sup o}). In the 34ID implementation, the first crystal sees unfocussed pink beam from an undulator. The second crystal has a {+-}5{sup o} motorized tilt motion around an axis parallel to its face and around the beam direction. In this paper preliminary measurement data obtained from Advanced Photon Source and the detail of the instrument design are presented.

  14. Resonant Tunneling in Double Bilayer Graphene Heterostructures

    NASA Astrophysics Data System (ADS)

    Fallahazad, Babak; Lee, Kayoung; Kang, Sangwoo; Xue, Jiamin; Larentis, Stefano; Corbet, Christopher; Kim, Kyounghwan; Movva, Hema; Taniguchi, Takashi; Watanabe, Kenji; Register, Leonard; Banerjee, Sanjay; Tutuc, Emanuel

    2015-03-01

    We present the realization and characterization of independently contacted and rotationally aligned double bilayer graphene heterostructures, that show gate-tunable tunneling resonances and negative differential resistance in their interlayer current-voltage characteristics. Our devices are fabricated by successively stacking mechanically exfoliated bilayer graphene and hexagonal boron nitride dielectric using a layer-by-layer transfer technique. The bilayers are rotationally aligned during the device fabrication by selecting flakes with straight edges, and using them as a reference for alignment. We determine the heterostructure energy band alignment at the tunneling resonance using the individual layer carrier densities, and including the chemical potential dependence on the carrier density. Our analysis show that the tunneling resonances occur when the charge neutrality points of the two bilayer graphene are energetically aligned, which suggests the resonances stem from the momentum conserving tunneling. This work has been supported by NRI-SWAN, ONR, and Intel.

  15. Weathering the Double Whammy.

    ERIC Educational Resources Information Center

    Wellman, Jane V.

    2002-01-01

    Discusses how governing boards can help their institutions weather the "double-whammy" of doing more with less: identify the institution's short-term and long-term challenges; refocus the institution's mission, planning, and programming; assess and integrate the institution's tuition, aid, and outreach strategies; redouble the institution's…

  16. Sun Packs Double Punch

    NASA Video Gallery

    On August 3, the sun packed a double punch, emitting a M6.0-class flare at 9:43 am EDT. This video is of the second, slightly stronger M9.3-class flare at 11:41 pm EDT. Both flares had significant ...

  17. Double resonator cantilever accelerometer

    DOEpatents

    Koehler, Dale R.

    1984-01-01

    A digital quartz accelerometer includes a pair of spaced double-ended tuning forks fastened at one end to a base and at the other end through a spacer mass. Transverse movement of the resonator members stresses one and compresses the other, providing a differential frequency output which is indicative of acceleration.

  18. Double resonator cantilever accelerometer

    DOEpatents

    Koehler, D.R.

    1982-09-23

    A digital quartz accelerometer includes a pair of spaced double-ended tuning forks fastened at one end to a base and at the other end through a spacer mass. Transverse movement of the resonator members stresses one and compresses the other, providing a differential frequency output which is indicative of acceleration.

  19. Venezuela to double Supermetanol

    SciTech Connect

    1997-04-23

    Pequiven, the petrochemical arm of Venezuelan state oil company PDVSA, is conducting feasibility studies to double the size of its 750,000-m.t./year Supermetanol methanol joint venture with Ecofuel at Jose. The twin unit would be onstream by the end of the decade and would increase Pequiven`s capacity to 2.3 million m.t./year.

  20. Optimal approximate doubles

    NASA Astrophysics Data System (ADS)

    Huang, Siendong

    2009-11-01

    The nonlocality of quantum states on a bipartite system \\mathcal {A+B} is tested by comparing probabilistic outcomes of two local observables of different subsystems. For a fixed observable A of the subsystem \\mathcal {A,} its optimal approximate double A' of the other system \\mathcal {B} is defined such that the probabilistic outcomes of A' are almost similar to those of the fixed observable A. The case of σ-finite standard von Neumann algebras is considered and the optimal approximate double A' of an observable A is explicitly determined. The connection between optimal approximate doubles and quantum correlations is explained. Inspired by quantum states with perfect correlation, like Einstein-Podolsky-Rosen states and Bohm states, the nonlocality power of an observable A for general quantum states is defined as the similarity that the outcomes of A look like the properties of the subsystem \\mathcal {B} corresponding to A'. As an application of optimal approximate doubles, maximal Bell correlation of a pure entangled state on \\mathcal {B}(\\mathbb {C}^{2})\\otimes \\mathcal {B}(\\mathbb {C}^{2}) is found explicitly.

  1. Replace Double Replacement

    NASA Astrophysics Data System (ADS)

    Martin, R. Bruce

    1999-01-01

    Reactions described as double replacements in high school texts are poorly described by this designation. The driving force for such reactions is precipitation of a solid derived from ions in solution or the production of water in acid-base reactions.

  2. Double-Entry Bookkeeping.

    ERIC Educational Resources Information Center

    Snyder, Herbert

    1999-01-01

    Explains the principles and mechanics of double-entry bookkeeping as a part of the accounting cycle to produce a functioning set of accounting records. Suggests that libraries need to have accurate and timely information about their spending to gain financial control and protect against fraud and abuse. (LRW)

  3. Double Helix Revisited.

    ERIC Educational Resources Information Center

    Glickstein, Neil M.

    1995-01-01

    Describes the use of James Watson's book, "The Double Helix," as a multidisciplinary way of introducing students to actual science; the scientific method; dilemmas encountered in the world of research; and the rich setting of personalities, politics, and history in post-World War II Europe. (MKR)

  4. A matterless double slit

    NASA Astrophysics Data System (ADS)

    King, Ben; di Piazza, Antonino; Keitel, Christoph H.

    2010-02-01

    Double slits provide incoming particles with a choice. Those that survive passage through the slits have chosen from two possible paths, which interfere to distribute them in a wave-like manner. Such wave-particle duality continues to be challenged and investigated in a broad range of disciplines with electrons, neutrons, helium atoms, C60 fullerenes, Bose-Einstein condensates and biological molecules. All variants have hitherto involved material constituents. We present a matterless double-slit scenario in which photons generated from virtual electron-positron pair annihilation in head-on collisions of a probe laser field with two ultra-intense laser beams form a double-slit interference pattern. Such electromagnetic fields are predicted to induce material-like behaviour in vacuum, supporting elastic scattering between photons. Our double-slit scenario presents, on the one hand, a realizable method with which to observe photon-photon scattering and, on the other hand, demonstrates the possibility of both controlling light with light and non-locally investigating features of the quantum vacuum structure.

  5. Double-Glazing Interferometry

    ERIC Educational Resources Information Center

    Toal, Vincent; Mihaylova, Emilia M.

    2009-01-01

    This note describes how white light interference fringes can be seen by observing the Moon through a double-glazed window. White light interferometric fringes are normally observed only in a well-aligned interferometer whose optical path difference is less than the coherence length of the light source, which is approximately one micrometer for…

  6. Design for Double Rainbow

    ERIC Educational Resources Information Center

    Thomas, Lisa Carlucci

    2011-01-01

    Rare is the inspirational, spontaneous, transformative moment shared among 20 million people. In the summer of 2010, people around the world were moved by the sighting of a double rainbow--almost a triple rainbow--"all the way across the sky" in Yosemite National Park. Caught on video and posted to by YouTube by Paul Vasquez in January 2010, the…

  7. Teaching the Double Layer.

    ERIC Educational Resources Information Center

    Bockris, J. O'M.

    1983-01-01

    Suggests various methods for teaching the double layer in electrochemistry courses. Topics addressed include measuring change in absolute potential difference (PD) at interphase, conventional electrode potential scale, analyzing absolute PD, metal-metal and overlap electron PDs, accumulation of material at interphase, thermodynamics of electrified…

  8. Superconducting Metallic Glass Transition-Edge-Sensors

    NASA Technical Reports Server (NTRS)

    Hays, Charles C. (Inventor)

    2013-01-01

    A superconducting metallic glass transition-edge sensor (MGTES) and a method for fabricating the MGTES are provided. A single-layer superconducting amorphous metal alloy is deposited on a substrate. The single-layer superconducting amorphous metal alloy is an absorber for the MGTES and is electrically connected to a circuit configured for readout and biasing to sense electromagnetic radiation.

  9. Apparatus for edge etching of semiconductor wafers

    NASA Technical Reports Server (NTRS)

    Casajus, A.

    1986-01-01

    A device for use in the production of semiconductors, characterized by etching in a rapidly rotating etching bath is described. The fast rotation causes the surface of the etching bath to assume the form of a paraboloid of revolution, so that the semiconductor wafer adjusted at a given height above the resting bath surface is only attacked by etchant at the edges.

  10. New applications of Spectral Edge image fusion

    NASA Astrophysics Data System (ADS)

    Hayes, Alex E.; Montagna, Roberto; Finlayson, Graham D.

    2016-05-01

    In this paper, we present new applications of the Spectral Edge image fusion method. The Spectral Edge image fusion algorithm creates a result which combines details from any number of multispectral input images with natural color information from a visible spectrum image. Spectral Edge image fusion is a derivative-based technique, which creates an output fused image with gradients which are an ideal combination of those of the multispectral input images and the input visible color image. This produces both maximum detail and natural colors. We present two new applications of Spectral Edge image fusion. Firstly, we fuse RGB-NIR information from a sensor with a modified Bayer pattern, which captures visible and near-infrared image information on a single CCD. We also present an example of RGB-thermal image fusion, using a thermal camera attached to a smartphone, which captures both visible and low-resolution thermal images. These new results may be useful for computational photography and surveillance applications.

  11. Helicopter rotor trailing edge noise. [noise prediction

    NASA Technical Reports Server (NTRS)

    Schlinker, R. H.; Amier, R. K.

    1981-01-01

    A two dimensional section of a helicopter main rotor blade was tested in an acoustic wind tunnel at close to full-scale Reynolds numbers to obtain boundary layer data and acoustic data for use in developing an acoustic scaling law and testing a first principles trailing edge noise theory. Results were extended to the rotating frame coordinate system to develop a helicopter rotor trailing edge noise prediction. Comparisons of the calculated noise levels with helicopter flyover spectra demonstrate that trailing edge noise contributes significantly to the total helicopter noise spectrum at high frequencies. This noise mechanism is expected to control the minimum rotor noise. In the case of noise radiation from a local blade segment, the acoustic directivity pattern is predicted by the first principles trailing edge noise theory. Acoustic spectra are predicted by a scaling law which includes Mach number, boundary layer thickness and observer position. Spectrum shape and sound pressure level are also predicted by the first principles theory but the analysis does not predict the Strouhal value identifying the spectrum peak.

  12. Students at the Edge of Space

    ERIC Educational Resources Information Center

    Kennon, Tillman; Roberts, Ed; Fuller, Teresa

    2008-01-01

    Space travel, even low Earth orbit, is probably several years away for most of us; however, students and teachers can research the edge of space by participating in the BalloonSat program. BalloonSat is an offshoot of the Space Grant Consortium's very successful RocketSat program. The Arkansas BalloonSat program consists of teacher-initiated…

  13. The Cognitive Dimension--"Edge of Darkness."

    ERIC Educational Resources Information Center

    McGuigan, Jim

    This paper discusses the cognitive effect of a highly successful 1985 British television program, "Edge of Darkness," which was viewed by millions and received critical plaudits and the accolade of the industry itself. The program is shown to represent a significant television event for formal and cognitive reasons that can usefully be related to…

  14. Strip edge cracking simulation in cold rolling

    SciTech Connect

    Hubert, C.; Dubar, L.; Dubar, M.; Dubois, A.

    2011-01-17

    This research work focuses on a specific defect which occurs during cold rolling of steel strips: edge-serration. Investigations on the industrial processes have led to the conclusion that this defect is the result of the edge-trimming and cold rolling sequences. The aim of this research work is to analyze the effect of the cutting process and the cold rolling on cracks occurrence, especially on strip edges.This study is performed using an experimental testing stand called Upsetting Rolling Test (URT). It allows to reproduce cold rolling contact parameters such as forward slip, reduction ratio and friction coefficients. Specimens sampled near trimmed industrial strip edges are deformed using the URT stand. Two sets of specimens with different stress states, obtained by annealing, are submitted to two reduction passes with extreme forward slips.Scanning electron microscopy observations added to 3D optical surface profiler topographies show that on one hand, forward slip has a major effect on cracks opening. On the other hand, cracks opening decreases according to high roll strip speed gradient. Concerning the heat-treated specimens, no crack appeared after all reduction passes, showing a large influence of the cutting process and consequently of the local stress state in the vicinity of the burnish and fracture regions.

  15. The Edges of the Ocean: An Introduction.

    ERIC Educational Resources Information Center

    Burke, Kevin

    1979-01-01

    Introduces a series of related articles on the study of ocean/continent boundaries (margins) within the framework of plate tectonics. Topics discussed include: early attempts to interpret ocean/continent boundaries, Atlantic-type margins, Pacific-type margins, the edges of ancient oceans, and future challenges in the study of continental margins.…

  16. Edge currents in frustrated Josephson junction ladders

    NASA Astrophysics Data System (ADS)

    Marques, A. M.; Santos, F. D. R.; Dias, R. G.

    2016-09-01

    We present a numerical study of quasi-1D frustrated Josephson junction ladders with diagonal couplings and open boundary conditions, in the large capacitance limit. We derive a correspondence between the energy of this Josephson junction ladder and the expectation value of the Hamiltonian of an analogous tight-binding model, and show how the overall superconducting state of the chain is equivalent to the minimum energy state of the tight-binding model in the subspace of one-particle states with uniform density. To satisfy the constraint of uniform density, the superconducting state of the ladder is written as a linear combination of the allowed k-states of the tight-binding model with open boundaries. Above a critical value of the parameter t (ratio between the intra-rung and inter-rung Josephson couplings) the ladder spontaneously develops currents at the edges, which spread to the bulk as t is increased until complete coverage is reached. Above a certain value of t, which varies with ladder size (t = 1 for an infinite-sized ladder), the edge currents are destroyed. The value t = 1 corresponds, in the tight-binding model, to the opening of a gap between two bands. We argue that the disappearance of the edge currents with this gap opening is not coincidental, and that this points to a topological origin for these edge current states.

  17. Social Justice as a Pedagogy of Edge

    ERIC Educational Resources Information Center

    Sonu, Debbie J.

    2010-01-01

    In this article, the author discusses social justice as a "pedagogy of edge." She argues that educators hold the privilege to begin reframing the dialogue on social justice as a relation of all subjects and to dredge from within the meanings drawn and practices made in honor of justice. This may require a shift away from social justice as a…

  18. The Cutting Edge, 1999-2000.

    ERIC Educational Resources Information Center

    Cutting Edge, 2000

    2000-01-01

    The Cutting Edge is a bimonthly newsletter of the Regional Center for Applied Technology and Training at Danville Community College (DCC) (Virginia) that provides the latest information on a wide range of issues including technology, business, employment trends, and new legislation. Articles from the first five issues discuss: (1) the July 2000…

  19. Diffraction Anomalous Near-Edge Structure

    NASA Astrophysics Data System (ADS)

    Moltaji, Habib O., Jr.

    1995-11-01

    To determine the atomic structure about atom of an element in a sample of a condensed multicomponent single crystal, contrast radiation is proposed with the use of Diffraction Anomalous Near-Edge Structure (DANES), which combines the long-range order sensitivity of the x-ray diffraction and short-range order of the x-ray absorption near-edge techniques. This is achieved by modulating the photon energy of the x-ray beam incident on the sample over a range of energies near an absorption edge of the selected element. Due to anomalous dispersion, x-ray diffraction, and x-ray absorption, the DANES intensity with respect to the selected element is obtained in a single experiment. I demonstrate that synchrotron DANES measurements for the single crystal of thin film and the powder samples and provide the same local atomic structural information as the x-ray absorption near-edge with diffraction condition and can be used to provide enhanced site selectivity. I demonstrate calculations of DAFS intensity and measurements of polarized DANES and XANES intensity.

  20. The Cutting Edge: Workplace English. Instructional Guide.

    ERIC Educational Resources Information Center

    El Paso Community Coll., TX. Literacy Center.

    The instructional guide for the Cutting Edge workplace literacy program, a cooperative project of El Paso Community College (Texas) and Levi Strauss and Company, is an expanded version of one appendix the project handbook. It describes and provides an instructional model for the three-part, job-specific, video-based program of English as a Second…

  1. Acoustic streaming of a sharp edge.

    PubMed

    Ovchinnikov, Mikhail; Zhou, Jianbo; Yalamanchili, Satish

    2014-07-01

    Anomalous acoustic streaming is observed emanating from sharp edges of solid bodies that are vibrating in fluids. The streaming velocities can be orders of magnitude higher than expected from the Rayleigh streaming at similar amplitudes of vibration. Acoustic velocity of fluid relative to a solid body diverges at a sharp edge, giving rise to a localized time-independent body force acting on the fluid. This force results in a formation of a localized jet. Two-dimensional numerical simulations are performed to predict acoustic streaming for low amplitude vibration using two methods: (1) Steady-state solution utilizing perturbation theory and (2) direct transient solution of the Navier-Stokes equations. Both analyses agree with each other and correctly predict the streaming of a sharp-edged vibrating blade measured experimentally. The origin of the streaming can be attributed to the centrifugal force of the acoustic fluid flow around a sharp edge. The dependence of this acoustic streaming on frequency and velocity is examined using dimensional analysis. The dependence law is devised and confirmed by numerical simulations.

  2. Directed triadic closure and edge deletion mechanism induce asymmetry in directed edge properties

    NASA Astrophysics Data System (ADS)

    Brot, Hilla; Muchnik, Lev; Louzoun, Yoram

    2015-01-01

    Many directed real world networks, such as the WWW, genetic regulation networks and economic networks exhibit significant differences between the properties of the incoming and outgoing edges, while the differences exhibited by other networks, such as Social Netw. are far more limited. This phenomenon is most evident in the differences between the distributions of incoming and outgoing degrees and direct clustering coefficients. There is currently no generic network generation model that would reproduce and tune these observed dissimilarities. We propose and empirically validate a simple and realistic model that can explain the emergence of the dissimilarities between the incoming and outgoing network degrees and clustering coefficients by combining directed triadic closure, random edge addition and directed edge removal. Surprisingly, we find that the difference between in and out degree distributions is attributed to asymmetries in the edge removal, highlighting the neglected yet crucial importance of edge removal mechanisms to the static and dynamic properties of real world networks. The model is governed by only two parameters: the first tunes the randomness of the edge addition mechanism, while the second controls the difference between the in and out degrees. The combination of these parameters reproduces the observed variety of directed degree distributions and clustering coefficients. Further comparisons of the model's microscopic dynamics against the empirically observed evolution of real world social network confirms that while quite simple, the model properly describes both the edge addition and deletion processes in directed networks.

  3. Tangential 2-D Edge Imaging for GPI and Edge/Impurity Modeling

    SciTech Connect

    Dr. Ricardo Maqueda; Dr. Fred M. Levinton

    2011-12-23

    Nova Photonics, Inc. has a collaborative effort at the National Spherical Torus Experiment (NSTX). This collaboration, based on fast imaging of visible phenomena, has provided key insights on edge turbulence, intermittency, and edge phenomena such as edge localized modes (ELMs) and multi-faceted axisymmetric radiation from the edge (MARFE). Studies have been performed in all these areas. The edge turbulence/intermittency studies make use of the Gas Puff Imaging diagnostic developed by the Principal Investigator (Ricardo Maqueda) together with colleagues from PPPL. This effort is part of the International Tokamak Physics Activity (ITPA) edge, scrape-off layer and divertor group joint activity (DSOL-15: Inter-machine comparison of blob characteristics). The edge turbulence/blob study has been extended from the current location near the midplane of the device to the lower divertor region of NSTX. The goal of this effort was to study turbulence born blobs in the vicinity of the X-point region and their circuit closure on divertor sheaths or high density regions in the divertor. In the area of ELMs and MARFEs we have studied and characterized the mode structure and evolution of the ELM types observed in NSTX, as well as the study of the observed interaction between MARFEs and ELMs. This interaction could have substantial implications for future devices where radiative divertor regions are required to maintain detachment from the divertor plasma facing components.

  4. Automated edge detection versus manual edge measurement in analysis of brachial artery reactivity: a comparison study.

    PubMed

    Williamson, Eric B; Bronas, Ulf G; Dengel, Donald R

    2008-09-01

    High resolution ultrasound, combined with computer imaging technology, is commonly used to measure changes in brachial artery diameter for the determination of endothelial-dependent vasodilation (EDD) and endothelial independent-vasodilation (EID). Currently, two methods of computerized edge-detection systems are in use to measure changes in artery diameter. One system involves the sonographer manually tracking the artery walls while the second system involves a computer automated edge-detection system that automatically tracks the artery wall. The purpose of this study was to compare the two types of computerized edge-detection systems for measuring vascular function and structure. One hundred fifty (female = 70, male = 80) participants agreed to participate. Baseline brachial diameter, carotid intima-medial thickness (cIMT), EDD and EID were measured by the two computerized edge-detection systems utilizing the same ultrasound B-mode image. Mean values (+/-standard error) for baseline diameter, cIMT, EDD and EID were 3.53 (+/-0.10) mm, 0.43 (+/-0.01) mm, 5.72 (+/-0.20)% and 22.17 (+/-0.60)%, respectively for the manual edge-detection software system. Mean values for baseline diameter, cIMT, EDD and EID were 3.59 (+/-0.10) mm, 0.44 (+/-0.01) mm, 7.33 (+/-0.30)% and 25.77 (+/-0.60)%, respectively for the automated edge-detection software system. Bland-Altman plots displayed large variations between the two edge-detection methods for assessing cIMT and changes in artery diameter following brachial EDD and EID. The results of the study demonstrate that manual and automated computerized edge-detection systems track dynamic changes in brachial artery diameter and cIMT measures differently. Therefore, caution should be used when comparing research utilizing different computerized edge-detection systems for measuring vascular function and structure.

  5. A Theory of Oscillating Edge Flames

    NASA Technical Reports Server (NTRS)

    Buckmaster, J.; Zhang, Yi

    1999-01-01

    It has been known for some years that when a near-limit flame spreads over a liquid pool of fuel, the edge of the flame can oscillate relative to a frame moving with the mean speed. Each period of oscillation is characterized by long intervals of modest motion during which the edge gases radiate like those of a diffusion flame, punctuated by bursts of rapid advance during which the edge gases radiate like those in a deflagration. Substantial resources have been brought to bear on this issue within the microgravity program, both experimental and numerical. It is also known that when a near-asphyxiated candle-flame burns at zero gravity, the edge of the (hemispherical) flame can oscillate violently prior to extinction. Thus a web-surfer, turning to the NASA web-site at http://microgravity.msfc.nasa.gov, and following the trail combustion science/experiments/experimental results/candle flame, will find photographs and a description of candle burning experiments carried out on board both the Space-shuttle and the Russian space station Mir. A brief report can also be found in the proceedings of the Fourth Workshop. And recently, in a third microgravity program, the leading edge of the flame supported by injection of ethane through the porous surface of a plate over which air is blown has been found to oscillate when conditions are close to blow-off. A number of important points can be made with respect to these observations: It is the edge itself which oscillates, advancing and retreating, not the diffusion flame that trails behind the edge; oscillations only occur under near limit conditions; in each case the Lewis number of the fuel is significantly larger than 1; and because of the edge curvature, the heat losses from the reacting edge structure are larger than those from the trailing diffusion flame. We propose a general theory for these oscillations, invoking Occam's 'Law of Parsimony' in an expanded form, to wit: The same mechanism is responsible for the

  6. Mapping Forest Edge Using Aerial Lidar

    NASA Astrophysics Data System (ADS)

    MacLean, M. G.

    2014-12-01

    Slightly more than 60% of Massachusetts is covered with forest and this land cover type is invaluable for the protection and maintenance of our natural resources and is a carbon sink for the state. However, Massachusetts is currently experiencing a decline in forested lands, primarily due to the expansion of human development (Thompson et al., 2011). Of particular concern is the loss of "core areas" or the areas within forests that are not influenced by other land cover types. These areas are of significant importance to native flora and fauna, since they generally are not subject to invasion by exotic species and are more resilient to the effects of climate change (Campbell et al., 2009). However, the expansion of development has reduced the amount of this core area, but the exact amount is still unknown. Current methods of estimating core area are not particularly precise, since edge, or the area of the forest that is most influenced by other land cover types, is quite variable and situation dependent. Therefore, the purpose of this study is to devise a new method for identifying areas that could qualify as "edge" within the Harvard Forest, in Petersham MA, using new remote sensing techniques. We sampled along eight transects perpendicular to the edge of an abandoned golf course within the Harvard Forest property. Vegetation inventories as well as Photosynthetically Active Radiation (PAR) at different heights within the canopy were used to determine edge depth. These measurements were then compared with small-footprint waveform aerial LiDAR datasets and imagery to model edge depths within Harvard Forest.

  7. Absorber topography dependence of phase edge effects

    NASA Astrophysics Data System (ADS)

    Shanker, Aamod; Sczyrba, Martin; Connolly, Brid; Waller, Laura; Neureuther, Andy

    2015-10-01

    Mask topography contributes to phase at the wafer plane, even for OMOG binary masks currently in use at the 22nm node in deep UV (193nm) lithography. Here, numerical experiments with rigorous FDTD simulation are used to study the impact of mask 3D effects on aerial imaging, by varying the height of the absorber stack and its sidewall angle. Using a thin mask boundary layer model to fit to rigorous simulations it is seen that increasing the absorber thickness, and hence the phase through the middle of a feature (bulk phase) monotonically changes the wafer-plane phase. Absorber height also influences best focus, revealed by an up/down shift in the Bossung plot (linewidth vs. defocus). Bossung plot tilt, however, responsible for process window variability at the wafer, is insensitive to changes in the absorber height (and hence also the bulk phase). It is seen to depend instead on EM edge diffraction from the thick mask edge (edge phase), but stays constant for variations in mask thickness within a 10% range. Both bulk phase and edge phase are also independent of sidewall angle fluctuation, which is seen to linearly affect the CD at the wafer, but does not alter wafer phase or the defocus process window. Notably, as mask topography varies, the effect of edge phase can be replicated by a thin mask model with 8nm wide boundary layers, irrespective of absorber height or sidewall angle. The conclusions are validated with measurements on phase shifting masks having different topographic parameters, confirming the strong dependence of phase variations at the wafer on bulk phase of the mask absorber.

  8. Laboratory modeling of edge wave generation over a plane beach by breaking waves

    NASA Astrophysics Data System (ADS)

    Abcha, Nizar; Ezersky, Alexander; Pelinovsky, Efim

    2015-04-01

    Edge waves play an important role in coastal hydrodynamics: in sediment transport, in formation of coastline structure and coastal bottom topography. Investigation of physical mechanisms leading to the edge waves generation allows us to determine their effect on the characteristics of spatially periodic patterns like crescent submarine bars and cusps observed in the coastal zone. In the present paper we investigate parametric excitation of edge wave with frequency two times less than the frequency of surface wave propagating perpendicular to the beach. Such mechanism of edge wave generation has been studied previously in a large number of papers using the assumption of non-breaking waves. This assumption was used in theoretical calculations and such conditions were created in laboratory experiments. In the natural conditions, the wave breaking is typical when edge waves are generated at sea beach. We study features of such processes in laboratory experiments. Experiments were performed in the wave flume of the Laboratory of Continental and Coast Morphodynamics (M2C), Caen. The flume is equipment with a wave maker controlled by computer. To model a plane beach, a PVC plate is placed at small angle to the horizontal bottom. Several resistive probes were used to measure characteristics of waves: one of them was used to measure free surface displacement near the wave maker and two probes were glued on the inclined plate. These probes allowed us to measure run-up due to parametrically excited edge waves. Run-up height is determined by processing a movie shot by high-speed camera. Sub-harmonic generation of standing edge waves is observed for definite control parameters: edge waves represent themselves a spatial mode with wavelength equal to double width of the flume; the frequency of edge wave is equal to half of surface wave frequency. Appearance of sub-harmonic mode instability is studied using probes and movie processing. The dependence of edge wave exponential

  9. Differential near-edge coherent diffractive imaging using a femtosecond high-harmonic XUV light source.

    PubMed

    Weise, Fabian; Neumark, Daniel M; Leone, Stephen R; Gessner, Oliver

    2012-11-19

    Element-specific contrast enhancement in tabletop coherent diffractive imaging (CDI) is demonstrated by employing an ultrafast extreme ultraviolet (XUV) light source with tunable photon energy. By combining two measurements performed at energies below and above the Al L(2,3) absorption edge, the spatial autocorrelation function of a micron-scale double pinhole in a 300 nm thick aluminum foil is retrieved despite a dominant background signal from directly transmitted light across the entire range of detectable diffraction angles. The fringe visibility in the diffraction patterns is 0 below the Al L(2,3) edge, 0.53 ± 0.06 above the edge, and 0.73 ± 0.08 in the differential image that combines the two measurements. The proof-of-principle experiment demonstrates that the variations of XUV optical constants in the vicinity of an inner-shell absorption edge can be utilized to improve the chemical sensitivity and image reconstruction quality of laboratory-based ultrafast imaging experiments.

  10. Line-edge roughness and the impact of stochastic processes on lithography scaling for Moore's Law

    NASA Astrophysics Data System (ADS)

    Mack, Chris A.

    2014-09-01

    Moore's Law, the idea that every two years or so chips double in complexity and the cost of a transistor is always in decline, has been the foundation of the semiconductor industry for nearly 50 years. The main technical force behind Moore's Law has been lithography scaling: shrinking of lithographic features at a rate faster than the increase in finished wafer costs. With smaller feature size comes the need for better control of those sizes during manufacturing. Critical dimension and overlay control must scale in proportion to feature size, and has done so for the last 50 years. But in the sub-50-nm feature size regime, a new problem has arisen: line-edge roughness due to the stochastic nature of the lithography process. Despite significant effort, this line-edge roughness has not scaled in proportion to feature size and is thus consuming an ever larger fraction of the feature size control budget. Projection of current trends predicts a collision course between lithography scaling needs and line-edge roughness reality. In the end, stochastic uncertainty in lithography and its manifestation as line-edge roughness will prove the ultimate limiter of resolution in semiconductor manufacturing.

  11. Double Degrees: Double the Trouble or Twice the Return?

    ERIC Educational Resources Information Center

    Russell, A. Wendy; Dolnicar, Sara; Ayoub, Marina

    2008-01-01

    Double degrees (also called joint or combined degrees)--programs of study combining two bachelor degrees--are increasingly popular in Australian universities, particularly among women. A case study using qualitative and quantitative surveys of current and past double degree students is presented. The study indicates that double degrees benefit…

  12. Rising Sea Levels: Truth or Scare?

    ERIC Educational Resources Information Center

    Peacock, Alan

    2007-01-01

    When "ITV News" ran an item that shocked the author, about rising sea levels that will have caused the entire evacuation of the islands by the end of this year, he began to wonder whether the Pacific Ocean is really rising as fast as this. The media reporting of such things can be a double-edged sword. On the one hand, it brought to the author's…

  13. Geometry-Based Edge Clustering for Graph Visualization

    SciTech Connect

    Cui, Wei W.; Zhou, Hong; Qu, Huamin; Wong, Pak C.; Li, X. M.

    2008-10-19

    Graphs have been widely used to model relationships among data. For large graphs, excessive edge crossings will make the display visually cluttered and thus difficult to explore. In this paper, we propose a novel geometry-based edge-clustering framework which can group edges into bundles to reduce the overall edge crossings. Our method uses a control mesh to guide the edge-clustering process; edge bundles can be formed by forcing all edges to pass through some control points on the mesh. The control mesh can be generated at different levels of detail either manually or automatically based on underlying graph patterns. Users can further interact with the edge-clustering results through several advanced visualization techniques such as color and opacity enhancement. Compared with other edge-clustering methods, our approach is intuitive, flexible, and efficient. The experiments on some large graphs demonstrate the effectiveness of our method.

  14. An ellipse detection algorithm based on edge classification

    NASA Astrophysics Data System (ADS)

    Yu, Liu; Chen, Feng; Huang, Jianming; Wei, Xiangquan

    2015-12-01

    In order to enhance the speed and accuracy of ellipse detection, an ellipse detection algorithm based on edge classification is proposed. Too many edge points are removed by making edge into point in serialized form and the distance constraint between the edge points. It achieves effective classification by the criteria of the angle between the edge points. And it makes the probability of randomly selecting the edge points falling on the same ellipse greatly increased. Ellipse fitting accuracy is significantly improved by the optimization of the RED algorithm. It uses Euclidean distance to measure the distance from the edge point to the elliptical boundary. Experimental results show that: it can detect ellipse well in case of edge with interference or edges blocking each other. It has higher detecting precision and less time consuming than the RED algorithm.

  15. Band-edge lasing and miniband lasing in 1-D dual-periodic photonic crystal

    NASA Astrophysics Data System (ADS)

    Ying, Cui-Feng; Zhou, Wen-Yuan; Li, Yi; Ye, Qing; Zhang, Chun-Ping; Tian, Jian-Guo

    2012-06-01

    Herein, we report two different dual-periodic Photonic Crystals (PCs) in dichromated gelatin emulsion which are fabricated by four-beam holography and double-exposure holography. The minibands with high Q-factors have been evidently located in both two structures. By taking into account the non-uniform distribution of material, the numerical results agree quite well with the experimental results. We also compared the band-edge lasing in single-periodic PC and miniband lasing in Moiré dual-periodic PC. Due to extremely flat dispersion and large mode volume of the miniband, high optical conversion efficiency in miniband lasing is achieved as compared with that of band-edge lasing. Such effect may provide potential applications in low-threshold lasers and ultra-sensitive fluorescent probes in biological assays.

  16. 4pi periodic Josephson current through a Quantum Spin-Hall edge

    NASA Astrophysics Data System (ADS)

    Dahlhaus, Jan; Beenakker, Carlo; Pikulin, Dmitry; Hyart, Timo; Schomerus, Henning

    2014-03-01

    The helical edge state of a quantum spin-Hall insulator can carry a supercurrent in equilibrium between two superconducting electrodes (separation L, coherence length ?). We calculate the maximum (critical) current Ic that can flow without dissipation along a single edge, going beyond the short-junction restriction L?? of earlier work, and find a dependence on the fermion parity of the ground state when L becomes larger than ?. Fermion-parity conservation doubles the critical current in the low-temperature, long-junction limit, while for a short junction Ic is the same with or without parity constraints. This provides a phase-insensitive, dc signature of the 4?-periodic Josephson effect.

  17. An experimental investigation of convective heat transfer at the leading edge of a gas turbine airfoil

    NASA Astrophysics Data System (ADS)

    Gendron, S.; Marchand, N. J.; Korn, C.; Immarigeon, J. P.; Kacprzynski, J. J.

    1992-06-01

    This paper describes the experimental methods used to determine the surface temperatures and heat-transfer coefficients at the leading edge, and elsewhere over the surface, of a specially designed double-edge wedge shell specimen subjected to cyclic heating in a high velocity hot gas stream generated by a burner rig. The methods included temperature measurements with thermocouples (embedded below the surface) as well as surface temperature measurements by optical pyrometry. The experiments were carried out at gas temperatures between 806 to 1323 C and velocities in the range from Mach 0.32 to Mach 0.39. The calibration procedures for each method, the various testing conditions to which the airfoil-like specimen was exposed and the results pertaining to the determination of the surface temperatures and heat-transfer coefficients are described and discussed.

  18. Edge detection of color images using the HSL color space

    NASA Astrophysics Data System (ADS)

    Weeks, Arthur R.; Felix, Carlos E.; Myler, Harley R.

    1995-03-01

    Various edge detectors have been proposed as well as several different types of adaptive edge detectors, but the performance of many of these edge detectors depends on the features and the noise present in the grayscale image. Attempts have been made to extend edge detection to color images by applying grayscale edge detection methods to each of the individual red, blue, and green color components as well as to the hue, saturation, and intensity color components of the color image. The modulus 2(pi) nature of the hue color component makes its detection difficult. For example, a hue of 0 and 2(pi) yields the same color tint. Normal edge detection of a color image containing adjacent pixels with hue of 0 and 2(pi) could yield the presence of an edge when an edge is really not present. This paper presents a method of mapping the 2(pi) modulus hue space to a linear space enabling the edge detection of the hue color component using the Sobel edge detector. The results of this algorithm are compared against the edge detection methods using the red, blue, and green color components. By combining the hue edge image with the intensity and saturation edge images, more edge information is observed.

  19. Mortality after percutaneous edge-to-edge mitral valve repair: a contemporary review

    PubMed Central

    de Beenhouwer, Thomas; Swaans, Martin J.; Post, Marco C.; van der Heyden, Jan A. S.; Eefting, Frank D.; Rensing, Benno J. W. M.

    2016-01-01

    Percutaneous edge-to-edge mitral valve (MV) repair is a relatively new treatment option for mitral regurgitation (MR). After the feasibility and safety having been proved in low-surgical-risk patients, the use of this procedure has shifted more to the treatment of high-risk patients. With the absence of randomized controlled trials (RCT) for this particular subgroup, observational studies try to add evidence to the safety aspect of this procedure. These also provide short- and mid-term mortality figures. Several mortality predictors have been identified, which may help the optimal selection of patients who will benefit most from this technique. In this article we provide an overview of the literature about mortality and its predictors in patients treated with the percutaneous edge-to-edge device. PMID:27054105

  20. Tunneling Spectroscopy of the Edge in Quantum Hall Systems in Cleaved-Edge Overgrowth Devices

    NASA Astrophysics Data System (ADS)

    Oh, J. H.; Hilke, M.; Tsui, D. C.; Pfeiffer, L. N.; West, K. W.

    2004-03-01

    We present experimental results on the tunneling into the edge of a two dimensional electron gas (2DEG) obtained with a GaAs/AlGaAs cleaved edge overgrown structure in a strong perpendicular magnetic field. While the 2DEG shows typical fractional quantum Hall features of a very high mobility system, the tunneling into the edge exhibits a cross-over from a many-particle behavior (Luttinger liquid) at low tunneling voltages to a single particle characteristic at high voltages, which reflects absence of a many-body state away from the Fermi level. At high enough voltages, the single particle characteristic induces an asymmetry when tunneling into the 2DEG compared to tunneling out of it, which can be understood in the context of the single particle Landau level spectral distribution at the edge.