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Sample records for early triangular capacities

  1. Early hominin auditory capacities.

    PubMed

    Quam, Rolf; Martínez, Ignacio; Rosa, Manuel; Bonmatí, Alejandro; Lorenzo, Carlos; de Ruiter, Darryl J; Moggi-Cecchi, Jacopo; Conde Valverde, Mercedes; Jarabo, Pilar; Menter, Colin G; Thackeray, J Francis; Arsuaga, Juan Luis

    2015-09-01

    Studies of sensory capacities in past life forms have offered new insights into their adaptations and lifeways. Audition is particularly amenable to study in fossils because it is strongly related to physical properties that can be approached through their skeletal structures. We have studied the anatomy of the outer and middle ear in the early hominin taxa Australopithecus africanus and Paranthropus robustus and estimated their auditory capacities. Compared with chimpanzees, the early hominin taxa are derived toward modern humans in their slightly shorter and wider external auditory canal, smaller tympanic membrane, and lower malleus/incus lever ratio, but they remain primitive in the small size of their stapes footplate. Compared with chimpanzees, both early hominin taxa show a heightened sensitivity to frequencies between 1.5 and 3.5 kHz and an occupied band of maximum sensitivity that is shifted toward slightly higher frequencies. The results have implications for sensory ecology and communication, and suggest that the early hominin auditory pattern may have facilitated an increased emphasis on short-range vocal communication in open habitats. PMID:26601261

  2. Early hominin auditory capacities

    PubMed Central

    Quam, Rolf; Martínez, Ignacio; Rosa, Manuel; Bonmatí, Alejandro; Lorenzo, Carlos; de Ruiter, Darryl J.; Moggi-Cecchi, Jacopo; Conde Valverde, Mercedes; Jarabo, Pilar; Menter, Colin G.; Thackeray, J. Francis; Arsuaga, Juan Luis

    2015-01-01

    Studies of sensory capacities in past life forms have offered new insights into their adaptations and lifeways. Audition is particularly amenable to study in fossils because it is strongly related to physical properties that can be approached through their skeletal structures. We have studied the anatomy of the outer and middle ear in the early hominin taxa Australopithecus africanus and Paranthropus robustus and estimated their auditory capacities. Compared with chimpanzees, the early hominin taxa are derived toward modern humans in their slightly shorter and wider external auditory canal, smaller tympanic membrane, and lower malleus/incus lever ratio, but they remain primitive in the small size of their stapes footplate. Compared with chimpanzees, both early hominin taxa show a heightened sensitivity to frequencies between 1.5 and 3.5 kHz and an occupied band of maximum sensitivity that is shifted toward slightly higher frequencies. The results have implications for sensory ecology and communication, and suggest that the early hominin auditory pattern may have facilitated an increased emphasis on short-range vocal communication in open habitats. PMID:26601261

  3. Early hominin auditory capacities.

    PubMed

    Quam, Rolf; Martínez, Ignacio; Rosa, Manuel; Bonmatí, Alejandro; Lorenzo, Carlos; de Ruiter, Darryl J; Moggi-Cecchi, Jacopo; Conde Valverde, Mercedes; Jarabo, Pilar; Menter, Colin G; Thackeray, J Francis; Arsuaga, Juan Luis

    2015-09-01

    Studies of sensory capacities in past life forms have offered new insights into their adaptations and lifeways. Audition is particularly amenable to study in fossils because it is strongly related to physical properties that can be approached through their skeletal structures. We have studied the anatomy of the outer and middle ear in the early hominin taxa Australopithecus africanus and Paranthropus robustus and estimated their auditory capacities. Compared with chimpanzees, the early hominin taxa are derived toward modern humans in their slightly shorter and wider external auditory canal, smaller tympanic membrane, and lower malleus/incus lever ratio, but they remain primitive in the small size of their stapes footplate. Compared with chimpanzees, both early hominin taxa show a heightened sensitivity to frequencies between 1.5 and 3.5 kHz and an occupied band of maximum sensitivity that is shifted toward slightly higher frequencies. The results have implications for sensory ecology and communication, and suggest that the early hominin auditory pattern may have facilitated an increased emphasis on short-range vocal communication in open habitats.

  4. Low Temperature Vacuum Synthesis of Triangular CoO Nanocrystal/Graphene Nanosheets Composites with Enhanced Lithium Storage Capacity

    PubMed Central

    Guan, Qun; Cheng, Jianli; Li, Xiaodong; Wang, Bin; Huang, Ling; Nie, Fude; Ni, Wei

    2015-01-01

    CoO nanocrystal/graphene nanosheets (GNS) composites, consisting of a triangular CoO nanocrystal of 2~20 nm on the surface of GNS, are synthesized by a mild synthetic method. First, cobalt acetate tetrahydrate is recrystallized in the alcohol solution at a low temperature. Then, graphene oxide mixed with cobalt-precursor followed by high vacuum annealing to form the CoO nanocrystal/GNS composites. The CoO nanocrystal/GNS composites exhibit a high reversible capacity of 1481.9 m Ah g−1 after 30 cycles with a high Coulombic efficiency of over 96% when used as anode materials for lithium ion battery. The excellent electrochemical performances may be attributed to the special structure of the composites. The well-dispersed triangular CoO nanocrystal on the substrate of conductive graphene can not only have a shorter diffusion length for lithium ions, better stress accommodation capability during the charge-discharge processes and more accessible active sites for lithium-ion storage and electrolyte wetting, but also possess a good conductive network, which can significantly improve the whole electrochemical performance. PMID:25961670

  5. Low Temperature Vacuum Synthesis of Triangular CoO Nanocrystal/Graphene Nanosheets Composites with Enhanced Lithium Storage Capacity.

    PubMed

    Guan, Qun; Cheng, Jianli; Li, Xiaodong; Wang, Bin; Huang, Ling; Nie, Fude; Ni, Wei

    2015-05-11

    CoO nanocrystal/graphene nanosheets (GNS) composites, consisting of a triangular CoO nanocrystal of 2~20 nm on the surface of GNS, are synthesized by a mild synthetic method. First, cobalt acetate tetrahydrate is recrystallized in the alcohol solution at a low temperature. Then, graphene oxide mixed with cobalt-precursor followed by high vacuum annealing to form the CoO nanocrystal/GNS composites. The CoO nanocrystal/GNS composites exhibit a high reversible capacity of 1481.9 m Ah g(-1) after 30 cycles with a high Coulombic efficiency of over 96% when used as anode materials for lithium ion battery. The excellent electrochemical performances may be attributed to the special structure of the composites. The well-dispersed triangular CoO nanocrystal on the substrate of conductive graphene can not only have a shorter diffusion length for lithium ions, better stress accommodation capability during the charge-discharge processes and more accessible active sites for lithium-ion storage and electrolyte wetting, but also possess a good conductive network, which can significantly improve the whole electrochemical performance.

  6. Low Temperature Vacuum Synthesis of Triangular CoO Nanocrystal/Graphene Nanosheets Composites with Enhanced Lithium Storage Capacity

    NASA Astrophysics Data System (ADS)

    Guan, Qun; Cheng, Jianli; Li, Xiaodong; Wang, Bin; Huang, Ling; Nie, Fude; Ni, Wei

    2015-05-01

    CoO nanocrystal/graphene nanosheets (GNS) composites, consisting of a triangular CoO nanocrystal of 2~20 nm on the surface of GNS, are synthesized by a mild synthetic method. First, cobalt acetate tetrahydrate is recrystallized in the alcohol solution at a low temperature. Then, graphene oxide mixed with cobalt-precursor followed by high vacuum annealing to form the CoO nanocrystal/GNS composites. The CoO nanocrystal/GNS composites exhibit a high reversible capacity of 1481.9 m Ah g-1 after 30 cycles with a high Coulombic efficiency of over 96% when used as anode materials for lithium ion battery. The excellent electrochemical performances may be attributed to the special structure of the composites. The well-dispersed triangular CoO nanocrystal on the substrate of conductive graphene can not only have a shorter diffusion length for lithium ions, better stress accommodation capability during the charge-discharge processes and more accessible active sites for lithium-ion storage and electrolyte wetting, but also possess a good conductive network, which can significantly improve the whole electrochemical performance.

  7. The Preterm Infant's Use of Triangular Bids at Three Months, Adjusted Age: Two Case Studies

    ERIC Educational Resources Information Center

    Hansen, Ellen Saeter

    2011-01-01

    This article focuses on preterm infants' early triangular capacity, restricted to the use of triangular bids in interaction with their parents. An observational setting, the Lausanne Trilogue Play (LTP), is used for studying the patterns of interaction. This is an approach focusing on the family as a whole. These observations are part of a study…

  8. Methane Trapping Capacity of the Early Martian Cryosphere

    NASA Astrophysics Data System (ADS)

    Lasue, J.; Langlais, B.; Quesnel, Y.; Chassefière, E.

    2014-07-01

    We demonstrate that the methane trapping capacity of the early martian cryosphere is comparable to the quantity possibly released by the early serpentinization that would have been necessary to generate the observed martian remanent magnetic field.

  9. Triangular ice crystals

    NASA Astrophysics Data System (ADS)

    Murray, Benjamin; Salzmann, Christoph; Heymsfield, Andrew; Neely, Ryan

    2014-05-01

    We are all familiar with the hexagonal form of snow crystals and it is well established that this shape is derived from the arrangement of water molecules in the crystal lattice. However, crystals with a triangular form are often found in the Earth's atmosphere and the reason for this non-hexagonal shape has remained elusive. Recent laboratory work has shed light on why ice crystals should take on this triangular or three-fold scalene habit. Studies of the crystal structure of ice have shown that ice which initially crystallises can be made of up of hexagonal layers which are interlaced with cubic layers to produce a 'stacking disordered ice'. The degree of stacking disorder can vary from crystals which are dominantly hexagonal with a few cubic stacking faults, through to ice where the cubic and hexagonal sequences are fully randomised. The introduction of stacking disorder to ice crystals reduces the symmetry of the crystal from 6-fold (hexagonal) to 3-fold (triangular); this offers an explanation for the long standing problem of why some atmospheric ice crystals have a triangular habit. We discuss the implications of triangular crystals for halos, radiative properties, and also discuss the implications for our understanding of the nucleation and early stages of ice crystal growth for ice crystals in the atmosphere.

  10. Early Education: The Creation of Capacity.

    ERIC Educational Resources Information Center

    Tumin, Melvin

    Every human being is always open to some degree; for example, open for learning, experience, change, improvement, or further degradation by his own standards or those of others. Every experience alters an individual's learning capacity. Therefore, to say a child is naturally of high or low intelligence with unlimited or limited learning power is…

  11. Aerobic Capacities of Early College High School Students

    ERIC Educational Resources Information Center

    Loflin, Jerry W.

    2014-01-01

    The Early College High School Initiative (ECHSI) was introduced in 2002. Since 2002, limited data, especially student physical activity data, have been published pertaining to the ECHSI. The purpose of this study was to examine the aerobic capacities of early college students and compare them to state and national averages. Early college students…

  12. Some early cases of aphasia and the capacity to sing.

    PubMed

    Johnson, Julene K; Graziano, Amy B

    2015-01-01

    This chapter examines early cases of aphasia that include observations of the capacity to sing. Although the majority of these cases were published in the late nineteenth century, earlier reports exist and provide insights into the early thinking about the capacity to sing in aphasia, a topic that continues to the present day. The observation that some patients with aphasia and limited speech output were able to sing the texts of songs inspired scholars to examine the relationship between music and language. Early ideas about the capacity to sing were provided by well-known neurologists, such as John Hughlings Jackson and Adolf Kussmaul. The work of Herbert Spencer about the origins and function of music heavily influenced Jackson and others in their thinking about aphasia. This work also led to an increased interest in understanding music abilities in persons with aphasia and, later, in the brain mechanisms of music. The chapter provides a background as to why there was an interest in the capacity to sing in persons with aphasia and what influenced early thinking on this topic. PMID:25684286

  13. Building Leadership Capacity in Early Childhood Pre-Service Teachers

    ERIC Educational Resources Information Center

    Campbell-Evans, Glenda; Stamopoulos, Elizabeth; Maloney, Carmel

    2014-01-01

    Building leadership capacity has emerged as a key concern within the early childhood profession in Australia as the sector responds to recent national reforms focusing on raising standards and improving quality provision of services. The purpose of this paper is to contribute to the discussion around these reforms and to make a case for changes…

  14. Some early cases of aphasia and the capacity to sing.

    PubMed

    Johnson, Julene K; Graziano, Amy B

    2015-01-01

    This chapter examines early cases of aphasia that include observations of the capacity to sing. Although the majority of these cases were published in the late nineteenth century, earlier reports exist and provide insights into the early thinking about the capacity to sing in aphasia, a topic that continues to the present day. The observation that some patients with aphasia and limited speech output were able to sing the texts of songs inspired scholars to examine the relationship between music and language. Early ideas about the capacity to sing were provided by well-known neurologists, such as John Hughlings Jackson and Adolf Kussmaul. The work of Herbert Spencer about the origins and function of music heavily influenced Jackson and others in their thinking about aphasia. This work also led to an increased interest in understanding music abilities in persons with aphasia and, later, in the brain mechanisms of music. The chapter provides a background as to why there was an interest in the capacity to sing in persons with aphasia and what influenced early thinking on this topic.

  15. Methane storage capacity of the early martian cryosphere

    NASA Astrophysics Data System (ADS)

    Lasue, Jeremie; Quesnel, Yoann; Langlais, Benoit; Chassefière, Eric

    2015-11-01

    Methane is a key molecule to understand the habitability of Mars due to its possible biological origin and short atmospheric lifetime. Recent methane detections on Mars present a large variability that is probably due to relatively localized sources and sink processes yet unknown. In this study, we determine how much methane could have been abiotically produced by early Mars serpentinization processes that could also explain the observed martian remanent magnetic field. Under the assumption of a cold early Mars environment, a cryosphere could trap such methane as clathrates in stable form at depth. The extent and spatial distribution of these methane reservoirs have been calculated with respect to the magnetization distribution and other factors. We calculate that the maximum storage capacity of such a clathrate cryosphere is about 2.1 × 1019-2.2 × 1020 moles of CH4, which can explain sporadic releases of methane that have been observed on the surface of the planet during the past decade (∼1.2 × 109 moles). This amount of trapped methane is sufficient for similar sized releases to have happened yearly during the history of the planet. While the stability of such reservoirs depends on many factors that are poorly constrained, it is possible that they have remained trapped at depth until the present day. Due to the possible implications of methane detection for life and its influence on the atmospheric and climate processes on the planet, confirming the sporadic release of methane on Mars and the global distribution of its sources is one of the major goals of the current and next space missions to Mars.

  16. NiH2 capacity fade during early cycling

    NASA Technical Reports Server (NTRS)

    Zagrodnik, Jeffrey P.

    1993-01-01

    Tests were conducted on nickel hydrogen batteries to determine the charge efficiency of the nickel electrode as a function of rate and temperature, cell discharge capacity, and capacity fade. Test procedures and results are presented in outline and graphic form.

  17. The Development of Visual Working Memory Capacity during Early Childhood

    ERIC Educational Resources Information Center

    Simmering, Vanessa R.

    2012-01-01

    The change detection task has been used in dozens of studies with adults to measure visual working memory capacity. Two studies have recently tested children in this task, suggesting a gradual increase in capacity from 5 years to adulthood. These results contrast with findings from an infant looking paradigm suggesting that capacity reaches…

  18. Endocranial capacity in an early hominid cranium from Sterkfontein, South Africa.

    PubMed

    Conroy, G C; Weber, G W; Seidler, H; Tobias, P V; Kane, A; Brunsden, B

    1998-06-12

    Two- and three-dimensional computer imaging shows that endocranial capacity in an approximately 2.8- to 2.6-million-year-old early hominid cranium (Stw 505) from Sterkfontein, South Africa, tentatively assigned to Australopithecus africanus, is approximately 515 cubic centimeters. Although this is the largest endocranial capacity recorded for this species, it is still markedly less than anecdotal reports of endocranial capacity exceeding 600 cubic centimeters. No australopithecine has an endocranial capacity approaching, let alone exceeding, 600 cubic centimeters. Some currently accepted estimates of early hominid endocranial capacity may be inflated, suggesting that the tempo and mode of early hominid brain evolution may need reevaluation. PMID:9624045

  19. Building Capacity through an Early Education Leadership Academy

    ERIC Educational Resources Information Center

    Goffin, Stacie G.

    2013-01-01

    In 2013, the early childhood education (ECE) field is paying limited attention to leadership development (Goffin & Janke, 2013; Goffin & Means, 2009). A recent survey of ECE leadership development programs suggests that the field does not fully recognize the potential of leadership to serve as a change catalyst, although there is evidence…

  20. Series of Reciprocal Triangular Numbers

    ERIC Educational Resources Information Center

    Bruckman, Paul; Dence, Joseph B.; Dence, Thomas P.; Young, Justin

    2013-01-01

    Reciprocal triangular numbers have appeared in series since the very first infinite series were summed. Here we attack a number of subseries of the reciprocal triangular numbers by methodically expressing them as integrals.

  1. Building Infant Mental Health Capacity through Consultation: Early Head Start's Approach

    ERIC Educational Resources Information Center

    Boss, Jennifer; Mann, Tammy L.; Randolph, Suzanne

    2004-01-01

    This article describes the Pathways to Prevention (PTP) infant mental health initiative conducted by Early Head Start (EHS). The authors note that staff members who want to build their early childhood programs' capacity in infant mental health are often at a loss about how to do it. They suggest establishing an intensive, ongoing relationship with…

  2. Preparing the Early Education and Care Workforce: The Capacity of Massachusetts' Institutions of Higher Education

    ERIC Educational Resources Information Center

    Marshall, Nancy L.; Dennehy, Julie; Starr, Elizabeth; Robeson, Wendy Wagner

    2005-01-01

    This study assesses the current capacity of Massachusetts' institutions of higher education (IHE) to prepare the early education and care (EEC) workforce, as well as the current state of progress on the elements identified in the Report of the Early Education and Care Advisory Committee as critical to advancing a professional development system.…

  3. Adaptive triangular mesh generation

    NASA Technical Reports Server (NTRS)

    Erlebacher, G.; Eiseman, P. R.

    1984-01-01

    A general adaptive grid algorithm is developed on triangular grids. The adaptivity is provided by a combination of node addition, dynamic node connectivity and a simple node movement strategy. While the local restructuring process and the node addition mechanism take place in the physical plane, the nodes are displaced on a monitor surface, constructed from the salient features of the physical problem. An approximation to mean curvature detects changes in the direction of the monitor surface, and provides the pulling force on the nodes. Solutions to the axisymmetric Grad-Shafranov equation demonstrate the capturing, by triangles, of the plasma-vacuum interface in a free-boundary equilibrium configuration.

  4. Behind the Starting Line: School Capacity Building in Early Childhood Education

    ERIC Educational Resources Information Center

    Ho, Dora; Chen, Shu-Chin Susan

    2013-01-01

    This paper describes the process of school capacity building in Hong Kong's early childhood education at a time when there was a quest for quality education. A local preschool was selected for the study, which took part in a university-school support programme through which consultancy was hired from a university to provide school-based…

  5. Impact of early fructose intake on metabolic profile and aerobic capacity of rats

    PubMed Central

    2011-01-01

    Background Metabolic syndrome is a disease that today affects millions of people around the world. Therefore, it is of great interest to implement more effective procedures for preventing and treating this disease. In search of a suitable experimental model to study the role of exercise in prevention and treatment of metabolic syndrome, this study examined the metabolic profile and the aerobic capacity of rats kept early in life on a fructose-rich diet, a substrate that has been associated with metabolic syndrome. Methods We used adult female Wistar rats fed during pregnancy and lactation with two diets: balanced or fructose-rich 60%. During breastfeeding, the pups were distributed in small (4/mother) or adequate (8/mother) litters. At 90 days of age, they were analyzed with respect to: glucose tolerance, peripheral insulin sensitivity, aerobic capacity and serum glucose, insulin, triglycerides, total cholesterol, LDL cholesterol and HDL cholesterol concentrations as well as measures of glycogen synthesis and glucose oxidation by the soleus muscle. Results It was found that the fructose rich diet led the animals to insulin resistance. The fructose fed rats kept in small litters also showed dyslipidemia, with increased serum concentrations of total cholesterol and triglycerides. Conclusion Neither the aerobic capacity nor the glucose oxidation rates by the skeletal muscle were altered by fructose-rich diet, indicating that the animal model evaluated is potentially interesting for the study of the role of exercise in metabolic syndrome. PMID:21223589

  6. Smoking and Early COPD as Independent Predictors of Body Composition, Exercise Capacity, and Health Status

    PubMed Central

    Bertani, André Luís; Garcia, Thaís; Mesquita, Carolina Bonfanti; Knaut, Caroline; Tanni, Suzana Erico

    2016-01-01

    The effects of tobacco smoke, mild/moderate COPD disease and their combined effect on health status (HS), body composition (BC), and exercise capacity (EC) impairment are still unclear. We hypothesized that smoking and early COPD have a joint negative influence on these outcomes. We evaluated 32 smokers (smoking history >10 pack/years), 32 mild/moderate COPD (current smokers or former smokers), and 32 never smokers. All individuals underwent medical and smoking status evaluations, pre and post-bronchodilator spirometry, BC [fat-free mass (FFM) and FFM index (FFMI)], EC [six-minute walk distance (6MWD)] and HS [Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36)]. FFM (p = 0.02) and FFMI (p = 0.008) were lower in COPD than never smokers. 6MWT, as a percentage of reference values for the Brazilian population, was lower in COPD and smokers than never smokers (p = 0.01). Smokers showed worse SF-36 score for functional capacity than never smokers (p<0.001). SF-36 score for physical functioning (p<0.001) and role-emotional (p<0.001) were impaired in COPD patients than smokers. SF-36 scores for physical functioning (p<0.001), role-physical (p = 0.01), bodily pain (p = 0.01), vitality (p = 0.04) and role-emotional (p<0.001) were lower in COPD than never smokers. Multiple linear regression analysis showed that both COPD diagnosis and smoking were inversely associated with FFMI, 6MWD and HS. Smoking and early COPD have a joint negative influence on body composition, exercise capacity and health status. PMID:27737010

  7. Probing the early development of visual working memory capacity with functional near-infrared spectroscopy

    PubMed Central

    Buss, Aaron T.; Fox, Nicholas; Boas, David A.; Spencer, John P.

    2013-01-01

    Visual working memory (VWM) is a core cognitive system with a highly limited capacity. The present study is the first to examine VWM capacity limits in early development using functional neuroimaging. We recorded optical neuroimaging data while 3- and 4-year-olds completed a change detection task where they detected changes in the shapes of objects after a brief delay. Near-infrared sources and detectors were placed over the following 10–20 positions: F3 and F5 in left frontal cortex, F4 and F6 in right frontal cortex, P3 and P5 in left parietal cortex, and P4 and P6 in right parietal cortex. The first question was whether we would see robust task-specific activation of the frontal-parietal network identified in the adult fMRI literature. This was indeed the case: three left frontal channels and 11 of 12 parietal channels showed a statistically robust difference between the concentration of oxygenated and deoxygenated hemoglobin following the presentation of the sample array. Moreover, four channels in the left hemisphere near P3, P5, and F5 showed a robust increase as the working memory load increased from 1–3 items. Notably, the hemodynamic response did not asymptote at 1–2 items as expected from previous fMRI studies with adults. Finally, 4-year-olds showed a more robust parietal response relative to 3-year-olds, and an increasing sensitivity to the memory load manipulation. These results demonstrate that fNIRS is an effective tool to study the neural processes that underlie the early development of VWM capacity. PMID:23707803

  8. Probing the early development of visual working memory capacity with functional near-infrared spectroscopy.

    PubMed

    Buss, Aaron T; Fox, Nicholas; Boas, David A; Spencer, John P

    2014-01-15

    Visual working memory (VWM) is a core cognitive system with a highly limited capacity. The present study is the first to examine VWM capacity limits in early development using functional neuroimaging. We recorded optical neuroimaging data while 3- and 4-year-olds completed a change detection task where they detected changes in the shapes of objects after a brief delay. Near-infrared sources and detectors were placed over the following 10-20 positions: F3 and F5 in left frontal cortex, F4 and F6 in right frontal cortex, P3 and P5 in left parietal cortex, and P4 and P6 in right parietal cortex. The first question was whether we would see robust task-specific activation of the frontal-parietal network identified in the adult fMRI literature. This was indeed the case: three left frontal channels and 11 of 12 parietal channels showed a statistically robust difference between the concentration of oxygenated and deoxygenated hemoglobin following the presentation of the sample array. Moreover, four channels in the left hemisphere near P3, P5, and F5 showed a robust increase as the working memory load increased from 1 to 3 items. Notably, the hemodynamic response did not asymptote at 1-2 items as expected from previous fMRI studies with adults. Finally, 4-year-olds showed a more robust parietal response relative to 3-year-olds, and an increasing sensitivity to the memory load manipulation. These results demonstrate that fNIRS is an effective tool to study the neural processes that underlie the early development of VWM capacity. PMID:23707803

  9. Subjectivity, objectivity, and triangular space.

    PubMed

    Britton, Ronald

    2004-01-01

    The author reviews his ideas on subjectivity, objectivity, and the third position in the psychoanalytic encounter, particularly in clinical work with borderline and narcissistic patients. Using the theories of Melanie Klein and Wilfred Bion as a basis, the author describes his concept of triangular space. A case presentation of a particular type of narcissistic patient illustrates the principles discussed.

  10. Building Buildings with Triangular Numbers

    ERIC Educational Resources Information Center

    Pagni, David L.

    2006-01-01

    Triangular numbers are used to unravel a new sequence of natural numbers here-to-fore not appearing on the Encyclopedia of Integer Sequences website. Insight is provided on the construction of the sequence using "buildings" as a viewable model of the sequence entries. A step-by-step analysis of the sequence pattern reveals a method for generating…

  11. Subjectivity, objectivity, and triangular space.

    PubMed

    Britton, Ronald

    2004-01-01

    The author reviews his ideas on subjectivity, objectivity, and the third position in the psychoanalytic encounter, particularly in clinical work with borderline and narcissistic patients. Using the theories of Melanie Klein and Wilfred Bion as a basis, the author describes his concept of triangular space. A case presentation of a particular type of narcissistic patient illustrates the principles discussed. PMID:14750465

  12. Preparing the Early Education and Care Workforce: A Guide to Conducting a Study of the Capacity of Higher Education Institutions

    ERIC Educational Resources Information Center

    Dennehy, Julie

    2006-01-01

    Many states have created professional development systems to support the ongoing and increased education and training needs of early care and education professionals. This guide describes lessons learned in Massachusetts about conducting a study of the capacity of institutions of higher education (IHEs) to prepare the early education and care…

  13. High precision triangular waveform generator

    DOEpatents

    Mueller, Theodore R.

    1983-01-01

    An ultra-linear ramp generator having separately programmable ascending and descending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by accurate reproduction and low drift over periods of several hours. The ascending and descending slopes are independently selectable.

  14. Early Auditory Evoked Potential Is Modulated by Selective Attention and Related to Individual Differences in Visual Working Memory Capacity

    PubMed Central

    Giuliano, Ryan J.; Karns, Christina M.; Neville, Helen J.; Hillyard, Steven A.

    2015-01-01

    A growing body of research suggests that the predictive power of working memory (WM) capacity for measures of intellectual aptitude is due to the ability to control attention and select relevant information. Crucially, attentional mechanisms implicated in controlling access to WM are assumed to be domain-general, yet reports of enhanced attentional abilities in individuals with larger WM capacities are primarily within the visual domain. Here, we directly test the link between WM capacity and early attentional gating across sensory domains, hypothesizing that measures of visual WM capacity should predict an individual’s capacity to allocate auditory selective attention. To address this question, auditory ERPs were recorded in a linguistic dichotic listening task, and individual differences in ERP modulations by attention were correlated with estimates of WM capacity obtained in a separate visual change detection task. Auditory selective attention enhanced ERP amplitudes at an early latency (ca. 70–90 msec), with larger P1 components elicited by linguistic probes embedded in an attended narrative. Moreover, this effect was associated with greater individual estimates of visual WM capacity. These findings support the view that domain-general attentional control mechanisms underlie the wide variation of WM capacity across individuals. PMID:25000526

  15. Strengthening Carrying Capacity of a Water Supply System under Climate Change with the Drought Early Warning System

    NASA Astrophysics Data System (ADS)

    Huang, Syujie; Liu, Tzuming; Li, Minghsu; Tung, Chingpin

    2016-04-01

    The carrying capacity of a water supply system is the maximal probable water supply amount under an acceptable risk which is related to the systematic combination of hydrology conditions, climatic conditions, and water infrastructures, for instance, reservoirs, weirs, and water treatment plants. Due to long-term imbalance of water supply and demand during the drought seasons, the carrying capacity of a water supply system may be affected gradually with more extreme climate events resulting from the climate change. To evaluate the carrying capacity of the water supply system under climate change, three major steps to build adaptation capacity under climate change are adopted, including problem identification and goal setting, current risk assessment, and future risk assessment. The carrying capacities for current climate condition and future climate condition were estimated respectively. The early warning system was taken as the effective measure to strengthen the carrying capacity for the uncertain changing climate. The water supply system of Chuoshui River basin in Taiwan is used as the case study. The system dynamics modeling software, Vensim, was used to build the water resources allocation model for Chuoshui River basin. To apply the seasonal climate forecasts released from Taiwan Central Weather Bureau (CWB) on modeling, a weather generator is adopted to generate daily weather data for the input of the hydrological component of GWLF model, to project inflows with the lead time of three months. Consequently, the water shortages with and without a drought early warning system were estimated to evaluate the effectiveness of a drought early warning system under climate change. Keywords: Climate change, Carrying capacity, Risk Assessment, Seasonal Climate Forecasts, Drought Early Warning System

  16. Beyond Fishing: KCDF's Approach to Capacity Development. Working Papers in Early Childhood Development, No. 32

    ERIC Educational Resources Information Center

    Mwaura, Nora

    2003-01-01

    In "Beyond Fishing," the Kenya Community Development Foundation (KCDF) documents its experiences as a local capacity building and grantmaking organisation and describes how it supports community based projects in developing their organisational capacity. In recent decades, development organisations have been supporting capacity building mainly…

  17. Salivary pH and Buffering Capacity as Risk Markers for Early Childhood Caries: A Clinical Study

    PubMed Central

    Ganesan, S

    2015-01-01

    ABSTRACT Background: The diagnostic utility of saliva is currently being explored in various branches of dentistry, remarkably in the field of caries research. This study was aimed to determine if assessment of salivary pH and buffering capacity would serve as reliable tools in risk prediction of early childhood caries (ECC). Materials and methods: Paraffin-stimulated salivary samples were collected from 50 children with ECC (group I) and 50 caries free children (group II). Salivary pH and buffering capacity (by titration with 0.1 N hydrochloric acid) were assessed using a handheld digital pH meter in both groups. The data obtained were subjected to statistical analysis. Results: Statistically, no significant difference was observed between both the groups for all salivary parameters assessed, except for the buffering capacity level at 150 μl titration of 0.1 N hydrochloric acid (p = 0.73; significant at 1% level). Conclusion: Salivary pH and buffering capacity may not serve as reliable markers for risk prediction of ECC. How to cite this article: Jayaraj D, Ganesan S. Salivary pH and Buffering Capacity as Risk Markers for Early Childhood Caries: A Clinical Study. Int J Clin Pediatr Dent 2015;8(3):167-171. PMID:26628849

  18. Experience from three years of local capacity development for tsunami early warning in Indonesia: challenges, lessons and the way ahead

    NASA Astrophysics Data System (ADS)

    Spahn, H.; Hoppe, M.; Vidiarina, H. D.; Usdianto, B.

    2010-07-01

    Five years after the 2004 tsunami, a lot has been achieved to make communities in Indonesia better prepared for tsunamis. This achievement is primarily linked to the development of the Indonesian Tsunami Early Warning System (InaTEWS). However, many challenges remain. This paper describes the experience with local capacity development for tsunami early warning (TEW) in Indonesia, based on the activities of a pilot project. TEW in Indonesia is still new to disaster management institutions and the public, as is the paradigm of Disaster Risk Reduction (DRR). The technology components of InaTEWS will soon be fully operational. The major challenge for the system is the establishment of clear institutional arrangements and capacities at national and local levels that support the development of public and institutional response capability at the local level. Due to a lack of information and national guidance, most local actors have a limited understanding of InaTEWS and DRR, and often show little political will and priority to engage in TEW. The often-limited capacity of local governments is contrasted by strong engagement of civil society organisations that opt for early warning based on natural warning signs rather than technology-based early warning. Bringing together the various actors, developing capacities in a multi-stakeholder cooperation for an effective warning system are key challenges for the end-to-end approach of InaTEWS. The development of local response capability needs to receive the same commitment as the development of the system's technology components. Public understanding of and trust in the system comes with knowledge and awareness on the part of the end users of the system and convincing performance on the part of the public service provider. Both sides need to be strengthened. This requires the integration of TEW into DRR, clear institutional arrangements, national guidance and intensive support for capacity development at local levels as well as

  19. Family Capacity-Building in Early Childhood Intervention: Do Context and Setting Matter?

    ERIC Educational Resources Information Center

    Dunst, Carl J.; Bruder, Mary Beth; Espe-Sherwindt, Marilyn

    2014-01-01

    Findings from a study investigating the effects of early intervention settings on the extent of parent involvement in IDEA Part C Infant and Toddler Programs are reported. Participants were 124 parents and other primary caregivers of children receiving early intervention in 22 states who completed an investigator-developed scale measuring…

  20. Extension's Capacity to Deliver Quality Early Childhood Professional Development

    ERIC Educational Resources Information Center

    Durden, Tonia R.; Mincemoyer, Claudia C.; Gerdes, Jennifer; Lodl, Kathleen

    2013-01-01

    In recent years much attention has focused on the role of enhancing a teacher's professional knowledge and skills in helping to improve the quality of early care experiences for young children birth-5. In the study reported here, an environmental scan of the early childhood professional development programs offered within the Extension system…

  1. Building the Leadership Capacity of Early Childhood Directors: An Evaluation of a Leadership Development Model

    ERIC Educational Resources Information Center

    Talan, Teri N.; Bloom, Paula J.; Kelton, Robyn E.

    2014-01-01

    While there is consensus among policymakers and practitioners about the importance of strong leadership in early childhood education, there is scant research on effective models of leadership development for administrators of early childhood programs, particularly those working in the child care sector. This is cause for concern because the…

  2. Effects of maternal separation, early handling, and gonadal sex on regional metabolic capacity of the preweanling rat brain.

    PubMed

    Spivey, Jaclyn M; Padilla, Eimeira; Shumake, Jason D; Gonzalez-Lima, F

    2011-01-01

    This is the first study to assess the effects of mother-infant separation on regional metabolic capacity in the preweanling rat brain. Mother-infant separation is generally known to be stressful for rat pups. Holtzman adolescent rats show a depressive-like behavioral phenotype after maternal separation during the preweanling period. However, information is lacking on the effects of maternal separation on the brains of rat pups. We addressed this issue by mapping the brains of preweanling Holtzman rat pups using cytochrome oxidase histochemistry, which reflects long-term changes in brain metabolic capacity, following two weeks of repeated, prolonged maternal separation, and compared this to both early handled and non-handled pups. Quantitative image analysis revealed that maternal separation reduced cytochrome oxidase activity in the medial prefrontal cortex and nucleus accumbens shell. Maternal separation reduced prefrontal cytochrome oxidase to a greater degree in female pups than in males. Early handling reduced cytochrome oxidase activity in the posterior parietal cortex, ventral tegmental area, and subiculum, but increased cytochrome oxidase activity in the lateral frontal cortex. The sex-dependent effects of early handling on cytochrome oxidase activity were limited to the medial prefrontal cortex. Regardless of separation group, females had greater cytochrome oxidase activity in the habenula and ventral tegmental area compared to males. These findings suggest that early life mother-infant separation results in dysfunction of prefrontal and mesolimbic regions in the preweanling rat brain that may contribute to behavioral changes later in life.

  3. Molecular rectification in triangularly shaped graphene nanoribbons.

    PubMed

    Liu, Hongmei; Wang, Hongbo; Zhao, Jianwei; Kiguchi, Manabu

    2013-02-15

    We present a theoretical study of electron transport in tailored zigzag graphene nanoribbons (ZGNRs) with triangular structure using density functional theory together with the nonequilibrium Green's function formalism. We find significant rectification with a favorite electron transfer direction from the vertex to the right edge. The triangular ZGNR connecting to the electrode with one thiol group at each terminal shows an average rectification ratio of 8.4 over the bias range from -1.0 to 1.0 V. This asymmetric electron transport property originates from nearly zero band gap of triangular ZGNR under negative bias, whereas a band gap opens under positive bias. When the molecule is connected to the electrode by multithiol groups, the current is enhanced due to strong interfacial coupling; however, the rectification ratio decreases. The simulation results indicate that the unique electronic states of triangular ZGNR are responsible for rectification, rather than the asymmetric anchoring groups.

  4. Triangular spectral elements for incompressible fluid flow

    NASA Technical Reports Server (NTRS)

    Mavriplis, C.; Vanrosendale, John

    1993-01-01

    We discuss the use of triangular elements in the spectral element method for direct simulation of incompressible flow. Triangles provide much greater geometric flexibility than quadrilateral elements and are better conditioned and more accurate when small angles arise. We employ a family of tensor product algorithms for triangles, allowing triangular elements to be handled with comparable arithmetic complexity to quadrilateral elements. The triangular discretizations are applied and validated on the Poisson equation. These discretizations are then applied to the incompressible Navier-Stokes equations and a laminar channel flow solution is given. These new triangular spectral elements can be combined with standard quadrilateral elements, yielding a general and flexible high order method for complex geometries in two dimensions.

  5. Measure of School Capacity for Improvement (MSCI): Early Field Test Findings

    ERIC Educational Resources Information Center

    Riffle, M. J. S.; Howley, C. W.; Ermolov, L. D.

    2004-01-01

    This study was conducted to confirm the validity and reliability of the 64-item Measure of School Capacity for Improvement (MSCI). The MSCI was designed to assess the degree to which schools possess the potential to become high performing learning communities, and was developed in response to a paucity of definition, operationalization, and…

  6. RF MEMS reconfigurable triangular patch antenna.

    SciTech Connect

    Nordquist, Christopher Daniel; Christodoulou, Christos George; Feldner, Lucas Matthew

    2005-01-01

    A Ka-band RF MEMS enabled frequency reconfigurable triangular microstrip patch antenna has been designed for monolithic integration with RF MEMS phase shifters to demonstrate a low-cost monolithic passive electronically scanned array (PESA). This paper introduces our first prototype reconfigurable triangular patch antenna currently in fabrication. The aperture coupled patch antenna is fabricated on a dual-layer quartz/alumina substrate using surface micromachining techniques.

  7. RF MEMS reconfigurable triangular patch antenna.

    SciTech Connect

    Christodoulou, Christos George; Nordquist, Christopher Daniel; Feldner, Lucas Matthew

    2005-07-01

    A Ka-band RF MEMS enabled frequency reconfigurable triangular microstrip patch antenna has been designed for monolithic integration with RF MEMS phase shifters to demonstrate a low-cost monolithic passive electronically scanned array (PESA). This paper introduces our first prototype reconfigurable triangular patch antenna currently in fabrication. The aperture coupled patch antenna is fabricated on a dual-layer quartz/alumina substrate using surface micromachining techniques.

  8. New mechanism of chaos in triangular billiards

    NASA Astrophysics Data System (ADS)

    Naydenov, S. V.; Naplekov, D. M.; Yanovsky, V. V.

    2013-12-01

    A new mechanism of weak chaos in triangular billiards has been proposed owing to the effect of cutting of beams of rays. A similar mechanism is also implemented in other polygonal billiards. Cutting of beams results in the separation of initially close rays at a finite angle by jumps in the process of reflections of beams at the vertices of a billiard. The opposite effect of joining of beams of rays occurs in any triangular billiard along with cutting. It has been shown that the cutting of beams has an absolute character and is independent of the form of a triangular billiard or the parameters of a beam. On the contrary, joining has a relative character and depends on the commensurability of the angles of the triangle with π. Joining always suppresses cutting in triangular billiards whose angles are commensurable with π. For this reason, their dynamics cannot be chaotic. In triangular billiards whose angles are rationally incommensurable with π, cutting always dominates, leading to weak chaos. The revealed properties are confirmed by numerical experiments on the phase portraits of typical triangular billiards.

  9. A New Framework for Childhood Health Promotion: The Role of Policies and Programs in Building Capacity and Foundations of Early Childhood Health

    PubMed Central

    Mistry, Kamila B.; Minkovitz, Cynthia S.; Riley, Anne W.; Johnson, Sara B.; Grason, Holly A.; Dubay, Lisa C.; Guyer, Bernard

    2012-01-01

    Although the connection between early life experiences and later health is becoming increasingly clear, what is needed, now, is a new organizing framework for childhood health promotion, grounded in the latest science. We review the evidence base to identify the steps in the overall pathway to ensuring better health for all children. A key factor in optimizing health in early childhood is building capacities of parents and communities. Although often overlooked, capacities are integral to building the foundations of lifelong health in early childhood. We outline a framework for policymakers and practitioners to guide future decision-making and investments in early childhood health promotion. PMID:22813416

  10. Nitric oxide diffusing capacity versus spirometry in the early diagnosis of emphysema in smokers.

    PubMed

    van der Lee, I; Gietema, H A; Zanen, P; van Klaveren, R J; Prokop, M; Lammers, J-W J; van den Bosch, J M M

    2009-12-01

    The diffusion capacity for nitric oxide (DLNO) is independent of pulmonary capillary blood volume and equals the membrane diffusing capacity. Therefore the DLNO could be more sensitive in detecting alveolar destruction than the DLCO. We measured flow-volumes curves, DLNO, DLCO, the transfer coefficients KNO (DLNO/VA) and KCO (DLCO/VA) and performed computed tomography (CT) scans in 263 randomly selected heavy smokers. Subjects with areas > or =1% of the total lung volume showing an attenuation <-950 Hounsfield Units were considered to have emphysema. In 36 subjects emphysema was diagnosed with CT, a low KNO was present in 94 subjects, and in 95 subjects a FEV1/FVC ratio <70% was seen. The area under the ROC curve for detection CT-based emphysema was 0.894 for the KNO, 0.822 for the KCO and 0.795 for FEV1/FVC, meaning that the KNO has a slightly higher sensitivity to detect emphysema than the KCO and FEV1/FVC. The positive predictive value of KNO however was low (34.7%), while the negative predictive value of KNO was very high (98.2%), indicating an emphysema exclusion test. The DLNO/DLCO ratio is significantly higher in the study group compared to normal subjects.

  11. Early trauma and affect: the importance of the body for the development of the capacity to symbolize.

    PubMed

    Willemsen, Hessel

    2014-11-01

    In this paper I aim to outline the importance of working clinically with affect when treating severely traumatized patients who have a limited capacity to symbolize. These patients, who suffer the loss of maternal care early in life, require the analyst to be closely attuned to the patient's distress through use of the countertransference and with significantly less attention paid to the transference. It is questionable whether we can speak of transference when there is limited capacity to form internal representations. The analyst's relationship with the patient is not necessarily used to make interpretations but, instead, the analyst's reverie functions therapeutically to develop awareness and containment of affect, first in the analyst's mind and, later, in the patient's, so that, in time, a relationship between the patient's mind and the body, as the first object, is made. In contrast to general object-relations theories, in which the first object is considered to be the breast or the mother, Ferrari (2004) proposes that the body is the first object in the emerging mind. Once a relationship between mind and body is established, symbolization becomes possible following the formation of internal representations of affective states in the mind, where previously there were few. Using Ferrari's body-mind model, two clinical case vignettes underline the need to use the countertransference with patients who suffered chronic developmental trauma in early childhood. PMID:25331507

  12. Early trauma and affect: the importance of the body for the development of the capacity to symbolize.

    PubMed

    Willemsen, Hessel

    2014-11-01

    In this paper I aim to outline the importance of working clinically with affect when treating severely traumatized patients who have a limited capacity to symbolize. These patients, who suffer the loss of maternal care early in life, require the analyst to be closely attuned to the patient's distress through use of the countertransference and with significantly less attention paid to the transference. It is questionable whether we can speak of transference when there is limited capacity to form internal representations. The analyst's relationship with the patient is not necessarily used to make interpretations but, instead, the analyst's reverie functions therapeutically to develop awareness and containment of affect, first in the analyst's mind and, later, in the patient's, so that, in time, a relationship between the patient's mind and the body, as the first object, is made. In contrast to general object-relations theories, in which the first object is considered to be the breast or the mother, Ferrari (2004) proposes that the body is the first object in the emerging mind. Once a relationship between mind and body is established, symbolization becomes possible following the formation of internal representations of affective states in the mind, where previously there were few. Using Ferrari's body-mind model, two clinical case vignettes underline the need to use the countertransference with patients who suffered chronic developmental trauma in early childhood.

  13. Numerical Capacities as Domain-Specific Predictors beyond Early Mathematics Learning: A Longitudinal Study

    PubMed Central

    Reigosa-Crespo, Vivian; González-Alemañy, Eduardo; León, Teresa; Torres, Rosario; Mosquera, Raysil; Valdés-Sosa, Mitchell

    2013-01-01

    The first aim of the present study was to investigate whether numerical effects (Numerical Distance Effect, Counting Effect and Subitizing Effect) are domain-specific predictors of mathematics development at the end of elementary school by exploring whether they explain additional variance of later mathematics fluency after controlling for the effects of general cognitive skills, focused on nonnumerical aspects. The second aim was to address the same issues but applied to achievement in mathematics curriculum that requires solutions to fluency in calculation. These analyses assess whether the relationship found for fluency are generalized to mathematics content beyond fluency in calculation. As a third aim, the domain specificity of the numerical effects was examined by analyzing whether they contribute to the development of reading skills, such as decoding fluency and reading comprehension, after controlling for general cognitive skills and phonological processing. Basic numerical capacities were evaluated in children of 3rd and 4th grades (n=49). Mathematics and reading achievements were assessed in these children one year later. Results showed that the size of the Subitizing Effect was a significant domain-specific predictor of fluency in calculation and also in curricular mathematics achievement, but not in reading skills, assessed at the end of elementary school. Furthermore, the size of the Counting Effect also predicted fluency in calculation, although this association only approached significance. These findings contrast with proposals that the core numerical competencies measured by enumeration will bear little relationship to mathematics achievement. We conclude that basic numerical capacities constitute domain-specific predictors and that they are not exclusively “start-up” tools for the acquisition of Mathematics; but they continue modulating this learning at the end of elementary school. PMID:24255710

  14. Numerical capacities as domain-specific predictors beyond early mathematics learning: a longitudinal study.

    PubMed

    Reigosa-Crespo, Vivian; González-Alemañy, Eduardo; León, Teresa; Torres, Rosario; Mosquera, Raysil; Valdés-Sosa, Mitchell

    2013-01-01

    The first aim of the present study was to investigate whether numerical effects (Numerical Distance Effect, Counting Effect and Subitizing Effect) are domain-specific predictors of mathematics development at the end of elementary school by exploring whether they explain additional variance of later mathematics fluency after controlling for the effects of general cognitive skills, focused on nonnumerical aspects. The second aim was to address the same issues but applied to achievement in mathematics curriculum that requires solutions to fluency in calculation. These analyses assess whether the relationship found for fluency are generalized to mathematics content beyond fluency in calculation. As a third aim, the domain specificity of the numerical effects was examined by analyzing whether they contribute to the development of reading skills, such as decoding fluency and reading comprehension, after controlling for general cognitive skills and phonological processing. Basic numerical capacities were evaluated in children of 3(rd) and 4(th) grades (n=49). Mathematics and reading achievements were assessed in these children one year later. Results showed that the size of the Subitizing Effect was a significant domain-specific predictor of fluency in calculation and also in curricular mathematics achievement, but not in reading skills, assessed at the end of elementary school. Furthermore, the size of the Counting Effect also predicted fluency in calculation, although this association only approached significance. These findings contrast with proposals that the core numerical competencies measured by enumeration will bear little relationship to mathematics achievement. We conclude that basic numerical capacities constitute domain-specific predictors and that they are not exclusively "start-up" tools for the acquisition of Mathematics; but they continue modulating this learning at the end of elementary school. PMID:24255710

  15. Numerical capacities as domain-specific predictors beyond early mathematics learning: a longitudinal study.

    PubMed

    Reigosa-Crespo, Vivian; González-Alemañy, Eduardo; León, Teresa; Torres, Rosario; Mosquera, Raysil; Valdés-Sosa, Mitchell

    2013-01-01

    The first aim of the present study was to investigate whether numerical effects (Numerical Distance Effect, Counting Effect and Subitizing Effect) are domain-specific predictors of mathematics development at the end of elementary school by exploring whether they explain additional variance of later mathematics fluency after controlling for the effects of general cognitive skills, focused on nonnumerical aspects. The second aim was to address the same issues but applied to achievement in mathematics curriculum that requires solutions to fluency in calculation. These analyses assess whether the relationship found for fluency are generalized to mathematics content beyond fluency in calculation. As a third aim, the domain specificity of the numerical effects was examined by analyzing whether they contribute to the development of reading skills, such as decoding fluency and reading comprehension, after controlling for general cognitive skills and phonological processing. Basic numerical capacities were evaluated in children of 3(rd) and 4(th) grades (n=49). Mathematics and reading achievements were assessed in these children one year later. Results showed that the size of the Subitizing Effect was a significant domain-specific predictor of fluency in calculation and also in curricular mathematics achievement, but not in reading skills, assessed at the end of elementary school. Furthermore, the size of the Counting Effect also predicted fluency in calculation, although this association only approached significance. These findings contrast with proposals that the core numerical competencies measured by enumeration will bear little relationship to mathematics achievement. We conclude that basic numerical capacities constitute domain-specific predictors and that they are not exclusively "start-up" tools for the acquisition of Mathematics; but they continue modulating this learning at the end of elementary school.

  16. Supporting early career health investigators in Kenya: A qualitative study of HIV/AIDS research capacity building

    PubMed Central

    Daniels, Joseph; Nduati, Ruth; Kiarie, James; Farquhar, Carey

    2015-01-01

    Introduction Strategies to transfer international health research training programs to sub-Saharan African institutions focus on developing cadres of local investigators who will lead such programs. Using a critical leadership theory framework, we conducted a qualitative study of one program to understand how collaborative training and research can support early career investigators in Kenya toward the program transfer goal. Methods We used purposive sampling methods and a semi-structured protocol to conduct in-depth interviews with US (N = 5) and Kenyan (N = 5) independent investigators. Transcripts were coded using a two-step process, and then compared with each other to identify major themes. Results A limited local research environment, funding needs and research career mentorship were identified as major influences on early career researchers. Institutional demands on Kenyan faculty to teach rather than complete research restricted investigators’ ability to develop research careers. This was coupled with lack of local funding to support research. Sustainable collaborations between Kenyan, US and other international investigators were perceived to mitigate these challenges and support early career investigators who would help build a robust local research environment for training. Conclusion Mutually beneficial collaborations between Kenyan and US investigators developed during training mitigate these challenges and build a supportive research environment for training. In these collaborations, early career investigators learn how to navigate the complex international research environment to build local HIV research capacity. Shared and mutually beneficial resources within international research collaborations are required to support early career investigators and plans to transfer health research training to African institutions. PMID:26113923

  17. Dietary restriction improves repopulation but impairs lymphoid differentiation capacity of hematopoietic stem cells in early aging.

    PubMed

    Tang, Duozhuang; Tao, Si; Chen, Zhiyang; Koliesnik, Ievgen Oleksandrovich; Calmes, Philip Gerald; Hoerr, Verena; Han, Bing; Gebert, Nadja; Zörnig, Martin; Löffler, Bettina; Morita, Yohei; Rudolph, Karl Lenhard

    2016-04-01

    Dietary restriction (DR) improves health, delays tissue aging, and elongates survival in flies and worms. However, studies on laboratory mice and nonhuman primates revealed ambiguous effects of DR on lifespan despite improvements in health parameters. In this study, we analyzed consequences of adult-onset DR (24 h to 1 yr) on hematopoietic stem cell (HSC) function. DR ameliorated HSC aging phenotypes, such as the increase in number of HSCs and the skewing toward myeloid-biased HSCs during aging. Furthermore, DR increased HSC quiescence and improved the maintenance of the repopulation capacity of HSCs during aging. In contrast to these beneficial effects, DR strongly impaired HSC differentiation into lymphoid lineages and particularly inhibited the proliferation of lymphoid progenitors, resulting in decreased production of peripheral B lymphocytes and impaired immune function. The study shows that DR-dependent suppression of growth factors and interleukins mediates these divergent effects caused by DR. Supplementation of insulin-like growth factor 1 partially reverted the DR-induced quiescence of HSCs, whereas IL-6/IL-7 substitutions rescued the impairment of B lymphopoiesis exposed to DR. Together, these findings delineate positive and negative effects of long-term DR on HSC functionality involving distinct stress and growth signaling pathways.

  18. Localized lasing modes of triangular organic microlasers.

    PubMed

    Lafargue, C; Lebental, M; Grigis, A; Ulysse, C; Gozhyk, I; Djellali, N; Zyss, J; Bittner, S

    2014-11-01

    We investigated experimentally the ray-wave correspondence in organic microlasers of various triangular shapes. Triangular billiards are of interest since they are the simplest cases of polygonal billiards and the existence and properties of periodic orbits in triangles are not yet fully understood. The microlasers with symmetric shapes that were investigated exhibited states localized on simple periodic orbits, and their lasing characteristics like spectra and far-field distributions could be well explained by the properties of the periodic orbits. Furthermore, asymmetric triangles that do not feature simple periodic orbits were studied. Their lasing properties were found to be more complicated and could not be explained by periodic orbits.

  19. Reducing quasilinear systems to block triangular form

    SciTech Connect

    Tunitsky, Dmitry V

    2013-03-31

    The paper is concerned with systems of n quasilinear partial differential equations of the first order with 2 independent variables. Using a geometric formalism for such equations, which goes back to Riemann, it is possible to assign a field of linear operators on an appropriate vector bundle to this type of quasilinear system. Several tests for a quasilinear system to be reducible to triangular or block triangular form are obtained in terms of this field; they supplement well known results on diagonalization and block diagonalization due to Haantjes and Bogoyavlenskij. Bibliography: 10 titles.

  20. Effect of progesterone, mifepristone, and estrogen treatment during early pregnancy on conceptus development and uterine capacity in Swine.

    PubMed

    Vallet, J L; Christenson, R K

    2004-01-01

    A series of experiments was performed to investigate the influence of progesterone at Days 2 and 3 of pregnancy on conceptus development and uterine capacity. In experiment 1, unilaterally hysterectomized-ovariectomized (UHO) white crossbred gilts were given no treatment, estradiol valerate (5 mg given on Days 11 and 12), or progesterone (200 mg/day on Days 2 and 3 after mating). On Day 105 of pregnancy, each fetus and its associated placenta were weighed, and the number of live and dead fetuses was recorded for each litter. Early progesterone treatment reduced (P < 0.05) litter size (a measure of uterine capacity in UHO gilts). In experiment 2, intact white crossbred gilts were mated, given no treatment or progesterone treatment on Days 2 and 3 of pregnancy, and farrowed. Progesterone treatment decreased (P < 0.05) pregnancy rates. In pregnant gilts, progesterone had no effect on the number of live or stillborn piglets at birth, and gestation length was decreased (P < 0.05). Progesterone treatment did not affect the number of large or small piglets. In experiment 3, intact gilts were mated at estrus and then received 1). no treatment or treatment with 2). 100 mg, 3). 200 mg, or 4). 400 mg mifepristone (also known as RU486) on Day 2 of pregnancy. On Day 11 of pregnancy, both uterine horns were flushed, the number and diameter of each conceptus was recorded, and the flushed material was assayed for total protein and acid phosphatase. The 400 mg mifepristone treatment decreased conceptus diameter (P < 0.05) and total protein (P = 0.06) in the uterine flushings. In experiment 4, UHO gilts were mated at estrus, injected with either corn oil (control) or mifepristone (400 mg) on Day 2 of pregnancy, and killed on Day 105 of pregnancy, and the number and weight of live fetuses and placentas was recorded. In contrast to the effect of progesterone treatment, mifepristone decreased uterine capacity by decreasing the number of small conceptuses. These data suggest that

  1. Optimizing triangular mesh generation from range images

    NASA Astrophysics Data System (ADS)

    Lu, Tianyu; Yun, David Y.

    2000-03-01

    An algorithm for the automatic reconstruction of triangular mesh surface model form range images is presented. The optimal piecewise linear surface approximation problem is defined as: given a set S of points uniformly sampled from a vibrate function f(x,y) on a rectangular grid of dimension W X H, find a minimum triangular mesh approximating the surface with vertices anchored at a subset S' of S, such that the deviation at any sample point is within a given bound of (epsilon) > 0. The algorithm deploys a multi- agent resource planning approach to achieve adaptive, accurate and concise piecewise linear approximation using the L-(infinity) norm. The resulting manifold triangular mesh can be directly used as 3D rendering model for visualization with controllable and guaranteed quality. Due to this dual optimality, the algorithm achieves both storage efficiency and visual quality. The error control scheme further facilitates the construction of models in multiple levels of details, which is desirable in animation and virtual reality moving scenes. Experiments with various benchmark range images form smooth functional surfaces to satellite terrain images yield succinct, accurate and visually pleasant triangular meshes. Furthermore, the independence and multiplicity of agents suggest a natural parallelism for triangulation computation, which provides a promising solution for the real-time exploration of large data sets.

  2. Basic Employability Skills: A Triangular Design Approach

    ERIC Educational Resources Information Center

    Rosenberg, Stuart; Heimler, Ronald; Morote, Elsa-Sofia

    2012-01-01

    Purpose: This paper seeks to examine the basic employability skills needed for job performance, the reception of these skills in college, and the need for additional training in these skills after graduation. Design/methodology/approach: The research was based on a triangular design approach, in which the attitudes of three distinct groups--recent…

  3. Solutions to the Triangular Bicycle Flags Problem

    ERIC Educational Resources Information Center

    Hartweg, Kim

    2005-01-01

    Students in a fifth-grade general education class and a second-grade gifted class participated in the Triangular Bicycle Flags problem. The results indicated that providing students with geometric experiences at the correct van Hiele level is necessary for helping students move from one level of understanding to the next.

  4. Experimental study of photonic crystal triangular lattices

    NASA Astrophysics Data System (ADS)

    Qin, Ruhu; Qin, Bo; Jin, Chongjun

    1999-06-01

    Triangular lattice photonic crystal behaving in the electromagnetic zones constructed from fused silica cylinders in styrofoam is fabricated. The transmission spectra of the photonic crystal with and without defects are measured. On this basis, the defect modes of photonic crystal were studied, and the potential applications of the photonic crystal are discussed.

  5. Optimal parallel solution of sparse triangular systems

    NASA Technical Reports Server (NTRS)

    Alvarado, Fernando L.; Schreiber, Robert

    1990-01-01

    A method for the parallel solution of triangular sets of equations is described that is appropriate when there are many right-handed sides. By preprocessing, the method can reduce the number of parallel steps required to solve Lx = b compared to parallel forward or backsolve. Applications are to iterative solvers with triangular preconditioners, to structural analysis, or to power systems applications, where there may be many right-handed sides (not all available a priori). The inverse of L is represented as a product of sparse triangular factors. The problem is to find a factored representation of this inverse of L with the smallest number of factors (or partitions), subject to the requirement that no new nonzero elements be created in the formation of these inverse factors. A method from an earlier reference is shown to solve this problem. This method is improved upon by constructing a permutation of the rows and columns of L that preserves triangularity and allow for the best possible such partition. A number of practical examples and algorithmic details are presented. The parallelism attainable is illustrated by means of elimination trees and clique trees.

  6. Transport Code for Regular Triangular Geometry

    1993-06-09

    DIAMANT2 solves the two-dimensional static multigroup neutron transport equation in planar regular triangular geometry. Both regular and adjoint, inhomogeneous and homogeneous problems subject to vacuum, reflective or input specified boundary flux conditions are solved. Anisotropy is allowed for the scattering source. Volume and surface sources are allowed for inhomogeneous problems.

  7. Two Spin Liquid phases in the anisotropic triangular Heisenberg model

    NASA Astrophysics Data System (ADS)

    Sorella, Sandro

    2005-03-01

    Recently there have been rather clean experimental realizations of the quantum spin 1/2 Heisenberg Hamiltonian on a 2D triangular lattice geometry in systems like Cs2Cu Cl4 and organic compounds like k-(ET)2Cu2(CN)3. These materials are nearly two dimensional and are characterized by an anisotropic antiferromagnetic superexchange. The strength of the spatial anisotropy can increase quantum fluctuations and can destabilize the magnetically ordered state leading to non conventional spin liquid phases. In order to understand these interesting phenomena we have studied, by Quantum Monte Carlo methods, the triangular lattice Heisenberg model as a function of the strength of this anisotropy, represented by the ratio r between the intra-chain nearest neighbor coupling J' and the inter-chain one J. We have found evidence of two spin liquid regions, well represented by projected BCS wave functions[1,2] of the type proposed by P. W. Anderson at the early stages of High temperature superconductivity [3]. The first spin liquid phase is stable for small values of the coupling r 0.6 and appears gapless and fractionalized, whereas the second one is a more conventional spin liquid, very similar to the one realized in the quantum dimer model in the triangular lattice[4]. It is characterized by a spin gap and a finite correlation length, and appears energetically favored in the region 0.6 r 0.9. The various phases are in good agreement with the experimental findings and supports the existence of spin liquid phases in 2D quantum spin-half systems. %%%%%%%%%%%%%%%%%% 1cm *[1] L. Capriotti F. Becca A. Parola and S. Sorella , Phys. Rev. Letters 87, 097201 (2001). *[2] S. Yunoki and S. Sorella Phys. Rev. Letters 92, 15003 (2004). *[3] P. W. Anderson, Science 235, 1186 (1987). *[4] P. Fendley, R. Moessner, and S. L. Sondhi Phys. Rev. B 66, 214513 (2002).

  8. Collisional diffusion in toroidal plasmas with elongation and triangularity

    SciTech Connect

    Martin, P.; Castro, E.; Haines, M. G.

    2007-05-15

    Collisional diffusion is analyzed for plasma tokamaks with different ellipticities and triangularities. Improved nonlinear equations for the families of magnetic surfaces are used here. Dimensionless average velocities are calculated as a function of the inductive electric field, elongation, triangularity, and Shafranov shift. Confinement has been found to depend significantly on triangularity.

  9. A comparison of growth, photosynthetic capacity and water stress in Eucalyptus globulus coppice regrowth and seedlings during early development.

    PubMed

    Drake, Paul L; Mendham, Daniel S; White, Don A; Ogden, Gary N

    2009-05-01

    Eucalyptus globulus Labill., a globally significant plantation species, is grown commercially in a multiple rotation framework. Second and subsequent crops of E. globulus may be established either by allowing the cut stumps to resprout (commonly referred to as coppice) or by replanting a new crop of seedlings. Currently, long-term growth data comparing coppice and seedling productivity in second or later rotations in southern Australia is limited. The capacity to predict productivity using these tools is dependent on an understanding of the physiology of seedlings and coppice in response to light, water and nutrient supply. In this study, we compared the intrinsic (independent of the immediate environment) and native (dependent on the immediate environment) physiology of E. globulus coppice and second-generation seedlings during their early development in the field. Coppice not only grew more rapidly, but also used more water and drew on stored soil water to a depth of at least 4.5 m during the first 2 years of growth, whereas the seedlings only accessed the top 0.9 m of the soil profile. During the same period, there was no significant difference between coppice and seedlings in either their stomatal response to leaf-to-air vapour pressure difference (D) or intrinsic water-use efficiency; CO(2)- and light-saturated rates of photosynthesis were greater in seedlings than that in coppice as were the quantum yield of photosynthesis and total leaf chlorophyll content. Thus, at a leaf scale, seedlings are potentially more productive per unit leaf area than coppice during early development, but this is not realised under ambient conditions. The underlying cause of this inherent difference is discussed in the context of the allocation of resources to above- and below-ground organs during early development.

  10. Triangular springs for modeling nonlinear membranes.

    PubMed

    Delingette, Hervé

    2008-01-01

    This paper provides a formal connexion between springs and continuum mechanics in the context of one-dimensional and two-dimensional elasticity. In a first stage, the equivalence between tensile springs and the finite element discretization of stretching energy on planar curves is established. Furthermore, when considering a quadratic strain function of stretch, we introduce a new type of springs called tensile biquadratic springs. In a second stage, we extend this equivalence to non-linear membranes (St Venant-Kirchhoff materials) on triangular meshes leading to triangular biquadratic and quadratic springs. Those tensile and angular springs produce isotropic deformations parameterized by Young modulus and Poisson ratios on unstructured meshes in an efficient and simple way. For a specific choice of the Poisson ratio, 0.3, we show that regular spring-mass models may be used realistically to simulate a membrane behavior. Finally, the different spring formulations are tested in pure traction and cloth simulation experiments.

  11. Efficient triangular adaptive meshes for tsunami simulations

    NASA Astrophysics Data System (ADS)

    Behrens, J.

    2012-04-01

    With improving technology and increased sensor density for accurate determination of tsunamogenic earthquake source parameters and consecutively uplift distribution, real-time simulations of even near-field tsunami hazard appears feasible in the near future. In order to support such efforts a new generation of tsunami models is currently under development. These models comprise adaptively refined meshes, in order to save computational resources (in areas of low wave activity) and still represent the inherently multi-scale behavior of a tsunami approaching coastal waters. So far, these methods have been based on oct-tree quadrilateral refinement. The method introduced here is based on binary tree refinement on triangular grids. By utilizing the structure stemming from the refinement strategy, a very efficient method can be achieved, with a triangular mesh, able to accurately represent complex boundaries.

  12. High-precision triangular-waveform generator

    DOEpatents

    Mueller, T.R.

    1981-11-14

    An ultra-linear ramp generator having separately programmable ascending and decending ramp rates and voltages is provided. Two constant current sources provide the ramp through an integrator. Switching of the current at current source inputs rather than at the integrator input eliminates switching transients and contributes to the waveform precision. The triangular waveforms produced by the waveform generator are characterized by accurate reproduction and low drift over periods of several hours. The ascending and descending slopes are independently selectable.

  13. Vertex-Atom-Dependent Rectification in Triangular h-BNC/Triangular Graphene Heterojunctions

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    First-principles calculations have shown dramatically unexpected rectifying regularities in particular heterojunction configurations with triangular hexagonal boron-nitride-carbon ( h-BNC) and triangular graphene (TG) sandwiched between two armchair graphene nanoribbon electrodes. When the triangular h-BNC and TG are linked by vertex atoms of nitrogen and carbon (boron and carbon), forward (reverse) rectifying performance can be observed. Moreover, for a certain linking mode, the larger the elemental proportion p (where p = N_{{{boron}} + {{nitrogen}}} /N_{{{boron}} + {{nitrogen}} + {{carbon}}} ) in the h-BNC, the larger the ratio for forward (reverse) rectification. A mechanism for these rectification behaviors is suggested. The findings provide insights into control of rectification behaviors in TG-based nanodevices.

  14. Impact of completeness of revascularization by coronary intervention on exercise capacity early after acute ST-elevation myocardial infarction

    PubMed Central

    2014-01-01

    Background The importance of achieving complete revascularization by percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (MI) on exercise capacity remains unclear. Objective To compare exercise capacity early after acute ST-elevation myocardial infarction (STEMI), in patients receiving PCI with stenting, between those completely revascularized (CR) and those incompletely revascularized (IR). Methods We retrospectively reviewed 326 patients [single-vessel disease (SVD) group, 118 patients; multivessel disease (MVD) with CR group, 112 patients; MVD with IR group, 96 patients] who underwent cardiopulmonary exercise testing 7–30 days after STEMI to measure peak oxygen uptake (VO2peak), oxygen uptake at anaerobic threshold (VO2AT), and peak oxygen pulse. Demographic data, presence of concomitant diseases, STEMI characteristics, and echocardiography and angiography findings were evaluated. Results Most patients were male (89.0%) and mean age was 55.6 ± 11.2 years. Ischemic ST deviation occurred in 7.1%, with no significant difference between groups. VO2peak and VO2AT did not differ significantly between groups, despite a trend to be lower in the CR and IR groups compared with the SVD group. Peak oxygen pulse was significantly higher in the SVD group than in the IR group (p = 0.005). After adjustment for age, gender, body mass index, cardiovascular risk factors, MI characteristics and echocardiography parameters, CR was not an independent predictor of VO2peak (OR = −0.123, 95% confidence interval [CI] -2.986 to 0.232, p = 0.093), VO2AT (OR = 0.002, 95% CI 1.735 to 1.773, p = 0.983), or peak oxygen pulse (OR = −0.102, 95% CI −1.435 to 0.105, p = 0.090). Conclusion CR in patients with STEMI treated with PCI for multivessel disease might show no benefit on short-term exercise tolerance over IR. PMID:24641986

  15. Functional capacity of people with early osteoarthritis: a comparison between subjects from the cohort hip and cohort knee (CHECK) and healthy ageing workers

    PubMed Central

    van Ittersum, M. W.; Groothoff, J. W.; Oostveen, J. C. M.; Oosterveld, F. G. J.; van der Schans, C. P.; Soer, R.; Reneman, M. F.

    2010-01-01

    Objective The prevalence of osteoarthritis (OA) increases, but the impact of the disorder on peoples’ functional capacity is not known. Therefore, the objective of this study was to compare self-reported health status and functional capacity of subjects with early OA of hip and/or knee to reference data of healthy working subjects and to assess whether this capacity is sufficient to meet physical job demands. Methods Self-reported health status and functional capacity of 93 subjects from the Cohort Hip and Cohort Knee (CHECK) were measured using the Short-Form 36 Health Survey and 6 tests of the Work Well Systems Functional Capacity Evaluation. Results were compared with reference data from 275 healthy workers, using t-tests. To compare the functional capacity with job demands, the proportions of subjects with OA performing lower than the p5 of reference data were calculated. Results Compared to healthy workers, the subjects (mean age 56) from CHECK at baseline reported a significantly worse physical health status, whereas the women (n = 78) also reported a worse mental health status. On the FCE female OA subjects performed significantly lower than their healthy working counterparts on all 6 tests. Male OA subjects performed lower than male workers on 3 tests. A substantial proportion of women demonstrated functional capacities that could be considered insufficient to perform jobs with low physical demands. Conclusions Functional capacity and self-reported health of subjects with early OA of the hips and knees were worse compared to healthy ageing workers. A substantial proportion of female subjects did not meet physical job demands. PMID:20490537

  16. Opening of triangular hole in triangular-shaped chemical vapor deposited hexagonal boron nitride crystal

    PubMed Central

    Sharma, Subash; Kalita, Golap; Vishwakarma, Riteshkumar; Zulkifli, Zurita; Tanemura, Masaki

    2015-01-01

    In-plane heterostructure of monolayer hexagonal boron nitride (h-BN) and graphene is of great interest for its tunable bandgap and other unique properties. Here, we reveal a H2-induced etching process to introduce triangular hole in triangular-shaped chemical vapor deposited individual h-BN crystal. In this study, we synthesized regular triangular-shaped h-BN crystals with the sizes around 2-10 μm on Cu foil by chemical vapor deposition (CVD). The etching behavior of individual h-BN crystal was investigated by annealing at different temperature in an H2:Ar atmosphere. Annealing at 900 °C, etching of h-BN was observed from crystal edges with no visible etching at the center of individual crystals. While, annealing at a temperature ≥950 °C, highly anisotropic etching was observed, where the etched areas were equilateral triangle-shaped with same orientation as that of original h-BN crystal. The etching process and well-defined triangular hole formation can be significant platform to fabricate planar heterostructure with graphene or other two-dimensional (2D) materials. PMID:25994455

  17. Graphene Triangular Ballistic Rectifier: Fabrication and Characterisation

    NASA Astrophysics Data System (ADS)

    Auton, Gregory; Kumar, Roshan Krishna; Hill, Ernie; Song, Aimin

    2016-09-01

    It has been shown that graphene can demonstrate ballistic transport at room temperature. This opens up a range of practical applications that do not require graphene to have a band gap, which is one of the most significant challenges for its use in the electronics industry. Here, the very latest high mobility graphene (>100,000 cm2 V-1 s-1) fabrication techniques will be demonstrated so that one such device, called the triangular ballistic rectifier (TBR), can be characterised. The TBR is a four-terminal device with a triangular anti-dot at their intersection; two sides of the triangle are positioned and angled such that ballistic carriers from the two input electrodes are redirected like billiard balls to one of the two output contacts irrespective of the instantaneous polarity of the input. A responsivity of 2400 mV mW-1 is demonstrated at room temperature from a low-frequency input signal. The ballistic nature of the device is justified and explained in more detail with low-temperature measurements.

  18. Kondo effects in triangular triple quantum dots

    NASA Astrophysics Data System (ADS)

    Oguri, Akira; Numata, Takahide; Nisikawa, Yunori; Hewson, A. C.

    2009-03-01

    We study the conductance through a triangular triple quantum dot, which is connected to two noninteracting leads, using the numerical renormalization group (NRG). It is found that the system shows a variety of Kondo effects depending on the filling of the triangle. The SU(4) Kondo effect occurs at half-filling, and a sharp conductance dip due to a phase lapse appears in the gate-voltage dependence. Furthermore, when four electrons occupy the three sites on average, a local S=1 moment, which is caused by the Nagaoka mechanism, is induced along the triangle. The temperature dependence of the entropy and spin susceptibility of the triangle shows that this moment is screened by the conduction electrons via two separate stages at different temperatures. The two-terminal and four-terminal conductances show a clear difference at the gate voltages, where the SU(4) or the S=1 Kondo effects occur[1]. We will also discuss effects of deformations of the triangular configuration, caused by the inhomogeneity in the inter-dot couplings and in the gate voltages. [4pt] [1] T.Numata, Y.Nisikawa, A.Oguri, and A.C.Hewson: arXiv:0808.3496.

  19. Laminar natural convection in right triangular enclosures

    NASA Astrophysics Data System (ADS)

    Fuad Kent, E.; Asmaz, E.; Ozerbay, S.

    2007-12-01

    In this study, natural convection in non-rectangular enclosures is analyzed numerically. Streamlines and isotherms are presented for different triangular enclosures with different boundary conditions and Rayleigh numbers. Mean Nusselt numbers on hot walls are also calculated in order to make comparisons between different cases. The solutions are obtained for different aspect ratios where boundary conditions represent the wintertime heating of an attic space. This made possible to investigate the effect of aspect ratio on natural convection. In this study, quarter circular enclosure, which is very similar to right triangles, is also examined. Consequently, we had the opportunity to analyze how shape changes affect the flow pattern. The results of the calculations are compared with the similar enclosures and boundary conditions.

  20. Maximum independent set on diluted triangular lattices

    NASA Astrophysics Data System (ADS)

    Fay, C. W., IV; Liu, J. W.; Duxbury, P. M.

    2006-05-01

    Core percolation and maximum independent set on random graphs have recently been characterized using the methods of statistical physics. Here we present a statistical physics study of these problems on bond diluted triangular lattices. Core percolation critical behavior is found to be consistent with the standard percolation values, though there are strong finite size effects. A transfer matrix method is developed and applied to find accurate values of the density and degeneracy of the maximum independent set on lattices of limited width but large length. An extrapolation of these results to the infinite lattice limit yields high precision results, which are tabulated. These results are compared to results found using both vertex based and edge based local probability recursion algorithms, which have proven useful in the analysis of hard computational problems, such as the satisfiability problem.

  1. Efficiency considerations in triangular adaptive mesh refinement.

    PubMed

    Behrens, Jörn; Bader, Michael

    2009-11-28

    Locally or adaptively refined meshes have been successfully applied to simulation applications involving multi-scale phenomena in the geosciences. In particular, for situations with complex geometries or domain boundaries, meshes with triangular or tetrahedral cells demonstrate their superior ability to accurately represent relevant realistic features. On the other hand, these methods require more complex data structures and are therefore less easily implemented, maintained and optimized. Acceptance in the Earth-system modelling community is still low. One of the major drawbacks is posed by indirect addressing due to unstructured or dynamically changing data structures and correspondingly lower efficiency of the related computations. In this paper, we will derive several strategies to circumvent the mentioned efficiency constraint. In particular, we will apply recent computational sciences methods in combination with results of classical mathematics (space-filling curves) in order to linearize the complex data and access structure.

  2. Triangular model integrating clinical teaching and assessment.

    PubMed

    Abdelaziz, Adel; Koshak, Emad

    2014-01-01

    Structuring clinical teaching is a challenge facing medical education curriculum designers. A variety of instructional methods on different domains of learning are indicated to accommodate different learning styles. Conventional methods of clinical teaching, like training in ambulatory care settings, are prone to the factor of coincidence in having varieties of patient presentations. Accordingly, alternative methods of instruction are indicated to compensate for the deficiencies of these conventional methods. This paper presents an initiative that can be used to design a checklist as a blueprint to guide appropriate selection and implementation of teaching/learning and assessment methods in each of the educational courses and modules based on educational objectives. Three categories of instructional methods were identified, and within each a variety of methods were included. These categories are classroom-type settings, health services-based settings, and community service-based settings. Such categories have framed our triangular model of clinical teaching and assessment.

  3. Biological synthesis of triangular gold nanoprisms

    NASA Astrophysics Data System (ADS)

    Shankar, S. Shiv; Rai, Akhilesh; Ankamwar, Balaprasad; Singh, Amit; Ahmad, Absar; Sastry, Murali

    2004-07-01

    The optoelectronic and physicochemical properties of nanoscale matter are a strong function of particle size. Nanoparticle shape also contributes significantly to modulating their electronic properties. Several shapes ranging from rods to wires to plates to teardrop structures may be obtained by chemical methods; triangular nanoparticles have been synthesized by using a seeded growth process. Here, we report the discovery that the extract from the lemongrass plant, when reacted with aqueous chloroaurate ions, yields a high percentage of thin, flat, single-crystalline gold nanotriangles. The nanotriangles seem to grow by a process involving rapid reduction, assembly and room-temperature sintering of 'liquid-like' spherical gold nanoparticles. The anisotropy in nanoparticle shape results in large near-infrared absorption by the particles, and highly anisotropic electron transport in films of the nanotriangles.

  4. Thermodynamic Properties in Triangular-Lattice Superconductors

    NASA Astrophysics Data System (ADS)

    Ma, Xixiao; Qin, Ling; Zhao, Huaisong; Lan, Yu; Feng, Shiping

    2016-06-01

    The study of superconductivity arising from doping a Mott insulator has become a central issue in the area of superconductivity. Within the framework of the kinetic-energy-driven superconducting (SC) mechanism, we discuss the thermodynamic properties in the triangular-lattice cobaltate superconductors. It is shown that a sharp peak in the specific heat appears at the SC transition temperature T_c, and then the specific heat varies exponentially as a function of temperature for temperatures T

  5. Quantum electric-dipole liquid on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Shen, Shi-Peng; Wu, Jia-Chuan; Song, Jun-Da; Sun, Xue-Feng; Yang, Yi-Feng; Chai, Yi-Sheng; Shang, Da-Shan; Wang, Shou-Guo; Scott, James F.; Sun, Young

    2016-02-01

    Geometric frustration and quantum fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets. Geometric frustration and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogues of quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19 with geometric frustration represents a promising candidate for the proposed electric-dipole liquid. We present a series of experimental lines of evidence, including dielectric permittivity, heat capacity and thermal conductivity measured down to 66 mK, to reveal the existence of an unusual liquid-like quantum phase in BaFe12O19, characterized by itinerant low-energy excitations with a small gap. The possible quantum liquids of electric dipoles in frustrated dielectrics open up a fresh playground for fundamental physics.

  6. Quantum electric-dipole liquid on a triangular lattice.

    PubMed

    Shen, Shi-Peng; Wu, Jia-Chuan; Song, Jun-Da; Sun, Xue-Feng; Yang, Yi-Feng; Chai, Yi-Sheng; Shang, Da-Shan; Wang, Shou-Guo; Scott, James F; Sun, Young

    2016-01-01

    Geometric frustration and quantum fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets. Geometric frustration and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogues of quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19 with geometric frustration represents a promising candidate for the proposed electric-dipole liquid. We present a series of experimental lines of evidence, including dielectric permittivity, heat capacity and thermal conductivity measured down to 66 mK, to reveal the existence of an unusual liquid-like quantum phase in BaFe12O19, characterized by itinerant low-energy excitations with a small gap. The possible quantum liquids of electric dipoles in frustrated dielectrics open up a fresh playground for fundamental physics. PMID:26843363

  7. Quantum electric-dipole liquid on a triangular lattice

    PubMed Central

    Shen, Shi-Peng; Wu, Jia-Chuan; Song, Jun-Da; Sun, Xue-Feng; Yang, Yi-Feng; Chai, Yi-Sheng; Shang, Da-Shan; Wang, Shou-Guo; Scott, James F.; Sun, Young

    2016-01-01

    Geometric frustration and quantum fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets. Geometric frustration and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogues of quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19 with geometric frustration represents a promising candidate for the proposed electric-dipole liquid. We present a series of experimental lines of evidence, including dielectric permittivity, heat capacity and thermal conductivity measured down to 66 mK, to reveal the existence of an unusual liquid-like quantum phase in BaFe12O19, characterized by itinerant low-energy excitations with a small gap. The possible quantum liquids of electric dipoles in frustrated dielectrics open up a fresh playground for fundamental physics. PMID:26843363

  8. Quantum electric-dipole liquid on a triangular lattice.

    PubMed

    Shen, Shi-Peng; Wu, Jia-Chuan; Song, Jun-Da; Sun, Xue-Feng; Yang, Yi-Feng; Chai, Yi-Sheng; Shang, Da-Shan; Wang, Shou-Guo; Scott, James F; Sun, Young

    2016-02-04

    Geometric frustration and quantum fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets. Geometric frustration and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogues of quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19 with geometric frustration represents a promising candidate for the proposed electric-dipole liquid. We present a series of experimental lines of evidence, including dielectric permittivity, heat capacity and thermal conductivity measured down to 66 mK, to reveal the existence of an unusual liquid-like quantum phase in BaFe12O19, characterized by itinerant low-energy excitations with a small gap. The possible quantum liquids of electric dipoles in frustrated dielectrics open up a fresh playground for fundamental physics.

  9. Low-cost Triangular Lattice Towers for Small Wind Turbines

    NASA Astrophysics Data System (ADS)

    Adhikari, Ram Chandra

    This thesis focuses on the study of low-cost steel and bamboo triangular lattice towers for small wind turbines. The core objective is to determine the material properties of bamboo and assess the feasibility of bamboo towers. Using the experimentally determined buckling resistance, elastic modulus, and Poisson's ratio, a 12 m high triangular lattice tower for a 500W wind turbine has been modeled as a tripod to formulate the analytical solutions for the stresses and tower deflections, which enables design of the tower based on buckling strength of tower legs. The tripod formulation combines the imposed loads, the base distance between the legs and tower height, and cross-sectional dimensions of the tower legs. The tripod model was used as a reference for the initial design of the bamboo tower and extended to finite element analysis. A 12 m high steel lattice tower was also designed for the same turbine to serve as a comparison to the bamboo tower. The primary result of this work indicates that bamboo is a valid structural material. The commercial software package ANSYS APDL was used to carry out the tower analysis, evaluate the validity of the tripod model, and extend the analysis for the tower design. For this purpose, a 12 m high steel lattice tower for a 500 W wind turbine was examined. Comparison of finite element analysis and analytical solution has shown that tripod model can be accurately used in the design of lattice towers. The tower designs were based on the loads and safety requirements of international standard for small wind turbine safety, IEC 61400-2. For connecting the bamboo sections in the lattice tower, a steel-bamboo adhesive joint combined with conventional lashing has been proposed. Also, considering the low durability of bamboo, periodic replacement of tower members has been proposed. The result of this study has established that bamboo could be used to construct cost-effective and lightweight lattice towers for wind turbines of 500 Watt

  10. Antioxidant, Iron Chelating and Tyrosinase Inhibitory Activities of Extracts from Talinum triangulare Leach Stem

    PubMed Central

    Oliveira Amorim, Ana Paula; Campos de Oliveira, Márcia Cristina; de Azevedo Amorim, Thiago; Echevarria, Aurea

    2013-01-01

    The aim of this work is to evaluate the antioxidant activity against the radical species DPPH, the reducing capacity against Fe II ions, and the inhibitory activity on the tyrosinase enzyme of the T. triangulare. Hydromethanolic crude extract provided two fractions after the liquid/liquid partition with chloroform. The Folin-Ciocalteu method determined the total phenolic content of the crude extract (CE) and the hydromethanolic fraction (Fraction 1), resulting in a concentration of 0.5853 g/100 g for Fraction 1, and 0.1400 g/100 g for the CE. Taking into account the results of the DPPH, the free radical scavenging capacity was confirmed. The formation of complexes with Fe II ions was evaluated by UV/visible spectrometry; results showed that CE has complexing power similar to the positive control (Gingko biloba extract).The inhibitory capacity of samples against the tyrosinase enzyme was determined by the oxidation of L-DOPA, providing IC50 values of 13.3 μg·mL−1 (CE) and 6.6 μg·mL−1 (Fraction 1). The values indicate that Fraction 1 was more active and showed a higher inhibitory power on the tyrosinase enzyme than the ascorbic acid, used as positive control. The hydromethanolic extract of T. triangulare proved to have powerful antioxidant activity and to inhibit the tyrosinase enzyme; its potential is increased after the partition with chloroform. PMID:26784338

  11. Coherently Tunable Triangular Trefoil Phaseonium Metamaterial

    NASA Astrophysics Data System (ADS)

    Nguyen, D. M.; Soci, Cesare; Ooi, C. H. Raymond

    2016-02-01

    Phaseonium is a three-level Λ quantum system, in which a coherent microwave and an optical control (pump) beams can be used to actively modulate the dielectric response. Here we propose a new metamaterial structure comprising of a periodic array of triangular phaseonium metamolecules arranged as a trefoil. We present a computational study of the spatial distribution of magnetic and electric fields of the probe light and the corresponding transmission and reflection, for various parameters of the optical and microwave beams. For specific values of the probing frequencies and control fields, the phaseonium can display either metallic or dielectric optical response. We find that, in the metallic regime, the phaseonium metamaterial structure supports extremely large transmission, with optical amplification at large enough intensity of the microwave thanks to strong surface plasmon coupling; while, in the dielectric regime without microwave excitation, the transmission bandwidth can be tuned by varying the control beam intensity. Implementation of such phaseonium metamaterial structure in solid-state systems, such as patterned crystals doped with rare-earth elements or dielectric matrices embedded with quantum dots, could enable a new class of actively tunable quantum metamaterials.

  12. Coherently Tunable Triangular Trefoil Phaseonium Metamaterial

    PubMed Central

    Nguyen, D. M.; Soci, Cesare; Ooi, C. H. Raymond

    2016-01-01

    Phaseonium is a three-level Λ quantum system, in which a coherent microwave and an optical control (pump) beams can be used to actively modulate the dielectric response. Here we propose a new metamaterial structure comprising of a periodic array of triangular phaseonium metamolecules arranged as a trefoil. We present a computational study of the spatial distribution of magnetic and electric fields of the probe light and the corresponding transmission and reflection, for various parameters of the optical and microwave beams. For specific values of the probing frequencies and control fields, the phaseonium can display either metallic or dielectric optical response. We find that, in the metallic regime, the phaseonium metamaterial structure supports extremely large transmission, with optical amplification at large enough intensity of the microwave thanks to strong surface plasmon coupling; while, in the dielectric regime without microwave excitation, the transmission bandwidth can be tuned by varying the control beam intensity. Implementation of such phaseonium metamaterial structure in solid-state systems, such as patterned crystals doped with rare-earth elements or dielectric matrices embedded with quantum dots, could enable a new class of actively tunable quantum metamaterials. PMID:26879520

  13. An Intervention to Increase Early Childhood Staff Capacity for Promoting Children's Social-Emotional Development in Preschool Settings

    ERIC Educational Resources Information Center

    Green, Beth L.; Malsch, Anna M.; Kothari, Brianne Hood; Busse, Jessica; Brennan, Eileen

    2012-01-01

    This article describes the development, implementation, and outcomes of a pilot intervention designed to enhance preschool programs' ability to support children's social-emotional development. Working with two Head Start programs, the intervention included (1) restructuring existing early childhood mental health consultation services; (2) engaging…

  14. Interior, detail at rear of theater showing partition with triangular ...

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

    Interior, detail at rear of theater showing partition with triangular roof projections. Doors lead to lobby. - Fitzsimons General Hospital, Theater, Northwest Corner of East McAfee Avenue & South Page Street, Aurora, Adams County, CO

  15. 7. NORTH EXTERIOR SIDE SHOWING TRIANGULAR KNEE BRACE SUPPORTS AND ...

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

    7. NORTH EXTERIOR SIDE SHOWING TRIANGULAR KNEE BRACE SUPPORTS AND ENCLOSED PORCH SCREENED WINDOWS. VIEW TO SOUTH. - Big Creek Hydroelectric System, Powerhouse 8, Operator Cottage, Big Creek, Big Creek, Fresno County, CA

  16. Magnetoresistance measurement of permalloy thin film rings with triangular fins

    NASA Astrophysics Data System (ADS)

    Lai, Mei-Feng; Hsu, Chia-Jung; Liao, Chun-Neng; Chen, Ying-Jiun; Wei, Zung-Hang

    2010-01-01

    Magnetization reversals in permalloy rings controlled by nucleation sites using triangular fins at the same side and diagonal with respect to the field direction are demonstrated by magnetoresistance measurement and micromagnetic simulation. In the ring with triangular fins at the same side, there exists two-step reversal from onion to flux-closure state (or vortex state) and then from flux-closure (or vortex state) to reverse onion state; in the ring with diagonal triangular fins, one-step reversal occurs directly from onion to reverse onion state. The reversal processes are repeatable and controllable in contrast to an ideal ring without triangular fins where one-step and two-step reversals occur randomly in sweep-up and sweep-down processes.

  17. The Centre of Mass of a Triangular Plate

    ERIC Educational Resources Information Center

    Slusarenko, Viktor; Rojas, Roberto; Fuster, Gonzalo

    2008-01-01

    We present a derivation for the coordinates of the centre of mass--or centre of gravity--of a homogeneous triangular plate by using scaling and symmetry. We scale the triangular plate by a factor of 2 and divide its area into four plates identical to the original. By symmetry, we assert that the centre of mass of two identical masses lies at the…

  18. An algorithm for propagating the square-root covariance matrix in triangular form

    NASA Technical Reports Server (NTRS)

    Tapley, B. D.; Choe, C. Y.

    1976-01-01

    A method for propagating the square root of the state error covariance matrix in lower triangular form is described. The algorithm can be combined with any triangular square-root measurement update algorithm to obtain a triangular square-root sequential estimation algorithm. The triangular square-root algorithm compares favorably with the conventional sequential estimation algorithm with regard to computation time.

  19. Free Vibration of Shear-Deformable General Triangular Plates

    NASA Astrophysics Data System (ADS)

    Karunasena, W.; Kitipornchai, S.

    1997-01-01

    An analysis of free vibration of shear-deformable general triangular plates with arbitrary combinations of boundary conditions is presented. The Reissner-Mindlin plate theory is used to incorporate shear deformation effects in the analysis. The triangular plate is first mapped onto a basic square plate. The Rayleigh-Ritz method with an admissible displacement function expressed as a product of a two-dimensional simple polynomial and a basic function is then used to obtain the governing eigenvalue equation. The basic function is chosen as the product of boundary expressions of the basic square plate, each raised to an appropriate power to satisfy the various geometric boundary conditions of the actual triangular plate Gaussian quadrature is used for numerical evaluation of stiffness and mass matrices. The natural frequencies of general triangular Mindlin plates with different combinations of free, simply supported and clamped conditions are determined. Wherever possible, the results are verified by comparison with existing published solutions. A comprehensive parametric study of natural frequencies of general triangular plates with all three edges clamped is presented graphically. No previous results are known to exist for general triangular Mindlin plates having arbitrary combinations of boundary conditions.

  20. The triangular maps with closed sets of periodic points

    NASA Astrophysics Data System (ADS)

    Kupka, Jiri

    2006-07-01

    In a recent paper we provided a characterization of triangular maps of the square, i.e., maps given by F(x,y)=(f(x),gx(y)), satisfying condition (P1) that any chain recurrent point is periodic. For continuous maps of the interval, there is a list of 18 other conditions equivalent to (P1), including (P2) that there is no infinite [omega]-limit set, (P3) that the set of periodic points is closed and (P4) that any regularly recurrent point is periodic, for instance. We provide an almost complete classification among these conditions for triangular maps, improve a result given by C. Arteaga [C. Arteaga, Smooth triangular maps of the square with closed set of periodic points, J. Math. Anal. Appl. 196 (1995) 987-997] and state an open problem concerning minimal sets of the triangular maps. The paper solves partially a problem formulated by A.N. Sharkovsky in the eighties. The mentioned open problem, the validity of (P4) => (P3), is related to the question whether some regularly recurrent point lies in the fibres over an f-minimal set possessing a regularly recurrent point. We answered this question in the positive for triangular maps with nondecreasing fiber maps. Consequently, the classification is completed for monotone triangular maps.

  1. Chemical compounds isolated from Talinum triangulare (Portulacaceae).

    PubMed

    de Oliveira Amorim, Ana Paula; de Carvalho, Almir Ribeiro; Lopes, Norberto Peporine; Castro, Rosane Nora; de Oliveira, Marcia Cristina Campos; de Carvalho, Mário Geraldo

    2014-10-01

    This first phytochemical study of Talinum triangulare Leach (Portulacaceae), also known as 'cariru', which is a commonly consumed food in Northern Brazil, allowed the isolation and structural determination of four new compounds: one acrylamide, 3-N-(acryloyl, N-pentadecanoyl) propanoic acid (5), and three new phaeophytins named (15(1)S, 17R, 18R)-Ficuschlorin D acid (3(1),3(2)-didehydro-7-oxo-17(3)-O-phytyl-rhodochlorin-15-acetic acid), (13), Talichorin A (17R, 18R)-phaeophytin b-15(1)-hidroxy, 15(2),15(3)-acetyl-13(1)-carboxilic acid (14), and (15(1)S, 17R, 18R)-phaeophytin b peroxylactone or (15(1)S, 17R, 18R)-hydroperoxy-ficuschlorin D (16), together with twelve known compounds, including four phaeophytins (11,12, 15 and 17). The structures of the compounds were established on the basis of 1D and 2D NMR, IR, HRESI-MS spectra, including GC-MS, and HPLC-UV analysis, as well as comparisons with the literature data. The CD spectra data analysis were used to define the absolute configuration of phaeophytins 12 (13(2)R, 17R, 18R)-13(2)-hydroxyphaeophytin a, 13 and 16, 15 (15(1)S, 17R, 18R)-3(1),3(2)-didehydro-15(1)-hydroxyrhodochlorin-15-acetic acid δ-lactone-15(2)-methyl-17(3)-phytyl ester and 17 (17R, 18R)-purpurin 18-phytyl ester. PMID:24799228

  2. Early-phase adaptations of traditional-speed vs. superslow resistance training on strength and aerobic capacity in sedentary individuals.

    PubMed

    Keeler, L K; Finkelstein, L H; Miller, W; Fernhall, B

    2001-08-01

    We performed a randomized exercise training study to assess the effects of traditional Nautilus-style (TR) or superslow (SS) strength training on muscular strength, body composition, aerobic capacity, and cardiovascular endurance. Subjects were 14 healthy, sedentary women, 19-45 years of age (mean +/- SD age, 32.7 +/- 8.9 years), randomized to either the SS or TR training protocols and trained 3 times per week for 10 weeks. Measurements were taken both before and after training, which included a maximal incremental exercise test on a cycle ergometer, body composition, and 1 repetition maximum (1RM) tests on 8 Nautilus machines. Both groups increased their strength significantly on all 8 exercises, whereas the TR group increased significantly more than the SS group on bench press (34% vs. 11%), torso arm (anterior lateral pull-down) (27% vs. 12%), leg press (33% vs. 7%), leg extension (56% vs. 24%), and leg curl (40% vs. 15%). Thus, the TR group's improvement in total exercise weight lifted was significantly greater than that of the SS group after testing (39% vs. 15%). Exercise duration on the cycle ergometer and work rate significantly improved for both groups, but there was no group-by-training interaction. No significant differences were found for body composition or additional aerobic variables measured. Both strength training protocols produced a significant improvement in strength during a 10-week training period, but the TR protocol produced better gains in the absence of changes in percentage of body fat, body mass index, lean body mass, and body weight. In addition, strength training alone did not improve Vo2max, yet short-term endurance increased.

  3. Early B blasts acquire a capacity for Ig class switch recombination that is lost as they become plasmablasts.

    PubMed

    Marshall, Jennifer L; Zhang, Yang; Pallan, Lalit; Hsu, Mei-Chi; Khan, Mahmood; Cunningham, Adam F; MacLennan, Ian C M; Toellner, Kai-Michael

    2011-12-01

    Rapid production of neutralizing antibody can be critical for limiting the spread of infection. Such early antibody results when B-cell blasts mature directly to plasmablasts without forming germinal centers. These extrafollicular responses can involve Ig class switch recombination (CSR), producing antibody that can readily disseminate through infected tissues. The present study identifies the differentiation stage where CSR occurs in an extrafollicular response induced by 4-hydroxy-3-nitrophenyl acetyl (NP) conjugated to Ficoll (NP-Ficoll). To do this, we took advantage of the antigen dose dependency of CSR in this response. Thus, while both 30 and 1 μg NP-Ficoll induce plasmablasts, only the higher antigen dose induces CSR. Activation-induce cytidine deaminase (AID) is critical for CSR and in keeping with this a proportion of NP-specific B-cell blasts induced by 30 μg NP-Ficoll express AID. None of the B blasts responding to the non-CSR-inducing 1 μg dose of NP-Ficoll express AID. We confirmed that CSR occurs in B blasts by demonstrating the presence of rearranged heavy-chain transcripts in B blasts in the 30 μg response. CSR in this extrafollicular response is confined to B blasts, because NP-specific plasmablasts, identified by expressing CD138 and Blimp-1, no longer express AID and cannot undergo CSR.

  4. Field-design optimization with triangular heliostat pods

    NASA Astrophysics Data System (ADS)

    Domínguez-Bravo, Carmen-Ana; Bode, Sebastian-James; Heiming, Gregor; Richter, Pascal; Carrizosa, Emilio; Fernández-Cara, Enrique; Frank, Martin; Gauché, Paul

    2016-05-01

    In this paper the optimization of a heliostat field with triangular heliostat pods is addressed. The use of structures which allow the combination of several heliostats into a common pod system aims to reduce the high costs associated with the heliostat field and therefore reduces the Levelized Cost of Electricity value. A pattern-based algorithm and two pattern-free algorithms are adapted to handle the field layout problem with triangular heliostat pods. Under the Helio100 project in South Africa, a new small-scale Solar Power Tower plant has been recently constructed. The Helio100 plant has 20 triangular pods (each with 6 heliostats) whose positions follow a linear pattern. The obtained field layouts after optimization are compared against the reference field Helio100.

  5. Synthesis of triangular Au core-Ag shell nanoparticles

    SciTech Connect

    Rai, Akhilesh; Chaudhary, Minakshi; Ahmad, Absar; Bhargava, Suresh; Sastry, Murali . E-mail: msastry@tatachemicals.com

    2007-07-03

    In this paper, we demonstrate a simple and reproducible method for the synthesis of triangular Au core-Ag shell nanoparticles. The triangular gold core is obtained by the reduction of gold ions by lemongrass extract. Utilizing the negative charge on the gold nanotriangles, silver ions are bound to their surface and thereafter reduced by ascorbic acid under alkaline conditions. The thickness of the silver shell may be modulated by varying the pH of the reaction medium. The formation of the Au core-Ag shell triangular nanostructures has been followed by UV-vis-NIR Spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM) measurements. The sharp vertices of the triangles coupled with the core-shell structure is expected to have potential for application in surface enhanced Raman spectroscopy and in the sensitive detection of biomolecules.

  6. Enriched environment has limited capacity for the correction of hippocampal memory-dependent schizoid behaviors in rats with early postnatal NMDAR dysfunction.

    PubMed

    Melik, Enver; Babar, Emine; Kocahan, Sayad; Guven, Mustafa; Akillioglu, Kubra

    2014-04-01

    Pre- and early postnatal stress can cause dysfunction of the N-methyl-d-aspartate receptor (NMDAR) and thereby promote the development of hippocampus memory-dependent schizoid abnormalities of navigation in space, time, and knowledge. An enriched environment improves mental abilities in humans and animals. Whether an enriched environment can prevent the development of schizoid symptoms induced by neonatal NMDAR dysfunction was the central question of our paper. The experimental animals were Wistar rats. Early postnatal NMDAR dysfunction was created by systemic treatment of rat pups with the NMDAR antagonist MK-801 at PD10-20 days. During the development period (PD21-90 days), the rats were reared in cognitively and physically enriched cages. Adult age rats were tested on navigation based on pattern separation and episodic memory in the open field and on auto-hetero-associations based on episodic and semantic memory in a step-through passive avoidance task. The results showed that postnatal NMDAR antagonism caused abnormal behaviors in both tests. An enriched environment prevented deficits in the development of navigation in space based on pattern separation and hetero-associations based on semantic memory. However, an enriched environment was unable to rescue navigation in space and auto-associations based on episodic memory. These data may contribute to the understanding that an enriched environment has a limited capacity for therapeutic interventions in protecting the development of schizoid syndromes in children and adolescents. PMID:24184288

  7. Enriched environment has limited capacity for the correction of hippocampal memory-dependent schizoid behaviors in rats with early postnatal NMDAR dysfunction.

    PubMed

    Melik, Enver; Babar, Emine; Kocahan, Sayad; Guven, Mustafa; Akillioglu, Kubra

    2014-04-01

    Pre- and early postnatal stress can cause dysfunction of the N-methyl-d-aspartate receptor (NMDAR) and thereby promote the development of hippocampus memory-dependent schizoid abnormalities of navigation in space, time, and knowledge. An enriched environment improves mental abilities in humans and animals. Whether an enriched environment can prevent the development of schizoid symptoms induced by neonatal NMDAR dysfunction was the central question of our paper. The experimental animals were Wistar rats. Early postnatal NMDAR dysfunction was created by systemic treatment of rat pups with the NMDAR antagonist MK-801 at PD10-20 days. During the development period (PD21-90 days), the rats were reared in cognitively and physically enriched cages. Adult age rats were tested on navigation based on pattern separation and episodic memory in the open field and on auto-hetero-associations based on episodic and semantic memory in a step-through passive avoidance task. The results showed that postnatal NMDAR antagonism caused abnormal behaviors in both tests. An enriched environment prevented deficits in the development of navigation in space based on pattern separation and hetero-associations based on semantic memory. However, an enriched environment was unable to rescue navigation in space and auto-associations based on episodic memory. These data may contribute to the understanding that an enriched environment has a limited capacity for therapeutic interventions in protecting the development of schizoid syndromes in children and adolescents.

  8. 14. INTERIOR, IN TRIANGULAR STORAGE AREA, IN SOUTHEAST AREA OF ...

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

    14. INTERIOR, IN TRIANGULAR STORAGE AREA, IN SOUTHEAST AREA OF BUILDING (EAST OF LOCKER/OFFICE/HEAD AREA), LOOKING EAST-NORTHEAST. - Oakland Naval Supply Center, Pier Transit Shed, South of D Street between First & Second Streets, Oakland, Alameda County, CA

  9. View of the demilune, a triangular piece of land that ...

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

    View of the demilune, a triangular piece of land that protected the rear of gorge wall of the fort. After the civil war, large earthen mounds were built in the demilune area. These mounds overlay four powder magazines and passageways to several gun emplacements. - Fort Pulaski, Cockspur Island, Savannah, Chatham County, GA

  10. Triangular Numbers, Gaussian Integers, and KenKen

    ERIC Educational Resources Information Center

    Watkins, John J.

    2012-01-01

    Latin squares form the basis for the recreational puzzles sudoku and KenKen. In this article we show how useful several ideas from number theory are in solving a KenKen puzzle. For example, the simple notion of triangular number is surprisingly effective. We also introduce a variation of KenKen that uses the Gaussian integers in order to…

  11. Triangular congenital cataract morphology associated with prenatal methamphetamine exposure.

    PubMed

    Clarke, Michael E; Schloff, Susan; Bothun, Erick D

    2009-08-01

    Bilateral congenital cataracts are often characterized by morphology, etiology, and related conditions. We report a case of unique congenital cataracts with triangular morphology and associated prenatal methamphetamine exposure. Although this association is likely coincidental, the cataract's morphology in light of the specific timing of prenatal drug use deserves reporting.

  12. Middle Passage in the Triangular Slave Trade: The West Indies

    ERIC Educational Resources Information Center

    Sawh, Ruth; Scales, Alice M.

    2006-01-01

    Our narrative focuses on the middle passage of the slave trade in the West Indies. Herein we describe why more men, women, and children were imported in the West Indies than other islands. Specifically, our aim was to address how slaves in the middle passage of the triangular slave trade were treated, how they sustained themselves, and how they…

  13. 6. SOUTH EXTERIOR SIDE SHOWING TRIANGULAR KNEE BRACE SUPPORTS AND ...

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

    6. SOUTH EXTERIOR SIDE SHOWING TRIANGULAR KNEE BRACE SUPPORTS AND ENCLOSED PORCH SCREENED WINDOWS. ON BASIC FLOOR-PLAN FOR THE SIX-ROOM HOUSE THIS END WAS THE FRONT ENTRANCE. VIEW TO NORTH. - Big Creek Hydroelectric System, Powerhouse 8, Operator Cottage, Big Creek, Big Creek, Fresno County, CA

  14. Hierarchically triangular prism structured Co3O4: Self-supported fabrication and photocatalytic property

    EPA Science Inventory

    The formation of ammonium cobalt (II) phosphate was utilized to synthesize unprecedented 3D structures of Co3O4, triangular prisms and trunk-like structures, via a self-supported and organics-free method. The length of a triangular side of the prepared 3D triangular prisms is ~1...

  15. Highly efficient reflective Dammann grating with a triangular structure.

    PubMed

    Wang, Jin; Zhou, Changhe; Ma, Jianyong; Zong, Yonghong; Jia, Wei

    2016-07-01

    A highly efficient reflective Dammann grating with a triangular structure operating at 1064 nm wavelength under normal incidence for TE polarization is designed and fabricated. Rigorous coupled wave analysis and particle swarm optimization algorithms are adopted to design and analyze the properties. The triangular reflective grating could cancel the 0th order, and the mechanism is clarified by the simplified modal method. The gratings are fabricated by direct laser writing lithography. The diffraction efficiency of fabricated grating is more than 86% at 1064 nm wavelength (97.6% in theory). This reflective grating should be a useful optical element in the field of high-power lasers as well as other reflective applications. PMID:27409211

  16. A Novel Triangular Shaped UWB Fractal Antenna Using Circular Slot

    NASA Astrophysics Data System (ADS)

    Shahu, Babu Lal; Pal, Srikanta; Chattoraj, Neela

    2016-03-01

    The article presents the design of triangular shaped fractal based antenna with circular slot for ultra wideband (UWB) application. The antenna is fed using microstrip line and has overall dimension of 24×24×1.6 mm3. The proposed antenna is covering the wide frequency bandwidth of 2.99-11.16 GHz and is achieved using simple fractal based triangular-circular geometries and asymmetrical ground plane. The antenna is designed and parametrical studies are performed using method of moment (MOM) based Full Wave Electromagnetic (EM) software Simulator Zeland IE3D. The prototype of proposed antenna is fabricated and tested to compare the simulated and measured results of various antenna parameters. The antenna has good impedance bandwidth, nearly constant gain and stable radiation pattern. Measured return loss shows fair agreement with simulated one. Also measured group delay variation obtained is less than 1.0 ns, which proves good time domain behavior of the proposed antenna.

  17. Three-dimensional vibrations of cantilevered right triangular plates

    NASA Astrophysics Data System (ADS)

    McGee, O. G.; Giaimo, G. T.

    1992-12-01

    The first known three-dimensional continuum vibration solutions for cantilevered right triangular plates with variable thickness are obtained using the Ritz method. Assumed displacement functions are in the form of algebraic polynomials, which satisfy the fixed face conditions exactly, and which are mathematically complete. Reasonably accurate natural frequencies are calculated for low aspect ratio, right triangular thin plates having arbitrary values of thickness taper ratios in the spanwise direction. Detailed numerical studies show that a three-dimensional analysis is essential to monitoring coupled-mode sensitivities in the variation of non-dimensional natural frequencies with increasing thickness taper ratio. Upper bound results, obtained using the present method, are compared with those obtained by other investigators using ordinary beam theories, two-dimensional finite element and finite difference procedures, and experimental methods. This unified comparison of upper and lower bound solutions is presented here with the aim of 'bracketing' the exact analytical solution of the subject problem.

  18. The free vibration of isotropic and specially orthotropic triangular plates

    NASA Astrophysics Data System (ADS)

    Kim, C. S.

    1991-05-01

    A relatively simple Rayleigh Ritz solution, with simple polynomials as the admissible functions, was given for the free vibration analysis of thin, isotropic and orthotropic, right triangular plates. Numerical results were obtained for plates of various aspect ratios and having all combinations of the classical free, simply supported and clamped boundary conditions. In the present paper, the method is extended to apply to plates of general triangular planform. The analysis remains relatively simple and the computational work remains less than that required when using the methods described in most eariler studies, whilst the accuracy is comparable. Sample studies illustrating the convergence of the solution are given and comparison with results available from the literature show the validity of the approach. Natural frequency parameters and nodal patterns have been determined for a fairly comprehensive selection of particular plates, a few of these results being reported here.

  19. Self-Avoiding Walks over Adaptive Triangular Grids

    NASA Technical Reports Server (NTRS)

    Heber, Gerd; Biswas, Rupak; Gao, Guang R.; Saini, Subhash (Technical Monitor)

    1998-01-01

    In this paper, we present a new approach to constructing a "self-avoiding" walk through a triangular mesh. Unlike the popular approach of visiting mesh elements using space-filling curves which is based on a geometric embedding, our approach is combinatorial in the sense that it uses the mesh connectivity only. We present an algorithm for constructing a self-avoiding walk which can be applied to any unstructured triangular mesh. The complexity of the algorithm is O(n x log(n)), where n is the number of triangles in the mesh. We show that for hierarchical adaptive meshes, the algorithm can be easily parallelized by taking advantage of the regularity of the refinement rules. The proposed approach should be very useful in the run-time partitioning and load balancing of adaptive unstructured grids.

  20. New triangular and quadrilateral plate-bending finite elements

    NASA Technical Reports Server (NTRS)

    Narayanaswami, R.

    1974-01-01

    A nonconforming plate-bending finite element of triangular shape and associated quadrilateral elements are developed. The transverse displacement is approximated within the element by a quintic polynomial. The formulation takes into account the effects of transverse shear deformation. Results of the static and dynamic analysis of a square plate, with edges simply supported or clamped, are compared with exact solutions. Good accuracy is obtained in all calculations.

  1. A Step-Wise Approach to Elicit Triangular Distributions

    NASA Technical Reports Server (NTRS)

    Greenberg, Marc W.

    2013-01-01

    Adapt/combine known methods to demonstrate an expert judgment elicitation process that: 1.Models expert's inputs as a triangular distribution, 2.Incorporates techniques to account for expert bias and 3.Is structured in a way to help justify expert's inputs. This paper will show one way of "extracting" expert opinion for estimating purposes. Nevertheless, as with most subjective methods, there are many ways to do this.

  2. Mott Insulating Ground State on a Triangular Surface Lattice

    SciTech Connect

    Weitering, H.; Shi, X.; Weitering, H.; Johnson, P.; Chen, J.; DiNardo, N.; DiNardo, N.; Kempa, K.

    1997-02-01

    Momentum-resolved direct and inverse photoemission spectra of the K/Si(111)-({radical}(3){times}{radical}(3))R30{degree}-B interface reveals the presence of strongly localized surface states. The K overlayer remains nonmetallic up to the saturation coverage. This system most likely presents the first experimental realization of a frustrated spin 1/2 Heisenberg antiferromagnet on a two-dimensional triangular lattice. {copyright} {ital 1997} {ital The American Physical Society}

  3. Development of Negative Triangularity Plasmas in DIII-D

    NASA Astrophysics Data System (ADS)

    Walker, M. L.

    2015-11-01

    We report on development of DIII-D electron cyclotron heated discharges with controlled negative triangularity plasma shapes, to evaluate the effect on electron heat transport in L-mode plasmas, as reported on TCV. Analysis of TCV data found that negative triangularity exerts a stabilizing influence on the trapped electron mode, the dominant instability in the conditions of those experiments. Major objectives of the DIII-D development are producing complementary plasmas, one with negative and one with positive triangularity, approximately symmetric in major radial coordinate and having similar density and current profiles. Major constraints include selection of plasma parameters and toroidal field to optimize fluctuation diagnostic measurements while preventing transition from L- to H-mode and deposition of EC heating power near the q=1 surface to limit sawteeth. Issues discussed are definition of control scenarios by which the pair of shapes are accessed and their resulting controllability under the constraints imposed by DIII-D shaping control. Supported by US DOE under DE-FC02-04ER54698.

  4. Natural convection in asymmetric triangular enclosures heated from below

    NASA Astrophysics Data System (ADS)

    Kamiyo, O. M.; Angeli, D.; Barozzi, G. S.; Collins, M. W.

    2014-11-01

    Triangular enclosures are typical configurations of attic spaces found in residential as well as industrial pitched-roof buildings. Natural convection in triangular rooftops has received considerable attention over the years, mainly on right-angled and isosceles enclosures. In this paper, a finite volume CFD package is employed to study the laminar air flow and temperature distribution in asymmetric rooftop-shaped triangular enclosures when heated isothermally from the base wall, for aspect ratios (AR) 0.2 <= AR <= 1.0, and Rayleigh number (Ra) values 8 × 105 <= Ra <= 5 × 107. The effects of Rayleigh number and pitch angle on the flow structure and temperature distributions within the enclosure are analysed. Results indicate that, at low pitch angle, the heat transfer between the cold inclined and the hot base walls is very high, resulting in a multi-cellular flow structure. As the pitch angle increases, however, the number of cells reduces, and the total heat transfer rate progressively reduces, even if the Rayleigh number, being based on the enclosure height, rapidly increases. Physical reasons for the above effect are inspected.

  5. Parabolic similariton Yb-fiber laser with triangular pulse evolution

    NASA Astrophysics Data System (ADS)

    Wang, Sijia; Wang, Lei

    2016-04-01

    We propose a novel mode-locked fiber laser design which features a passive nonlinear triangular pulse formation and self-similar parabolic pulse amplification intra cavity. Attribute to the nonlinear reshaping progress in the passive fiber, a triangular-profiled pulse with negative-chirp is generated and paved the way for rapid and efficient self-similar parabolic evolution in a following short-length high-gain fiber. In the meanwhile, the accompanied significantly compressed narrow spectrum from this passive nonlinear reshaping also gives the promise of pulse stabilization and gain-shaping robustness without strong filtering. The resulting short average intra-cavity pulse duration, low amplified spontaneous emission (ASE) and low intra-cavity power loss are essential for the low-noise operation. Simulations predict this modelocked fiber laser allows for high-energy ultra-short transform-limited pulse generation exceeding the gain bandwidth. The output pulse has a de-chirped duration (full-width at half maximum, FWHM) of 27 fs. In addition to the ultrafast laser applications, the proposed fiber laser scheme can support low-noise parabolic and triangular pulse trains at the same time, which are also attractive in optical pulse shaping, all-optical signal processing and high-speed communication applications.

  6. Effects of dietary addition of heat-killed Mycobacterium phlei on growth performance, immune status and anti-oxidative capacity in early weaned piglets.

    PubMed

    Zhong, Jin-Feng; Wu, Wei-Gao; Zhang, Xiao-Qing; Tu, Wei; Liu, Zhen-Xiang; Fang, Re-Jun

    2016-08-01

    The contradiction between high susceptibility of early weaned piglets to enteric pathogens and rigid restriction of antibiotic use in the diet is still prominent in the livestock production industry. To address this issue, the study was designed to replace dietary antibiotics partly or completely by an immunostimulant, namely heat-killed Mycobacterium phlei (M. phlei). Piglets (n = 192) were randomly assigned to one of the four groups: (1) basal diet (Group A), (2) basal diet + a mixture of antibiotics (80 mg/kg diet, Group B), (3) basal diet + a mixture of antibiotics (same as in Group B, but 40 mg/kg diet) + heat-killed M. phlei (1.5 g/kg diet) (Group C) and (4) basal diet + heat-killed M. phlei (3 g/kg diet) (Group D). All piglets received the respective diets from days 21 to 51 of age and were weaned at the age of 28 d. Compared with the Control (Group A), in all other groups the average daily gain, average daily feed intake, small intestinal villus height:crypt depth ratio and protein levels of occludin and ZO-1 in the jejunal mucosa were increased. A decreased incidence of diarrhoea in conjunction with an increased sIgA concentration in the intestinal mucosa and serum IL-12 and IFN-γ concentrations was found in groups supplemented with heat-killed M. phlei (Groups C and D), but not in Group B. Groups C and D also showed decreased IL-2 concentrations in the intestinal mucosa with lower TLR4 and phosphor-IκB protein levels. The antioxidant capacity was reinforced in Groups C and D, as evidenced by the reduction in malondialdehyde and enhanced activities of antioxidant enzymes in serum. These data indicate that heat-killed M. phlei is a promising alternative to antibiotic use for early weaned piglets via induction of protective immune responses. PMID:27216553

  7. Early BMP, Wnt and Ca(2+)/PKC pathway activation predicts the bone forming capacity of periosteal cells in combination with calcium phosphates.

    PubMed

    Bolander, Johanna; Chai, Yoke Chin; Geris, Liesbet; Schrooten, Jan; Lambrechts, Dennis; Roberts, Scott J; Luyten, Frank P

    2016-04-01

    The development of osteoinductive calcium phosphate- (CaP) based biomaterials has, and continues to be, a major focus in the field of bone tissue engineering. However, limited insight into the spatiotemporal activation of signalling pathways has hampered the optimisation of in vivo bone formation and subsequent clinical translation. To gain further knowledge regarding the early molecular events governing bone tissue formation, we combined human periosteum derived progenitor cells with three types of clinically used CaP-scaffolds, to obtain constructs with a distinct range of bone forming capacity in vivo. Protein phosphorylation together with gene expression for key ligands and target genes were investigated 24 hours after cell seeding in vitro, and 3 and 12 days post ectopic implantation in nude mice. A computational modelling approach was used to deduce critical factors for bone formation 8 weeks post implantation. The combined Ca(2+)-mediated activation of BMP-, Wnt- and PKC signalling pathways 3 days post implantation were able to discriminate the bone forming from the non-bone forming constructs. Subsequently, a mathematical model able to predict in vivo bone formation with 96% accuracy was developed. This study illustrates the importance of defining and understanding CaP-activated signalling pathways that are required and sufficient for in vivo bone formation. Furthermore, we demonstrate the reliability of mathematical modelling as a tool to analyse and deduce key factors within an empirical data set and highlight its relevance to the translation of regenerative medicine strategies. PMID:26901484

  8. Modelling of Motion of Bodies Near Triangular Lagrangian Points

    NASA Astrophysics Data System (ADS)

    Bobrov, O. A.

    In this paper, we consider a system of three bodies connected by gravity, two of which are of comparable mass (the Sun and Jupiter), and the third is negligible and it is located in one of the triangular Lagrange points (restricted 3 - body problem). We used the equations of motion in a planar coordinate system that rotates together with massive bodies. Several programs have been written in the programming environment Pascal ABC, in order to build the trajectory of a small body, to indicate the osculating orbit around a massive body, to display equipotential surfaces.

  9. Frustration and correlations in stacked triangular-lattice Ising antiferromagnets

    NASA Astrophysics Data System (ADS)

    Burnell, F. J.; Chalker, J. T.

    2015-12-01

    We study multilayer triangular-lattice Ising antiferromagnets with interlayer interactions that are weak and frustrated in an abc stacking. By analyzing a coupled height model description of these systems, we show that they exhibit a classical spin liquid regime at low temperature, in which both intralayer and interlayer correlations are strong but there is no long-range order. Diffuse scattering in this regime is concentrated on a helix in reciprocal space, as observed for charge ordering in the materials LuFe2O4 and YbFe2O4 .

  10. INTEGRATING A LINEAR INTERPOLATION FUNCTION ACROSS TRIANGULAR CELL BOUNDARIES

    SciTech Connect

    J. R. WISEMAN; J. S. BROCK

    2000-04-01

    Computational models of particle dynamics often exchange solution data with discretized continuum-fields using interpolation functions. These particle methods require a series expansion of the interpolation function for two purposes: numerical analysis used to establish the model's consistency and accuracy, and logical-coordinate evaluation used to locate particles within a grid. This report presents discrete-expansions for a linear interpolation function commonly used within triangular cell geometries. Discrete-expansions, unlike a Taylor's series, account for interpolation discontinuities across cell boundaries and, therefore, are valid throughout a discretized domain. Verification of linear discrete-expansions is demonstrated on a simple test problem.

  11. A triangular element based on generalized potential energy concepts

    NASA Technical Reports Server (NTRS)

    Thomas, G. R.; Gallagher, R. H.

    1976-01-01

    Stiffness equations are formulated for a doubly-curved triangular thin shell finite element. The strain energy component of the potential energy is first expressed in terms of displacements and displacement gradients with the aid of consistent deep shell strain-displacement equations. The element in-plane and normal displacement fields are approximated by complete cubic polynomials. These functions do not satisfy the interelement displacement admissibility conditions. Satisfaction is forced by the imposition of constraint conditions on the interelement boundaries; the constraints represent the modification of the potential energy. Some numerical results for a pinched cylinder, a cylindrical sphere, and a pinched sphere are examined.

  12. Triangular preconditioners for saddle point problems with a penalty term

    SciTech Connect

    Klawonn, A.

    1996-12-31

    Triangular preconditioners for a class of saddle point problems with a penalty term are considered. An important example is the mixed formulation of the pure displacement problem in linear elasticity. It is shown that the spectrum of the preconditioned system is contained in a real, positive interval, and that the interval bounds can be made independent of the discretization and penalty parameters. This fact is used to construct bounds of the convergence rate of the GMRES method used with an energy norm. Numerical results are given for GMRES and BI-CGSTAB.

  13. Triangular Black Phosphorus Atomic Layers by Liquid Exfoliation.

    PubMed

    Seo, Soonjoo; Lee, Hyun Uk; Lee, Soon Chang; Kim, Yooseok; Kim, Hyeran; Bang, Junhyeok; Won, Jonghan; Kim, Youngjun; Park, Byoungnam; Lee, Jouhahn

    2016-01-01

    Few-layer black phosphorus (BP) is the most promising material among the two-dimensional materials due to its layered structure and the excellent semiconductor properties. Currently, thin BP atomic layers are obtained mostly by mechanical exfoliation of bulk BP, which limits applications in thin-film based electronics due to a scaling process. Here we report highly crystalline few-layer black phosphorus thin films produced by liquid exfoliation. We demonstrate that the liquid-exfoliated BP forms a triangular crystalline structure on SiO2/Si (001) and amorphous carbon. The highly crystalline BP layers are faceted with a preferred orientation of the (010) plane on the sharp edge, which is an energetically most favorable facet according to the density functional theory calculations. Our results can be useful in understanding the triangular BP structure for large-area applications in electronic devices using two-dimensional materials. The sensitivity and selectivity of liquid-exfoliated BP to gas vapor demonstrate great potential for practical applications as sensors. PMID:27026070

  14. Triangular covariance factorizations for. Ph.D. Thesis. - Calif. Univ.

    NASA Technical Reports Server (NTRS)

    Thornton, C. L.

    1976-01-01

    An improved computational form of the discrete Kalman filter is derived using an upper triangular factorization of the error covariance matrix. The covariance P is factored such that P = UDUT where U is unit upper triangular and D is diagonal. Recursions are developed for propagating the U-D covariance factors together with the corresponding state estimate. The resulting algorithm, referred to as the U-D filter, combines the superior numerical precision of square root filtering techniques with an efficiency comparable to that of Kalman's original formula. Moreover, this method is easily implemented and involves no more computer storage than the Kalman algorithm. These characteristics make the U-D method an attractive realtime filtering technique. A new covariance error analysis technique is obtained from an extension of the U-D filter equations. This evaluation method is flexible and efficient and may provide significantly improved numerical results. Cost comparisons show that for a large class of problems the U-D evaluation algorithm is noticeably less expensive than conventional error analysis methods.

  15. Honeycomb and triangular domain wall networks in heteroepitaxial systems

    NASA Astrophysics Data System (ADS)

    Elder, K. R.; Chen, Z.; Elder, K. L. M.; Hirvonen, P.; Mkhonta, S. K.; Ying, S.-C.; Granato, E.; Huang, Zhi-Feng; Ala-Nissila, T.

    2016-05-01

    A comprehensive study is presented for the influence of misfit strain, adhesion strength, and lattice symmetry on the complex Moiré patterns that form in ultrathin films of honeycomb symmetry adsorbed on compact triangular or honeycomb substrates. The method used is based on a complex Ginzburg-Landau model of the film that incorporates elastic strain energy and dislocations. The results indicate that different symmetries of the heteroepitaxial systems lead to distinct types of domain wall networks and phase transitions among various surface Moiré patterns and superstructures. More specifically, the results show a dramatic difference between the phase diagrams that emerge when a honeycomb film is adsorbed on substrates of honeycomb versus triangular symmetry. It is also shown that in the small deformation limit, the complex Ginzburg-Landau model reduces to a two-dimensional sine-Gordon free energy form. This free energy can be solved exactly for one dimensional patterns and reveals the role of domains walls and their crossings in determining the nature of the phase diagrams.

  16. Triangular Black Phosphorus Atomic Layers by Liquid Exfoliation

    PubMed Central

    Seo, Soonjoo; Lee, Hyun Uk; Lee, Soon Chang; Kim, Yooseok; Kim, Hyeran; Bang, Junhyeok; Won, Jonghan; Kim, Youngjun; Park, Byoungnam; Lee, Jouhahn

    2016-01-01

    Few-layer black phosphorus (BP) is the most promising material among the two-dimensional materials due to its layered structure and the excellent semiconductor properties. Currently, thin BP atomic layers are obtained mostly by mechanical exfoliation of bulk BP, which limits applications in thin-film based electronics due to a scaling process. Here we report highly crystalline few-layer black phosphorus thin films produced by liquid exfoliation. We demonstrate that the liquid-exfoliated BP forms a triangular crystalline structure on SiO2/Si (001) and amorphous carbon. The highly crystalline BP layers are faceted with a preferred orientation of the (010) plane on the sharp edge, which is an energetically most favorable facet according to the density functional theory calculations. Our results can be useful in understanding the triangular BP structure for large-area applications in electronic devices using two-dimensional materials. The sensitivity and selectivity of liquid-exfoliated BP to gas vapor demonstrate great potential for practical applications as sensors. PMID:27026070

  17. Triangular Black Phosphorus Atomic Layers by Liquid Exfoliation.

    PubMed

    Seo, Soonjoo; Lee, Hyun Uk; Lee, Soon Chang; Kim, Yooseok; Kim, Hyeran; Bang, Junhyeok; Won, Jonghan; Kim, Youngjun; Park, Byoungnam; Lee, Jouhahn

    2016-03-30

    Few-layer black phosphorus (BP) is the most promising material among the two-dimensional materials due to its layered structure and the excellent semiconductor properties. Currently, thin BP atomic layers are obtained mostly by mechanical exfoliation of bulk BP, which limits applications in thin-film based electronics due to a scaling process. Here we report highly crystalline few-layer black phosphorus thin films produced by liquid exfoliation. We demonstrate that the liquid-exfoliated BP forms a triangular crystalline structure on SiO2/Si (001) and amorphous carbon. The highly crystalline BP layers are faceted with a preferred orientation of the (010) plane on the sharp edge, which is an energetically most favorable facet according to the density functional theory calculations. Our results can be useful in understanding the triangular BP structure for large-area applications in electronic devices using two-dimensional materials. The sensitivity and selectivity of liquid-exfoliated BP to gas vapor demonstrate great potential for practical applications as sensors.

  18. Triangular Black Phosphorus Atomic Layers by Liquid Exfoliation

    NASA Astrophysics Data System (ADS)

    Seo, Soonjoo; Lee, Hyun Uk; Lee, Soon Chang; Kim, Yooseok; Kim, Hyeran; Bang, Junhyeok; Won, Jonghan; Kim, Youngjun; Park, Byoungnam; Lee, Jouhahn

    2016-03-01

    Few-layer black phosphorus (BP) is the most promising material among the two-dimensional materials due to its layered structure and the excellent semiconductor properties. Currently, thin BP atomic layers are obtained mostly by mechanical exfoliation of bulk BP, which limits applications in thin-film based electronics due to a scaling process. Here we report highly crystalline few-layer black phosphorus thin films produced by liquid exfoliation. We demonstrate that the liquid-exfoliated BP forms a triangular crystalline structure on SiO2/Si (001) and amorphous carbon. The highly crystalline BP layers are faceted with a preferred orientation of the (010) plane on the sharp edge, which is an energetically most favorable facet according to the density functional theory calculations. Our results can be useful in understanding the triangular BP structure for large-area applications in electronic devices using two-dimensional materials. The sensitivity and selectivity of liquid-exfoliated BP to gas vapor demonstrate great potential for practical applications as sensors.

  19. Chiral Bosonic Mott Insulator on the Frustrated Triangular Lattice

    NASA Astrophysics Data System (ADS)

    Parameswaran, Siddharth; Zaletel, Michael; Rüegg, Andreas; Altman, Ehud

    2014-03-01

    We study the superfluid and insulating phases of interacting bosons on the triangular lattice with an inverted dispersion, corresponding to frustrated hopping between sites. The resulting single-particle dispersion has multiple minima at nonzero wavevectors in momentum space, in contrast to the unique zero-wavevector minimum of the unfrustrated problem. As a consequence, the superfluid phase is unstable against developing additional chiral order that breaks time reversal (T) and parity (P) symmetries by forming a condensate at nonzero wavevector. We demonstrate that the loss of superfluidity can lead to an even more exotic phase, the chiral Mott insulator, with nontrivial current order that breaks T, P. These results are obtained via variational estimates, as well as a combination of bosonization and DMRG of triangular ladders, which taken together permit a fairly complete characterization of the phase diagram. We discuss the relevance of these phases to optical lattice experiments, as well as signatures of chiral symmetry breaking in time-of-flight images. We acknowledge support from NSF Grants 1066293 (SP, EA) and DGE-1106400 (MPZ), the Simons Foundation (SP), the Swiss National Science Foundation (AR), the ISF, BSF, ERC Synergy UQUAM program and the Miller Institute at UC Berkeley (EA).

  20. Chiral bosonic Mott insulator on the frustrated triangular lattice

    NASA Astrophysics Data System (ADS)

    Zaletel, Michael P.; Parameswaran, S. A.; Rüegg, Andreas; Altman, Ehud

    2014-04-01

    We study the superfluid and insulating phases of interacting bosons on the triangular lattice with an inverted dispersion, corresponding to frustrated hopping between sites. The resulting single-particle dispersion has multiple minima at nonzero wave vectors in momentum space, in contrast to the unique zero-wave-vector minimum of the unfrustrated problem. As a consequence, the superfluid phase is unstable against developing additional chiral order that breaks time-reversal (T) and parity (P) symmetries by forming a condensate at nonzero wave vector. We demonstrate that the loss of superfluidity can lead to an even more exotic phase, the chiral Mott insulator, with nontrivial current order that breaks T ,P. These results are obtained via variational estimates, as well as a combination of bosonization and density-matrix renormalization group of triangular ladders, which, taken together, permit a fairly complete characterization of the phase diagram. We discuss the relevance of these phases to optical lattice experiments, as well as signatures of chiral symmetry breaking in time-of-flight images.

  1. RKKY interaction in triangular MoS2 nanoflakes

    NASA Astrophysics Data System (ADS)

    Mastrogiuseppe, Diego; Avalos-Ovando, Oscar; Ulloa, Sergio

    Transition-metal dichalcogenides (TMDs), such as MoS2, possess unique electronic and optical properties, making them promising for optospintronics. Exfoliation and CVD growth processes produce nanoflakes of different shapes, often triangular with zigzag edges. Magnetic impurities in this material interact indirectly through the TMD conduction electrons/holes. Using an effective 3-orbital tight-binding model, we study the Ruderman-Kittel-Kasuya-Yosida interaction between magnetic impurities in p-doped triangular flakes with zigzag termination. We analyze the interaction as function of impurity separation along high symmetry directions in the nanoflake, considering hybridization to different Mo orbitals, and different fillings. The interaction is anisotropic for impurities in the interior of the flake. However, when impurities lie on the edges of the crystallite, the effective exchange is Ising-like, reflecting the presence of z2-orbitals associated with edge states. Other interactions are possible by selecting impurity positions and orbital character of the states in their neighborhood. Our results can be tested with local probes, such as spin-polarized STM Supported by NSF DMR-1508325.

  2. Coupled spin-charge order in frustrated itinerant triangular magnets

    NASA Astrophysics Data System (ADS)

    Reja, Sahinur; Ray, Rajyavardhan; van den Brink, Jeroen; Kumar, Sanjeev

    2015-04-01

    We uncover four spin-charge ordered ground states in the strong coupling limit of the Kondo lattice model on triangular geometry. The results are obtained using Monte Carlo simulations, with a classical treatment of localized moments. Two of the states at one-third electronic filling (n =1 /3 ) consist of decorated ferromagnetic chains coupled antiferromagnetically with the neighboring chains. The third magnetic ground state is noncollinear, consisting of antiferromagnetic chains separated by a pair of canted ferromagnetic chains. An even more unusual magnetic ground state, a variant of the 120∘ Yafet-Kittel phase, is discovered at n =2 /3 . These magnetic orders are stabilized by opening a gap in the electronic spectrum: a "band effect." All the phases support modulations in the electronic charge density due to the presence of magnetically inequivalent sites. In particular, the charge ordering pattern found at n =2 /3 is observed in various triangular lattice systems, such as 2 H -AgNiO2, 3 R -AgNiO2, and NaxCoO2 .

  3. SHIFT: a distributed runoff model using irregular triangular facets*1

    NASA Astrophysics Data System (ADS)

    Palacios-Vélez, Oscar Luis; Cuevas-Renaud, Baltasar

    1992-06-01

    SHIFT (Sistema HIdrológico de Facetas Triangulares) is a computational system that allows for the: (1) creation, editing and visualization of a watershed Digital Elevation Model (DEM), based on the Triangular Irregular Network (TIN) concepts; (2) input and interpolation of soil, river-bed, and rainfall data; and (3) calculation and routing of runoff in all the facets and reaches. The TIN DEM model is constructed from a set of points, where the slope changes abruptly. Afterwards, the drainage network is automatically identified and an interactive editor allows the addition or deletion of points to eliminate network discontinuities. Rainfall data are interpolated by means of a procedure based on the minimization of the bending energy of a thin plate. In order to calculate and route the runoff, the system determines the routing sequence of river segments and for each one: identifies the facets forming the contributing area; and determines a cascade of overland flow planes. Then, for each element and time interval, the system calculates the infiltration and routes the resultant runoff by a numerical solution of the kinematic wave equations. This information is saved and the user can see the hydrograph for any facet or reach.

  4. Self-assembly of triangular quantum dots on (111)A substrates by droplet epitaxy

    SciTech Connect

    Jo, M.; Mano, T.; Abbarchi, M.; Kuroda, T.; Sakoda, K.

    2014-05-15

    We report the self-assembly of triangular GaAs quantum dots (QDs) on (111)A substrates using droplet epitaxy. Shape transition from hexagonal to triangular QDs is observed with increasing crystallizing temperature. The mechanism of the morphological change is discussed in terms of different growth rates of step edges on a (111)A substrate.

  5. Collision-geometry fluctuations and triangular flow in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Alver, B.; Roland, G.

    2010-05-01

    We introduce the concepts of participant triangularity and triangular flow in heavy-ion collisions, analogous to the definitions of participant eccentricity and elliptic flow. The participant triangularity characterizes the triangular anisotropy of the initial nuclear overlap geometry and arises from event-by-event fluctuations in the participant-nucleon collision points. In studies using a multiphase transport model (AMPT), a triangular flow signal is observed that is proportional to the participant triangularity and corresponds to a large third Fourier coefficient in two-particle azimuthal correlation functions. Using two-particle azimuthal correlations at large pseudorapidity separations measured by the PHOBOS and STAR experiments, we show that this Fourier component is also present in data. Ratios of the second and third Fourier coefficients in data exhibit similar trends as a function of centrality and transverse momentum as in AMPT calculations. These findings suggest a significant contribution of triangular flow to the ridge and broad away-side features observed in data. Triangular flow provides a new handle on the initial collision geometry and collective expansion dynamics in heavy-ion collisions.

  6. Electron sharing and anion-π recognition in molecular triangular prisms.

    PubMed

    Schneebeli, Severin T; Frasconi, Marco; Liu, Zhichang; Wu, Yilei; Gardner, Daniel M; Strutt, Nathan L; Cheng, Chuyang; Carmieli, Raanan; Wasielewski, Michael R; Stoddart, J Fraser

    2013-12-01

    Stacking on a full belly: Triangular molecular prisms display electron sharing among their triangularly arranged naphthalenediimide (NDI) redox centers. Their electron-deficient cavities encapsulate linear triiodide anions, leading to the formation of supramolecular helices in the solid state. Chirality transfer is observed from the six chiral centers of the filled prisms to the single-handed helices.

  7. Collision-geometry fluctuations and triangular flow in heavy-ion collisions

    SciTech Connect

    Alver, B.; Roland, G.

    2010-05-15

    We introduce the concepts of participant triangularity and triangular flow in heavy-ion collisions, analogous to the definitions of participant eccentricity and elliptic flow. The participant triangularity characterizes the triangular anisotropy of the initial nuclear overlap geometry and arises from event-by-event fluctuations in the participant-nucleon collision points. In studies using a multiphase transport model (AMPT), a triangular flow signal is observed that is proportional to the participant triangularity and corresponds to a large third Fourier coefficient in two-particle azimuthal correlation functions. Using two-particle azimuthal correlations at large pseudorapidity separations measured by the PHOBOS and STAR experiments, we show that this Fourier component is also present in data. Ratios of the second and third Fourier coefficients in data exhibit similar trends as a function of centrality and transverse momentum as in AMPT calculations. These findings suggest a significant contribution of triangular flow to the ridge and broad away-side features observed in data. Triangular flow provides a new handle on the initial collision geometry and collective expansion dynamics in heavy-ion collisions.

  8. Electron sharing and anion-π recognition in molecular triangular prisms.

    PubMed

    Schneebeli, Severin T; Frasconi, Marco; Liu, Zhichang; Wu, Yilei; Gardner, Daniel M; Strutt, Nathan L; Cheng, Chuyang; Carmieli, Raanan; Wasielewski, Michael R; Stoddart, J Fraser

    2013-12-01

    Stacking on a full belly: Triangular molecular prisms display electron sharing among their triangularly arranged naphthalenediimide (NDI) redox centers. Their electron-deficient cavities encapsulate linear triiodide anions, leading to the formation of supramolecular helices in the solid state. Chirality transfer is observed from the six chiral centers of the filled prisms to the single-handed helices. PMID:24227594

  9. Mitochondrial and peroxisomal fatty acid oxidation capacities increase in the skeletal muscles of young pigs during early postnatal development but are not affected by cold stress.

    PubMed

    Herpin, Patrick; Vincent, Annie; Fillaut, Martine; Bonito, Bruno Piteira; Hocquette, Jean-François

    2003-01-01

    In pigs, the optimal utilization of energy substrates within muscle fibers is a prerequisite of the utmost importance for successful adaptation to extra-uterine life. In the present work we demonstrate that fatty acid (FA) oxidative capacities increased within the first five days of life in piglet skeletal muscle. Mitochondrial FA oxidation capacities increased more in the rhomboideus oxidative than in the longissimus lumborum glycolytic muscle (+114% vs. +62%, P < 0.001). The apparent rate of fatty acid degradation by peroxisomes represents 30 to 40% of total FA oxidation capacities and increased by about 170% (P < 0.001) with age in both muscles. The postnatal enhancement of skeletal muscle oxidative capacities was further supported by a rise in acid-soluble and long-chain acylcamitine tissue levels (+67%, P < 0.01), and plasma levels of albumin (+160%, P < 0.001). Cold stress had no effect on mitochondrial and peroxisomal FA oxidation but greatly enhanced (+61%, P < 0.05) the circulating levels of non-esterified fatty acids at five days of life.

  10. Combined natural convection and radiation in a triangular enclosure

    NASA Astrophysics Data System (ADS)

    Hasani, Syed Muhammad Fakhir

    The problem of combined natural convection and radiation heat transfer of a gray absorbing-emitting and isotropically scattering medium in a triangular enclosure is solved numerically in this dissertation. Interactions of natural convection and radiation occur in many engineering applications such as electronic cooling, solar heating, crystal growth, fire propagation etc. The radiation effect was neglected from many of the previous studies due to the complexities associated with radiation modeling. The triangular enclosure considered in the present study has been used by researchers in the past to model flows inside attic spaces, solar stills and near shore water circulation in lakes and rivers. Previous pure natural convection studies in this geometry had produced conflicting results and the effect of radiation was not considered prior to this study. The objectives of this study are: (i) to obtain a numerical solution for the combined natural convection and radiation problem in a triangular enclosure, (ii) to study the influence of radiation on thermal instabilities present in pure natural convection flow in this geometry, (iii) to perform parametric study and (iv) to verify the results of pure natural convection flow using more accurate QUICK scheme. The problem is mathematically formulated and a Fortran computer program is developed to meet the desired objectives. The two dimensional stream function equation, the time-dependent vorticity transport and energy equations, and the radiative transport equation are solved simultaneously for uniform temperature boundary conditions. Two different sets of boundary conditions are employed with inclined surfaces considered hot for one and cold for the other. The stream function equation is solved using successive overrelaxation whereas the vorticity transport and energy equations are solved using third-order upwinding QUICK scheme while the radiative transport solution is sought by means of Discrete Ordinates Method. Two

  11. Extraordinary room-temperature photoluminescence in triangular WS2 monolayers.

    PubMed

    Gutiérrez, Humberto R; Perea-López, Nestor; Elías, Ana Laura; Berkdemir, Ayse; Wang, Bei; Lv, Ruitao; López-Urías, Florentino; Crespi, Vincent H; Terrones, Humberto; Terrones, Mauricio

    2013-08-14

    Individual monolayers of metal dichalcogenides are atomically thin two-dimensional crystals with attractive physical properties different from those of their bulk counterparts. Here we describe the direct synthesis of WS2 monolayers with triangular morphologies and strong room-temperature photoluminescence (PL). The Raman response as well as the luminescence as a function of the number of S-W-S layers is also reported. The PL weakens with increasing number of layers due to a transition from direct band gap in a monolayer to indirect gap in multilayers. The edges of WS2 monolayers exhibit PL signals with extraordinary intensity, around 25 times stronger than that at the platelet's center. The structure and chemical composition of the platelet edges appear to be critical for PL enhancement.

  12. Solving sparse triangular linear systems on parallel computers

    NASA Technical Reports Server (NTRS)

    Anderson, Edward; Saad, Youcef

    1989-01-01

    This paper describes and compares three parallel algorithms for solving sparse triangular systems of equations. These methods involve some preprocessing overhead and are primarily of interest in solving many systems with the same coefficient matrix. The first approach is to use a fixed blocksize and form the inverse of the diagonal blocks. The second approach is to use a variable blocksize and reorder the unknowns so that the diagonal blocks are diagonal matrices. The latter technique is called level scheduling because of how it is represented in the adjacency graph, and both row-wise and jagged diagonal storage for the off-diagonal blocks are considered. These techniques are analyzed for general parallel computers and experiments are presented for the eight-processor Alliant FX/8.

  13. Quantum Paramagnet in a π Flux Triangular Lattice Hubbard Model.

    PubMed

    Rachel, Stephan; Laubach, Manuel; Reuther, Johannes; Thomale, Ronny

    2015-04-24

    We propose the π flux triangular lattice Hubbard model (π THM) as a prototypical setup to stabilize magnetically disordered quantum states of matter in the presence of charge fluctuations. The quantum paramagnetic domain of the π THM that we identify for intermediate Hubbard U is framed by a Dirac semimetal for weak coupling and by 120° Néel order for strong coupling. Generalizing the Klein duality from spin Hamiltonians to tight-binding models, the π THM maps to a Hubbard model which corresponds to the (J_{H},J_{K})=(-1,2) Heisenberg-Kitaev model in its strong coupling limit. The π THM provides a promising microscopic testing ground for exotic finite-U spin liquid ground states amenable to numerical investigation. PMID:25955072

  14. Field-induced decays in XXZ triangular-lattice antiferromagnets

    NASA Astrophysics Data System (ADS)

    Maksimov, P. A.; Zhitomirsky, M. E.; Chernyshev, A. L.

    2016-10-01

    We investigate field-induced transformations in the dynamical response of the XXZ model on the triangular lattice that are associated with the anharmonic magnon coupling and decay phenomena. Detailed theoretical predictions are made for Ba3CoSb2O9 , which provides a close realization of the spin-1/2 XXZ model. We demonstrate that dramatic modifications in the magnon spectrum must occur in low out-of-plane fields that are easily achievable for this material. The hallmark of the effect is a coexistence of the clearly distinct well-defined magnon excitations with significantly broadened ones in different regions of the k -ω space. The field-induced decays are generic for this class of models and become more prominent at larger anisotropies and in higher fields.

  15. Spin Fluctuations from Hertz to Terahertz on a Triangular Lattice.

    PubMed

    Nambu, Yusuke; Gardner, Jason S; MacLaughlin, Douglas E; Stock, Chris; Endo, Hitoshi; Jonas, Seth; Sato, Taku J; Nakatsuji, Satoru; Broholm, Collin

    2015-09-18

    The temporal magnetic correlations of the triangular-lattice antiferromagnet NiGa_{2}S_{4} are examined through 13 decades (10^{-13}-1 sec) using ultrahigh-resolution inelastic neutron scattering, muon spin relaxation, and ac and nonlinear susceptibility measurements. Unlike the short-ranged spatial correlations, the temperature dependence of the temporal correlations show distinct anomalies. The spin fluctuation rate decreases precipitously upon cooling towards T^{*}=8.5 K, but fluctuations on the microsecond time scale then persist in an anomalous dynamical regime for 4 K

  16. Effective-medium theory of a filamentous triangular lattice.

    PubMed

    Mao, Xiaoming; Stenull, Olaf; Lubensky, T C

    2013-04-01

    We present an effective-medium theory that includes bending as well as stretching forces, and we use it to calculate the mechanical response of a diluted filamentous triangular lattice. In this lattice, bonds are central-force springs, and there are bending forces between neighboring bonds on the same filament. We investigate the diluted lattice in which each bond is present with a probability p. We find a rigidity threshold p(b) which has the same value for all positive bending rigidity and a crossover characterizing bending, stretching, and bend-stretch coupled elastic regimes controlled by the central-force rigidity percolation point at p(CF)=/~2/3 of the lattice when fiber bending rigidity vanishes. PMID:23679437

  17. Effective-medium theory of a filamentous triangular lattice

    NASA Astrophysics Data System (ADS)

    Mao, Xiaoming; Stenull, Olaf; Lubensky, T. C.

    2013-04-01

    We present an effective-medium theory that includes bending as well as stretching forces, and we use it to calculate the mechanical response of a diluted filamentous triangular lattice. In this lattice, bonds are central-force springs, and there are bending forces between neighboring bonds on the same filament. We investigate the diluted lattice in which each bond is present with a probability p. We find a rigidity threshold pb which has the same value for all positive bending rigidity and a crossover characterizing bending, stretching, and bend-stretch coupled elastic regimes controlled by the central-force rigidity percolation point at pCF≃2/3 of the lattice when fiber bending rigidity vanishes.

  18. Factorizable Upwind Schemes: The Triangular Unstructured Grid Formulation

    NASA Technical Reports Server (NTRS)

    Sidilkover, David; Nielsen, Eric J.

    2001-01-01

    The upwind factorizable schemes for the equations of fluid were introduced recently. They facilitate achieving the Textbook Multigrid Efficiency (TME) and are expected also to result in the solvers of unparalleled robustness. The approach itself is very general. Therefore, it may well become a general framework for the large-scale, Computational Fluid Dynamics. In this paper we outline the triangular grid formulation of the factorizable schemes. The derivation is based on the fact that the factorizable schemes can be expressed entirely using vector notation. without explicitly mentioning a particular coordinate frame. We, describe the resulting discrete scheme in detail and present some computational results verifying the basic properties of the scheme/solver.

  19. A transient, quadratic nodal method for triangular-Z geometry

    SciTech Connect

    DeLorey, T.F.

    1993-06-01

    Many systematically-derived nodal methods have been developed for Cartesian geometry due to the extensive interest in Light Water Reactors. These methods typically model the transverse-integrated flux as either an analytic or low order polynomial function of position within the node. Recently, quadratic nodal methods have been developed for R-Z and hexagonal geometry. A static and transient quadratic nodal method is developed for triangular-Z geometry. This development is particularly challenging because the quadratic expansion in each node must be performed between the node faces and the triangular points. As a consequence, in the 2-D plane, the flux and current at the points of the triangles must be treated. Quadratic nodal equations are solved using a non-linear iteration scheme, which utilizes the corrected, mesh-centered finite difference equations, and forces these equations to match the quadratic equations by computing discontinuity factors during the solution. Transient nodal equations are solved using the improved quasi-static method, which has been shown to be a very efficient solution method for transient problems. Several static problems are used to compare the quadratic nodal method to the Coarse Mesh Finite Difference (CMFD) method. The quadratic method is shown to give more accurate node-averaged fluxes. However, it appears that the method has difficulty predicting node leakages near reactor boundaries and severe material interfaces. The consequence is that the eigenvalue may be poorly predicted for certain reactor configurations. The transient methods are tested using a simple analytic test problem, a heterogeneous heavy water reactor benchmark problem, and three thermal hydraulic test problems. Results indicate that the transient methods have been implemented correctly.

  20. A Generalization of the Formula for the Triangular Number of the Sum and Product of Natural Numbers

    ERIC Educational Resources Information Center

    Asiru, M. A.

    2008-01-01

    This note generalizes the formula for the triangular number of the sum and product of two natural numbers to similar results for the triangular number of the sum and product of "r" natural numbers. The formula is applied to derive formula for the sum of an odd and an even number of consecutive triangular numbers.

  1. The β2-adrenoceptor agonist formoterol improves structural and functional regenerative capacity of skeletal muscles from aged rat at the early stages of postinjury.

    PubMed

    Conte, Talita C; Silva, Lucila H; Silva, Meiricris T; Hirabara, Sandro M; Oliveira, Antonio C; Curi, Rui; Moriscot, Anselmo S; Aoki, Marcelo S; Miyabara, Elen H

    2012-05-01

    Skeletal muscles from old rats fail to completely regenerate following injury. This study investigated whether pharmacological stimulation of β2-adrenoceptors in aged muscles following injury could improve their regenerative capacity, focusing on myofiber size recovery. Young and aged rats were treated with a subcutaneous injection of β2-adrenergic agonist formoterol (2 μg/kg/d) up to 10 and 21 days after soleus muscle injury. Formoterol-treated muscles from old rats evaluated at 10 and 21 days postinjury showed reduced inflammation and connective tissue but a similar number of regenerating myofibers of greater caliber when compared with their injured controls. Formoterol minimized the decrease in tetanic force and increased protein synthesis and mammalian target of rapamycin phosphorylation in old muscles at 10 days postinjury. Our results suggest that formoterol improves structural and functional regenerative capacity of regenerating skeletal muscles from aged rats by increasing protein synthesis via mammalian target of rapamycin activation. Furthermore, formoterol may have therapeutic benefits in recovery following muscle damage in senescent individuals.

  2. Fraunhofer diffraction of Laguerre-Gaussian beam caused by a dynamic superposed dual-triangular aperture

    NASA Astrophysics Data System (ADS)

    Li, Xinzhong; Tai, Yuping; Nie, Zhaogang; Wang, Hui; Li, Hehe; Wang, Jingge; Tang, Jie; Wang, Yishan

    2015-12-01

    We investigate the Fraunhofer diffraction of a Laguerre-Gaussian (LG) beam incident on a dynamic superposed dual-triangular aperture. The evolution of the diffraction pattern from this aperture is analyzed experimentally and theoretically. A special aperture, called the hex-star triangular aperture, demonstrates interesting diffraction patterns. Further, the diffraction properties of integer, half-integer, and fractional orders of topological charges at the Fraunhofer zone are studied by using the hex-star triangular aperture. This study can provide additional information to enhance the understanding of the diffraction properties of the LG beam transmitted through a complex aperture.

  3. Triangular lattice of carbon nanotube arrays for negative index of refraction and subwavelength lensing effect

    SciTech Connect

    Wang, Y.; Wang, X.; Rybczynski, J.; Wang, D.Z.; Kempa, K.; Ren, Z.F.

    2005-04-11

    Self-assembly of polystyrene microspheres has been utilized in a two-step masking technique to prepare triangular lattices of catalytic nanodots at low cost. Subsequent triangular lattices of aligned carbon nanotubes on a silicon substrate are achieved by plasma-enhanced chemical vapor deposition. Nickel is used both in the nanodots and in the secondary mask. The triangular lattices of carbon nanotube arrays as two-dimensional photonic crystals show higher geometrical symmetry than the hexagonal lattices previously reported, enabling broader applications including negative index of refraction and subwavelength lensing effect.

  4. Morphological and anthropological aspects of human triangular deciduous lower first molar teeth.

    PubMed

    Kitagawa, Y; Manabe, Y; Oyamada, J; Rokutanda, A

    1996-04-01

    The crown and root morphology, and bilateral occurrence of human deciduous lower first molars that exhibited a triangular occlusal outline, taken from excavated samples of Japanese, Jomonese and Iraqi origin, were investigated. The crowns of triangular teeth had smaller mesiodistal and larger buccolingual diameters than normally shaped deciduous lower first molars. An elongated buccolingual diameter was derived from the buccal projection of the distobuccal cusp and lingual projection of the portion between the metaconid and distolingual cusp. In this analysis, all triangular deciduous lower first molars in which root morphology could be observed were accompanied by additional distolingual roots. Correlation between the right- and left-hand sides of this trait was high.

  5. Photonic generation of triangular waveform signals by using a dual-parallel Mach-Zehnder modulator.

    PubMed

    Li, J; Ning, T; Pei, L; Peng, W; Jia, N; Zhou, Q; Wen, X

    2011-10-01

    A photonic approach to generate triangular waveform signals is proposed and analyzed. With active bias control, two sub-MZMs (MZ-a and MZ-b) of a dual-parallel Mach-Zehnder modulator (DP-MZM) operate at minimum transmission point, leaving the main MZM (MZ-c) at quadrature transmission point. Triangular waveform can be observed by a parameter setting of modulation index. The proposal is first analyzed and then validated by simulation. The key significance of the scheme is that it is capable of generating triangular waveform signals via a sinusoid local oscillator.

  6. Reconstruction of Congenital Isolated Alar Defect Using Mutaf Triangular Closure Technique in Pediatric Patients.

    PubMed

    Temel, Metin; Gunal, Ertan; Kahraman, Serif Samil

    2016-06-01

    Congenital isolated alar defects are extremely rare, occurring in approximately 1 in 20,000 to 40,000 live births. The patients are presented here of 2 pediatric patients operated on for congenital isolated alar defect. The reconstruction of congenital isolated alar defects was made in a 3-layered fashion. The skin defects were covered using the Mutaf triangular closure technique in which 2 cutaneous local flaps are designed in an unequal Z-plasty manner. Conchal cartilage graft was used between the skin and mucosal closure to replace the missing part of the lower lateral cartilage in these patients. The early results were promising in Patient 1, but sufficient improvement was detected in the alar cartilage postoperative follow-up period in Patient 2. Hence, this patient required revision 1 to 2 years postoperatively. This technique provides excellent aesthetic and functional results, except for this problem in Tessier 2 cleft patients. The use of the Stair step flap technique with Mutaf triangle closure technique achieved cosmetically and functionally excellent results in the reconstruction and repair of a large, irregular, narrow cleft, in the inadequate rotation of the lateral part of the lower lateral cartilage. However, because of this problem, evaluation of the long-term follow-up of patients is necessary. PMID:27192642

  7. EPDM Based Double Slope Triangular Enclosure Solar Collector: A Novel Approach

    PubMed Central

    Qureshi, Shafiq R.; Khan, Waqar A.

    2014-01-01

    Solar heating is one of the important utilities of solar energy both in domestic and industrial sectors. Evacuated tube heaters are a commonly used technology for domestic water heating. However, increasing cost of copper and nickel has resulted in huge initial cost for these types of heaters. Utilizing solar energy more economically for domestic use requires new concept which has low initial and operating costs together with ease of maintainability. As domestic heating requires only nominal heating temperature to the range of 60–90°C, therefore replacing nickel coated copper pipes with any cheap alternate can drastically reduce the cost of solar heater. We have proposed a new concept which utilizes double slope triangular chamber with EPDM based synthetic rubber pipes. This has reduced the initial and operating costs substantially. A detailed analytical study was carried out to design a novel solar heater. On the basis of analytical design, a prototype was manufactured. Results obtained from the experiments were found to be in good agreement with the analytical study. A maximum error of 10% was recorded at noon. However, results show that error is less than 5% in early and late hours. PMID:24688407

  8. Immediate Return to Ambulation and Improved Functional Capacity for Rehabilitation in Complex Regional Pain Syndrome following Early Implantation of a Spinal Cord Stimulation System.

    PubMed

    Goff, Brandon Jesse; Naber, Jeremy Wingseng; McCallin, John Patrick; Lopez, Edward Michael; Guthmiller, Kevin Brant; Lautenschlager, Karl Alan; Lai, Tristan Toll; Hommer, Dean Harry; Marin, Gonzalez Raul

    2014-01-01

    Complex regional pain syndrome (CRPS) is a neuropathic pain condition that is characterized by vasomotor, sensory, sudomotor, and motor symptoms. Spinal cord stimulation (SCS) has been successfully utilized for the treatment of pain refractory to conventional therapies. We present a case of a previously highly functioning 54-year-old female who developed a rarely reported case of idiopathic CRPS of the right ankle which spontaneously occurred four months after an uncomplicated anterior cervical disc fusion. This condition resulted in severe pain and functional impairment that was unresponsive to pharmacological management. The patient's rehabilitation was severely stymied by her excruciating pain. However, with the initiation of spinal cord stimulation, her pain was adequately controlled allowing for progression to full unassisted ambulation, advancing functional capacity, and improving quality of life. This case report supports the concept that rapid progression to neuromodulation, rather than delays that occur due to attempts at serial sympathetic blocks, may better control symptoms leading allowing for a more meaningful recovery.

  9. Electric generator using a triangular diamagnetic levitating rotor system.

    PubMed

    Ho, Joe Nhut; Wang, Wei-Chih

    2009-02-01

    This paper describes a feasibility study of creating a small low friction and low maintenance generator using a diamagnetically stabilized levitating rotor. The planar rotor described in this paper uses a triangular configuration of magnets that generates emf by passing over coils placed below the rotor. Equations were developed to predict the generated emf from coils with two different coil geometries. Additionally, this paper provides a method for estimating optimal coil size and position for the planar rotor presented for both segmental arc and circular coils to obtain maximum power output. Experiments demonstrated that the emf generated in the coils matches well with the predicted wave forms for each case, and the optimization theory gives good prediction to outcome of induced waveforms. For the segmental arc coil design, the induced emf was 1.7 mV at a radial frequency of 21.8 rad/s. For the circular coil design, the emf was 1.25 mV at a radial frequency of 28.1 rad/s. PMID:19256668

  10. Thermoviscoplastic analysis of fibrous periodic composites using triangular subvolumes

    NASA Technical Reports Server (NTRS)

    Walker, Kevin P.; Freed, Alan D.; Jordan, Eric H.

    1993-01-01

    The nonlinear viscoplastic behavior of fibrous periodic composites is analyzed by discretizing the unit cell into triangular subvolumes. A set of these subvolumes can be configured by the analyst to construct a representation for the unit cell of a periodic composite. In each step of the loading history, the total strain increment at any point is governed by an integral equation which applies to the entire composite. A Fourier series approximation allows the incremental stresses and strains to be determined within a unit cell of the periodic lattice. The nonlinearity arising from the viscoplastic behavior of the constituent materials comprising the composite is treated as fictitious body force in the governing integral equation. Specific numerical examples showing the stress distributions in the unit cell of a fibrous tungsten/copper metal matrix composite under viscoplastic loading conditions are given. The stress distribution resulting in the unit cell when the composite material is subjected to an overall transverse stress loading history perpendicular to the fibers is found to be highly heterogeneous, and typical homogenization techniques based on treating the stress and strain distributions within the constituent phases as homogeneous result in large errors under inelastic loading conditions.

  11. Multi-domain electromagnetic absorption of triangular quantum rings

    NASA Astrophysics Data System (ADS)

    Sitek, Anna; Thorgilsson, Gunnar; Gudmundsson, Vidar; Manolescu, Andrei

    2016-06-01

    We present a theoretical study of the unielectronic energy spectra, electron localization, and optical absorption of triangular core–shell quantum rings. We show how these properties depend on geometric details of the triangle, such as side thickness or corners’ symmetry. For equilateral triangles, the lowest six energy states (including spin) are grouped in an energy shell, are localized only around corner areas, and are separated by a large energy gap from the states with higher energy which are localized on the sides of the triangle. The energy levels strongly depend on the aspect ratio of the triangle sides, i.e., thickness/length ratio, in such a way that the energy differences are not monotonous functions of this ratio. In particular, the energy gap between the group of states localized in corners and the states localized on the sides strongly decreases with increasing the side thickness, and then slightly increases for thicker samples. With increasing the thickness the low-energy shell remains distinct but the spatial distribution of these states spreads. The behavior of the energy levels and localization leads to a thickness-dependent absorption spectrum where one transition may be tuned in the THz domain and a second transition can be tuned from THz to the infrared range of electromagnetic spectrum. We show how these features may be further controlled with an external magnetic field. In this work the electron–electron Coulomb repulsion is neglected.

  12. Low-Reynolds number compressible flow around a triangular airfoil

    NASA Astrophysics Data System (ADS)

    Munday, Phillip; Taira, Kunihiko; Suwa, Tetsuya; Numata, Daiju; Asai, Keisuke

    2013-11-01

    We report on the combined numerical and experimental effort to analyze the nonlinear aerodynamics of a triangular airfoil in low-Reynolds number compressible flow that is representative of wings on future Martian air vehicles. The flow field around this airfoil is examined for a wide range of angles of attack and Mach numbers with three-dimensional direct numerical simulations at Re = 3000 . Companion experiments are conducted in a unique Martian wind tunnel that is placed in a vacuum chamber to simulate the Martian atmosphere. Computational findings are compared with pressure sensitive paint and direct force measurements and are found to be in agreement. The separated flow from the leading edge is found to form a large leading-edge vortex that sits directly above the apex of the airfoil and provides enhanced lift at post stall angles of attack. For higher subsonic flows, the vortical structures elongate in the streamwise direction resulting in reduced lift enhancement. We also observe that the onset of spanwise instability for higher angles of attack is delayed at lower Mach numbers. Currently at Mitsubishi Heavy Industries, Ltd., Nagasaki.

  13. Multi-domain electromagnetic absorption of triangular quantum rings

    NASA Astrophysics Data System (ADS)

    Sitek, Anna; Thorgilsson, Gunnar; Gudmundsson, Vidar; Manolescu, Andrei

    2016-06-01

    We present a theoretical study of the unielectronic energy spectra, electron localization, and optical absorption of triangular core-shell quantum rings. We show how these properties depend on geometric details of the triangle, such as side thickness or corners’ symmetry. For equilateral triangles, the lowest six energy states (including spin) are grouped in an energy shell, are localized only around corner areas, and are separated by a large energy gap from the states with higher energy which are localized on the sides of the triangle. The energy levels strongly depend on the aspect ratio of the triangle sides, i.e., thickness/length ratio, in such a way that the energy differences are not monotonous functions of this ratio. In particular, the energy gap between the group of states localized in corners and the states localized on the sides strongly decreases with increasing the side thickness, and then slightly increases for thicker samples. With increasing the thickness the low-energy shell remains distinct but the spatial distribution of these states spreads. The behavior of the energy levels and localization leads to a thickness-dependent absorption spectrum where one transition may be tuned in the THz domain and a second transition can be tuned from THz to the infrared range of electromagnetic spectrum. We show how these features may be further controlled with an external magnetic field. In this work the electron-electron Coulomb repulsion is neglected.

  14. Multi-domain electromagnetic absorption of triangular quantum rings.

    PubMed

    Sitek, Anna; Thorgilsson, Gunnar; Gudmundsson, Vidar; Manolescu, Andrei

    2016-06-01

    We present a theoretical study of the unielectronic energy spectra, electron localization, and optical absorption of triangular core-shell quantum rings. We show how these properties depend on geometric details of the triangle, such as side thickness or corners' symmetry. For equilateral triangles, the lowest six energy states (including spin) are grouped in an energy shell, are localized only around corner areas, and are separated by a large energy gap from the states with higher energy which are localized on the sides of the triangle. The energy levels strongly depend on the aspect ratio of the triangle sides, i.e., thickness/length ratio, in such a way that the energy differences are not monotonous functions of this ratio. In particular, the energy gap between the group of states localized in corners and the states localized on the sides strongly decreases with increasing the side thickness, and then slightly increases for thicker samples. With increasing the thickness the low-energy shell remains distinct but the spatial distribution of these states spreads. The behavior of the energy levels and localization leads to a thickness-dependent absorption spectrum where one transition may be tuned in the THz domain and a second transition can be tuned from THz to the infrared range of electromagnetic spectrum. We show how these features may be further controlled with an external magnetic field. In this work the electron-electron Coulomb repulsion is neglected.

  15. Agglomerative percolation on the Bethe lattice and the triangular cactus

    NASA Astrophysics Data System (ADS)

    Chae, Huiseung; Yook, Soon-Hyung; Kim, Yup

    2013-08-01

    Agglomerative percolation (AP) on the Bethe lattice and the triangular cactus is studied to establish the exact mean-field theory for AP. Using the self-consistent simulation method based on the exact self-consistent equations, the order parameter P∞ and the average cluster size S are measured. From the measured P∞ and S, the critical exponents βk and γk for k = 2 and 3 are evaluated. Here, βk and γk are the critical exponents for P∞ and S when the growth of clusters spontaneously breaks the Zk symmetry of the k-partite graph. The obtained values are β2 = 1.79(3), γ2 = 0.88(1), β3 = 1.35(5) and γ3 = 0.94(2). By comparing these exponents with those for ordinary percolation (β∞ = 1 and γ∞ = 1), we also find β∞ < β3 < β2 and γ∞ > γ3 > γ2. These results quantitatively verify the conjecture that the AP model belongs to a new universality class if the Zk symmetry is broken spontaneously, and the new universality class depends on k.

  16. Degenerate Quasicrystal of Hard Triangular Bipyramids Stabilized by Entropic Forces

    NASA Astrophysics Data System (ADS)

    Haji-Akbari, Amir; Engel, Michael; Glotzer, Sharon

    2012-02-01

    The assembly of hard polyhedra into novel ordered structures has recently received much attention. Here we focus on triangular bipyramids (TBPs)- i.e. dimers of hard tetrahedra- which pack densely in a simple triclinic crystal with two particles per unit cell [1]. This packing is referred to as the TBP crystal. We show that hard TBPs do not form this densest packing in simulation. Instead, they assemble into a different, far more complicated structure, a dodecagonal quasicrystal, which, in the level of monomers, is identical to the quasicrystal recently discovered in the hard tetrahedron system [2], but the way that tetrahedra pair into TBPs in the nearest neighbor network is random, making it the first degenerate quasicrystal reported in the literature [3]. This notion of degeneracy is in the level of decorating individual tiles and is different from the degeneracy of a quasiperiodic random tiling arising from phason flips [4]. The (3.4.3^2.4) approximant of the quasicrystal is shown to be more stable than the TBP crystal at densities below 79.7%.[4pt] [1] Chen ER, Engel M, Sharon SC, Disc. Comp. Geom. 44:253 (2010).[0pt] [2] Haji-Akbari A, Engel M, et al. Nature 462:773 (2009).[0pt] [3] Haji-Akbari A, Engel M, Glotzer SC, arXiv:1106.5561 [PRL, in press].[0pt] [4] Elser V, PRL 54: 1730 (1985)

  17. Vortex structure and dynamics in kagome and triangular pinning potentials

    SciTech Connect

    Laguna, M. F.; Balseiro, C. A.; Dominguez, D.; Nori, Franco

    2001-09-01

    We study the dynamics of thermally driven superconducting vortices in two types of periodic pinning potentials: kagome and triangular. For the first, second, and third matching fields, we obtain the corresponding ground-state vortex configurations and their phase diagrams. We analyze the system properties by looking at the vortex trajectories and the structure factor, as well as the linear and angular diffusion. The temperature versus pinning force phase diagram is analyzed in detail for each matching field. When the temperature is varied, we observe several stages of lattice pinning and melting. In most of the cases we find, for decreasing temperature, first a pinning of vortices and afterwards a freezing transition of the interstitial vortices. The intermediate regime corresponds to interstitial vortices in a confined liquidlike state and pinned vortices. The kagome pinning potential shows interesting behavior at low temperatures: there is a phase with rotating vortex triangles caged by kagome hexagons (''cooperative ring elementary excitations''), and there is geometric frustration for T{yields}0 with a nearly degenerate ground state.

  18. Fluid Interfaces of Triangular Containers in Reduced Gravity Environments

    NASA Technical Reports Server (NTRS)

    Guttromson, Jayleen; Manning, Robert; Collicott, Steven H.

    2002-01-01

    Capillary dominated fluid dynamics will be examined in a reduced-gravity environment onboard the KC-135; in particular, the behavior of the lower portion of the meniscus in triangular tank geometries. Seven clear acrylic tanks were constructed to view seven angles of the four geometries. Silicon oil with two different viscosities, 2cs and 5cs silicon oil, were used on different days of the flight. Six tanks and one control tank are filled with a certain viscosity fluid for each flight day. During each parabola, three tanks are tested at time. The experimental tanks are exchanged between parabola sets on the KC-135. The 60deg -60deg -60deg control tank is viewed throughout the flight. To gather data, two digital video cameras and one digital still camera are placed perpendicular the viewing surface. To provide a greater contrast in the meniscus, an EL backlighting sheet was used to backlight the tanks. These images and video are then digitized, passed through NASA's mini-tracker software, and compared to a theory published my M. M. Weislogel, "Fluid Interface Phenomena in a Low-Gravity Environment: Recent Results from Drop Tower Experimentation." By focusing on a lower portion of the meniscus and using longer periods of reduced gravity, this experiment may confirm that a stationary point exists on the fluid surface. This information will enable better designing of propellant management devices, especially satellite propellant refilling and gas venting. Also, biological and material processing systems in reduced gravity environments will benefit from this data.

  19. Multi-domain electromagnetic absorption of triangular quantum rings.

    PubMed

    Sitek, Anna; Thorgilsson, Gunnar; Gudmundsson, Vidar; Manolescu, Andrei

    2016-06-01

    We present a theoretical study of the unielectronic energy spectra, electron localization, and optical absorption of triangular core-shell quantum rings. We show how these properties depend on geometric details of the triangle, such as side thickness or corners' symmetry. For equilateral triangles, the lowest six energy states (including spin) are grouped in an energy shell, are localized only around corner areas, and are separated by a large energy gap from the states with higher energy which are localized on the sides of the triangle. The energy levels strongly depend on the aspect ratio of the triangle sides, i.e., thickness/length ratio, in such a way that the energy differences are not monotonous functions of this ratio. In particular, the energy gap between the group of states localized in corners and the states localized on the sides strongly decreases with increasing the side thickness, and then slightly increases for thicker samples. With increasing the thickness the low-energy shell remains distinct but the spatial distribution of these states spreads. The behavior of the energy levels and localization leads to a thickness-dependent absorption spectrum where one transition may be tuned in the THz domain and a second transition can be tuned from THz to the infrared range of electromagnetic spectrum. We show how these features may be further controlled with an external magnetic field. In this work the electron-electron Coulomb repulsion is neglected. PMID:27102909

  20. Ergodicity and quantum correlations in irrational triangular billiards

    NASA Astrophysics Data System (ADS)

    Araújo Lima, T.; Rodríguez-Pérez, S.; de Aguiar, F. M.

    2013-06-01

    Pseudochaotic properties are systematically investigated in a one-parameter family of irrational triangular billiards (all angles irrational with π). The absolute value of the position correlation function Cx(t) decays like ˜t-α. Fast (α≈1) and slow (0<α<1) decays are observed, thus indicating that the irrational triangles do not share a unique ergodic dynamics, which, instead, may vary smoothly between the opposite limits of strong mixing (α=1) and regular behaviors (α=0). Upgrading previous data, spectral statistical properties of the quantized counterparts are computed from 150000 energy eigenvalues numerically calculated for each billiard. Gaussian orthogonal ensemble spectral fluctuations are observed when α≈1 and intermediate statistics are found otherwise. Our irrational billiards have zero Kolmogorov-Sinai entropy and essentially infinity genus. Thus, differently from previous works on rational (pseudointegrable) enclosures, our results provide a missing classical-quantum correspondence regarding the ergodic hierarchy for a set of nonchaotic systems that might enjoy the strong mixing property.

  1. Comparison of some isoparametric mappings for curved triangular spectral elements

    NASA Astrophysics Data System (ADS)

    Pasquetti, Richard

    2016-07-01

    Using the spectral element method (SEM), or more generally hp-finite elements (hp-FEM), it is possible to solve with high accuracy various kinds of problems governed by partial differential equations (PDEs), see e.g. [1,2]. However, as soon as the physical domain is not polygonal, the accuracy quickly deteriorates if curved elements are not implemented. This is the reason why various methods have been developed during the last decades, starting from the celebrated transfinite interpolation proposed for quadrangular elements in [3]. In this note we revisit this problem for triangular elements, based on the use of Fekete points for interpolations and of Gauss points for quadratures, i.e. when using the so-called Fekete-Gauss approximation. As detailed in [4], such an approach shows the so-called spectral accuracy. However, differently to the quadrangles based SEM, it does not involve diagonal mass matrices, see e.g. [5-7] and references herein for works trying to preserve this nice property that is especially useful when addressing evolution problems with an explicit time marching. In the frame of the Fekete-Gauss TSEM (T, for triangle), the present study clearly points out the importance of a good choice of the bending procedure by comparing different isoparametric mappings for the Poisson and Grad-Shafranov PDEs.

  2. The Free Flexural Vibration of Symmetric Angle-Ply Triangular Composite Laminates

    NASA Astrophysics Data System (ADS)

    Liew, K. M.; Chiam, T. C.

    1994-02-01

    This paper reports an extension of previous work [1] to the study of the free flexural vibration analysis of symmetrically laminated triangular plates. The analysis is performed by using a simple and straightforward pb-2 Rayleigh-Ritz method. A governing frequency equation for the laminated triangular plates with different combinations of free, simply supported or clamped edge conditions is derived. Although only the vibration frequencies for cantilevered right-angled and isosceles triangular plates are reported, the method is readily applied to general triangular laminated plates. In the present analysis, the effects of material properties, the number of layers and different fibre stacking sequences of various composites on the vibration frequencies are investigated. Convergence tests have been carried out for selected plate examples to demonstrate the accuracy of the solutions.

  3. [Fluorescence Resonance Energy Transfer Detection of Cobalt Ions by Silver Triangular Nanoplates and Rhodamine 6G].

    PubMed

    Zhang, Xiu-qing; Peng, Jun; Ling, Jian; Liu, Chao-juan; Cao, Qiu-e; Ding, Zhong-tao

    2015-04-01

    In the present paper, the authors studied fluorescence resonance energy transfer (FRET) phenomenon between silver triangular nanoplates and bovine serum albumin (BSA)/Rhodamine 6G fluorescence complex, and established a fluorescence method for the detection of cobalt ions. We found that when increasing the silver triangular nanoplates added to certain concentrations of fluorescent bovine serum albumin (BSA)/Rhodamine 6G complex, the fluorescence of Rhodamine 6G would be quenched up to 80% due to the FRET between the quencher and donor. However, in the presence of cobalt ions, the disassociation of the fluorescent complex from silver triangular nanoplates occurred and the fluorescence of the Rhodamine 6G recovered. The recovery of fluorescence intensity rate (I/I0) has a good relationship with the cobalt ion concentration (cCO2+) added. Thus, the authors developed a fluorescence method for the detection of cobalt ions based on the FRET of silver triangular nanoplates and Rhodamine 6G.

  4. Error estimates of triangular finite elements under a weak angle condition

    NASA Astrophysics Data System (ADS)

    Mao, Shipeng; Shi, Zhongci

    2009-08-01

    In this note, by analyzing the interpolation operator of Girault and Raviart given in [V. Girault, P.A. Raviart, Finite element methods for Navier-Stokes equations, Theory and algorithms, in: Springer Series in Computational Mathematics, Springer-Verlag, Berlin,1986] over triangular meshes, we prove optimal interpolation error estimates for Lagrange triangular finite elements of arbitrary order under the maximal angle condition in a unified and simple way. The key estimate is only an application of the Bramble-Hilbert lemma.

  5. Modelling and simulation of parallel triangular triple quantum dots (TTQD) by using SIMON 2.0

    NASA Astrophysics Data System (ADS)

    Fathany, Maulana Yusuf; Fuada, Syifaul; Lawu, Braham Lawas; Sulthoni, Muhammad Amin

    2016-04-01

    This research presents analysis of modeling on Parallel Triple Quantum Dots (TQD) by using SIMON (SIMulation Of Nano-structures). Single Electron Transistor (SET) is used as the basic concept of modeling. We design the structure of Parallel TQD by metal material with triangular geometry model, it is called by Triangular Triple Quantum Dots (TTQD). We simulate it with several scenarios using different parameters; such as different value of capacitance, various gate voltage, and different thermal condition.

  6. Improving the use of ranking in virtual screening against HIV-1 integrase with triangular numbers and including ligand profiling with antitargets.

    PubMed

    García-Sosa, Alfonso T; Maran, Uko

    2014-11-24

    A delicate balance exists between a drug molecule's toxicity and its activity. Indeed, efficacy, toxicity, and side effect problems are a common cause for the termination of drug candidate compounds and development projects. To address this, an antitarget interaction profile is built and combined with virtual screening and cross docking for new inhibitors of HIV-1 integrase, in order to consider possible off-target interactions as early as possible in a drug or hit discovery program. New ranking techniques using triangular numbers improve ranking information on the compounds and recovery of known inhibitors into the top compounds using different docking programs. This improved ranking arises from using consensus of ranks between docking programs and ligand efficiencies to derive a new rank, instead of using absolute score values, or average of ranks. The triangular number rerank also allowed the objective combination of results from several protein targets or screen conditions and several programs. Triangular number reranking conserves more information than other reranking methods such as average of scores or averages of ranks. In addition, the use of triangular numbers for reranking makes possible the use of thresholds with a justified leeway based on the number of available known inhibitors, so that the majority of the compounds above the threshold in ranks compare to the compounds that have known experimentally determined biological activity. The battery of anti- or off-targets can be tailored to specific molecular or drug design challenges. In silico filters can thus be deployed in successive stages, for prefiltering, activity profiling, and for further analysis and triaging of libraries of compounds. PMID:25303089

  7. Immediate Return to Ambulation and Improved Functional Capacity for Rehabilitation in Complex Regional Pain Syndrome following Early Implantation of a Spinal Cord Stimulation System.

    PubMed

    Goff, Brandon Jesse; Naber, Jeremy Wingseng; McCallin, John Patrick; Lopez, Edward Michael; Guthmiller, Kevin Brant; Lautenschlager, Karl Alan; Lai, Tristan Toll; Hommer, Dean Harry; Marin, Gonzalez Raul

    2014-01-01

    Complex regional pain syndrome (CRPS) is a neuropathic pain condition that is characterized by vasomotor, sensory, sudomotor, and motor symptoms. Spinal cord stimulation (SCS) has been successfully utilized for the treatment of pain refractory to conventional therapies. We present a case of a previously highly functioning 54-year-old female who developed a rarely reported case of idiopathic CRPS of the right ankle which spontaneously occurred four months after an uncomplicated anterior cervical disc fusion. This condition resulted in severe pain and functional impairment that was unresponsive to pharmacological management. The patient's rehabilitation was severely stymied by her excruciating pain. However, with the initiation of spinal cord stimulation, her pain was adequately controlled allowing for progression to full unassisted ambulation, advancing functional capacity, and improving quality of life. This case report supports the concept that rapid progression to neuromodulation, rather than delays that occur due to attempts at serial sympathetic blocks, may better control symptoms leading allowing for a more meaningful recovery. PMID:25525522

  8. Immediate Return to Ambulation and Improved Functional Capacity for Rehabilitation in Complex Regional Pain Syndrome following Early Implantation of a Spinal Cord Stimulation System

    PubMed Central

    Goff, Brandon Jesse; Naber, Jeremy Wingseng; McCallin, John Patrick; Lopez, Edward Michael; Guthmiller, Kevin Brant; Lautenschlager, Karl Alan; Lai, Tristan Toll; Hommer, Dean Harry; Marin, Gonzalez Raul

    2014-01-01

    Complex regional pain syndrome (CRPS) is a neuropathic pain condition that is characterized by vasomotor, sensory, sudomotor, and motor symptoms. Spinal cord stimulation (SCS) has been successfully utilized for the treatment of pain refractory to conventional therapies. We present a case of a previously highly functioning 54-year-old female who developed a rarely reported case of idiopathic CRPS of the right ankle which spontaneously occurred four months after an uncomplicated anterior cervical disc fusion. This condition resulted in severe pain and functional impairment that was unresponsive to pharmacological management. The patient's rehabilitation was severely stymied by her excruciating pain. However, with the initiation of spinal cord stimulation, her pain was adequately controlled allowing for progression to full unassisted ambulation, advancing functional capacity, and improving quality of life. This case report supports the concept that rapid progression to neuromodulation, rather than delays that occur due to attempts at serial sympathetic blocks, may better control symptoms leading allowing for a more meaningful recovery. PMID:25525522

  9. Reliability and flexural behavior of triangular and T-reinforced concrete beams

    NASA Astrophysics Data System (ADS)

    Al-Ansari, Mohammed S.

    2015-12-01

    The paper studied the behavior of reinforced concrete triangular and T-beams. Three reinforced concrete beams were tested experimentally and analyzed analytically using the finite element method. Their reliability was also assessed using the reliability index approach. The results showed that the finite element vertical displacements compared well with those obtained experimentally. They also showed that the vertical displacements obtained using the finite element method were larger than those obtained experimentally. This is a strong indication that the finite element results were conservative and reliable. The results showed that the triangular beams exhibited higher ductility at failure than did the T-beam. The plastic deformations at failure of the triangular beams were higher than that of the T-beam. This is a strong indication of the higher ductility of the triangular beams compared to the T-beam. Triangular beams exhibited smaller cracks than did T-beams for equal areas of steel and concrete. The design moment strengths M c computed using the American Concrete Institute (ACI) design formulation were safe and close to those computed using experimental results. The experimental results validated the reliability analysis results, which stated that the triangular beams are more reliable than T-beams for equal areas of steel and concrete.

  10. Forced convection of turbulent flow in triangular ducts with different angles and surface roughnesses

    NASA Astrophysics Data System (ADS)

    Leung, C. W.; Wong, T. T.; Kang, H. J.

    The experimental investigations were consisting of two parts. The first part was carried out to study the effect of corner geometry on the steady-state forced convection inside horizontal isosceles triangular ducts with sharp corners. The electrically-heated triangular duct was used to simulate the triangular passage of a plate-fin compact heat exchanger. The isosceles triangular ducts were manufactured with duralumin, and fabricated with the same length of 2.4m and hydraulic diameter of 0.44m, but five different apex angles (i.e. θa=15∘,30∘, 40∘,60∘, and 90∘) respectively. The investigation was performed under turbulent flow condition covering a wide range of Reynolds number (i.e. 7000<=ReD<=20000). It was found that the best thermal performance is achieved with the apex angle of 60∘. The second part was performed to investigate the effect of surface roughness on the forced convection of the same system. Horizontal equilateral triangular ducts with an apex angle of 60∘ were fabricated with the same length and hydraulic diameter, but different average surface roughnesses of 1.2 m,3.0 m and 11.5 m respectively. It was concluded that the duct with a higher surface roughness will have a better heat transfer performance. Non-dimensional expressions for the determination of the heat transfer coefficient of the triangular ducts with different apex angles and surface roughnesses were also developed.

  11. [Assessment of legal capacity and testamentary capacity].

    PubMed

    Dreßing, H; Foerster, K; Leygraf, J; Schneider, F

    2014-11-01

    The assessment of legal capacity and testamentary capacity require thorough knowledge of the legal framework and the relevant case law. This paper explains the concept of the legal capacity to contract and the concept of testamentary capacity with respect to German civil law. The relevance of major mental disorders for the assessment of legal capacity and testamentary capacity is discussed.

  12. Energy levels of double triangular graphene quantum dots

    SciTech Connect

    Liang, F. X.; Jiang, Z. T. Zhang, H. Y.; Li, S.; Lv, Z. T.

    2014-09-28

    We investigate theoretically the energy levels of the coupled double triangular graphene quantum dots (GQDs) based on the tight-binding Hamiltonian model. The double GQDs including the ZZ-type, ZA-type, and AA-type GQDs with the two GQDs having the zigzag or armchair boundaries can be coupled together via different interdot connections, such as the direct coupling, the chains of benzene rings, and those of carbon atoms. It is shown that the energy spectrum of the coupled double GQDs is the amalgamation of those spectra of the corresponding two isolated GQDs with the modification triggered by the interdot connections. The interdot connection is inclined to lift up the degeneracies of the energy levels in different degree, and as the connection changes from the direct coupling to the long chains, the removal of energy degeneracies is suppressed in ZZ-type and AA-type double GQDs, which indicates that the two coupled GQDs are inclined to become decoupled. Then we consider the influences on the spectra of the coupled double GQDs induced by the electric fields applied on the GQDs or the connection, which manifests as the global spectrum redistribution or the local energy level shift. Finally, we study the symmetrical and asymmetrical energy spectra of the double GQDs caused by the substrates supporting the two GQDs, clearly demonstrating how the substrates affect the double GQDs' spectrum. This research elucidates the energy spectra of the coupled double GQDs, as well as the mechanics of manipulating them by the electric field and the substrates, which would be a significant reference for designing GQD-based devices.

  13. Psyplot: Visualizing rectangular and triangular Climate Model Data with Python

    NASA Astrophysics Data System (ADS)

    Sommer, Philipp

    2016-04-01

    The development and use of climate models often requires the visualization of geo-referenced data. Creating visualizations should be fast, attractive, flexible, easily applicable and easily reproducible. There is a wide range of software tools available for visualizing raster data, but they often are inaccessible to many users (e.g. because they are difficult to use in a script or have low flexibility). In order to facilitate easy visualization of geo-referenced data, we developed a new framework called "psyplot," which can aid earth system scientists with their daily work. It is purely written in the programming language Python and primarily built upon the python packages matplotlib, cartopy and xray. The package can visualize data stored on the hard disk (e.g. NetCDF, GeoTIFF, any other file format supported by the xray package), or directly from the memory or Climate Data Operators (CDOs). Furthermore, data can be visualized on a rectangular grid (following or not following the CF Conventions) and on a triangular grid (following the CF or UGRID Conventions). Psyplot visualizes 2D scalar and vector fields, enabling the user to easily manage and format multiple plots at the same time, and to export the plots into all common picture formats and movies covered by the matplotlib package. The package can currently be used in an interactive python session or in python scripts, and will soon be developed for use with a graphical user interface (GUI). Finally, the psyplot framework enables flexible configuration, allows easy integration into other scripts that uses matplotlib, and provides a flexible foundation for further development.

  14. The Wnt Receptor Ryk Reduces Neuronal and Cell Survival Capacity by Repressing FOXO Activity During the Early Phases of Mutant Huntingtin Pathogenicity

    PubMed Central

    Tourette, Cendrine; Farina, Francesca; Vazquez-Manrique, Rafael P.; Orfila, Anne-Marie; Voisin, Jessica; Hernandez, Sonia; Offner, Nicolas; Parker, J. Alex; Menet, Sophie; Kim, Jinho; Lyu, Jungmok; Choi, Si Ho; Cormier, Kerry; Edgerly, Christina K.; Bordiuk, Olivia L.; Smith, Karen; Louise, Anne; Halford, Michael; Stacker, Steven; Vert, Jean-Philippe; Ferrante, Robert J.; Lu, Wange; Neri, Christian

    2014-01-01

    The Wnt receptor Ryk is an evolutionary-conserved protein important during neuronal differentiation through several mechanisms, including γ-secretase cleavage and nuclear translocation of its intracellular domain (Ryk-ICD). Although the Wnt pathway may be neuroprotective, the role of Ryk in neurodegenerative disease remains unknown. We found that Ryk is up-regulated in neurons expressing mutant huntingtin (HTT) in several models of Huntington's disease (HD). Further investigation in Caenorhabditis elegans and mouse striatal cell models of HD provided a model in which the early-stage increase of Ryk promotes neuronal dysfunction by repressing the neuroprotective activity of the longevity-promoting factor FOXO through a noncanonical mechanism that implicates the Ryk-ICD fragment and its binding to the FOXO co-factor β-catenin. The Ryk-ICD fragment suppressed neuroprotection by lin-18/Ryk loss-of-function in expanded-polyQ nematodes, repressed FOXO transcriptional activity, and abolished β-catenin protection of mutant htt striatal cells against cell death vulnerability. Additionally, Ryk-ICD was increased in the nucleus of mutant htt cells, and reducing γ-secretase PS1 levels compensated for the cytotoxicity of full-length Ryk in these cells. These findings reveal that the Ryk-ICD pathway may impair FOXO protective activity in mutant polyglutamine neurons, suggesting that neurons are unable to efficiently maintain function and resist disease from the earliest phases of the pathogenic process in HD. PMID:24960609

  15. The Wnt receptor Ryk reduces neuronal and cell survival capacity by repressing FOXO activity during the early phases of mutant huntingtin pathogenicity.

    PubMed

    Tourette, Cendrine; Farina, Francesca; Vazquez-Manrique, Rafael P; Orfila, Anne-Marie; Voisin, Jessica; Hernandez, Sonia; Offner, Nicolas; Parker, J Alex; Menet, Sophie; Kim, Jinho; Lyu, Jungmok; Choi, Si Ho; Cormier, Kerry; Edgerly, Christina K; Bordiuk, Olivia L; Smith, Karen; Louise, Anne; Halford, Michael; Stacker, Steven; Vert, Jean-Philippe; Ferrante, Robert J; Lu, Wange; Neri, Christian

    2014-06-01

    The Wnt receptor Ryk is an evolutionary-conserved protein important during neuronal differentiation through several mechanisms, including γ-secretase cleavage and nuclear translocation of its intracellular domain (Ryk-ICD). Although the Wnt pathway may be neuroprotective, the role of Ryk in neurodegenerative disease remains unknown. We found that Ryk is up-regulated in neurons expressing mutant huntingtin (HTT) in several models of Huntington's disease (HD). Further investigation in Caenorhabditis elegans and mouse striatal cell models of HD provided a model in which the early-stage increase of Ryk promotes neuronal dysfunction by repressing the neuroprotective activity of the longevity-promoting factor FOXO through a noncanonical mechanism that implicates the Ryk-ICD fragment and its binding to the FOXO co-factor β-catenin. The Ryk-ICD fragment suppressed neuroprotection by lin-18/Ryk loss-of-function in expanded-polyQ nematodes, repressed FOXO transcriptional activity, and abolished β-catenin protection of mutant htt striatal cells against cell death vulnerability. Additionally, Ryk-ICD was increased in the nucleus of mutant htt cells, and reducing γ-secretase PS1 levels compensated for the cytotoxicity of full-length Ryk in these cells. These findings reveal that the Ryk-ICD pathway may impair FOXO protective activity in mutant polyglutamine neurons, suggesting that neurons are unable to efficiently maintain function and resist disease from the earliest phases of the pathogenic process in HD.

  16. Stepping back to gain perspective: pregnancy loss history, depression, and parenting capacity in the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B).

    PubMed

    Price, Sarah Kye

    2008-01-01

    Previous empirical studies of pregnancy loss have predominantly focused on complex grief response and emergent problems associated with future parenting in self-selected samples of bereaved women. This article presents findings from a retrospective secondary data analysis conducted with a racially and ethnically diverse sample of currently parenting women in the United States (N = 10,688) that examined the relationships among pregnancy loss history, current maternal depressive symptoms, and mother-infant interaction with the enrolled child. Study findings underscore a racial-ethnic disparity in pregnancy loss history for African American women, whereas current maternal depressive symptoms remain fairly constant across racial-ethnic groups. Multiple loss history is associated with a slight elevation in overall symptoms of depression, but there is no relationship between pregnancy loss history and current mother-infant interaction in the study sample. An important limitation in this study is that the Early Childhood Longitudinal Study, Birth Cohort (ECLS-B) data does not allow for inferences specific to the type of loss, gestational age of fetus, time since loss, or whether the loss was spontaneous or induced. However, study findings highlight areas of incongruity between clinical and population-based research that deserve further investigation. Ultimately, the findings from this population-based research contribute to a wider perspective regarding maternal response to reproductive loss that can inform future research and targeted bereavement support. PMID:18693378

  17. Properties of plane discrete Poisson-Voronoi tessellations on triangular tiling formed by the Kolmogorov-Johnson-Mehl-Avrami growth of triangular islands.

    PubMed

    Korobov, A

    2011-08-01

    Discrete uniform Poisson-Voronoi tessellations of two-dimensional triangular tilings resulting from the Kolmogorov-Johnson-Mehl-Avrami (KJMA) growth of triangular islands have been studied. This shape of tiles and islands, rarely considered in the field of random tessellations, is prompted by the birth-growth process of Ir(210) faceting. The growth mode determines a triangular metric different from the Euclidean metric. Kinetic characteristics of tessellations appear to be metric sensitive, in contrast to area distributions. The latter have been studied for the variant of nuclei growth to the first impingement in addition to the conventional case of complete growth. Kiang conjecture works in both cases. The averaged number of neighbors is six for all studied densities of random tessellations, but neighbors appear to be mainly different in triangular and Euclidean metrics. Also, the applicability of the obtained results for simulating birth-growth processes when the 2D nucleation and impingements are combined with the 3D growth in the particular case of similar shape and the same orientation of growing nuclei is briefly discussed.

  18. Enhancement of photovoltaic cell performance using periodic triangular gratings

    NASA Astrophysics Data System (ADS)

    Bordatchev, Evgueni; Tauhiduzzaman, Mohammed; Dey, Rajat

    2014-01-01

    The solar energy industry strives to produce more efficient and yet cost effective solar panels each consisting of an array of photovoltaic (PV) cells. The goal of this study was to enhance the performance of PV cells through increasing the cells' optical efficiency defined as a percentage of surface incident light that reaches the PV material. This was achieved through the reduction of waveguide decoupling loss and Fresnel reflection losses by integrating specific nonimaging micro-optical structures on the top surface of existing PV cells. Due to this integration, optical efficiency and performance were increased through the enhancement of light trapping, light guiding, and in-coupling functionalities. Periodic triangular gratings (PTGs) were designed, nonsequentially modeled, optimized, and fabricated in polydimethylsiloxane as proposed micro-optical structures. Then the performance of PV cells with and without integrated PTGs was evaluated and compared. Initial optical simulation results show that an original PV cell (without PTG) exhibits an average optical efficiency of 32.7% over a range of incident light angles between 15 and 90 deg. Integration of the PTG allows the capture of incoming sunlight by total internal reflection (TIR), whence it is reflected back onto the PV cell for multiple consecutive chances for absorption and PV conversion. Geometry of the PTG was optimized with respect to an angle of light incidence of {15, 30, 45, 60, 75, 90} deg. Optical efficiency of the geometrically optimized PTGs was then analyzed under the same set of incident light angles and a maximum optical efficiency of 54.1% was observed for a PV cell with integrated PTG optimized at 90 deg. This is a 53.3% relative improvement in optical performance when compared to an original PV cell. Functional PTG prototypes were then fabricated with optical surface quality (below 10 nm Ra) and integrated with PV cells demonstrating an increase in maximum power by 1.08 mW/cm (7

  19. Triangularity and dipole asymmetry in relativistic heavy ion collisions

    SciTech Connect

    Teaney, Derek; Yan Li

    2011-06-15

    We introduce a cumulant expansion to parametrize possible initial conditions in relativistic heavy ion collisions. We show that the cumulant expansion converges and that it can systematically reproduce the results of Glauber type initial conditions. At third order in the gradient expansion the cumulants characterize the triangularity and the dipole asymmetry of the initial entropy distribution. We show that for midperipheral collisions the orientation angle of the dipole asymmetry {psi}{sub 1,3} has a 20% preference out of plane. This leads to a small net v{sub 1} out of plane. In peripheral and midcentral collisions the orientation angles {psi}{sub 1,3} and {psi}{sub 3,3} are strongly correlated, but this correlation disappears towards central collisions. We study the ideal hydrodynamic response to these cumulants and determine the associated v{sub 1}/{epsilon}{sub 1} and v{sub 3}/{epsilon}{sub 3} for a massless ideal gas equation of state. The space time development of v{sub 1} and v{sub 3} is clarified with figures. These figures show that v{sub 1} and v{sub 3} develop toward the edge of the nucleus, and consequently the final spectra are more sensitive to the viscous dynamics of freezeout. The hydrodynamic calculations for v{sub 3} are provisionally compared to Alver and Roland fit of STAR inclusive two-particle correlation functions. Finally, we propose to measure the v{sub 1} associated with the dipole asymmetry and the correlations between {psi}{sub 1,3} and {psi}{sub 3,3} by measuring a two-particle correlation with respect to the participant plane . The hydrodynamic prediction for this correlation function is several times larger than a correlation currently measured by the STAR collaboration . This experimental measurement would provide

  20. Simulations of spall experiments in 316L stainless steel conducted with square and triangular waves

    NASA Astrophysics Data System (ADS)

    Seaman, Lynn; Gray, G. T.(Rusty), III

    2005-07-01

    Triangular stress waves are more like those from applications (laser, explosives, nuclear) but laboratory experiments for studying spall damage generally provide square-topped waves. Gray et al (2003) performed four impact experiments in 316L stainless steel, two with square waves and two with triangular, achieving void damage in all but the lower-stress (6.6 GPa) triangular-wave sample. Simulations with the nucleation-and-growth model DFRACT exhibit fair correspondence with the damage in those tests showing damage, but also indicate damage in the triangular-wave test showing no damage. We are examining mechanisms which may delay the initiation of void damage or otherwise alter the expected damage processes in the model. Reference: G.T. (Rusty) Gray III, N. K. Bourne, B.L. Henrie, and J.C.F. Millet, Influence of Shock-Wave Profile Shape (Triangular ``Taylor-Wave'' versus Square-Topped) on the Spallation Response of 316L Stainless Steel, J. Phys. IV France 110 (2003), page 773-778,

  1. Comparison of two-transsacral-screw fixation versus triangular osteosynthesis for transforaminal sacral fractures.

    PubMed

    Min, Kyong S; Zamorano, David P; Wahba, George M; Garcia, Ivan; Bhatia, Nitin; Lee, Thay Q

    2014-09-01

    Transforaminal pelvic fractures are high-energy injuries that are translationally and rotationally unstable. This study compared the biomechanical stability of triangular osteosynthesis vs 2-transsacral-screw fixation in the repair of a transforaminal pelvic fracture model. A transforaminal fracture model was created in 10 cadaveric lumbopelvic specimens. Five of the specimens were stabilized with triangular osteosynthesis, which consisted of unilateral L5-to-ilium lumbopelvic fixation and ipsilateral iliosacral screw fixation. The remaining 5 were stabilized with a 2-transsacral-screw fixation technique that consisted of 2 transsacral screws inserted across S1. All specimens were loaded cyclically and then loaded to failure. Translation and rotation were measured using the MicroScribe 3D digitizing system (Revware Inc, Raleigh, North Carolina). The 2-transsacral-screw group showed significantly greater stiffness than the triangular osteosynthesis group (2-transsacral-screw group, 248.7 N/mm [standard deviation, 73.9]; triangular osteosynthesis group, 125.0 N/mm [standard deviation, 66.9]; P=.02); however, ultimate load and rotational stiffness were not statistically significant. Compared with triangular osteosynthesis fixation, the use of 2 transsacral screws provides a comparable biomechanical stability profile in both translation and rotation. This newly revised 2-transsacral-screw construct offers the traumatologist an alternative method of repair for vertical shear fractures that provides biplanar stability. It also offers the advantage of percutaneous placement in either the prone or supine position.

  2. [From the preoedipal to the oedipal: Kafka as an example of the problems of transition from dyadic to triangular relationships].

    PubMed

    Odağ, Celal

    2004-01-01

    In early childhood, the mother is the primary object of the child's dyadic relationship, and mother and child form a unity together. In the oedipal period, however, the father enters this dyadic unity, and it is with his entry that the dyad becomes triangular and begins to incorporate features of a triangular relationship. In some cases the father may even replace the mother, thereby reducing the mother's relevance. Kafka is an interesting example of this unusual case. In addition, a close look at Kafka's psychopathology facilitates a better understanding of the interdependency of preoedipal, oedipal and adolescent stages. A psychoanalytic approach to Kafka reveals severe disturbances of these major developmental steps, which, on their part, impede the development of Kafka's individual identity. It is against this background that Kafka's author identity will be analysed in greater detail, by regarding representations of separatedness, continuity, and originality in his literary work to be expressions of his author identity. One further assumption of this paper is that Kafka's ideal self and superego are not separate from each other. His feelings of guilt, shame and fear demonstrate that these instances are very much intertwined and not distinct from each other. The reader's emotional agony while reading some of Kafka's work signalizes that Kafka's ideal self and superego form a unity together. Psychoanalysts, however, commonly accept that, in normal development, ideal self and superego should become separate entities, and continue their activities separately. It seems as though Kafka's ideal self and superego have not gained sovereignty yet, and likewise, it is difficult to separate the son's superego or ideal self from his father's.

  3. [From the preoedipal to the oedipal: Kafka as an example of the problems of transition from dyadic to triangular relationships].

    PubMed

    Odağ, Celal

    2004-01-01

    In early childhood, the mother is the primary object of the child's dyadic relationship, and mother and child form a unity together. In the oedipal period, however, the father enters this dyadic unity, and it is with his entry that the dyad becomes triangular and begins to incorporate features of a triangular relationship. In some cases the father may even replace the mother, thereby reducing the mother's relevance. Kafka is an interesting example of this unusual case. In addition, a close look at Kafka's psychopathology facilitates a better understanding of the interdependency of preoedipal, oedipal and adolescent stages. A psychoanalytic approach to Kafka reveals severe disturbances of these major developmental steps, which, on their part, impede the development of Kafka's individual identity. It is against this background that Kafka's author identity will be analysed in greater detail, by regarding representations of separatedness, continuity, and originality in his literary work to be expressions of his author identity. One further assumption of this paper is that Kafka's ideal self and superego are not separate from each other. His feelings of guilt, shame and fear demonstrate that these instances are very much intertwined and not distinct from each other. The reader's emotional agony while reading some of Kafka's work signalizes that Kafka's ideal self and superego form a unity together. Psychoanalysts, however, commonly accept that, in normal development, ideal self and superego should become separate entities, and continue their activities separately. It seems as though Kafka's ideal self and superego have not gained sovereignty yet, and likewise, it is difficult to separate the son's superego or ideal self from his father's. PMID:15622512

  4. Density matrix renormalization group study of triangular Kitaev-Heisenberg model

    NASA Astrophysics Data System (ADS)

    Sota, Shigetoshi; Sjinjo, Kazuya; Shirakawa, Tomonori; Tohyama, Takami; Yunoki, Seiji

    2015-03-01

    Topological insulator has been one of the most active subjects in the current condensed matter physics. For most of topological insulators electron correlations are considered to be not essential. However, in the case where electron correlations are strong, novel phases such as a spin liquid phase can emerge in competition with a spin-orbit coupling. Here, using the density matrix renormalization group method, we investigate magnetic phase of a triangular Kitaev-Heisenberg (quantum compass) model that contains a spin-orbital interaction and spin frustration in the antiferromagnetic region. The triangular Kitaev-Heisenberg model is regarded as a dual model of the honeycomb Kitaev-Heisenberg model that is usually employed to discuss A2CuO3 (A=Na, K). Systematically calculating ground state energy, entanglement entropy, entanglement spectrum, and spin-spin correlation functions, we discuss the duality between the triangular and the honeycomb Kitaev-Heisenberg model as well as the ground state magnetic phases.

  5. On Modeling and Analysis of MIMO Wireless Mesh Networks with Triangular Overlay Topology

    DOE PAGES

    Cao, Zhanmao; Wu, Chase Q.; Zhang, Yuanping; Shiva, Sajjan G.; Gu, Yi

    2015-01-01

    Multiple input multiple output (MIMO) wireless mesh networks (WMNs) aim to provide the last-mile broadband wireless access to the Internet. Along with the algorithmic development for WMNs, some fundamental mathematical problems also emerge in various aspects such as routing, scheduling, and channel assignment, all of which require an effective mathematical model and rigorous analysis of network properties. In this paper, we propose to employ Cartesian product of graphs (CPG) as a multichannel modeling approach and explore a set of unique properties of triangular WMNs. In each layer of CPG with a single channel, we design a node coordinate scheme thatmore » retains the symmetric property of triangular meshes and develop a function for the assignment of node identity numbers based on their coordinates. We also derive a necessary-sufficient condition for interference-free links and combinatorial formulas to determine the number of the shortest paths for channel realization in triangular WMNs.« less

  6. Transformation of design formulae for feed line of triangular microstrip antenna

    NASA Astrophysics Data System (ADS)

    Mathur, Monika; Singh, Ghanshyam; Bhatnagar, S. K.; Swami, Swati; Vats, Abhijat

    2016-03-01

    In wireless communication system microstrip antenna is the key component. Popular shapes of patch for microstrip are rectangular, triangular and circular. A new transformation design formulae for feed line of rectangular microstrip antenna by using equivalent design concept were presented by the authors. That says one designed antenna for a given frequency on any substrate can be transformed into another substrate material for the same design frequency by simply multiply a factor ψ to the all dimensions of patch, length of feed line and some power of ψ for feed line width (where ψ is the square root of the ratio of dielectric constants of those two designs). This paper presents that the same formulae of that rectangular transformation feed line can also be applicable for triangular shape microstrip antenna transformation. The process was repeated for the triangular shape patch microstrip antenna as applied for rectangular shape and the simulation results were surprisingly the same for it by applying the same transformation formulae.

  7. Extended particle swarm optimisation method for folding protein on triangular lattice.

    PubMed

    Guo, Yuzhen; Wu, Zikai; Wang, Ying; Wang, Yong

    2016-02-01

    In this study, the authors studied the protein structure prediction problem by the two-dimensional hydrophobic-polar model on triangular lattice. Particularly the non-compact conformation was modelled to fold the amino acid sequence into a relatively larger triangular lattice, which is more biologically realistic and significant than the compact conformation. Then protein structure prediction problem was abstracted to match amino acids to lattice points. Mathematically, the problem was formulated as an integer programming and they transformed the biological problem into an optimisation problem. To solve this problem, classical particle swarm optimisation algorithm was extended by the single point adjustment strategy. Compared with square lattice, conformations on triangular lattice are more flexible in several benchmark examples. They further compared the authors' algorithm with hybrid of hill climbing and genetic algorithm. The results showed that their method was more effective in finding solution with lower energy and less running time.

  8. Extended particle swarm optimisation method for folding protein on triangular lattice.

    PubMed

    Guo, Yuzhen; Wu, Zikai; Wang, Ying; Wang, Yong

    2016-02-01

    In this study, the authors studied the protein structure prediction problem by the two-dimensional hydrophobic-polar model on triangular lattice. Particularly the non-compact conformation was modelled to fold the amino acid sequence into a relatively larger triangular lattice, which is more biologically realistic and significant than the compact conformation. Then protein structure prediction problem was abstracted to match amino acids to lattice points. Mathematically, the problem was formulated as an integer programming and they transformed the biological problem into an optimisation problem. To solve this problem, classical particle swarm optimisation algorithm was extended by the single point adjustment strategy. Compared with square lattice, conformations on triangular lattice are more flexible in several benchmark examples. They further compared the authors' algorithm with hybrid of hill climbing and genetic algorithm. The results showed that their method was more effective in finding solution with lower energy and less running time. PMID:26816397

  9. Interpreting medium ring canonical conformers by a triangular plane tessellation of the macrocycle

    NASA Astrophysics Data System (ADS)

    Khalili, Pegah; Barnett, Christopher B.; Naidoo, Kevin J.

    2013-05-01

    Cyclic conformational coordinates are essential for the distinction of molecular ring conformers as the use of Cremer-Pople coordinates have illustrated for five- and six-membered rings. Here, by tessellating medium rings into triangular planes and using the relative angles made between triangular planes we are able to assign macrocyclic pucker conformations into canonical pucker conformers such as chairs, boats, etc. We show that the definition is straightforward compared with other methods popularly used for small rings and that it is computationally simple to implement for complex macrocyclic rings. These cyclic conformational coordinates directly couple to the motion of individual nodes of a ring. Therefore, they are useful for correlating the physical properties of macrocycles with their ring pucker and measuring the dynamic ring conformational behavior. We illustrate the triangular tessellation, assignment, and pucker analysis on 7- and 8-membered rings. Sets of canonical states are given for cycloheptane and cyclooctane that have been previously experimentally analysed.

  10. The evidence for synthesis of truncated triangular silver nanoplates in the presence of CTAB

    SciTech Connect

    He Xin; Zhao Xiujian Chen Yunxia; Feng Jinyang

    2008-04-15

    Truncated triangular silver nanoplates were prepared by a solution-phase approach, which involved the seed-mediated growth of silver nanoparticles in the presence of cetyltrimethylammonium bromide (CTAB) at 40 deg. C. The result of X-ray diffraction indicates that the as-prepared nanoparticles are made of pure face centered cubic silver. Transmission electron microscopy and atomic force microscopy studies show that the truncated triangular silver nanoplates, with edge lengths of 50 {+-} 5 nm and thicknesses of 27 {+-} 3 nm, are oriented differently on substrates of a copper grid and a fresh mica flake. The corners of these nanoplates are round. The selected area electron diffraction analysis reveals that the silver nanoplates are single crystals with an atomically flat surface. We determine the holistic morphology of truncated triangular silver nanoplates through the above measurements with the aid of computer-aided 3D perspective images.

  11. Mechanical Properties of 3-D Printed Cellular Foams with triangular cells

    NASA Astrophysics Data System (ADS)

    Bunga, Pratap Kumar

    In the present work, poly lactic acid (PLA) is used as a model system to investigate the mechanical behavior of 3-D printed foams with triangular cells. Solid PLA tension and compression specimens and foams made of PLA were fabricated using fused deposition 3-D printing technique. The solid PLA tension specimens were characterized for their densities and found to be about 10% lower in density as compared to their bulk counter parts. The triangular foams had a relative density of about 64%. The relationships between the structure of the foams and its deformation behavior under compression along two in-plane directions were characterized. Furthermore, simple finite element models were developed to understand the observed deformation behavior of triangular foams.

  12. Post-Newtonian effects on Lagrange's equilateral triangular solution for the three-body problem

    SciTech Connect

    Ichita, Takumi; Yamada, Kei; Asada, Hideki

    2011-04-15

    Continuing work initiated in earlier publications [Yamada, Asada, Phys. Rev. D 82, 104019 (2010); ibid.83, 024040 (2011)], we investigate the post-Newtonian effects on Lagrange's equilateral triangular solution for the three-body problem. For three finite masses, it is found that the equilateral triangular configuration satisfies the post-Newtonian equation of motion in general relativity, if and only if all three masses are equal. When a test mass is included, the equilateral configuration is possible for two cases: (1) one mass is finite and the other two are zero, or (2) two of the masses are finite and equal, and the third one is zero, namely, a symmetric binary with a test mass. The angular velocity of the post-Newtonian equilateral triangular configuration is always smaller than the Newtonian one, provided that the masses and the side length are the same.

  13. Complete band gaps and deaf bands of triangular and honeycomb water-steel phononic crystals

    NASA Astrophysics Data System (ADS)

    Hsiao, Fu-Li; Khelif, Abdelkrim; Moubchir, Hanane; Choujaa, Abdelkrim; Chen, Chii-Chang; Laude, Vincent

    2007-02-01

    Phononic crystals with triangular and honeycomb lattices are investigated experimentally and theoretically. They are composed of arrays of steel cylinders immersed in water. The measured transmission spectra reveal the existence of complete band gaps but also of deaf bands. Band gaps and deaf bands are identified by comparing band structure computations, obtained by a periodic-boundary finite element method, with transmission simulations, obtained using the finite difference time domain method. The appearance of flat bands and the polarization of the associated eigenmodes is also discussed. Triangular and honeycomb phononic crystals with equal cylinder diameter and smallest spacing are compared. As previously obtained with air-solid phononic crystals, it is found that the first complete band gap opens for the honeycomb lattice but not for the triangular lattice, thanks to symmetry reduction.

  14. Effects of Shannon entropy and electric field on polaron in RbCl triangular quantum dot

    NASA Astrophysics Data System (ADS)

    M, Tiotsop; A, J. Fotue; S, C. Kenfack; N, Issofa; H, Fotsin; L, C. Fai

    2016-04-01

    In this paper, the time evolution of the quantum mechanical state of a polaron is examined using the Pekar type variational method on the condition of the electric-LO-phonon strong-coupling and polar angle in RbCl triangular quantum dot. We obtain the eigenenergies, and the eigenfunctions of the ground state, and the first excited state respectively. This system in a quantum dot can be treated as a two-level quantum system qubit and the numerical calculations are performed. The effects of Shannon entropy and electric field on the polaron in the RbCl triangular quantum dot are also studied.

  15. Vibration of triangular plates: Point supports, mixed edges and partial internal curved supports

    NASA Astrophysics Data System (ADS)

    Liew, K. M.; Wang, C. M.

    1994-05-01

    A numerical method, which is a hybrid form of the Rayleigh-Ritz method and the Lagrangian multiplier method, is presented in this paper for the vibration analysis of general triangular plates with complicated supported conditions. These support conditions include internal clamped or simple point supports, mixed periphery boundary conditions and partial internal curved supports. Several plate examples are used to illustrate the method. Apart from the limiting cases of some of these triangular plates with point supports where existing results are available for comparison, the frequency parameters presented in this paper are new. They should be valuable to designers in some industrial applications.

  16. Controllable galvanic synthesis of triangular Ag-Pd alloy nanoframes for efficient electrocatalytic methanol oxidation.

    PubMed

    Xu, Lin; Luo, Zhimin; Fan, Zhanxi; Yu, Sijia; Chen, Junze; Liao, Yusen; Xue, Can

    2015-06-01

    Triangular Ag-Pd alloy nanoframes were successfully synthesized through galvanic replacement by using Ag nanoprisms as sacrificial templates. The ridge thickness of the Ag-Pd alloy nanoframes could be readily tuned by adjusting the amount of the Pd source during the reaction. These obtained triangular Ag-Pd alloy nanoframes exhibit superior electrocatalytic activity for the methanol oxidation reaction as compared with the commercial Pd/C catalyst due to the alloyed Ag-Pd composition as well as the hollow-framed structures. This work would be highly impactful in the rational design of future bimetallic alloy nanostructures with high catalytic activity for fuel cell systems.

  17. Theoretical characteristics in supersonic flow of two types of control surfaces on triangular wings

    NASA Technical Reports Server (NTRS)

    Tucker, Warren A; Nelson, Robert L

    1949-01-01

    Methods based on the linearized theory for supersonic flow were used to find the characteristics of two types of control surfaces on thin triangular wings. The first type, the constant-chord partial-span flap, was considered to extend either outboard from the center of the wing or inboard from the wing tip. The second type, the full-triangular-tip flap, was treated only for the case in which the Mach number component normal to the leading edge is supersonic. For each type, expressions were found for the lift, rolling-moment, pitching-moment, and hinge-moment characteristics.

  18. Magnetic phase diagram of the coupled triangular spin tubes for CsCrF4

    NASA Astrophysics Data System (ADS)

    Seki, Kouichi; Okunishi, Kouichi

    2015-06-01

    Using Monte Carlo simulations, we explore the magnetic phase diagram of triangular spin tubes coupled with a ferromagnetic intertube interaction for CsCrF4. The planar structure of the coupled tubes is topologically equivalent to the kagome-triangular lattice, which induces nontrivial frustration effects in the system. We particularly find that, depending on the intertube coupling, various ordered phases are actually realized, such as incommensurate order, ferromagnetic order, and cuboc order, which is characterized by the noncoplanar spin structure of the 12 sublattices accompanying the spin chirality breaking. We also discuss the relevance of the results to recent experiments on CsCrF4.

  19. Current density and poloidal magnetic field for toroidal elliptic plasmas with triangularity

    SciTech Connect

    Martin, P.; Haines, M.G.; Castro, E.

    2005-08-15

    Changes in the poloidal magnetic field around a tokamak magnetic surface due to different values of triangularity and ellipticity are analyzed in this paper. The treatment here presented allows the determination of the poloidal magnetic field from knowledge of the toroidal current density. Different profiles of these currents are studied. Improvements in the analytic forms of the magnetic surfaces have also been found. The treatment has been performed using a recent published system of coordinates. Suitable analytic equations have been used for the elliptic magnetic surfaces with triangularity and Shafranov shift.

  20. A Computer Program for the Reactivity and Kinetic Parameters for Two-Dimensional Triangular Geometry by Transport Perturbation Theory.

    1990-04-25

    Version 00 TPTRIA calculates reactivity, effective delayed neutron fractions and mean generation time for two-dimensional triangular geometry on the basis of neutron transport perturbation theory. DIAMANT2 (also designated as CCC-414), is a multigroup two-dimensional discrete ordinates transport code system for triangular and hexagonal geometry which calculates direct and adjoint angular fluxes.

  1. Single crystal growth and heat capacity measurements of triangular lattice R2Pt6Ga15 (R =rare earth)

    NASA Astrophysics Data System (ADS)

    Matsumoto, Y.; Ueda, T.; Ohara, S.

    2016-02-01

    We have succeeded in synthesizing the single crystal of R2Pt6Ga15 (R=La-Nd, Sm- Lu) with hexagonal Sc0.67Fe2Si5-type structure using Ga self flux method. The crystal structure was confirmed by the powder X-ray method. The unit-cell volume V of R2Pt6Ga15 follows the lanthanide concentration except R = Ce, Eu and Yb, indicating that the valences of R = La, Pr, Nd, Sm, Gd-Tm, and Lu ion are trivalent, whereas those of R = Ce, Eu and Yb ion are deviate from trivalent. We have measured the specific heat C(T) of R2Pt6Ga15. It is found that the magnetic order takes place in R2Pt6Ga15 (R=Pr, Nd, Sm-Tm). Moreover, the multiple phase transitions were observed in R2Pt6Ga15 (R = Nd, Eu, Gd and Ho).

  2. Gapless quantum spin liquid ground state in the two-dimensional spin-1/2 triangular antiferromagnet YbMgGaO4

    PubMed Central

    Li, Yuesheng; Liao, Haijun; Zhang, Zhen; Li, Shiyan; Jin, Feng; Ling, Langsheng; Zhang, Lei; Zou, Youming; Pi, Li; Yang, Zhaorong; Wang, Junfeng; Wu, Zhonghua; Zhang, Qingming

    2015-01-01

    Quantum spin liquid (QSL) is a novel state of matter which refuses the conventional spin freezing even at 0 K. Experimentally searching for the structurally perfect candidates is a big challenge in condensed matter physics. Here we report the successful synthesis of a new spin-1/2 triangular antiferromagnet YbMgGaO4 with symmetry. The compound with an ideal two-dimensional and spatial isotropic magnetic triangular-lattice has no site-mixing magnetic defects and no antisymmetric Dzyaloshinsky-Moriya (DM) interactions. No spin freezing down to 60 mK (despite θw ~ −4 K), the power-law temperature dependence of heat capacity and nonzero susceptibility at low temperatures suggest that YbMgGaO4 is a promising gapless (≤|θw|/100) QSL candidate. The residual spin entropy, which is accurately determined with a non-magnetic reference LuMgGaO4, approaches zero (<0.6%). This indicates that the possible QSL ground state (GS) of the frustrated spin system has been experimentally achieved at the lowest measurement temperatures. PMID:26552727

  3. Phase diagrams of the Ising-Heisenberg chain with S = 1/2 triangular XXZ clusters

    SciTech Connect

    Ohanyan, V.

    2010-03-15

    The one-dimensional spin system consisted of triangular S = 1/2 XXZ Heisenberg clusters alternating with single Ising spins is considered. Partition function of the system is calculated exactly within the transfer-matrix formalism. T = 0 ground state phase diagrams, corresponding to different regions of the values of system parameters, are obtained.

  4. Temperley's triangular lattice compact cluster model: exact solution in terms of the q series

    NASA Astrophysics Data System (ADS)

    Glasser, M. L.; Privman, V.; Svrakic, N. M.

    1987-12-01

    Temperley's model (1952) of self-supporting stackings of circles in a triangular lattice array against a line wall is solved exactly in terms of q hypergeometric functions. For N circles, the number of different configurations is described by the large-N asymptotic law A lambda N, with A=0.312 36. . . and lambda =1.735 66. . . .

  5. Phase diagram and unusual magnetic excitations in distorted triangular lattice antiferromagnet α- CaCr204

    NASA Astrophysics Data System (ADS)

    Ducatman, Samuel; Perkins, Natalia

    2013-03-01

    While it is well known that the ground state of the isotropic Heisenberg model on a triangular lattice is the so called 120° structure, its appearance on the distorted triangular lattice is rather unusual. This case has been recently observed in the distorted triangular lattice antiferromagnet α-CaCr2O4 [S. Toth et al, PRB 84, 054452 (2011)] which shows the onset of the 120° long-range magnetic order below TN = 42 . 6 K . Recent neutron scattering experiments also revealed that this compound has unusual magnetic excitations with a dispersion with roton-like minima at momenta different from those corresponding to its 120°-magnetic order [S. Toth et al, PRL 109, 127203 (2012)]. Motivated by these experimental findings, we calculate a magnetic phase diagram and excitation spectrum of anisotropic Heisenberg Hamiltonian on triangular lattice. We showed that at the parameters characterizing α-CaCr2O4 compound, the ground state is indeed the 120°-structure, however, other possible magnetic orderings are very close in energy. We compute the dispersion of magnetic excitations to order 1/S and compare it with the neutron scattering data. supported by the grant NSF-DMR-0844115

  6. Investigation of localization of DNA molecules using triangular metal electrodes with varying separation

    NASA Astrophysics Data System (ADS)

    Prasad, D. Nagendra; Ghonge, Sudarshan; Banerjee, Souri

    2016-04-01

    In this paper we investigate the effect of separation of triangular metal electrodes with both convex and concave geometries, on the localization of suspended DNA molecules under the combined effect of dielectrophoresis and AC electro-osmosis through simulations using COMSOL Multiphysics. Trapping points are realized within the electrodes which are found to vary with the separation of the electrodes.

  7. Arthroscopic repair of peripheral triangular fibrocartilage complex tears with suture welding: a technical report.

    PubMed

    Badia, Alejandro; Jiménez, Alexis

    2006-10-01

    This report presents a method of arthroscopic repair of the peripheral triangular fibrocartilage complex tears that replaces traditional suture knots with ultrasonic welding of sutures. This will help eliminate potential causes of ulnar-sided wrist discomfort during the postoperative period.

  8. A simple method for understanding the triangular growth patterns of transition metal dichalcogenide sheets

    SciTech Connect

    Zhu, Siya; Wang, Qian

    2015-10-15

    Triangular nanoflake growth patterns have been commonly observed in synthesis of transition metal dichalcogenide sheets and their hybrid structures. Triangular nanoflakes not only show exceptional properties, but also can serve as building blocks for two or three dimensional structures. In this study, taking the MoS{sub 2} system as a test case, we propose a Matrix method to understand the mechanism of such unique growth pattern. Nanoflakes with different edge types are mathematically described with configuration matrices, and the total formation energy is calculated as the sum of the edge formation energies and the chemical potentials of sulfur and molybdenum. Based on energetics, we find that three triangular patterns with the different edge configurations are energetically more favorable in different ranges of the chemical potential of sulfur, which are in good agreement with experimental observations. Our algorithm has high efficiency and can deal with nanoflakes in microns which are beyond the ability of ab-initio method. This study not only elucidates the mechanism of triangular nanoflake growth patterns in experiment, but also provides a clue to control the geometric configurations in synthesis.

  9. Resistance calculation of three-dimensional triangular and hexagonal prism lattices

    NASA Astrophysics Data System (ADS)

    Owaidat, M. Q.; Asad, J. H.

    2016-09-01

    The resistance between two arbitrary lattice sites in infinite three-dimensional triangular and hexagonal prism lattice networks of equal resistances, that have not been studied before, is computed by using lattice Green's function technique. For large separation between lattice points we numerically calculate the asymptotic value of the resistance for these lattices.

  10. Augmenting data rate performance for higher order modulation in triangular index profile multicore fiber interconnect

    NASA Astrophysics Data System (ADS)

    Mishra, Jitendra K.; Priye, Vishnu; Rahman, B. M. A.

    2016-07-01

    A triangular profile multicore fiber (MCF) optical interconnect (OI) is investigated to augment performance that typically degrades at high data rates for higher order modulation in a short reach transmission system. Firstly, probability density functions (PDFs) variation with inter-core crosstalk is calculated for 8-core MCF OI with different index profile in the core and it was observed that the triangular profile MCF OI is the most crosstalk tolerant. Next, symbol error probability (SEP) for higher order quadrature phase shift keying (QPSK) modulated signal due to inter-core crosstalk is analytically obtained and their dependence on typical characteristic parameters are examined. Further, numerical simulations are carried out to compare the error performance of QPSK for step index and triangular index MCF OI by generating eye diagram at 40 Gbps per channel. Finally, it is shown that MCF OI with triangular index profile supporting QPSK has double spectral efficiency with tolerable trade off in SEP as compared with those of binary phase shift keying (BPSK) at high data rates which is scalable up to 5 Tbps.

  11. Optimizing the US Diagnosis of Biliary Atresia with a Modified Triangular Cord Thickness and Gallbladder Classification.

    PubMed

    Zhou, Lu-Yao; Wang, Wei; Shan, Quan-yuan; Liu, Bao-xian; Zheng, Yan-ling; Xu, Zuo-feng; Xu, Ming; Pan, Fu-shun; Lu, Ming-de; Xie, Xiao-yan

    2015-10-01

    Purpose To evaluate the diagnostic performance of ultrasonography (US) in the identification and exclusion of biliary atresia with a modified triangular cord thickness metric together with a gallbladder classification scheme, as well as hepatic artery (HA) diameter and liver and spleen size, in a large sample of jaundiced infants. Materials and Methods The ethics committee approved this study, and written informed parental consent was obtained. In 273 infants with conjugated hyperbilirubinemia (total bilirubin level ≥ 31.2 μmol/L, with direct bilirubin level > indirect bilirubin level), detailed abdominal US was performed to exclude biliary atresia. Biliary atresia was found in 129 infants and ruled out in 144. A modified triangular cord thickness was measured at the anterior branch of the right portal vein, and a gallbladder classification scheme was identified that incorporated the appearance of the gallbladder and a gallbladder length-to-width ratio of up to 5.2 when the lumen was visualized, as well as HA diameter and liver and spleen size. Reference standard diagnosis was based on results of one or more of the following: surgery, liver biopsy, cholangiography, and clinical follow-up. Area under the receiver operating characteristic curve (AUC) analysis, binary logistic regression analysis, Fisher exact test, and unpaired t test were performed. Results Triangular cord thickness, HA diameter, ratio of gallbladder length to gallbladder width, liver size, and spleen size exhibited statistically significant differences (all P < .05) between the group with biliary atresia and the group without. AUCs of triangular cord thickness, ratio of gallbladder length to width, and HA diameter were 0.952, 0.844, and 0.838, respectively. Logistic regression analysis demonstrated that these three US parameters were significantly associated (all P < .05) with biliary atresia. The combination of triangular cord thickness and gallbladder classification could yield comparable AUCs

  12. Multi-frequency excitation of stiffened triangular plates for large amplitude oscillations

    NASA Astrophysics Data System (ADS)

    Askari, H.; Saadatnia, Z.; Esmailzadeh, E.; Younesian, D.

    2014-10-01

    Free and forced vibrations of triangular plate are investigated. Diverse types of stiffeners were attached onto the plate to suppress the undesirable large-amplitude oscillations. The governing equation of motion for a triangular plate, based on the von Kármán theory, is developed and the nonlinear ordinary differential equation of the system using Galerkin approach is obtained. Closed-form expressions for the free undamped and large-amplitude vibration of an orthotropic triangular elastic plate are presented using the two well-known analytical methods, namely, the energy balance method and the variational approach. The frequency responses in the closed-form are presented and their sensitivities with respect to the initial amplitudes are studied. An error analysis is performed and the vibration behavior, as well as the accuracy of the solution methods, is evaluated. Different types of the stiffened triangular plates are considered in order to cover a wide range of practical applications. Numerical simulations are carried out and the validity of the solution procedure is explored. It is demonstrated that the two methods of energy balance and variational approach have been quite straightforward and reliable techniques to solve those nonlinear differential equations. Subsequently, due to the importance of multiple resonant responses in engineering design, multi-frequency excitations are considered. It is assumed that three periodic forces are applied to the plate in three specific positions. The multiple time scaling method is utilized to obtain approximate solutions for the frequency resonance cases. Influences of different parameters, namely, the position of applied forces, geometry and the number of stiffeners on the frequency response of the triangular plates are examined.

  13. Modeling and simulation of optical properties of noble metals triangular nanoprisms

    NASA Astrophysics Data System (ADS)

    Alsheheri, Soad

    Gold and silver has gained huge attention across the scientific community for its applications arising from its plasmonic properties. The optical properties achieved by these materials via excitation of plasmons is very unique to these materials and used as diagnostic and therapeutic agents in the field of medicine, and as sensors in a gamut of disciplines such as energy and environmental protection to name a few. Surface plasmon resonance (SPR) properties of the gold and silver are size and shape dependent. Of the various shapes reported in literature, triangular nanoprisms has tunable optical properties in the visible and near IR region by manipulating the structural features such as thickness, edge length, and morphology of tip. To understand the effect of these parameters on dipole surface plasmon resonance we have constructed triangular silver nanoprism and sandwich of gold and triangular nanoprism using Optiwave FDTD. Silver triangular nanoprism has exhibited blue shift on introduction of truncation and the blue shift continued further with depth of truncation. Similar observations were made for increase in thickness of nanoprism. In contrast, increase in edge length of the nanoprism has introduced a blue shift in dipole surface plasmon resonance. Coupling of gold and silver as sandwich with a dielectric material has introduced two plasmon resonance peaks in the visible and near IR region. In contrast to individual silver triangular nanoprism, increasing the edge length and thickness of gold and silver has introduced a red shift. Interestingly, thickness of the dielectric layer controls the wavelength of the dipole plasmon resonance of metals in the sandwich and its strength.

  14. Synthesis and functionalization of heteroatom-bridged bicyclocalixaromatics, large molecular triangular prisms with electron-rich and -deficient aromatic interiors.

    PubMed

    Naseer, Muhammad Moazzam; Wang, De-Xian; Zhao, Liang; Huang, Zhi-Tang; Wang, Mei-Xiang

    2011-03-18

    The synthesis and functionalization of oxygen and nitrogen atom bridged bicyclocalixaromatics of triangular prism structures are reported. By means of a fragment coupling approach, molecular triangular prisms of electron-rich and electron-deficient aromatic interiors were prepared using 1,3,5-tri(p-hydroxyphenyl)benzene and 2,4,6-tri(p-aminophenyl)triazine as base units and chlorotriazines as pillars. Aromatic nucleophilic substitution reaction of chlorotriazine moieties with functionalized amines led to triangular prisms with functionalizations on the peripheral edge positions, while functionalized triangular prisms on the vertex nitrogen positions were obtained using 2,4,6-tri[(p-allylamino)phenyl]triazine derivative as a starting material. Symmetrical and distorted molecular triangular prisms in the solid state were revealed by X-ray crystallography. As evidenced by NMR spectroscopic data, however, all cage molecules synthesized most probably adopted highly symmetric triangular prism structures in solution phase. The functionalized shape-persistent triangular prism structures might find applications in molecular recognition and in the construction of higher and more sophisticated molecular architectures in supramolecular chemistry.

  15. De Novo Assembly of the Whole Transcriptome of the Wild Embryo, Preleptocephalus, Leptocephalus, and Glass Eel of Anguilla japonica and Deciphering the Digestive and Absorptive Capacities during Early Development.

    PubMed

    Hsu, Hsiang-Yi; Chen, Shu-Hwa; Cha, Yuh-Ru; Tsukamoto, Katsumi; Lin, Chung-Yen; Han, Yu-San

    2015-01-01

    Natural stocks of Japanese eel (Anguilla japonica) have decreased drastically because of overfishing, habitat destruction, and changes in the ocean environment over the past few decades. However, to date, artificial mass production of glass eels is far from reality because of the lack of appropriate feed for the eel larvae. In this study, wild glass eel, leptocephali, preleptocephali, and embryos were collected to conduct RNA-seq. Approximately 279 million reads were generated and assembled into 224,043 transcripts. The transcript levels of genes coding for digestive enzymes and nutrient transporters were investigated to estimate the capacities for nutrient digestion and absorption during early development. The results showed that the transcript levels of protein digestion enzymes were higher than those of carbohydrate and lipid digestion enzymes in the preleptocephali and leptocephali, and the transcript levels of amino acid transporters were also higher than those of glucose and fructose transporters and the cholesterol transporter. In addition, the transcript levels of glucose and fructose transporters were significantly raising in the leptocephali. Moreover, the transcript levels of protein, carbohydrate, and lipid digestion enzymes were balanced in the glass eel, but the transcript levels of amino acid transporters were higher than those of glucose and cholesterol transporters. These findings implied that preleptocephali and leptocephali prefer high-protein food, and the nutritional requirements of monosaccharides and lipids for the eel larvae vary with growth. An online database (http://molas.iis.sinica.edu.tw/jpeel/) that will provide the sequences and the annotated results of assembled transcripts was established for the eel research community. PMID:26406914

  16. De Novo Assembly of the Whole Transcriptome of the Wild Embryo, Preleptocephalus, Leptocephalus, and Glass Eel of Anguilla japonica and Deciphering the Digestive and Absorptive Capacities during Early Development.

    PubMed

    Hsu, Hsiang-Yi; Chen, Shu-Hwa; Cha, Yuh-Ru; Tsukamoto, Katsumi; Lin, Chung-Yen; Han, Yu-San

    2015-01-01

    Natural stocks of Japanese eel (Anguilla japonica) have decreased drastically because of overfishing, habitat destruction, and changes in the ocean environment over the past few decades. However, to date, artificial mass production of glass eels is far from reality because of the lack of appropriate feed for the eel larvae. In this study, wild glass eel, leptocephali, preleptocephali, and embryos were collected to conduct RNA-seq. Approximately 279 million reads were generated and assembled into 224,043 transcripts. The transcript levels of genes coding for digestive enzymes and nutrient transporters were investigated to estimate the capacities for nutrient digestion and absorption during early development. The results showed that the transcript levels of protein digestion enzymes were higher than those of carbohydrate and lipid digestion enzymes in the preleptocephali and leptocephali, and the transcript levels of amino acid transporters were also higher than those of glucose and fructose transporters and the cholesterol transporter. In addition, the transcript levels of glucose and fructose transporters were significantly raising in the leptocephali. Moreover, the transcript levels of protein, carbohydrate, and lipid digestion enzymes were balanced in the glass eel, but the transcript levels of amino acid transporters were higher than those of glucose and cholesterol transporters. These findings implied that preleptocephali and leptocephali prefer high-protein food, and the nutritional requirements of monosaccharides and lipids for the eel larvae vary with growth. An online database (http://molas.iis.sinica.edu.tw/jpeel/) that will provide the sequences and the annotated results of assembled transcripts was established for the eel research community.

  17. De Novo Assembly of the Whole Transcriptome of the Wild Embryo, Preleptocephalus, Leptocephalus, and Glass Eel of Anguilla japonica and Deciphering the Digestive and Absorptive Capacities during Early Development

    PubMed Central

    Cha, Yuh-Ru; Tsukamoto, Katsumi; Lin, Chung-Yen; Han, Yu-San

    2015-01-01

    Natural stocks of Japanese eel (Anguilla japonica) have decreased drastically because of overfishing, habitat destruction, and changes in the ocean environment over the past few decades. However, to date, artificial mass production of glass eels is far from reality because of the lack of appropriate feed for the eel larvae. In this study, wild glass eel, leptocephali, preleptocephali, and embryos were collected to conduct RNA-seq. Approximately 279 million reads were generated and assembled into 224,043 transcripts. The transcript levels of genes coding for digestive enzymes and nutrient transporters were investigated to estimate the capacities for nutrient digestion and absorption during early development. The results showed that the transcript levels of protein digestion enzymes were higher than those of carbohydrate and lipid digestion enzymes in the preleptocephali and leptocephali, and the transcript levels of amino acid transporters were also higher than those of glucose and fructose transporters and the cholesterol transporter. In addition, the transcript levels of glucose and fructose transporters were significantly raising in the leptocephali. Moreover, the transcript levels of protein, carbohydrate, and lipid digestion enzymes were balanced in the glass eel, but the transcript levels of amino acid transporters were higher than those of glucose and cholesterol transporters. These findings implied that preleptocephali and leptocephali prefer high-protein food, and the nutritional requirements of monosaccharides and lipids for the eel larvae vary with growth. An online database (http://molas.iis.sinica.edu.tw/jpeel/) that will provide the sequences and the annotated results of assembled transcripts was established for the eel research community. PMID:26406914

  18. One-pot synthesis of triangular gold nanoplates allowing broad and fine tuning of edge length

    NASA Astrophysics Data System (ADS)

    Miranda, Adelaide; Malheiro, Eliana; Skiba, Elżbieta; Quaresma, Pedro; Carvalho, Patrícia A.; Eaton, Peter; de Castro, Baltazar; Shelnutt, John A.; Pereira, Eulália

    2010-10-01

    A photocatalytic approach was used to synthesize triangular nanoplates in aqueous solution. The synthesis is based on the reduction of a gold salt using a tin(iv) porphyrin as photocatalyst, cetyltrimethylammonium bromide (CTAB) as a stabilizing agent, and triethanolamine (TEA) as the final electron donor. The average edge length of the triangular nanoplates can be easily changed in the range 45-250 nm by varying the concentration of photocatalyst, and fine-tuning of the average edge length is achieved by varying the concentration of CTAB. Study of the mechanism of formation of the nanoplates by UV-vis and by transmission electron microscopy (TEM) shows that there is a first stage where formation of 5 nm seeds takes place, further growth is probably by fusion and by direct reduction of gold onto the preformed nanoparticles. The nanoparticles formed during the photocatalytic reduction of the gold precursor show an irregular shape that evolves to regular triangular nanoplates after ripening in solution for 24 h.A photocatalytic approach was used to synthesize triangular nanoplates in aqueous solution. The synthesis is based on the reduction of a gold salt using a tin(iv) porphyrin as photocatalyst, cetyltrimethylammonium bromide (CTAB) as a stabilizing agent, and triethanolamine (TEA) as the final electron donor. The average edge length of the triangular nanoplates can be easily changed in the range 45-250 nm by varying the concentration of photocatalyst, and fine-tuning of the average edge length is achieved by varying the concentration of CTAB. Study of the mechanism of formation of the nanoplates by UV-vis and by transmission electron microscopy (TEM) shows that there is a first stage where formation of 5 nm seeds takes place, further growth is probably by fusion and by direct reduction of gold onto the preformed nanoparticles. The nanoparticles formed during the photocatalytic reduction of the gold precursor show an irregular shape that evolves to regular

  19. Predicting natural-convection-dominated phase change problems by control volume unstructured triangular grid: Applications to the melting of pure metal

    SciTech Connect

    Hong, Z.C.; Liou, J.H.

    1998-02-20

    Control volume methods have recently been developed for fluid flow and heat transfer on unstructured meshes. In this study, the authors extend these methods to implement the solution of natural-convection-dominated melting of gallium by a fixed-grid method. A simple, robust, and reliable explicit numerical method (MAC method) is applied for an unstructured triangular grid. This investigation also applies the implicit SIMPLER method for an unstructured triangular grid. Results obtained from the unstructured triangular grid correlate well with the structured mesh computations and experimental data. Also, the feasibility of applying the triangular grid to complex geometric problems is demonstrated by calculating two different triangular domains.

  20. Intimacy, passion, and commitment among married individuals: further testing of the triangular theory of love.

    PubMed

    Lemieux, R; Hale, J L

    2000-12-01

    The Triangular Theory of Love has created much interest among researchers in relational communication. Previous attempts at evaluating the theory have proven problematic. Specifically, the problems centered around the measurement of the theory's three components of intimacy, passion, commitment. Recent research, which employed a new measure, offered support for the theory's primary assumptions. To expand upon this, the current study factor analyzed data from a sample of 213 married individuals. Current results provided support for the triangular theory's primary assumptions. The principal components factor analysis with varimax rotation indicated support for three distinct and reliable factors. The three components were also significantly related to scores for relational satisfaction. Stepwise regression analysis indicated that each component was a significant predictor of relational satisfaction. Men scored significantly higher on intimacy than women.

  1. Spin-Chirality-Driven Ferroelectricity on a Perfect Triangular Lattice Antiferromagnet

    DOE PAGES

    Mitamura, H.; Watanuki, R.; Kaneko, Koji; Onozaki, N.; Amou, Y.; Kittaka, S.; Kobayashi, Riki; Shimura, Y.; Yamamoto, I.; Suzuki, K.; et al

    2014-10-01

    Magnetic field (B) variation of the electrical polarization Pc ( ∥c) of the perfect triangular lattice antiferromagnet RbFe(MoO4)2 is examined up to the saturation point of the magnetization for B⊥c. Pc is observed only in phases for which chirality is predicted in the in-plane magnetic structures. No strong anomaly is observed in Pc at the field at which the spin modulation along the c axis, and hence the spin helicity, exhibits a discontinuity to the commensurate state. These results indicate that the ferroelectricity in this compound originates predominantly from the spin chirality, the explanation of which would require a newmore » mechanism for magnetoferroelectricity. Lastly, the obtained field-temperature phase diagrams of ferroelectricity well agree with those theoretically predicted for the spin chirality of a Heisenberg spin triangular lattice antiferromagnet.« less

  2. Spin-Chirality-Driven Ferroelectricity on a Perfect Triangular Lattice Antiferromagnet

    SciTech Connect

    Mitamura, H.; Watanuki, R.; Kaneko, Koji; Onozaki, N.; Amou, Y.; Kittaka, S.; Kobayashi, Riki; Shimura, Y.; Yamamoto, I.; Suzuki, K.; Chi, Songxue; Sakakibara, T.

    2014-10-01

    Magnetic field (B) variation of the electrical polarization Pc ( ∥c) of the perfect triangular lattice antiferromagnet RbFe(MoO4)2 is examined up to the saturation point of the magnetization for B⊥c. Pc is observed only in phases for which chirality is predicted in the in-plane magnetic structures. No strong anomaly is observed in Pc at the field at which the spin modulation along the c axis, and hence the spin helicity, exhibits a discontinuity to the commensurate state. These results indicate that the ferroelectricity in this compound originates predominantly from the spin chirality, the explanation of which would require a new mechanism for magnetoferroelectricity. Lastly, the obtained field-temperature phase diagrams of ferroelectricity well agree with those theoretically predicted for the spin chirality of a Heisenberg spin triangular lattice antiferromagnet.

  3. Discovery of the K4 Structure Formed by a Triangular π Radical Anion.

    PubMed

    Mizuno, Asato; Shuku, Yoshiaki; Suizu, Rie; Matsushita, Michio M; Tsuchiizu, Masahisa; Reta Mañeru, Daniel; Illas, Francesc; Robert, Vincent; Awaga, Kunio

    2015-06-24

    The K4 structure was theoretically predicted for trivalent chemical species, such as sp(2) carbon. However, since attempts to synthesize the K4 carbon have not succeeded, this allotrope has been regarded as a crystal form that might not exist in nature. In the present work, we carried out electrochemical crystallization of the radical anion salts of a triangular molecule, naphthalene diimide (NDI)-Δ, using various electrolytes. X-ray crystal analysis of the obtained crystals revealed the K4 structure, which was formed by the unique intermolecular π overlap directed toward three directions from the triangular-shape NDI-Δ radical anions. Electron paramagnetic resonance and static magnetic measurements confirmed the radical anion state of NDI-Δ and indicated an antiferromagnetic intermolecular interaction with the Weiss constant of θ = -10 K. The band structure calculation suggested characteristic features of the present material, such as a metallic ground state, Dirac cones, and flat bands.

  4. Tailoring graphene magnetism by zigzag triangular holes: A first-principles thermodynamics study

    DOE PAGES

    Khan, Muhammad Ejaz; Zhang, P.; Sun, Yi -Yang; Zhang, S. B.; Kim, Yong -Hyun

    2016-03-30

    In this study, we discuss the thermodynamic stability and magnetic property of zigzag triangular holes (ZTHs) in graphene based on the results of first-principles density functional theory calculations. We find that ZTHs with hydrogen-passivated edges in mixed sp2/sp3 configurations (z211) could be readily available at experimental thermodynamic conditions, but ZTHs with 100% sp2 hydrogen-passivation (z1) could be limitedly available at high temperature and ultra-high vacuum conditions. Graphene magnetization near the ZTHs strongly depends on the type and the size of the triangles. While metallic z1 ZTHs exhibit characteristic edge magnetism due to the same-sublattice engineering, semiconducting z211 ZTHs do showmore » characteristic corner magnetism when the size is small < 2 nm. Our findings could be useful for experimentally tailoring metal-free carbon magnetism by simply fabricating triangular holes in graphene.« less

  5. Electronic properties of triangular and hexagonal MoS2 quantum dots

    NASA Astrophysics Data System (ADS)

    Pavlović, S.; Peeters, F. M.

    2015-04-01

    Using the tight-binding approach, we calculate the electronic structure of triangular and hexagonal MoS2 quantum dots. Due to the orbital asymmetry we show that it is possible to form quantum dots with the same shape but having different electronic properties. The electronic states of triangular and hexagonal quantum dots are explored, as well as the local and total density of states and the convergence towards the bulk spectrum with dot size is investigated. Our calculations show that: (1) edge states appear in the band gap, (2) that there are a larger number of electronic states in the conduction band as compared to the valence band, and (3) the relative number of edge states decreases with increasing dot size.

  6. Apex-angle-dependent resonances in triangular split-ring resonators

    NASA Astrophysics Data System (ADS)

    Burnett, Max A.; Fiddy, Michael A.

    2016-02-01

    Along with other frequency selective structures (Pendry et al. in IEEE Trans Microw Theory Tech 47(11):2075-2084, 1999) (circles and squares), triangular split-ring resonators (TSRRs) only allow frequencies near the center resonant frequency to propagate. Further, TSRRs are attractive due to their small surface area (Vidhyalakshmi et al. in Stopband characteristics of complementary triangular split ring resonator loaded microstrip line, 2011), comparatively, and large quality factors ( Q) as previously investigated by Gay-Balmaz et al. (J Appl Phys 92(5):2929-2936, 2002). In this work, we examine the effects of varying the apex angle on the resonant frequency, the Q factor, and the phase shift imparted by the TSRR element within the GHz frequency regime.

  7. Research of photonic-assisted triangular-shaped pulses generation based on quadrupling RF modulation

    NASA Astrophysics Data System (ADS)

    Yuan, Jin; Ning, Ti-gang; Li, Jing; Li, Yue-qin; Chen, Hong-yao; Zhang, Chan

    2015-05-01

    We propose an approach to generate optical triangular-shaped pulse train with tunable repetition rate using quadrupling radio frequency (RF) modulation and optical grating dispersion-induced power fading. In this work, a piece of chirped fiber Bragg grating (FBG) is employed as the dispersive media to remove the undesired 8th harmonic in optical intensity. Thus, the generated harmonics of optical intensity can be corresponding to the first two Fourier components of typical periodic triangular pulses. This work also analyzes the impacts of the extinction ratio and the bias voltage drift on the harmonic distortion suppression ratio. After that, the value of the extinction ratio and the range of the bias voltage drift can be obtained. The advantage of this proposal is that it can generate high order frequency-multiplexed optical pulses train which can be applied in all optical signal processing and other fields.

  8. Surface enhanced Raman scattering, antibacterial and antifungal active triangular gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Smitha, S. L.; Gopchandran, K. G.

    2013-02-01

    Shape controlled syntheses of gold nanoparticles have attracted a great deal of attention as their optical, electronic, magnetic and biological properties are strongly dependent on the size and shape of the particles. Here is a report on the surface enhanced Raman scattering (SERS) activity of Cinnamomum zeylanicum leaf broth reduced gold nanoparticles consisting of triangular and spherical like particles, using 2-aminothiophenol (2-ATP) and crystal violet (CV) as probe molecules. Nanoparticles prepared with a minimum leaf broth concentration, having a greater number of triangular like particles exhibit a SERS activity of the order of 107. The synthesized nanoparticles exhibit efficient antibacterial activity against the tested gram negative bacterium Escherichia coli and gram positive bacterium Staphylococcus aureus. Investigations on the antifungal activity of the synthesized nanoparticles against Aspergillus niger and Fusarium oxysporum positive is also discussed.

  9. Tailoring graphene magnetism by zigzag triangular holes: A first-principles thermodynamics study

    NASA Astrophysics Data System (ADS)

    Khan, Muhammad Ejaz; Zhang, P.; Sun, Yi-Yang; Zhang, S. B.; Kim, Yong-Hyun

    2016-03-01

    We discuss the thermodynamic stability and magnetic property of zigzag triangular holes (ZTHs) in graphene based on the results of first-principles density functional theory calculations. We find that ZTHs with hydrogen-passivated edges in mixed sp2/sp3 configurations (z211) could be readily available at experimental thermodynamic conditions, but ZTHs with 100% sp2 hydrogen-passivation (z1) could be limitedly available at high temperature and ultra-high vacuum conditions. Graphene magnetization near the ZTHs strongly depends on the type and the size of the triangles. While metallic z1 ZTHs exhibit characteristic edge magnetism due to the same-sublattice engineering, semiconducting z211 ZTHs do show characteristic corner magnetism when the size is small <2 nm. Our findings could be useful for experimentally tailoring metal-free carbon magnetism by simply fabricating triangular holes in graphene.

  10. Suture welding for arthroscopic repair of peripheral triangular fibrocartilage complex tears.

    PubMed

    Badia, Alejandro; Khanchandani, Prakash

    2007-03-01

    This report presents a method of arthroscopic repair of the peripheral triangular fibrocartilage tears by using ultrasonic suture welding technique, thus avoiding the need for traditional suture knots. This technique eliminates the potential causes of ulnar-sided wrist discomfort especially during the postoperative period. Twenty-three patients (9 women and 14 men; mean age, 35 years; range, 18-52 years) were operated during a 1-year period in 2001 for Palmer grade 1B triangular fibrocartilage complex tear and followed up for 17 months. At the final follow-up, the average wrist arc of motion was as follows: extension, 65 degrees; flexion, 56 degrees; supination, 80 degrees; pronation, 78 degrees; radial deviation, 12 degrees; and ulnar deviation, 25 degrees. Grip strength measured with a dynamometer (Jamar) averaged 81% of the contralateral side at the final evaluation (range, 53%-105%).

  11. Linear and nonlinear intersubband optical properties in a triangular quantum ring

    NASA Astrophysics Data System (ADS)

    Nasri, Djillali; Bettahar, N.

    2015-12-01

    Using the effective mass approximation, within the plane wave expansion, the linear and nonlinear coefficients absorption and the refractive index changes relative to the intersubband transitions in the conduction band of an AlxGa1-xAs/ GaAs/AlxGa1-xAs triangular quantum ring for an x-polarization and an y-polarization of the incident light are calculated. It is found that the transition energy between the ground state and the first two excited states and their related optical matrix are strongly influenced by the length of the side of the inner triangle, leading to a red-shift and blue-shift of the resonant peaks of the intersubband optical absorption, for an x-polarized light absorption and an y-polarized light absorption respectively. Our results are qualitatively similar to those of a triangular quantum wire in the presence of an intense laser field in recent literature.

  12. Rational design of crystalline supermicroporous covalent organic frameworks with triangular topologies

    NASA Astrophysics Data System (ADS)

    Dalapati, Sasanka; Addicoat, Matthew; Jin, Shangbin; Sakurai, Tsuneaki; Gao, Jia; Xu, Hong; Irle, Stephan; Seki, Shu; Jiang, Donglin

    2015-07-01

    Covalent organic frameworks (COFs) are an emerging class of highly ordered porous polymers with many potential applications. They are currently designed and synthesized through hexagonal and tetragonal topologies, limiting the access to and exploration of new structures and properties. Here, we report that a triangular topology can be developed for the rational design and synthesis of a new class of COFs. The triangular topology features small pore sizes down to 12 Å, which is among the smallest pores for COFs reported to date, and high π-column densities of up to 0.25 nm-2, which exceeds those of supramolecular columnar π-arrays and other COF materials. These crystalline COFs facilitate π-cloud delocalization and are highly conductive, with a hole mobility that is among the highest reported for COFs and polygraphitic ensembles.

  13. Coupled-wave model for triangular-lattice photonic crystal with transverse electric polarization.

    PubMed

    Sakai, Kyosuke; Yue, Jianglin; Noda, Susumu

    2008-04-28

    We present a coupled-wave model for a triangular-lattice two-dimensional (2D) photonic crystal (PC) with a transverse electric (TE) polarization and derive a set of coupled-wave equations. We use these equations to obtain analytic expressions that describe the relations between the resonant mode frequencies and the coupling constants. We calculate the resonant mode frequencies for a PC composed of circular holes. These agree well with the frequencies calculated using the 2D plane wave expansion method. We also evaluate the coupling constants of fabricated samples using their measured resonant mode frequencies. Our analytic expressions allow the design and evaluation of feedback strength in triangular-lattice 2D PC cavities.

  14. Erosion Triangular Facets as Markers of Order in an Open Dissipative System

    NASA Astrophysics Data System (ADS)

    Paliaga, Guido

    2015-07-01

    The complexity and non-linearity of the morphogenetic system which is responsible for shaping the Earth's surface have been widely recognised by many authors who have documented the fractal nature of erosion. In this paper, two peculiar kinds of landforms are compared to point out ordered structures, i.e. triangular facets that arise in different geomorphic systems, due to the principle of morphologic convergence. Occurrence of triangular facets has been documented in mountainous areas in relation to base level changes and hydrographical network evolution; similarly shaped landforms are present even in recent tectonic uplift areas along faults. The spatial distribution of the two kinds of facets has been investigated in two river basins located in Liguria (northern Italy) and in a mountainous area in Oman. The results of this analysis document the different spatial features of the two kinds of facets.

  15. Tuning phonon transmission and thermal conductance by roughness at rectangular and triangular Si/Ge interface

    NASA Astrophysics Data System (ADS)

    Jia, Lin; Ju, Shenghong; Liang, Xingang; Zhang, Xing

    2016-09-01

    Using the atomistic Green’s functions method in combination with the Landauer formula, we show that the phonon transmission and thermal conductance of periodic rectangular-shaped and triangular-shaped Si/Ge interfaces are both enhanced and tunable by roughness. For triangular-shaped interface, there is maximum phonon transmission and conductance with increasing roughness height, and the conductance can be tuned maximally by 22.3% compared with the flat interface. The maximum conductance of rectangular-shaped interface is enhanced by about 11.1%. The competing mechanisms between the broadening frequency transport window of rough interface and the increasing diffusing phonon scattering at the interface with higher roughness introduce the maximum transmission and conductance. Similar result is also obtained in non-periodic interfaces. The presented results provide insights into the thermal design of interfaces in nanoscale devices.

  16. Measured and predicted root-mean-square errors in square and triangular antenna mesh facets

    NASA Technical Reports Server (NTRS)

    Fichter, W. B.

    1989-01-01

    Deflection shapes of square and equilateral triangular facets of two tricot-knit, gold plated molybdenum wire mesh antenna materials were measured and compared, on the basis of root mean square (rms) differences, with deflection shapes predicted by linear membrane theory, for several cases of biaxial mesh tension. The two mesh materials contained approximately 10 and 16 holes per linear inch, measured diagonally with respect to the course and wale directions. The deflection measurement system employed a non-contact eddy current proximity probe and an electromagnetic distance sensing probe in conjunction with a precision optical level. Despite experimental uncertainties, rms differences between measured and predicted deflection shapes suggest the following conclusions: that replacing flat antenna facets with facets conforming to parabolically curved structural members yields smaller rms surface error; that potential accuracy gains are greater for equilateral triangular facets than for square facets; and that linear membrane theory can be a useful tool in the design of tricot knit wire mesh antennas.

  17. Tomographic particle image velocimetry over a triangular prism in unidirectional flows

    NASA Astrophysics Data System (ADS)

    Sou, In Mei; Calantoni, Joseph

    2011-11-01

    Using tomographic particle image velocimetry (Tomo-PIV), the full three-dimensional-three-component (3D-3C) flow structure and turbulence characteristics over a triangular prism in a recirculating water tunnel were investigated. Here we present preliminary results from a new Tomo-PIV system for subcritical Froude number flows. Large-scale vortex shedding from the tip of the triangular prism is observed. Results of coherent structure organization analyzed by 3D vorticity calculation will be presented. Using the full 3D-3C instantaneous velocity field, turbulent kinetic energy is directly evaluated without any of the assumptions often needed for 2D PIV measurements. Details of the experimental setup including a unique device designed to perform our Tomo-PIV volume calibration will be discussed. We perform an in-depth turbulent kinetic energy budget and explore the feasibility of extending the measurement technique to other complex flows.

  18. Rational design of crystalline supermicroporous covalent organic frameworks with triangular topologies

    PubMed Central

    Dalapati, Sasanka; Addicoat, Matthew; Jin, Shangbin; Sakurai, Tsuneaki; Gao, Jia; Xu, Hong; Irle, Stephan; Seki, Shu; Jiang, Donglin

    2015-01-01

    Covalent organic frameworks (COFs) are an emerging class of highly ordered porous polymers with many potential applications. They are currently designed and synthesized through hexagonal and tetragonal topologies, limiting the access to and exploration of new structures and properties. Here, we report that a triangular topology can be developed for the rational design and synthesis of a new class of COFs. The triangular topology features small pore sizes down to 12 Å, which is among the smallest pores for COFs reported to date, and high π-column densities of up to 0.25 nm−2, which exceeds those of supramolecular columnar π-arrays and other COF materials. These crystalline COFs facilitate π-cloud delocalization and are highly conductive, with a hole mobility that is among the highest reported for COFs and polygraphitic ensembles. PMID:26178865

  19. Sparse triangular solves for ILU revisited: data layout crucial to better performance.; .

    SciTech Connect

    Smith, B.; Zhang, H.

    2011-11-01

    A key to good processor utilization for sparse matrix computations is storing the data in the format that is most conducive to fast access by the memory system. In particular, for sparse matrix triangular solves the traditional compressed sparse matrix format is poor, and minor adjustments to the data structure can increase the processor utilization dramatically. Such adjustments involve storing the L and U factors separately and storing the U rows 'backwards' so that they are accessed in a simple streaming fashion during the triangular solves. Changes to the PETSc libraries to use this modified storage format resulted in over twice the floating-point rate for some matrices. This improvement can be accounted for by a decrease in the cache misses and TLB (transaction lookaside buffer) misses in the modified code.

  20. Numerical Simulation of Flow Through Equilateral Triangular Duct Under Constant Wall Heat Flux Boundary Condition

    NASA Astrophysics Data System (ADS)

    Kumar, Rajneesh; Kumar, Anoop; Goel, Varun

    2016-06-01

    The force convective heat transfer in an equilateral triangular duct of different wall heat flux configurations was analysed for the laminar hydro-dynamically developed and thermally developing flow by the use of finite volume method. Unstructured meshing was generated by multi-block technique and set of governing equations were discretized using second-order accurate up-wind scheme and numerically solved by SIMPLE Algorithm. For ensuring accuracy, grid independence study was also done. Numerical methodology was verified by comparing results with previous work and predicted results showed good agreement with them (within error of ±5 %). The different combinations of constant heat flux boundary condition were analysed and their effect on heat transfer and fluid flow for different Reynolds number was also studied. The results of different combinations were compared with the case of force convective heat transfer in the equilateral triangular duct with constant heat flux on all three walls.

  1. Edge structures and properties of triangular antidots in single-layer MoS2

    NASA Astrophysics Data System (ADS)

    Gan, Li-Yong; Cheng, Yingchun; Schwingenschlögl, Udo; Yao, Yingbang; Zhao, Yong; Zhang, Xi-xiang; Huang, Wei

    2016-08-01

    Density functional theory and experiments are employed to shed light on the edge structures of antidots in O etched single-layer MoS2. The equilibrium morphology is found to be the zigzag Mo edge with each Mo atom bonded to two O atoms, in a wide range of O chemical potentials. Scanning electron microscopy shows that the orientation of the created triangular antidots is opposite to the triangular shape of the single-layer MoS2 samples, in agreement with the theoretical predictions. Furthermore, edges induced by O etching turn out to be p-doped, suggesting an effective strategy to realize p-type MoS2 devices.

  2. Detecting one-mode communities in bipartite networks by bipartite clustering triangular

    NASA Astrophysics Data System (ADS)

    Cui, Yaozu; Wang, Xingyuan

    2016-09-01

    In this paper, an algorithm is proposed to detect one-mode community structures in bipartite networks, and to deduce which one-mode community structures are weighted. After analyzing the topological properties in bipartite networks, bipartite clustering triangular is introduced. First, bipartite networks are projected into two weighted one-mode networks by bipartite clustering triangular. Then all the maximal sub-graphs from two one-mode weighted networks are extracted and the maximal sub-graphs are merged together using a weighted clustering threshold. In addition, the proposed algorithm successfully finds overlapping vertices between one-mode communities. Experimental results using some real-world network data shows that the performance of the proposed algorithm is satisfactory.

  3. Characteristic morphologies of triangular defects on Si-face 4H-SiC epitaxial films

    NASA Astrophysics Data System (ADS)

    Yamashita, T.; Naijo, T.; Matsuhata, H.; Momose, K.; Osawa, H.; Okumura, H.

    2016-01-01

    Triangular defects with a characteristic morphology consisting of a 3C-type structure were investigated on Si-face 4H-SiC epitaxial films using electron microscopy. Two types of triangular defects were investigated: one with a single valley on the surface along the [ 11 2 bar 0 ] direction and another with several parallel ridges and valleys called "washboard-like defects". The defects with a single valley had a characteristic domain structure consisting of four 3C crystals, which is similar to that of previously reported comet-shaped defects on the C-face. It is shown that the 3C domain in the washboard-like defect is covered by 4H layers with a washboard-like morphology.

  4. An Algorithm to Compute Abelian Subalgebras in Linear Algebras of Upper-Triangular Matrices

    NASA Astrophysics Data System (ADS)

    Ceballos, Manuel; Núñez, Juan; Tenorio, Ángel F.

    2009-08-01

    This paper deals with the maximal abelian dimension of the Lie algebra hn, of n×n upper-triangular matrices. Regarding this, we obtain an algorithm which computes abelian subalgebras of hn as well as its implementation (and a computational study) by using the symbolic computation package MAPLE, where the order n of the matrices in hn is the unique input needed. Let us note that the algorithm also allows us to obtain a maximal abelian subalgebra of hn.

  5. The maximal Abelian dimension of linear algebras formed by strictly upper triangular matrices

    NASA Astrophysics Data System (ADS)

    Benjumea, J. C.; Núñez, J.; Tenorio, Á. F.

    2007-09-01

    We compute the largest dimension of the Abelian Lie subalgebras contained in the Lie algebra mathfrak{g}_n of n×n strictly upper triangular matrices, where n ∈ ℕ {1}. We do this by proving a conjecture, which we previously advanced, about this dimension. We introduce an algorithm and use it first to study the two simplest particular cases and then to study the general case.

  6. A simplified perturbation theory for equilibrium properties of triangular-well fluids

    NASA Astrophysics Data System (ADS)

    Largo, J.; Solana, J. R.

    2000-09-01

    A simple expression for the first coordination shell of the radial distribution function of the reference hard-sphere fluid is used in combination with Barker-Henderson perturbation theory to obtain the thermodynamic properties of triangular-well fluids. These properties are expressed analytically in terms of density, temperature, and range of the potential. It is found that the results are accurate for a wide range of densities and temperatures in comparison with existing simulation data.

  7. ARANEA, a program for generating unstructured triangular meshes with a JAVA Graphics User Interface*

    NASA Astrophysics Data System (ADS)

    Marchand, Richard; Charbonneau-Lefort, Mathieu; Dumberry, Mathieu; Pronovost, Benoit

    2001-09-01

    ARANEA is a program that automatically generates unstructured triangular meshes on two-dimensional planar domains. The program implements a Graphics User Interface (GUI) that enables the user to read, edit and save a number of components required in the construction of a mesh. The program is written in JAVA, version 1.1. It is useful for constructing meshes of the type required to solve partial differential equations with finite elements over complex two-dimensional domains.

  8. Effective side length formula for resonant frequency of equilateral triangular microstrip antenna

    NASA Astrophysics Data System (ADS)

    Guney, Kerim; Kurt, Erhan

    2016-02-01

    A novel and accurate expression is obtained by employing the differential evolution algorithm for the effective side length (ESL) of the equilateral triangular microstrip antenna (ETMA). This useful formula allows the antenna engineers to accurately calculate the ESL of the ETMA. The computed resonant frequencies (RFs) show very good agreement with the experimental RFs when this accurate ESL formula is utilised for the computation of the RFs for the first five modes.

  9. Photomediated synthesis of silver triangular bipyramids and prisms: the effect of pH and BSPP.

    PubMed

    Zhang, Jian; Langille, Mark R; Mirkin, Chad A

    2010-09-01

    The photomediated synthesis of silver right triangular bipyramids and prisms has been studied, and we have determined that pH and [BSPP]/[Ag(+)] ratio (bis(p-sulfonatophenyl)phenylphosphine, BSPP) finely control the reaction rate and, consequently, the crystal growth pathway and morphology of final products. A fast reaction rate, realized at a high pH such as 10 or 11 and a [BSPP]/[Ag(+)] ratio close to 1.0, is necessary to synthesize (100)-faceted right triangular bipyramids in high yield by preferential deposition on (111) facets of planar-twinned seeds. A slower reaction rate, which occurs at lower pH or higher [BSPP]/[Ag(+)] ratios, results in preferential deposition on (100) facets of planar-twinned seeds and the formation of nanoparticles possessing a larger surface area defined by (111) facets, such as truncated triangular bipyramids or prisms. BSPP further influences the reaction rate by ensuring a relatively constant concentration of aqueous Ag(+). In the absence of BSPP, the aqueous [Ag(+)] steadily decreases as it is consumed and results in a continuously decreasing reaction rate, which changes the preferred facet for silver deposition. At the beginning of the reaction, growth on (111) facets almost exclusively occurs and results in the formation of right triangular bipyramids, which only have (100) facets. When the reaction rate is decreased due to the consumption of Ag(+) through the course of the reaction, the facet deposition preference changes from (111) to (100) and results in the formation of truncated bitetrahedra, with (111) facets, as the predominant product.

  10. Triangular Ag-Pd alloy nanoprisms: rational synthesis with high-efficiency for electrocatalytic oxygen reduction

    NASA Astrophysics Data System (ADS)

    Xu, Lin; Luo, Zhimin; Fan, Zhanxi; Zhang, Xiao; Tan, Chaoliang; Li, Hai; Zhang, Hua; Xue, Can

    2014-09-01

    We report the generation of triangular Ag-Pd alloy nanoprisms through a rationally designed synthetic strategy based on silver nanoprisms as sacrificial templates. The galvanic replacement between Ag nanoprisms and H2PdCl4 along with co-reduction of Ag+/Pd2+ is responsible for the formation of final prismatic Ag-Pd alloy nanostructures. Significantly, these Ag-Pd alloy nanoprisms exhibited superior electrocatalytic activity for the oxygen reduction reaction (ORR) as compared with the commercial Pd/C catalyst. Such a high catalytic activity is attributed to not only the alloyed Ag-Pd composition but also the dominant {111} facets of the triangular Ag-Pd nanoprisms. This work demonstrates the rational design of bimetallic alloy nanostructures with control of selective crystal facets that are critical to achieve high catalytic activity for fuel cell systems.We report the generation of triangular Ag-Pd alloy nanoprisms through a rationally designed synthetic strategy based on silver nanoprisms as sacrificial templates. The galvanic replacement between Ag nanoprisms and H2PdCl4 along with co-reduction of Ag+/Pd2+ is responsible for the formation of final prismatic Ag-Pd alloy nanostructures. Significantly, these Ag-Pd alloy nanoprisms exhibited superior electrocatalytic activity for the oxygen reduction reaction (ORR) as compared with the commercial Pd/C catalyst. Such a high catalytic activity is attributed to not only the alloyed Ag-Pd composition but also the dominant {111} facets of the triangular Ag-Pd nanoprisms. This work demonstrates the rational design of bimetallic alloy nanostructures with control of selective crystal facets that are critical to achieve high catalytic activity for fuel cell systems. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03600j

  11. Ganglion Cyst Associated with Triangular Fibrocartilage Complex Tear That Caused Ulnar Nerve Compression

    PubMed Central

    Cinar, Can; Tasdelen, Neslihan

    2015-01-01

    Summary: Ganglions are the most frequently seen soft-tissue tumors in the hand. Nerve compression due to ganglion cysts at the wrist is rare. We report 2 ganglion cysts arising from triangular fibrocartilage complex, one of which caused ulnar nerve compression proximal to the Guyon's canal, leading to ulnar neuropathy. Ganglion cysts seem unimportant, and many surgeons refrain from performing a general hand examination. PMID:25878929

  12. Local rules for protein folding on a triangular lattice and generalized hydrophobicity in the HP model

    SciTech Connect

    Agarwala, R.; Batzoglou, S.; Dancik, V.

    1997-06-01

    We consider the problem of determining the three-dimensional folding of a protein given its one-dimensional amino acid sequence. We use the HP model for protein folding proposed by Dill, which models protein as a chain of amino acid residues that are either hydrophobic or polar, and hydrophobic interactions are the dominant initial driving force for the protein folding. Hart and Istrail gave approximation algorithms for folding proteins on the cubic lattice under HP model. In this paper, we examine the choice of a lattice by considering its algorithmic and geometric implications and argue that triangular lattice is a more reasonable choice. We present a set of folding rules for a triangular lattice and analyze the approximation ratio which they achieve. In addition, we introduce a generalization of the HP model to account for residues having different levels of hydrophobicity. After describing the biological foundation for this generalization, we show that in the new model we are able to achieve similar constant factor approximation guarantees on the triangular lattice as were achieved in the standard HP model. While the structures derived from our folding rules are probably still far from biological reality, we hope that having a set of folding rules with different properties will yield more interesting folds when combined.

  13. Tunable multi-wavelength polymer laser based on a triangular-lattice photonic crystal structure

    NASA Astrophysics Data System (ADS)

    Huang, Wenbin; Pu, Donglin; Qiao, Wen; Wan, Wenqiang; Liu, Yanhua; Ye, Yan; Wu, Shaolong; Chen, Linsen

    2016-08-01

    A continuously tunable multi-wavelength polymer laser based on a triangular-lattice photonic crystal cavity is demonstrated. The triangular-lattice resonator was initially fabricated through multiple interference exposure and was then replicated into a low refractive index polymer via UV-nanoimprinting. The blend of a blue-emitting conjugated polymer and a red-emitting one was used as the gain medium. Three periods in the scalene triangular-lattice structure yield stable tri-wavelength laser emission (625.5 nm, 617.4 nm and 614.3 nm) in six different directions. A uniformly aligned liquid crystal (LC) layer was incorporated into the cavity as the top cladding layer. Upon heating, the orientation of LC molecules and thus the effective refractive index of the lasing mode changes which continuously shifts the lasing wavelength. A maximum tuning range of 12.2 nm was observed for the lasing mode at 625.5 nm. This tunable tri-wavelength polymer laser is simple constructed and cost-effective. It may find application in the fields of biosensors and photonic integrated circuits.

  14. Two-dimensional orthogonal DCT expansion in trapezoid and triangular blocks and modified JPEG image compression.

    PubMed

    Ding, Jian-Jiun; Huang, Ying-Wun; Lin, Pao-Yen; Pei, Soo-Chang; Chen, Hsin-Hui; Wang, Yu-Hsiang

    2013-09-01

    In the conventional JPEG algorithm, an image is divided into eight by eight blocks and then the 2-D DCT is applied to encode each block. In this paper, we find that, in addition to rectangular blocks, the 2-D DCT is also orthogonal in the trapezoid and triangular blocks. Therefore, instead of eight by eight blocks, we can generalize the JPEG algorithm and divide an image into trapezoid and triangular blocks according to the shapes of objects and achieve higher compression ratio. Compared with the existing shape adaptive compression algorithms, as we do not try to match the shape of each object exactly, the number of bytes used for encoding the edges can be less and the error caused from the high frequency component at the boundary can be avoided. The simulations show that, when the bit rate is fixed, our proposed algorithm can achieve higher PSNR than the JPEG algorithm and other shape adaptive algorithms. Furthermore, in addition to the 2-D DCT, we can also use our proposed method to generate the 2-D complete and orthogonal sine basis, Hartley basis, Walsh basis, and discrete polynomial basis in a trapezoid or a triangular block.

  15. Anisotropic spin model of strong spin-orbit-coupled triangular antiferromagnets

    NASA Astrophysics Data System (ADS)

    Li, Yao-Dong; Wang, Xiaoqun; Chen, Gang

    2016-07-01

    Motivated by the recent experimental progress on the strong spin-orbit-coupled rare-earth triangular antiferromagnet, we analyze the highly anisotropic spin model that describes the interaction between the spin-orbit-entangled Kramers' doublet local moments on the triangular lattice. We apply the Luttinger-Tisza method, the classical Monte Carlo simulation, and the self-consistent spin wave theory to analyze the anisotropic spin Hamiltonian. The classical phase diagram includes the 120∘ state and two distinct stripe-ordered phases. The frustration is very strong and significantly suppresses the ordering temperature in the regimes close to the phase boundary between two ordered phases. Going beyond the semiclassical analysis, we include the quantum fluctuations of the spin moments within a self-consistent Dyson-Maleev spin-wave treatment. We find that the strong quantum fluctuations melt the magnetic order in the frustrated regions. We explore the magnetic excitations in the three different ordered phases as well as in strong magnetic fields. Our results provide a guidance for the future theoretical study of the generic model and are broadly relevant for strong spin-orbit-coupled triangular antiferromagnets such as YbMgGaO4, RCd3P3 , RZn3P3 , RCd3As3 , RZn3As3 , and R2O2CO3 .

  16. Classical and quantum dynamics of a periodically driven particle in a triangular well

    SciTech Connect

    Flatte, M.E.; Holthaus, M.

    1996-01-01

    We investigate the correspondence between classical and quantum mechanics for periodically time dependent Hamiltonian systems, using the example of a periodically forced particle in a one-dimensional triangular well potential. In particular, we consider quantum mechanical Floquet states associated with resonances in the classical phase space. When the classical motion exhibits subharmonic resonances, the corresponding Floquet states maintain the driving field{close_quote}s periodicity through dynamical tunneling. This principle applies both to Floquet states associated with classical invariant vortex tubes surrounding stable, elliptic periodic orbits and to Floquet states that are associated with unstable, hyperbolic periodic orbits. The triangular well model also poses a yet unsolved mathematical problem, related to perturbation theory for systems with a dense pure point spectrum. The present approximate analytical and numerical results indicate that quantum tunneling between different resonance zones is of crucial importance for the question whether the driven triangular well has a dense point or an absolutely continuous quasienergy spectrum, or whether there is a transition from the one to the other. Copyright {copyright} 1996 Academic Press, Inc.

  17. Nonchaotic evolution of triangular configuration due to gravitational radiation reaction in the three-body problem

    NASA Astrophysics Data System (ADS)

    Yamada, Kei; Asada, Hideki

    2016-04-01

    Continuing work initiated in an earlier publication [H. Asada, Phys. Rev. D 80, 064021 (2009)], the gravitational radiation reaction to Lagrange's equilateral triangular solution of the three-body problem is investigated in an analytic method. The previous work is based on the energy balance argument, which is sufficient for a two-body system because the number of degrees of freedom (the semimajor axis and the eccentricity in quasi-Keplerian cases, for instance) equals that of the constants of motion such as the total energy and the orbital angular momentum. In a system with three (or more) bodies, however, the number of degrees of freedom is more than that of the constants of motion. Therefore, the present paper discusses the evolution of the triangular system by directly treating the gravitational radiation reaction force to each body. The perturbed equations of motion are solved by using the Laplace transform technique. It is found that the triangular configuration is adiabatically shrinking and is kept in equilibrium by increasing the orbital frequency due to the radiation reaction if the mass ratios satisfy the Newtonian stability condition. Long-term stability involving the first post-Newtonian corrections is also discussed.

  18. Natural convection heat transfer in vertical triangular subchannel in Zirconia-water nanofluid

    NASA Astrophysics Data System (ADS)

    Tandian, N. P.; Alkharboushi, A. A. K.; Kamajaya, K.

    2015-09-01

    Natural convection heat transfer in vertical triangular sub-channel has important role in cooling mechanism of the APWR and the PHWR nuclear reactors. Unfortunately, natural convection correlation equations for such geometry are scarcely available. Recent studies showed that ZrO2-water nanofluid has a good prospect to be used in the nuclear reactor technology due to its low neutron absorption cross section. Although several papers have reported transport properties of ZrO2-water nanofluids, practically there is no correlation equation for predicting natural convection heat transfer in a vertical triangular sub-channel in ZrO2-water nanofluid. Therefore, a study for finding such heat transfer correlation equation has been done by utilizing Computational Fluid Dynamics software and reported in this paper. In the study, natural convection heat transfer in a vertical triangular sub-channel has been simulated at several values of heat transfer flux within 9.1 to 30.9 kW/m2 range and ZrO2 concentrations of 0 (pure water), 0.27, and 3 volume-% of ZrO2. The study shows that the ZrO2 concentration has no significant influence to the natural convection heat transfer at those concentration levels. The obtained theoretical heat transfer correlation equations were verified through experiment, and they showed very similar results. The correlation equations are reported in this paper.

  19. A triangular model of dimensionless runoff producing rainfall hyetographs in Texas

    USGS Publications Warehouse

    Asquith, W.H.; Bumgarner, J.R.; Fahlquist, L.S.

    2003-01-01

    A synthetic triangular hyetograph for a large data base of Texas rainfall and runoff is needed. A hyetograph represents the temporal distribution of rainfall intensity at a point or over a watershed during a storm. Synthetic hyetographs are estimates of the expected time distribution for a design storm and principally are used in small watershed hydraulic structure design. A data base of more than 1,600 observed cumulative hyetographs that produced runoff from 91 small watersheds (generally less than about 50 km2) was used to provide statistical parameters for a simple triangular shaped hyetograph model. The model provides an estimate of the average hyetograph in dimensionless form for storm durations of 0 to 24 hours and 24 to 72 hours. As a result of this study, the authors concluded that the expected dimensionless cumulative hyetographs of 0 to 12 hour and 12 to 24 hour durations were sufficiently similar to be combined with minimal information loss. The analysis also suggests that dimensionless cumulative hyetographs are independent of the frequency level or return period of total storm depth and thus are readily used for many design applications. The two triangular hyetographs presented are intended to enhance small watershed design practice in applicable parts of Texas.

  20. Magnetization Process of Spin-1/2 Heisenberg Antiferromagnets on a Layered Triangular Lattice

    NASA Astrophysics Data System (ADS)

    Yamamoto, Daisuke; Marmorini, Giacomo; Danshita, Ippei

    2016-02-01

    We study the magnetization process of the spin-1/2 antiferromagnetic Heisenberg model on a layered triangular lattice by means of a numerical cluster mean-field method with a scaling scheme (CMF+S). It has been known that antiferromagnetic spins on a two-dimensional (2D) triangular lattice with quantum fluctuations exhibit a one-third magnetization plateau in the magnetization curve under magnetic field. We demonstrate that the CMF+S quantitatively reproduces the magnetization curve including the stabilization of the plateau. We also discuss the effects of a finite interlayer coupling, which is unavoidable in real quasi-2D materials. It has been recently argued for a model of the layered-triangular-lattice compound Ba3CoSb2O9 that such interlayer coupling can induce an additional first-order transition at a strong field. We present the detailed CMF+S results for the magnetization and susceptibility curves of the fundamental Heisenberg Hamiltonian in the presence of magnetic field and weak antiferromagnetic interlayer coupling. The extra first-order transition appears as a quite small jump in the magnetization curve and a divergence in the susceptibility at a strong magnetic field ˜0.712 of the saturation field.

  1. Ising antiferromagnet on a finite triangular lattice with free boundary conditions

    NASA Astrophysics Data System (ADS)

    Kim, Seung-Yeon

    2015-11-01

    The exact integer values for the density of states of the Ising model on an equilateral triangular lattice with free boundary conditions are evaluated up to L = 24 spins on a side for the first time by using the microcanonical transfer matrix. The total number of states is 2 N s = 2300 ≈ 2.037 × 1090 for L = 24, where N s = L( L+1)/2 is the number of spins. Classifying all 2300 spin states according to their energy values is an enormous work. From the density of states, the exact partition function zeros in the complex temperature plane of the triangular-lattice Ising model are evaluated. Using the density of states and the partition function zeros, we investigate the properties of the triangularlattice Ising antiferromagnet. The scaling behavior of the ground-state entropy and the form of the correlation length at T = 0 are studied for the triangular-lattice Ising antiferromagnet with free boundary conditions. Also, the scaling behavior of the Fisher edge singularity is investigated.

  2. Robust band gap and half-metallicity in graphene with triangular perforations

    NASA Astrophysics Data System (ADS)

    Gregersen, Søren Schou; Power, Stephen R.; Jauho, Antti-Pekka

    2016-06-01

    Ideal graphene antidot lattices are predicted to show promising band gap behavior (i.e., EG≃500 meV) under carefully specified conditions. However, for the structures studied so far this behavior is critically dependent on superlattice geometry and is not robust against experimentally realistic disorders. Here we study a rectangular array of triangular antidots with zigzag edge geometries and show that their band gap behavior qualitatively differs from the standard behavior which is exhibited, e.g., by rectangular arrays of armchair-edged triangles. In the spin unpolarized case, zigzag-edged antidots give rise to large band gaps compared to armchair-edged antidots, irrespective of the rules which govern the existence of gaps in armchair-edged antidot lattices. In addition the zigzag-edged antidots appear more robust than armchair-edged antidots in the presence of geometrical disorder. The inclusion of spin polarization within a mean-field Hubbard approach gives rise to a large overall magnetic moment at each antidot due to the sublattice imbalance imposed by the triangular geometry. Half-metallic behavior arises from the formation of spin-split dispersive states near the Fermi energy, reducing the band gaps compared to the unpolarized case. This behavior is also found to be robust in the presence of disorder. Our results highlight the possibilities of using triangular perforations in graphene to open electronic band gaps in systems with experimentally realistic levels of disorder, and furthermore, of exploiting the strong spin dependence of the system for spintronic applications.

  3. A Simple Synthesis of Triangular All-Metal Aromatics Allowing Access to Isolobal All-Metal Heteroaromatics.

    PubMed

    Wang, Yanlan; Deyris, Pierre-Alexandre; Caneque, Tatiana; Blanchard, Florent; Li, Yanling; Bigi, Franca; Maggi, Raimondo; Blanchard, Sebastien; Maestri, Giovanni; Malacria, Max

    2015-08-24

    A simple synthetic method allows the one-pot assembly of C3 -symmetric, 44-core-valence-electron, triangular Pd or Pt clusters and their heterobimetallic mixed Pd/Pt analogues. These mixed metal complexes are the first examples of stable triangular all-metal heteroaromatics. In contrast to traditional heteroaromatic molecules formed combining main-group elements, they actually retain structural and electronic features of their homonuclear analogues.

  4. Implementations of the optimal multigrid algorithm for the cell-centered finite difference on equilateral triangular grids

    SciTech Connect

    Ewing, R.E.; Saevareid, O.; Shen, J.

    1994-12-31

    A multigrid algorithm for the cell-centered finite difference on equilateral triangular grids for solving second-order elliptic problems is proposed. This finite difference is a four-point star stencil in a two-dimensional domain and a five-point star stencil in a three dimensional domain. According to the authors analysis, the advantages of this finite difference are that it is an O(h{sup 2})-order accurate numerical scheme for both the solution and derivatives on equilateral triangular grids, the structure of the scheme is perhaps the simplest, and its corresponding multigrid algorithm is easily constructed with an optimal convergence rate. They are interested in relaxation of the equilateral triangular grid condition to certain general triangular grids and the application of this multigrid algorithm as a numerically reasonable preconditioner for the lowest-order Raviart-Thomas mixed triangular finite element method. Numerical test results are presented to demonstrate their analytical results and to investigate the applications of this multigrid algorithm on general triangular grids.

  5. Triangular gold nanoparticles conjugated with peptide ligands: a new class of inhibitor for Candida albicans secreted aspartyl proteinase.

    PubMed

    Jebali, Ali; Hajjar, Farzaneh Haji Esmaeil; Hekmatimoghaddam, Seyedhossein; Kazemi, Bahram; De La Fuente, Jesus M; Rashidi, Mohsen

    2014-08-15

    The aim of this study was to find the peptide ligands to inhibit Candida albicans secreted aspartyl proteinase 2 (Sap2). First, a ligand library, containing 300 different peptides, was constructed, and their interaction with Sap2 was separately calculated by molecular dynamic software. Second, 10 peptide ligands with the lowest intermolecular energy were selected. Then, triangular gold nanoparticles were synthesized, and separately conjugated with the peptide ligands. After synthesis, antifungal property and Sap inactivation of conjugated triangular gold nanoparticles, peptide ligands, and naked triangular gold nanoparticle were separately assessed, against thirty clinical isolates of C. albicans. In this study, we measured the uptake of conjugated and naked nanoparticles by atomic adsorption spectroscopy. This study showed that naked triangular gold nanoparticle and all conjugated triangular gold nanoparticles had high antifungal activity, but no peptide ligands had such activity. Of 300 peptide ligands, the peptide containing N-Cys-Lys-Lys-Arg-Met-Met-Lys-Ser-Met-Cys-C and its conjugate had the highest capability to inhibit Sap. Moreover, the uptake assay demonstrated that triangular gold nanoparticles conjugated with the peptide ligand had the highest uptake.

  6. High throughput continuous titration based on a flow ratiometry controlled with feedback-based variable triangular waves and subsequent fixed triangular waves.

    PubMed

    Tanaka, Hideji; Baba, Tsutomu

    2005-10-15

    We propose a new approach for high-throughput continuous titration based on a flow ratiometry. The method was applied to potentiometric titrations of acids and bases. A base solution, the flow rate F(B) of which was varied in response to controller output voltage V(c), was merged with an acid solution under constant total (acid+base) flow rate. Downstream, the pH of the mixed solution was measured with a flow-through glass electrode. Initially, V(c), and thus F(B) was increased linearly. At the instant the equivalence point (EP) was sensed, the ramp direction of V(c) was reversed from upward to downward. The direction was reversed to upward when EP was sensed again. Such the feedback-based operation gives a triangular waveform of V(c), because there is a delay corresponding mainly to the transit time of merged solutions to reach the sensor. The value of V(c) that gives EP composition, V(E), was estimated by averaging the most recent maximum and minimum values of V(c). Next, fixed triangular waves of V(c) was used to control F(B). The amplitude and the scan rate of the waves were fixed narrower and faster, respectively, than those in the feedback-based operation in order to improve the throughput rate. The EP can be located as long as the scan range covers V(E). These automated processes limited the titration to just the narrow range around EP, and thus realized extremely high throughput rate of maximally 17.6 titrations per minute (=3.4s per titration) at R.S.D.=0.35%. PMID:18970249

  7. Dating human cultural capacity using phylogenetic principles.

    PubMed

    Lind, J; Lindenfors, P; Ghirlanda, S; Lidén, K; Enquist, M

    2013-01-01

    Humans have genetically based unique abilities making complex culture possible; an assemblage of traits which we term "cultural capacity". The age of this capacity has for long been subject to controversy. We apply phylogenetic principles to date this capacity, integrating evidence from archaeology, genetics, paleoanthropology, and linguistics. We show that cultural capacity is older than the first split in the modern human lineage, and at least 170,000 years old, based on data on hyoid bone morphology, FOXP2 alleles, agreement between genetic and language trees, fire use, burials, and the early appearance of tools comparable to those of modern hunter-gatherers. We cannot exclude that Neanderthals had cultural capacity some 500,000 years ago. A capacity for complex culture, therefore, must have existed before complex culture itself. It may even originated long before. This seeming paradox is resolved by theoretical models suggesting that cultural evolution is exceedingly slow in its initial stages. PMID:23648831

  8. Triangular Nests!

    ERIC Educational Resources Information Center

    Powell, R. I.

    2002-01-01

    Shows how integer-sided triangles can be nested, each nest having a single enclosing isosceles triangle. Brings to light what can be seen as a relatively simple generalization of Pythagoras' theorem, a result that should be readily accessible to many secondary school pupils. (Author/KHR)

  9. Augmented heat transfer in a triangular duct by using multiple swirling jets

    SciTech Connect

    Hwang, J.J.; Cheng, C.S.

    1999-08-01

    In the modern gas turbine design, the trend is toward high inlet gas temperature (1400--1500 C) for improving thermal efficiency and power density. Here, measurements of detailed heat transfer coefficients on two principal walls of a triangular duct with a swirling flow are undertaken by using a transient liquid crystal technique. The vertex corners of the triangular duct are 45, 45, and 90 deg. The swirl-motioned airflow is induced by an array of tangential jets on the side entries. The effects of flow Reynolds number (8600 {le} Re {le} 21,000) and the jet inlet angle ({alpha} = 75, 45, and 30 deg) are examined. Flow visualization by using smoke injection is conducted for better understanding the complicated flow phenomena in the swirling-flow channel. Results show that the heat transfer for {alpha} = 75 deg is enhanced mainly by the wall jets as well as the impinging jets; while the mechanisms of heat transfer enhancement for {alpha} = 45 and 30 deg could be characterized as the swirling-flow cooling. On the bottom wall, jets at {alpha} = 75 deg produce the best wall-averaged heat transfer due to the strongest wall-jet effect among the three angles ({alpha}) investigated. On the target wall, however, the heat transfer enhancements by swirling flow ({alpha} = 45 and 30 deg) are slightly higher than those by impinging jets ({alpha} = 75 deg). Correlations for wall-averaged Nusselt number for the bottom and target walls of the triangular duct are developed in terms of the flow Reynolds number for different jet inlet angles.

  10. A microcomputer program for energy assessment and aggregation using the triangular probability distribution

    USGS Publications Warehouse

    Crovelli, R.A.; Balay, R.H.

    1991-01-01

    A general risk-analysis method was developed for petroleum-resource assessment and other applications. The triangular probability distribution is used as a model with an analytic aggregation methodology based on probability theory rather than Monte-Carlo simulation. Among the advantages of the analytic method are its computational speed and flexibility, and the saving of time and cost on a microcomputer. The input into the model consists of a set of components (e.g. geologic provinces) and, for each component, three potential resource estimates: minimum, most likely (mode), and maximum. Assuming a triangular probability distribution, the mean, standard deviation, and seven fractiles (F100, F95, F75, F50, F25, F5, and F0) are computed for each component, where for example, the probability of more than F95 is equal to 0.95. The components are aggregated by combining the means, standard deviations, and respective fractiles under three possible siutations (1) perfect positive correlation, (2) complete independence, and (3) any degree of dependence between these two polar situations. A package of computer programs named the TRIAGG system was written in the Turbo Pascal 4.0 language for performing the analytic probabilistic methodology. The system consists of a program for processing triangular probability distribution assessments and aggregations, and a separate aggregation routine for aggregating aggregations. The user's documentation and program diskette of the TRIAGG system are available from USGS Open File Services. TRIAGG requires an IBM-PC/XT/AT compatible microcomputer with 256kbyte of main memory, MS-DOS 3.1 or later, either two diskette drives or a fixed disk, and a 132 column printer. A graphics adapter and color display are optional. ?? 1991.

  11. A quantum fidelity study of the anisotropic next-nearest-neighbour triangular lattice Heisenberg model

    NASA Astrophysics Data System (ADS)

    Thesberg, Mischa; Sørensen, Erik S.

    2014-10-01

    Ground- and excited-state quantum fidelities in combination with generalized quantum fidelity susceptibilites, obtained from exact diagonalizations, are used to explore the phase diagram of the anisotropic next-nearest-neighbour triangular Heisenberg model. Specifically, the J‧ - J2 plane of this model, which connects the J1 - J2 chain and the anisotropic triangular lattice Heisenberg model, is explored using these quantities. Through the use of a quantum fidelity associated with the first excited-state, in addition to the conventional ground-state fidelity, the BKT-type transition and Majumdar-Ghosh point of the J1 - J2 chain (J‧ = 0) are found to extend into the J‧ - J2 plane and connect with points on the J2 = 0 axis thereby forming bounded regions in the phase diagram. These bounded regions are then explored through the generalized quantum fidelity susceptibilities χρ, χ120\\circ , χD and χCAF which are associated with the spin stiffness, 120° spiral order parameter, dimer order parameter and collinear antiferromagnetic order parameter respectively. These quantities are believed to be extremely sensitive to the underlying phase and are thus well suited for finite-size studies. Analysis of the fidelity susceptibilities suggests that the J‧, J2 ≪ J phase of the anisotropic triangular model is either a collinear antiferromagnet or possibly a gapless disordered phase that is directly connected to the Luttinger phase of the J1 - J2 chain. Furthermore, the outer region is dominated by incommensurate spiral physics as well as dimer order.

  12. Relaxation properties in a diffusive model of extended objects on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Šćepanović, J. R.; Budinski-Petković, Lj.; Lončarević, I.; Petković, M.; Jakšić, Z. M.; Vrhovac, S. B.

    2013-03-01

    In a preceding paper, Šćepanović et al. [J.R. Šćepanović, I. Lončarević, Lj. Budinski-Petković, Z.M. Jakšić, S.B. Vrhovac, Phys. Rev. E 84 (2011) 031109. http://dx.doi.org/10.1103/PhysRevE.84.031109] studied the diffusive motion of k-mers on the planar triangular lattice. Among other features of this system, we observed that the suppression of rotational motion results in a subdiffusive dynamics on intermediate length and time scales. We also confirmed that systems of this kind generally exhibit heterogeneous dynamics. Here we extend this analysis to objects of various shapes that can be made by self-avoiding random walks on a triangular lattice. We start by studying the percolation properties of random sequential adsorption of extended objects on a triangular lattice. We find that for various objects of the same length, the threshold ρp∗ of more compact shapes exceeds the ρp∗ of elongated ones. At the lower densities of ρp∗, the long-time decay of the self-intermediate scattering function (SISF) is characterized by the Kohlrausch-Williams-Watts law. It is found that near the percolation threshold ρp∗, the decay of SISF to zero occurs via the power-law for sufficiently low wave-vectors. Our results establish that power-law divergence of the relaxation time τ as a function of density ρ occurs at a shape-dependent critical density ρc above the percolation threshold ρp∗. In the case of k-mers, the critical density ρc cannot be distinguished from the closest packing limit ρ⪅1. For other objects, the critical density ρc is usually below the jamming limit ρ.

  13. Electronic properties of gated triangular graphene quantum dots: Magnetism, correlations, and geometrical effects

    NASA Astrophysics Data System (ADS)

    Potasz, P.; Güçlü, A. D.; Wójs, A.; Hawrylak, P.

    2012-02-01

    We present a theory of electronic properties of gated triangular graphene quantum dots with zigzag edges as a function of size and carrier density. We focus on electronic correlations, spin, and geometrical effects using a combination of atomistic tight-binding, Hartree-Fock, and configuration interaction methods (TB + HF + CI), including long-range Coulomb interactions. The single-particle energy spectrum of triangular dots with zigzag edges exhibits a degenerate shell at the Fermi level with a degeneracy Nedge proportional to the edge size. We determine the effect of the electron-electron interactions on the ground state, the total spin, and the excitation spectrum as a function of a shell filling and the degeneracy of the shell using TB + HF + CI for Nedge<12 and approximate CI method for Nedge⩾12. For a half-filled neutral shell we find spin-polarized ground state for structures up to N=500 atoms in agreement with previous ab initio and mean-field calculations and in agreement with Lieb's theorem for a Hubbard model on a bipartite lattice. Adding a single electron leads to the complete spin depolarization for Nedge⩽9. For larger structures, the spin depolarization is shown to occur at different filling factors. Away from half-fillings excess electrons(holes) are shown to form Wigner-like spin-polarized triangular molecules corresponding to large gaps in the excitation spectrum. The validity of conclusions is assessed by a comparison of results obtained from different levels of approximations. While for the charge-neutral system all methods give qualitatively similar results, away from the charge neutrality an inclusion of all Coulomb scattering terms is necessary to produce results presented here.

  14. Partitioning a chordal graph into transitive subgraphs for parallel sparse triangular solution

    SciTech Connect

    Peyton, B.W. ); Pothen, A. . Dept. of Computer Science); Yuan, Xiaoqing )

    1992-12-01

    A recent approach for solving sparse triangular systems of equations on massively parallel computers employs a factorization of the triangular coefficient matrix to obtain a representation of its inverse in product form. The number of general communication steps required by this approach is proportional to the number of factors in the factorization. The triangular matrix can be symmetrically permuted to minimize the number of factors over suitable classes of permutations, and thereby the complexity of the parallel algorithm can be minimized. Algorithms for minimizing the number of factors over several classes of permutations have been considered in earlier work. Let F = L+L[sup T] denote the symmetric filled matrix corresponding to a Cholesky factor L, and let G[sub F] denote the adjacency graph of F. In this paper we consider the problem of minirriizing the number of factors over all permutations which preserve the structure of G[sub F]. The graph model of this problem is to partition the vertices G[sub F] into the fewest transitively closed subgraphs over all perfect elimination orderings while satisfying a certain precedence relationship. The solution to this chordal graph partitioning problem can be described by a greedy scheme which eliminates a largest permissible subgraph at each step. Further, the subgraph eliminated at each step can be characterized in terms of lengths of chordless paths in the current elimination graph. This solution relies on several results concerning transitive perfect elimination orderings introduced in this paper. We describe a partitioning algorithm with [Omicron]([vert bar]V[vert bar] + [vert bar]E[vert bar]) time and space complexity.

  15. Partitioning a chordal graph into transitive subgraphs for parallel sparse triangular solution

    SciTech Connect

    Peyton, B.W.; Pothen, A.; Yuan, Xiaoqing

    1992-12-01

    A recent approach for solving sparse triangular systems of equations on massively parallel computers employs a factorization of the triangular coefficient matrix to obtain a representation of its inverse in product form. The number of general communication steps required by this approach is proportional to the number of factors in the factorization. The triangular matrix can be symmetrically permuted to minimize the number of factors over suitable classes of permutations, and thereby the complexity of the parallel algorithm can be minimized. Algorithms for minimizing the number of factors over several classes of permutations have been considered in earlier work. Let F = L+L{sup T} denote the symmetric filled matrix corresponding to a Cholesky factor L, and let G{sub F} denote the adjacency graph of F. In this paper we consider the problem of minirriizing the number of factors over all permutations which preserve the structure of G{sub F}. The graph model of this problem is to partition the vertices G{sub F} into the fewest transitively closed subgraphs over all perfect elimination orderings while satisfying a certain precedence relationship. The solution to this chordal graph partitioning problem can be described by a greedy scheme which eliminates a largest permissible subgraph at each step. Further, the subgraph eliminated at each step can be characterized in terms of lengths of chordless paths in the current elimination graph. This solution relies on several results concerning transitive perfect elimination orderings introduced in this paper. We describe a partitioning algorithm with {Omicron}({vert_bar}V{vert_bar} + {vert_bar}E{vert_bar}) time and space complexity.

  16. Variational Monte Carlo study of chiral spin liquid in quantum antiferromagnet on the triangular lattice

    NASA Astrophysics Data System (ADS)

    Hu, Wen-Jun; Gong, Shou-Shu; Sheng, D. N.

    2016-08-01

    By using Gutzwiller projected fermionic wave functions and variational Monte Carlo technique, we study the spin-1 /2 Heisenberg model with the first-neighbor (J1), second-neighbor (J2), and additional scalar chiral interaction JχSi.(Sj×Sk) on the triangular lattice. In the nonmagnetic phase of the J1-J2 triangular model with 0.08 ≲J2/J1≲0.16 , recent density-matrix renormalization group (DMRG) studies [Zhu and White, Phys. Rev. B 92, 041105(R) (2015), 10.1103/PhysRevB.92.041105 and Hu, Gong, Zhu, and Sheng, Phys. Rev. B 92, 140403(R) (2015), 10.1103/PhysRevB.92.140403] find a possible gapped spin liquid with the signal of a competition between a chiral and a Z2 spin liquid. Motivated by the DMRG results, we consider the chiral interaction JχSi.(Sj×Sk) as a perturbation for this nonmagnetic phase. We find that with growing Jχ, the gapless U(1) Dirac spin liquid, which has the best variational energy for Jχ=0 , exhibits the energy instability towards a gapped spin liquid with nontrivial magnetic fluxes and nonzero chiral order. We calculate topological Chern number and ground-state degeneracy, both of which identify this flux state as the chiral spin liquid with fractionalized Chern number C =1 /2 and twofold topological degeneracy. Our results indicate a positive direction to stabilize a chiral spin liquid near the nonmagnetic phase of the J1-J2 triangular model.

  17. Arthroscopic Trans-osseous Suture of Peripheral Triangular Fibrocartilage Complex Tear.

    PubMed

    Jegal, Midum; Heo, Kang; Kim, Jong Pil

    2016-10-01

    The importance of foveal repair of the triangular fibrocartilage complex (TFCC) on stability of the distal radioulnar joint (DRUJ) has been emphasized with increasing knowledge of the anatomy and biomechanics of the TFCC and DRUJ. Although both open and arthroscopic techniques have been described for improving DRUJ stability, there has been a marked evolution of arthroscopic TFCC repair technique with successful clinical outcome. Recently, an arthroscopic trans-osseous technique has been described to repair foveal tears of the TFCC. The advantage of the technique is that it allows for anatomical repair of both the superficial and deep layers. This article describes the details of this novel technique. PMID:27595945

  18. Destruction of spin-nematic order on randomly depleted triangular lattices

    NASA Astrophysics Data System (ADS)

    Lovell, Simon; Demidio, Jonathan; Kaul, Ribhu

    2015-03-01

    We consider the spin-1 Heisenberg model with biquadratic interactions on a 2-dimensional triangular lattice with random site dilution. It has been shown for this model that the ground state on a clean lattice exhibits spin nematic order. Using the stochastic series expansion (SSE) quantum Monte Carlo (QMC) algorithm, we study the nature of the order-disorder transition in the thermodynamic limit by extrapolating the ground state nematic order averaged over disorder realizations. This research was partially financially supported by NSF DMR-1056536.

  19. Phase Diagram of the Antiferromagnetic Blume-Capel Model on Triangular Lattice

    NASA Astrophysics Data System (ADS)

    Park, Sojeong; Kwak, Wooseop

    2016-08-01

    We perform Monte-Carlo simulations of the anti-ferromagnetic (AF) spin-1 Blume- Capel (BC) model and the AF Ising model on triangular lattice. We estimate the exact critical magnetic fields for both models at zero temperature using the Wang-Landau sampling method. We also show the phase diagrams and the critical lines for the models using the joint density functions. We find that the shapes of critical lines for the models are identical, but the phase transitions across the critical lines are different.

  20. Variational Monte Carlo study of chiral spin liquid in quantum antiferromagnet on the triangular lattice

    NASA Astrophysics Data System (ADS)

    Hu, Wenjun; Gong, Shoushu; Sheng, Donna; Donna Sheng Team

    We investigate the Heisenberg model with chiral coupling on the triangular lattice by using Gutzwiller projected fermionic states and the variational Monte Carlo technique. As the chiral coupling grows, a gapped spin liquid with non-trivial magnetic fluxes and nonzero chiral order is stabilized. Furthermore, we calculate the topological Chern number and the degeneracy of the ground state, both of which lead us to identify this flux state as the chiral spin liquid with C = 1 / 2 fractionalized Chern number. Finally, we add spatial anisotropy in the model to study the effects for the chiral order.

  1. Scattering of electromagnetic waves from surfaces with conformal mapping: An example of a triangular plate.

    PubMed

    Chui, S T; Wang, Shubo; Chan, C T

    2016-03-01

    We discuss a way to exploit conformal mapping to study the response of a finite metallic film of arbitrary shape to an external electromagnetic field at finite frequencies. This provides a simple way to understand different physics issues and provides insights that include the issue of vorticity and eddy current and the nature of the divergent electric field at the boundaries and at corners. We study an example of an equilateral triangular plate and find good agreement with results obtained with traditional numerical techniques.

  2. Triangular-barrier quantum rod photodiodes: Their fabrication and detector characteristics

    SciTech Connect

    Ohmori, M.; Kobayashi, Y.; Vitushinskiy, P.; Nakamura, S.; Kojima, T.; Sakaki, H.

    2014-02-24

    We have fabricated a GaAs-based triangular-barrier photodiode, in which self-assembled InGaAs quantum rods (Q-rods) are embedded in its barrier region. Transport study at 100 K has shown that electrons start to flow mainly through Q-rods when a bias is set above a threshold. Upon illumination, photo-generated holes are found to accumulate in the middle portion of Q-rods and efficiently lower the local barrier height, yielding the responsivity as high as 10{sup 5} A/W at the incident light of 1 fW.

  3. Magnetic correlations in the Hubbard model on triangular and Kagomé lattices.

    PubMed

    Bulut, N; Koshibae, W; Maekawa, S

    2005-07-15

    In order to study the magnetic properties of frustrated metallic systems, we present, for the first time, quantum Monte Carlo data on the magnetic susceptibility of the Hubbard model on triangular and kagomé lattices. We show that the underlying lattice structure determines the nature and the doping dependence of the magnetic fluctuations. In particular, in the doped kagomé case we find strong short-range magnetic correlations, which makes the metallic kagomé systems a promising field for studies of superconductivity.

  4. Algebraic Bethe ansatz for the XXX chain with triangular boundaries and Gaudin model

    NASA Astrophysics Data System (ADS)

    Cirilo António, N.; Manojlović, N.; Salom, I.

    2014-12-01

    We implement fully the algebraic Bethe ansatz for the XXX Heisenberg spin chain in the case when both boundary matrices can be brought to the upper-triangular form. We define the Bethe vectors which yield the strikingly simple expression for the off shell action of the transfer matrix, deriving the spectrum and the relevant Bethe equations. We explore further these results by obtaining the off shell action of the generating function of the Gaudin Hamiltonians on the corresponding Bethe vectors through the so-called quasi-classical limit. Moreover, this action is as simple as it could possibly be, yielding the spectrum and the Bethe equations of the Gaudin model.

  5. Decoupling systems of hydrodynamic type into subsystems with block-triangular interaction

    NASA Astrophysics Data System (ADS)

    Tunitsky, D. V.

    2015-12-01

    This paper is devoted to systems of n inhomogeneous equations of hydrodynamic type with two independent variables. Using a geometric formalism for such systems which goes back to Riemann, one can associate with every system of hydrodynamic type a vector field and a field of linear operators acting on an appropriate tangent bundle. In terms of these fields, we obtain a number of tests for inhomogeneous systems of hydrodynamic type to be decoupled into subsystems with block-triangular interaction. These tests supplement Bogoyavlenskii's well-known results on decoupling of homogeneous systems of hydrodynamic type into non-interacting subsystems.

  6. Quantum phases of Bose-Bose mixtures on a triangular lattice

    NASA Astrophysics Data System (ADS)

    He, Liang; Li, Yongqiang; Altman, Ehud; Hofstetter, Walter

    2012-10-01

    We investigate the zero-temperature quantum phases of a Bose-Bose mixture on a triangular lattice using the bosonic dynamical mean-field theory (BDMFT). We consider the case of total filling where geometric frustration arises for asymmetric hopping. We map out a rich ground-state phase diagram including xy-ferromagnetic, spin-density wave, superfluid, and supersolid phases. In particular, we identify a stripe spin-density wave phase for highly asymmetric hopping. On top of the spin-density wave, we find that the system generically shows weak charge (particle) density wave order.

  7. Bound magneto-polaron in triangular quantum dot qubit under an electric field

    NASA Astrophysics Data System (ADS)

    Fotue, A. J.; Issofa, N.; Tiotsop, M.; Kenfack, S. C.; Tabue Djemmo, M. P.; Wirngo, A. V.; Fotsin, H.; Fai, L. C.

    2016-02-01

    In this paper, we examine the time evolution of the quantum mechanical state of a magnetopolaron using the Pekar type variational method on the electric-LO-phonon strong coupling in a triangular quantum dot with Coulomb impurity. We obtain the Eigen energies and the Eigen functions of the ground state and the first excited state, respectively. This system in a quantum dot is treated as a two-level quantum system qubit and numerical calculations are done. The Shannon entropy and the expressions relating the period of oscillation and the electron-LO-phonon coupling strength, the Coulomb binding parameter and the polar angle are derived.

  8. Two-dimensional Euler computations on a triangular mesh using an upwind, finite-volume scheme

    NASA Technical Reports Server (NTRS)

    Whitaker, D. L.; Grossman, B.; Lohner, R.

    1989-01-01

    A numerical procedure was developed for the finite-volume solution of the Euler equations on unstructured triangular meshes based on a flux-difference split upwind method. Techniques for implementing Roe's (1985) approximate Reimann solver together with the preprocessing MUSCL differencing on unstructured grids are presented. Applications and comparisons with structured grid problems are carried out for a supersonic shock reflection problem, the supersonic flow over a blunt body, the transonic flow over NACA 0012 and RAE 2822 airfoils, and the flow about a double element Karman-Trefftz airfoil.

  9. Comparison of magnetoresistances of triangular and rectangular ballistic graphene npn junctions

    NASA Astrophysics Data System (ADS)

    Morikawa, Sei; Masubuchi, Satroru; Watanabe, Kenji; Taniguchi, Takashi; Machida, Tomoki

    2016-10-01

    We compared the magnetotransport properties of ballistic graphene npn junctions with two different geometries. We found that a rectangular npn junction shows a positive magnetoresistance around zero magnetic field; this finding can be explained by the suppression of Klein tunneling in a finite magnetic field. In contrast, a triangular npn junction shows a negative magnetoresistance because the transmission is enhanced in a commensurability magnetic field where the ballistic carriers in a cyclotron motion are injected perpendicularly to both the np and pn interfaces. These results suggest possibilities for manipulating ballistic carrier trajectories through the designs of local-gate geometries.

  10. The effect of visible-light intensity on shape evolution and antibacterial properties of triangular silver nanostructures

    NASA Astrophysics Data System (ADS)

    Ashkarran, Ali Akbar

    2016-08-01

    Triangular silver nanostructures represent a novel class of nanomaterials with tunable surface plasmon resonance (SPR). By controlling the size and geometry of these structures, their SPR peaks could be tuned from the visible to the near-infrared region with numerous applications in optoelectronic, sensors, nanomedicine and specially cancer diagnosis and treatment. In this study, triangular silver nanostructures were prepared by photoinducing of spherical silver nanoparticles (NPs) with an average diameter of 10 nm. Transmission electron microscopy (TEM) and ultra violet visible (UV-Vis) spectroscopy were used to characterize silver triangles. We have found that uniform triangular silver nanostructures can be obtained using an appropriate visible-light illumination to the primary spherical silver NPs. TEM images indicated that formation of triangular structures depends on the intensity of light source. The effect of intensity of visible-light source on the geometry and size distribution of silver triangles was investigated. It was found that formation of triangular structures in addition to their size and shape evolution strongly depends on the intensity of the light illumination. Furthermore, a comparative study on the antibacterial activities of silver triangles of different sizes reveals that silver triangles experience a size-dependent interaction with the gram-negative Escherichia coli bacteria.

  11. Dating human cultural capacity using phylogenetic principles

    PubMed Central

    Lind, J.; Lindenfors, P.; Ghirlanda, S.; Lidén, K.; Enquist, M.

    2013-01-01

    Humans have genetically based unique abilities making complex culture possible; an assemblage of traits which we term “cultural capacity”. The age of this capacity has for long been subject to controversy. We apply phylogenetic principles to date this capacity, integrating evidence from archaeology, genetics, paleoanthropology, and linguistics. We show that cultural capacity is older than the first split in the modern human lineage, and at least 170,000 years old, based on data on hyoid bone morphology, FOXP2 alleles, agreement between genetic and language trees, fire use, burials, and the early appearance of tools comparable to those of modern hunter-gatherers. We cannot exclude that Neanderthals had cultural capacity some 500,000 years ago. A capacity for complex culture, therefore, must have existed before complex culture itself. It may even originated long before. This seeming paradox is resolved by theoretical models suggesting that cultural evolution is exceedingly slow in its initial stages. PMID:23648831

  12. Numerical investigation of Al2O3/water nanofluid laminar convective heat transfer through triangular ducts.

    PubMed

    Zeinali Heris, Saeed; Noie, Seyyed Hossein; Talaii, Elham; Sargolzaei, Javad

    2011-02-28

    In this article, laminar flow-forced convective heat transfer of Al2O3/water nanofluid in a triangular duct under constant wall temperature condition is investigated numerically. In this investigation, the effects of parameters, such as nanoparticles diameter, concentration, and Reynolds number on the enhancement of nanofluids heat transfer is studied. Besides, the comparison between nanofluid and pure fluid heat transfer is achieved in this article. Sometimes, because of pressure drop limitations, the need for non-circular ducts arises in many heat transfer applications. The low heat transfer rate of non-circular ducts is one the limitations of these systems, and utilization of nanofluid instead of pure fluid because of its potential to increase heat transfer of system can compensate this problem. In this article, for considering the presence of nanoparticl: es, the dispersion model is used. Numerical results represent an enhancement of heat transfer of fluid associated with changing to the suspension of nanometer-sized particles in the triangular duct. The results of the present model indicate that the nanofluid Nusselt number increases with increasing concentration of nanoparticles and decreasing diameter. Also, the enhancement of the fluid heat transfer becomes better at high Re in laminar flow with the addition of nanoparticles.

  13. Reversible Burst of Transcriptional Changes during Induction of Crassulacean Acid Metabolism in Talinum triangulare1[OPEN

    PubMed Central

    Winter, Klaus

    2016-01-01

    Drought tolerance is a key factor for agriculture in the 21st century as it is a major determinant of plant survival in natural ecosystems as well as crop productivity. Plants have evolved a range of mechanisms to cope with drought, including a specialized type of photosynthesis termed Crassulacean acid metabolism (CAM). CAM is associated with stomatal closure during the day as atmospheric CO2 is assimilated primarily during the night, thus reducing transpirational water loss. The tropical herbaceous perennial species Talinum triangulare is capable of transitioning, in a facultative, reversible manner, from C3 photosynthesis to weakly expressed CAM in response to drought stress. The transcriptional regulation of this transition has been studied. Combining mRNA-Seq with targeted metabolite measurements, we found highly elevated levels of CAM-cycle enzyme transcripts and their metabolic products in T. triangulare leaves upon water deprivation. The carbohydrate metabolism is rewired to reduce the use of reserves for growth to support the CAM-cycle and the synthesis of compatible solutes. This large-scale expression dataset of drought-induced CAM demonstrates transcriptional regulation of the C3–CAM transition. We identified candidate transcription factors to mediate this photosynthetic plasticity, which may contribute in the future to the design of more drought-tolerant crops via engineered CAM. PMID:26530316

  14. Dissolution-recrystallization mechanism for the conversion of silver nanospheres to triangular nanoplates.

    PubMed

    Yang, Jun; Zhang, Qingbo; Lee, Jim Yang; Too, Heng-Phon

    2007-04-01

    A solution chemistry method for transforming polycrystalline Ag spherical particles into single crystalline triangular Ag nanoplates has been developed. The synthesis consists of three consecutive steps: (1) the synthesis of Ag nanospheres by NaBH(4) reduction of AgNO(3) in the presence of sodium citrate; (2) the conversion of citrate-stabilized Ag nanospheres into SDS (sodium dodecyl sulfate)-stabilized Ag nanospheres, and (3) the aging of the SDS-stabilized Ag nanospheres in 0.01 M NaCl solution. Our study indicates that the shape evolved through a Ag nanoparticle dissolution- and re-deposition process; and demonstrated the critical role of SDS in the process: SDS regulates the dynamics in the dissolved O(2)/Cl(-) etching of the Ag nanospheres and the reduction of the released Ag(+) by citrate ions in the same solution. SDS also functions as a shape-directing agent to assimilate the Ag(0) atoms into single crystalline triangular Ag nanoplates. A model for the shape conversion is also proposed which provides the clue for the synthesis of anisotropic Ag nanoparticles with other shapes (rods, wires, cubes, etc.).

  15. Noncollinear and noncoplanar magnetic order in the extended Hubbard model on anisotropic triangular lattice

    NASA Astrophysics Data System (ADS)

    Pasrija, Kanika; Kumar, Sanjeev

    2016-05-01

    Motivated by the importance of noncollinear and noncoplanar magnetic phases in determining various electrical properties in magnets, we investigate the magnetic phase diagram of the extended Hubbard model on an anisotropic triangular lattice. We map out the ground-state phase diagram within a mean-field scheme that treats collinear, noncollinear, and noncoplanar phases on equal footing. In addition to the standard ferromagnet and 120∘ antiferromagnet states, we find the four-sublattice flux, the 3Q noncoplanar, and the noncollinear charge-ordered states to be stable at specific values of filling fraction n . Inclusion of a nearest-neighbor Coulomb repulsion leads to intriguing spin-charge-ordered phases. The most notable of these are the collinear and noncollinear magnetic states at n =2 /3 , which occur together with a pinball-liquid-like charge order. Our results demonstrate that the elementary single-orbital extended Hubbard model on a triangular lattice hosts unconventional spin-charge ordered phases, which are similar to those reported in more complex and material-specific electronic Hamiltonians.

  16. Measuring Electrolyte Impedance and Noise Simultaneously by Triangular Waveform Voltage and Principal Component Analysis.

    PubMed

    Xu, Shanzhi; Wang, Peng; Dong, Yonggui

    2016-01-01

    In order to measure the impedance variation process in electrolyte solutions, a method of triangular waveform voltage excitation is investigated together with principal component analysis (PCA). Using triangular waveform voltage as the excitation signal, the response current during one duty cycle is sampled to construct a measurement vector. The measurement matrix is then constructed by the measurement vectors obtained from different measurements. After being processed by PCA, the changing information of solution impedance is contained in the loading vectors while the response current and noise information is contained in the score vectors. The measurement results of impedance variation by the proposed signal processing method are independent of the equivalent impedance model. The noise-induced problems encountered during equivalent impedance calculation are therefore avoided, and the real-time variation information of noise in the electrode-electrolyte interface can be extracted at the same time. Planar-interdigitated electrodes are experimentally tested for monitoring the KCl concentration variation process. Experimental results indicate that the measured impedance variation curve reflects the changing process of solution conductivity, and the amplitude distribution of the noise during one duty cycle can be utilized to analyze the contact conditions of the electrode and electrolyte interface. PMID:27110787

  17. High-Order Hyperbolic Residual-Distribution Schemes on Arbitrary Triangular Grids

    NASA Technical Reports Server (NTRS)

    Mazaheri, Alireza; Nishikawa, Hiroaki

    2015-01-01

    In this paper, we construct high-order hyperbolic residual-distribution schemes for general advection-diffusion problems on arbitrary triangular grids. We demonstrate that the second-order accuracy of the hyperbolic schemes can be greatly improved by requiring the scheme to preserve exact quadratic solutions. We also show that the improved second-order scheme can be easily extended to third-order by further requiring the exactness for cubic solutions. We construct these schemes based on the LDA and the SUPG methodology formulated in the framework of the residual-distribution method. For both second- and third-order-schemes, we construct a fully implicit solver by the exact residual Jacobian of the second-order scheme, and demonstrate rapid convergence of 10-15 iterations to reduce the residuals by 10 orders of magnitude. We demonstrate also that these schemes can be constructed based on a separate treatment of the advective and diffusive terms, which paves the way for the construction of hyperbolic residual-distribution schemes for the compressible Navier-Stokes equations. Numerical results show that these schemes produce exceptionally accurate and smooth solution gradients on highly skewed and anisotropic triangular grids, including curved boundary problems, using linear elements. We also present Fourier analysis performed on the constructed linear system and show that an under-relaxation parameter is needed for stabilization of Gauss-Seidel relaxation.

  18. Suppression of Secondary Electron Emission using Triangular Grooved Surface in the ILC Dipole and Wiggler Magnets

    SciTech Connect

    Wang, L.; Bane, K.; Chen, C.; Himel, T.; Munro, M.; Pivi, M.; Raubenheimer, T.; Stupakov, G.; /SLAC

    2007-07-06

    The development of an electron cloud in the vacuum chambers of high intensity positron and proton storage rings may limit machine performance. The suppression of electrons in a magnet is a challenge for the positron damping ring of the International Linear Collider (ILC) as well as the Large Hadron Collider. Simulation show that grooved surfaces can significantly reduce the electron yield in a magnet. Some of the secondary electrons emitted from the grooved surface return to the surface within a few gyrations, resulting in a low effective secondary electron yield (SEY) of below 1.0 A triangular surface is an effective, technologically attractive mitigation with a low SEY and a weak dependence on the scale of the corrugations and the external magnetic field. A chamber with triangular grooved surface is proposed for the dipole and wiggler sections of the ILC and will be tested in KEKB in 2007. The strategy of electron cloud control in ILC and the optimization of the grooved chamber such as the SEY, impedance as well as the manufacturing of the chamber, are also discussed.

  19. Reversible Burst of Transcriptional Changes during Induction of Crassulacean Acid Metabolism in Talinum triangulare.

    PubMed

    Brilhaus, Dominik; Bräutigam, Andrea; Mettler-Altmann, Tabea; Winter, Klaus; Weber, Andreas P M

    2016-01-01

    Drought tolerance is a key factor for agriculture in the 21st century as it is a major determinant of plant survival in natural ecosystems as well as crop productivity. Plants have evolved a range of mechanisms to cope with drought, including a specialized type of photosynthesis termed Crassulacean acid metabolism (CAM). CAM is associated with stomatal closure during the day as atmospheric CO2 is assimilated primarily during the night, thus reducing transpirational water loss. The tropical herbaceous perennial species Talinum triangulare is capable of transitioning, in a facultative, reversible manner, from C3 photosynthesis to weakly expressed CAM in response to drought stress. The transcriptional regulation of this transition has been studied. Combining mRNA-Seq with targeted metabolite measurements, we found highly elevated levels of CAM-cycle enzyme transcripts and their metabolic products in T. triangulare leaves upon water deprivation. The carbohydrate metabolism is rewired to reduce the use of reserves for growth to support the CAM-cycle and the synthesis of compatible solutes. This large-scale expression dataset of drought-induced CAM demonstrates transcriptional regulation of the C3-CAM transition. We identified candidate transcription factors to mediate this photosynthetic plasticity, which may contribute in the future to the design of more drought-tolerant crops via engineered CAM.

  20. Numerical investigation of Al2O3/water nanofluid laminar convective heat transfer through triangular ducts

    PubMed Central

    2011-01-01

    In this article, laminar flow-forced convective heat transfer of Al2O3/water nanofluid in a triangular duct under constant wall temperature condition is investigated numerically. In this investigation, the effects of parameters, such as nanoparticles diameter, concentration, and Reynolds number on the enhancement of nanofluids heat transfer is studied. Besides, the comparison between nanofluid and pure fluid heat transfer is achieved in this article. Sometimes, because of pressure drop limitations, the need for non-circular ducts arises in many heat transfer applications. The low heat transfer rate of non-circular ducts is one the limitations of these systems, and utilization of nanofluid instead of pure fluid because of its potential to increase heat transfer of system can compensate this problem. In this article, for considering the presence of nanoparticl: es, the dispersion model is used. Numerical results represent an enhancement of heat transfer of fluid associated with changing to the suspension of nanometer-sized particles in the triangular duct. The results of the present model indicate that the nanofluid Nusselt number increases with increasing concentration of nanoparticles and decreasing diameter. Also, the enhancement of the fluid heat transfer becomes better at high Re in laminar flow with the addition of nanoparticles. PMID:21711694

  1. Mean streamwise velocity measurements in a triple jet of equilateral triangular configuration

    SciTech Connect

    Moustafa, G.H. . Coll. of Engineering); Sundararajan, T. . Dept. of Mechanical Engineering); Rathakrishnan, E. . Dept. of Aerospace Engineering)

    1993-09-01

    Multijet flows arise in several applications such as jet engine/rocket combustors, the thrust augmenting ejectors for VTOL/STOL aircraft, and industrial gas burners. In order to achieve proper combustion, thrust development, and reduction in the noise level, it is often desirable to control the inter-mixing between the jets and also the entrainment of the surrounding atmosphere. This, in turn, requires a detailed study of the behavior of high speed jets in multijet configuration. The situation of interest here is an array of three axisymmetric nozzles set in a common end wall with equal spacing in a triangular configuration. The reason why this particular configuration has been chosen is that it promotes bending of the jet axes toward each other, thus leading to greater mixing. In the present study, experiments have been conducted to investigate the effect of stagnation pressure ratio and nozzle spacing upon the mean flow characteristic of compressible jets in triangular configuration. The individual flow features of the vertex jet and the base twin jet are analyzed and their contributions to the axis switching as well as the overall triple jet behavior are highlighted.

  2. Atomic-scale dynamics of triangular hole growth in monolayer hexagonal boron nitride under electron irradiation

    NASA Astrophysics Data System (ADS)

    Ryu, Gyeong Hee; Park, Hyo Ju; Ryou, Junga; Park, Jinwoo; Lee, Jongyeong; Kim, Gwangwoo; Shin, Hyeon Suk; Bielawski, Christopher W.; Ruoff, Rodney S.; Hong, Suklyun; Lee, Zonghoon

    2015-06-01

    The production of holes by electron beam irradiation in hexagonal boron nitride (hBN), which has a lattice similar to that of graphene, is monitored over time using atomic resolution transmission electron microscopy. The holes appear to be initiated by the formation of a vacancy of boron and grow in a manner that retains an overall triangular shape. The hole growth process involves the formation of single chains of B and N atoms and is accompanied by the ejection of atoms and bundles of atoms along the hole edges, as well as atom migration. These observations are compared to density functional theory calculations and molecular dynamics simulations.The production of holes by electron beam irradiation in hexagonal boron nitride (hBN), which has a lattice similar to that of graphene, is monitored over time using atomic resolution transmission electron microscopy. The holes appear to be initiated by the formation of a vacancy of boron and grow in a manner that retains an overall triangular shape. The hole growth process involves the formation of single chains of B and N atoms and is accompanied by the ejection of atoms and bundles of atoms along the hole edges, as well as atom migration. These observations are compared to density functional theory calculations and molecular dynamics simulations. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01473e

  3. High-Order Residual-Distribution Schemes for Discontinuous Problems on Irregular Triangular Grids

    NASA Technical Reports Server (NTRS)

    Mazaheri, Alireza; Nishikawa, Hiroaki

    2016-01-01

    In this paper, we develop second- and third-order non-oscillatory shock-capturing hyperbolic residual distribution schemes for irregular triangular grids, extending our second- and third-order schemes to discontinuous problems. We present extended first-order N- and Rusanov-scheme formulations for hyperbolic advection-diffusion system, and demonstrate that the hyperbolic diffusion term does not affect the solution of inviscid problems for vanishingly small viscous coefficient. We then propose second- and third-order blended hyperbolic residual-distribution schemes with the extended first-order Rusanov-scheme. We show that these proposed schemes are extremely accurate in predicting non-oscillatory solutions for discontinuous problems. We also propose a characteristics-based nonlinear wave sensor for accurately detecting shocks, compression, and expansion regions. Using this proposed sensor, we demonstrate that the developed hyperbolic blended schemes do not produce entropy-violating solutions (unphysical stocks). We then verify the design order of accuracy of these blended schemes on irregular triangular grids.

  4. Measuring Electrolyte Impedance and Noise Simultaneously by Triangular Waveform Voltage and Principal Component Analysis

    PubMed Central

    Xu, Shanzhi; Wang, Peng; Dong, Yonggui

    2016-01-01

    In order to measure the impedance variation process in electrolyte solutions, a method of triangular waveform voltage excitation is investigated together with principal component analysis (PCA). Using triangular waveform voltage as the excitation signal, the response current during one duty cycle is sampled to construct a measurement vector. The measurement matrix is then constructed by the measurement vectors obtained from different measurements. After being processed by PCA, the changing information of solution impedance is contained in the loading vectors while the response current and noise information is contained in the score vectors. The measurement results of impedance variation by the proposed signal processing method are independent of the equivalent impedance model. The noise-induced problems encountered during equivalent impedance calculation are therefore avoided, and the real-time variation information of noise in the electrode-electrolyte interface can be extracted at the same time. Planar-interdigitated electrodes are experimentally tested for monitoring the KCl concentration variation process. Experimental results indicate that the measured impedance variation curve reflects the changing process of solution conductivity, and the amplitude distribution of the noise during one duty cycle can be utilized to analyze the contact conditions of the electrode and electrolyte interface. PMID:27110787

  5. Spontaneous formation of kagome network and Dirac half-semimetal on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Akagi, Yutaka; Motome, Yukitoshi

    2015-04-01

    In spin-charge coupled systems, geometrical frustration of underlying lattice structures can give rise to nontrivial magnetic orders and electronic states. Here we explore such a possibility in the Kondo lattice model with classical localized spins on a triangular lattice by using a variational calculation and simulated annealing. We find that the system exhibits a four-sublattice collinear ferrimagnetic phase at 5/8 filling for a large Hund's-rule coupling. In this state, the system spontaneously differentiates into the up-spin kagome network and the isolated down-spin sites, which we call the kagome network formation. In the kagome network state, the system becomes Dirac half-semimetallic: The electronic structure shows a massless Dirac node at the Fermi level, and the Dirac electrons are almost fully spin polarized due to the large Hund's-rule coupling. We also study the effect of off-site Coulomb repulsion in the kagome network phase where the system is effectively regarded as a 1/3-filling spinless fermion system on the kagome lattice. We find that, at the level of the mean-field approximation, a √{3 }×√{3 } -type charge order occurs in the kagome network state, implying the possibility of fractional charge excitations in this triangular lattice system. Moreover, we demonstrate that the kagome network formation with fully polarized Dirac electrons are controllable by an external magnetic field.

  6. When circles become triangular: how transsaccadic predictions shape the perception of shape.

    PubMed

    Herwig, Arvid; Weiss, Katharina; Schneider, Werner X

    2015-03-01

    Human vision is characterized by a consistent pattern of saccadic eye movements. With each saccade, internal object representations change their retinal position and spatial resolution. This raises the question as to how peripheral perception is affected by imminent saccadic eye movements. Here, we suggest that saccades are accompanied by a prediction of their perceptual consequences (i.e., the foveation of the target object). Accordingly, peripheral perception should be biased toward previously associated foveal input. In this study, we first exposed participants to an altered visual stimulation where one object systematically changed its shape during saccades. Subsequently, participants had to judge the shape of briefly presented peripheral saccade targets. The results showed that targets were perceived as less curved for objects that previously changed from more circular in the periphery to more triangular in the fovea. Similarly, shapes were perceived as more curved for objects that previously changed from triangular to circular. Thus, peripheral perception seems to depend not solely on the current input but also on memorized experiences, enabling predictions about the perceptual consequences of saccadic eye movements.

  7. A mass-redistributed finite element method (MR-FEM) for acoustic problems using triangular mesh

    NASA Astrophysics Data System (ADS)

    He, Z. C.; Li, Eric; Liu, G. R.; Li, G. Y.; Cheng, A. G.

    2016-10-01

    The accuracy of numerical results using standard finite element method (FEM) in acoustic problems will deteriorate with increasing frequency due to the "dispersion error". Such dispersion error depends on the balance between the "stiffness" and "mass" of discretization equation systems. This paper reports an improved finite element method (FEM) for solving acoustic problems by re-distributing the mass in the mass matrix to "tune" the balance, aiming to minimize the dispersion errors. This is done by shifting the integration point locations when computing the entries of the mass matrix, while ensuring the mass conservation. The new method is verified through the detailed numerical error analysis, and a strategy is also proposed for the best mass redistribution in terms of minimizing dispersion error. The relative dispersion error of present mass-redistributed finite element method (MR-FEM) is found to be much smaller than the FEM solution, in both theoretical prediction and numerical examination. The present MR-FEM works well by using the linear triangular elements that can be generated automatically, which enables automation in computation and saving computational cost in mesh generation. Numerical examples demonstrate the advantages of MR-FEM, in comparison with the standard FEM using the same triangular meshes and quadrilateral meshes.

  8. Rise time of inverted triangular prism intruder in vibrating granular bed: Experiments and model

    NASA Astrophysics Data System (ADS)

    Nuraini, N.; Adriani, I. K.; Baladram, M. S.; Viridi, S.

    2012-05-01

    Experiment results and a qualitative model of the phenomenon called Brazil nut effect (BNE) with inverted triangular prism are reported in this work. The model is constructed by considering some forces (earth gravitational force, buoyant force, and fluid viscous force) and using Newton's second law of motion. The rise time of BNE T is defined as time needed for the intruder to be on granular surface with all of his parts (no part is still immersed in the granular bed). One side of the triangular base of the intruder l is varied from 1.5 to 5 cm with other two sides are kept in constant values (1 and 3 cm). It has been observed in experiment that l with value 3-4 cm gives the smaller rise time. Plot of T versus l has the form of concave up parabolic curve with minimum lies at l between 3-4 cm. This observation has been confirmed by the proposed model with the same order of magnitude and similar curve trend.

  9. Analysis and Improvement of Upwind and Centered Schemes on Quadrilateral and Triangular Meshes

    NASA Technical Reports Server (NTRS)

    Huynh, H. T.

    2003-01-01

    Second-order accurate upwind and centered schemes are presented in a framework that facilitates their analysis and comparison. The upwind scheme employed consists of a reconstruction step (MUSCL approach) followed by an upwind step (Roe's flux-difference splitting). The two centered schemes are of Lax-Friedrichs (L-F) type. They are the nonstaggered versions of the Nessyahu-Tadmor (N-T) scheme and the CE/SE method with epilson = 1/2. The upwind scheme is extended to the case of two spatial dimensions (2D) in a straightforward manner. The N-T and CE/SE schemes are extended in a manner similar to the 2D extensions of the CE/SE scheme by Wang and Chang for a triangular mesh and by Zhang, Yu, and Chang for a quadrilateral mesh. The slope estimates, however, are simplified. Fourier stability and accuracy analyses are carried out for these schemes for the standard 1D and the 2D quadrilateral mesh cases. In the nonstandard case of a triangular mesh, the triangles must be paired up when analyzing the upwind and N-T schemes. An observation resulting in an extended N-T scheme which is faster and uses only one-third of the storage for flow data compared with the CE/SE method is presented. Numerical results are shown. Other improvements to the schemes are discussed.

  10. Magnetic Correlations in the Triangular Antiferromagnet TbInO3

    NASA Astrophysics Data System (ADS)

    Sala, Gabriele; Clark, Lucy; Maharaj, Dalini; Stone, Matthew B.; Knight, Kevin S.; Cheong, Sang-Wook; Gaulin, Bruce D.

    TbInO3 crystallizes with a hexagonal P63 cm structure in which layers of edge-sharing triangles of magnetic Tb3+ ions are separated by non-magnetic [InO5]7- units. TbInO3, therefore, realizes an excellent opportunity to explore the behavior of a two-dimensional magnetic triangular lattice, a canonical model of geometric frustration. Here we present our study of a polycrystalline sample of TbInO3. Our high resolution powder neutron diffraction data (HRPD, ISIS) of TbInO3 confirm that the triangular layers of Tb3+ remain undistorted to at least 0 . 46 K. Magnetic susceptibility data follow Curie-Weiss behavior over a wide range of T with θ = - 17 . 19 (3) K indicating the dominance of antiferromagnetic correlations. The susceptibility data also show an absence of conventional long-range spin order down to at least 0 . 55 K, reflecting the frustrated nature of TbInO3. Elastic magnetic diffuse neutron scattering (SEQUOIA, SNS) is observed below ~ 15 K, due to the presence of static two-dimensional spin correlations. The spectrum of crystal field excitations in TbInO3 appears to have an exotic form due to the existence of two crystallographically distinct Tb3+ sites and leads to a strong Ising anisotropy of the spin symmetry.

  11. Using Chebyshev polynomials and approximate inverse triangular factorizations for preconditioning the conjugate gradient method

    NASA Astrophysics Data System (ADS)

    Kaporin, I. E.

    2012-02-01

    In order to precondition a sparse symmetric positive definite matrix, its approximate inverse is examined, which is represented as the product of two sparse mutually adjoint triangular matrices. In this way, the solution of the corresponding system of linear algebraic equations (SLAE) by applying the preconditioned conjugate gradient method (CGM) is reduced to performing only elementary vector operations and calculating sparse matrix-vector products. A method for constructing the above preconditioner is described and analyzed. The triangular factor has a fixed sparsity pattern and is optimal in the sense that the preconditioned matrix has a minimum K-condition number. The use of polynomial preconditioning based on Chebyshev polynomials makes it possible to considerably reduce the amount of scalar product operations (at the cost of an insignificant increase in the total number of arithmetic operations). The possibility of an efficient massively parallel implementation of the resulting method for solving SLAEs is discussed. For a sequential version of this method, the results obtained by solving 56 test problems from the Florida sparse matrix collection (which are large-scale and ill-conditioned) are presented. These results show that the method is highly reliable and has low computational costs.

  12. Linear analysis of a backward wave oscillator with triangular corrugated slow wave structure

    NASA Astrophysics Data System (ADS)

    Saber, Md. Ghulam; Sagor, Rakibul Hasan; Amin, Md. Ruhul

    2016-05-01

    In this work, a backward wave oscillator (BWO) with triangularly corrugated periodic metallic slow wave structure (TrCSWS) driven by an infinitely thin annular electron beam is studied using linear theory. The electron beam is assumed to be guided by a strong magnetic field. The triangular axial profile of the SWS is approximated by a Fourier series in order to apply the linear Rayleigh-Fourier (R-F) theory that has long been used in the theoretical analysis of BWOs with sinusoidally corrugated SWS (SCSWS). The dispersion equation for various beam parameters has been solved and the temporal growth rate (TGR) of the electromagnetic wave for the fundamental TM_{01} mode is calculated numerically. The TGR values for different beam parameters have been compared with those of the BWO with SCSWS, semi-circularly corrugated SWS (SCCSWS) and trapezoidally corrugated SWS (TCSWS). In order to compare the TGR values, the amplitude of corrugation of the TrCSWS is varied so that its dispersion curve of TM_{01} mode almost coincides with that of the SCSWS and TCSWS. The study reveals that the performance (in terms of TGR) of the proposed BWO with TrCSWS is comparable to that of other BWOs with SCSWS and TCSWS for the same set of beam parameters and it provides significantly better performance than SCCSWS. So, the proposed TrCSWS that can easily be constructed may replace SCSWS, SCCSWS or TCSWS as their viable alternative.

  13. Guiding 2.94 μm using low-loss microstructured antiresonant triangular-core fibers

    NASA Astrophysics Data System (ADS)

    Chen, Yang; Saleh, Mohammed F.; Joly, Nicolas Y.; Biancalana, Fabio

    2016-04-01

    We introduce a new simple design of hollow-core microstructured fiber targeted to guide mid-infrared light at a wavelength of 2.94 μm. The fiber has a triangular-core supported via silica-glass webs enclosed by a large hollow capillary tube. The fiber specific dimensions are determined by the anti-resonant guiding mechanism. For a triangular-core with side length 100 μm, the fiber has a minimum transmission loss 0.08 ± 0.005 dB/m and dispersion 2.3 ps/km/nm at the operational wavelength of 2.94 μm.

  14. Heat Capacity Analysis Report

    SciTech Connect

    A. Findikakis

    2004-11-01

    The purpose of this report is to provide heat capacity values for the host and surrounding rock layers for the waste repository at Yucca Mountain. The heat capacity representations provided by this analysis are used in unsaturated zone (UZ) flow, transport, and coupled processes numerical modeling activities, and in thermal analyses as part of the design of the repository to support the license application. Among the reports that use the heat capacity values estimated in this report are the ''Multiscale Thermohydrologic Model'' report, the ''Drift Degradation Analysis'' report, the ''Ventilation Model and Analysis Report, the Igneous Intrusion Impacts on Waste Packages and Waste Forms'' report, the ''Dike/Drift Interactions report, the Drift-Scale Coupled Processes (DST and TH Seepage) Models'' report, and the ''In-Drift Natural Convection and Condensation'' report. The specific objective of this study is to determine the rock-grain and rock-mass heat capacities for the geologic stratigraphy identified in the ''Mineralogic Model (MM3.0) Report'' (BSC 2004 [DIRS 170031], Table 1-1). This report provides estimates of the heat capacity for all stratigraphic layers except the Paleozoic, for which the mineralogic abundance data required to estimate the heat capacity are not available. The temperature range of interest in this analysis is 25 C to 325 C. This interval is broken into three separate temperature sub-intervals: 25 C to 95 C, 95 C to 114 C, and 114 C to 325 C, which correspond to the preboiling, trans-boiling, and postboiling regimes. Heat capacity is defined as the amount of energy required to raise the temperature of a unit mass of material by one degree (Nimick and Connolly 1991 [DIRS 100690], p. 5). The rock-grain heat capacity is defined as the heat capacity of the rock solids (minerals), and does not include the effect of water that exists in the rock pores. By comparison, the rock-mass heat capacity considers the heat capacity of both solids and pore

  15. A discontinuous Galerkin method for the shallow water equations in spherical triangular coordinates

    NASA Astrophysics Data System (ADS)

    Läuter, Matthias; Giraldo, Francis X.; Handorf, Dörthe; Dethloff, Klaus

    2008-12-01

    A global model of the atmosphere is presented governed by the shallow water equations and discretized by a Runge-Kutta discontinuous Galerkin method on an unstructured triangular grid. The shallow water equations on the sphere, a two-dimensional surface in R3, are locally represented in terms of spherical triangular coordinates, the appropriate local coordinate mappings on triangles. On every triangular grid element, this leads to a two-dimensional representation of tangential momentum and therefore only two discrete momentum equations. The discontinuous Galerkin method consists of an integral formulation which requires both area (elements) and line (element faces) integrals. Here, we use a Rusanov numerical flux to resolve the discontinuous fluxes at the element faces. A strong stability-preserving third-order Runge-Kutta method is applied for the time discretization. The polynomial space of order k on each curved triangle of the grid is characterized by a Lagrange basis and requires high-order quadature rules for the integration over elements and element faces. For the presented method no mass matrix inversion is necessary, except in a preprocessing step. The validation of the atmospheric model has been done considering standard tests from Williamson et al. [D.L. Williamson, J.B. Drake, J.J. Hack, R. Jakob, P.N. Swarztrauber, A standard test set for numerical approximations to the shallow water equations in spherical geometry, J. Comput. Phys. 102 (1992) 211-224], unsteady analytical solutions of the nonlinear shallow water equations and a barotropic instability caused by an initial perturbation of a jet stream. A convergence rate of O(Δx) was observed in the model experiments. Furthermore, a numerical experiment is presented, for which the third-order time-integration method limits the model error. Thus, the time step Δt is restricted by both the CFL-condition and accuracy demands. Conservation of mass was shown up to machine precision and energy conservation

  16. Nonequilibrium heat capacity.

    PubMed

    Mandal, Dibyendu

    2013-12-01

    Development of steady state thermodynamics and statistical mechanics depends crucially on our ability to extend the notions of equilibrium thermodynamics to nonequilibrium steady states (NESS). The present paper considers the extension of heat capacity. A modified definition is proposed which continues to maintain the same relation to steady state Shannon entropy as in equilibrium, thus providing a thermodynamically consistent treatment of NESS heat capacity.

  17. Liquid heat capacity lasers

    DOEpatents

    Comaskey, Brian J.; Scheibner, Karl F.; Ault, Earl R.

    2007-05-01

    The heat capacity laser concept is extended to systems in which the heat capacity lasing media is a liquid. The laser active liquid is circulated from a reservoir (where the bulk of the media and hence waste heat resides) through a channel so configured for both optical pumping of the media for gain and for light amplification from the resulting gain.

  18. Problems of Excess Capacity

    NASA Technical Reports Server (NTRS)

    Douglas, G.

    1972-01-01

    The problems of excess capacity in the airline industry are discussed with focus on the following topics: load factors; fair rate of return on investment; service-quality rivalry among airlines; pricing (fare) policies; aircraft production; and the impacts of excess capacity on operating costs. Also included is a discussion of the interrelationships among these topics.

  19. Who needs capacity?

    PubMed

    Buchanan, Alec

    2015-01-01

    The UK Law Commission's Discussion Paper, Criminal Liability: Insanity and Automatism, recommends introducing the concept of capacity to the insanity defence. The concept of capacity has an established role in those parts of the law that concern the validity of the decisions that people make, for instance in composing a will or entering into a contract. Making mental capacity a criterion for criminal responsibility in a mentally disordered defendant, however, is potentially problematic. First, the term capacity already has several different meanings in the literature on the jurisprudence of mental abnormality. Second, using the concept of capacity in the way that the Law Commission proposes poses difficulties that relate to the provision of testimony by expert witnesses.

  20. Who needs capacity?

    PubMed

    Buchanan, Alec

    2015-01-01

    The UK Law Commission's Discussion Paper, Criminal Liability: Insanity and Automatism, recommends introducing the concept of capacity to the insanity defence. The concept of capacity has an established role in those parts of the law that concern the validity of the decisions that people make, for instance in composing a will or entering into a contract. Making mental capacity a criterion for criminal responsibility in a mentally disordered defendant, however, is potentially problematic. First, the term capacity already has several different meanings in the literature on the jurisprudence of mental abnormality. Second, using the concept of capacity in the way that the Law Commission proposes poses difficulties that relate to the provision of testimony by expert witnesses. PMID:25939285

  1. Fabrication of a label-free plasmon immunosensor based on triangular silver nanoplates

    NASA Astrophysics Data System (ADS)

    Dong, Peipei; Lin, Yuanyuan; Di, Junwei

    2013-08-01

    In this work, we have firstly electrodeposited small gold seeds (average diameter of ~40 nm) onto transparent indium tin oxide (ITO) thin film coated glass. Then silver triangular nanoplates with edge lengths of ~200 nm were fabricated using seed-mediated growth method. The localized surface plasmon resonance (LSPR) peak was located at ~700 nm. Finally, a label-free plasmon immunosensor was prepared by directly immobilizing goat anti-mouse IgG onto silver surface. The performance of the LSPR immunosensor was investigated. The red-shift of the biosensor was linearly proportional to mouse IgG concentration ranged from 5 ng/mL to 500 ng/mL, with a detection limit of 2 ng/mL. The label-free immunosensor was simple, sensitive and selective.

  2. Theory of a competitive spin liquid state for weak Mott insulators on the triangular lattice.

    PubMed

    Mishmash, Ryan V; Garrison, James R; Bieri, Samuel; Xu, Cenke

    2013-10-11

    We propose a novel quantum spin liquid state that can explain many of the intriguing experimental properties of the low-temperature phase of the organic spin liquid candidate materials κ-(BEDT-TTF)2Cu2(CN)3 and EtMe3Sb[Pd(dmit)2]2. This state of paired fermionic spinons preserves all symmetries of the system, and it has a gapless excitation spectrum with quadratic bands that touch at momentum k[over →]=0. This quadratic band touching is protected by symmetries. Using variational Monte Carlo techniques, we show that this state has highly competitive energy in the triangular lattice Heisenberg model supplemented with a realistically large ring-exchange term.

  3. Ground state pairing correlation competes in the doped triangular lattice Hubbard model

    NASA Astrophysics Data System (ADS)

    Cheng, Shuai; Wang, Xin; Liu, Suhang; Ma, Tianxing

    2014-11-01

    By using the constrained path quantum Monte carlo method, we study the ground state paring correlations in the t - U - V Hubbard model on the triangular lattice. It is shown that pairings with various symmetries dominate in different electron filling regions. The pairing correlation with fn-wave symmetry dominates over other pairings around half fillings, and as the electron filling decreases away from the half filling, the d + id-wave pairing correlation tends to dominate. As the electron filling is bellow the Van Hove singularity, the f-wave pairing dominates. These crossovers are due to the interplay of electronic correlation and geometric frustration, associating with the competition between the antiferromagnetic correlations and ferromagnetic fluctuations. Our findings reveal the possible magnetic origin of superconductivity, and also provide useful information for the understanding of superconductivity in NaxCoO2·H2O and the organic compounds.

  4. Ultrathin dendritic Pt3Cu triangular pyramid caps with enhanced electrocatalytic activity.

    PubMed

    Kuang, Yun; Cai, Zhao; Zhang, Ying; He, Dongsheng; Yan, Xiuling; Bi, Yongmin; Li, Yaping; Li, Ziyou; Sun, Xiaoming

    2014-10-22

    Here we report on the synthesis of novel dendritic Pt3Cu triangular pyramid caps via a solvothermal coreduction method. These caps had three-dimensional caved structures with ultrathin branches, as evidenced by high-resolution transmission electron microscopy (HRTEM) and HAADF-STEM characterization. Tuning the reduction kinetics of two metal precursors by an iodide ion was believed to be the key for the formation of an alloyed nanostructure. Electro-oxidation of methanol and formic acid showed dramatically improved electrocatalytic activities and poison-tolerance for these nanoalloys as compared to commercial Pt/C catalysts, which was attributed to their unique open porous structure with interconnected network, ultrahigh surface areas, as well as synergetic effect of the two metallic components.

  5. Order by disorder in the antiferromagnetic Ising model on an elastic triangular lattice

    PubMed Central

    Shokef, Yair; Souslov, Anton; Lubensky, T. C.

    2011-01-01

    Geometrically frustrated materials have a ground-state degeneracy that may be lifted by subtle effects, such as higher-order interactions causing small energetic preferences for ordered structures. Alternatively, ordering may result from entropic differences between configurations in an effect termed order by disorder. Motivated by recent experiments in a frustrated colloidal system in which ordering is suspected to result from entropy, we consider in this paper the antiferromagnetic Ising model on a deformable triangular lattice. We calculate the displacements exactly at the microscopic level and, contrary to previous studies, find a partially disordered ground state of randomly zigzagging stripes. Each such configuration is deformed differently and thus has a unique phonon spectrum with distinct entropy, lifting the degeneracy at finite temperature. Nonetheless, due to the free-energy barriers between the ground-state configurations, the system falls into a disordered glassy state. PMID:21730164

  6. Energy circulations in singular beams diffracted through an isosceles right triangular aperture

    NASA Astrophysics Data System (ADS)

    Bahl, Monika; Senthilkumaran, P.

    2015-07-01

    The Poynting vector in a singular optical field follows a helical path. Hence, it is the presence of a phase singularity that provides the circulating energy flow component to an optical field. These circulations in turn are responsible for the orbital angular momentum of light. This field when diffracted through an isosceles right triangular aperture generates straight line fringes in the far-field diffraction. We have addressed the modifications that happen to the energy circulations and the orbital angular momentum of light due to diffraction. Transverse components of the energy circulations in the diffracted field are studied by the Helmholtz-Hodge decomposition method. Interference experiments are presented to reveal the presence of phase singularities in the diffraction. This paper presents a complete analysis of the phase, phase gradient, and the intensity distributions in the diffraction pattern.

  7. Parametric investigation of boundary layer control using triangular micro vortex generators

    NASA Astrophysics Data System (ADS)

    Bagheri, Milad; Muslmani, Motassem Al; Masood, Asad; Khosravi, Mahmood; Atef Mahmoud, Mohamed; Cardoz, Aniket; Akkuwari, Abdulrahman; Alanezi, Yusuf; Kim, Young

    2014-03-01

    Improving the aerodynamic performance of an airfoil is one of the primary interests of the Aerodynamicists. Such performance improvement can be achieved using passive or active flow control devices. One of such passive devices having a compact size along with an effective performance is the Micro Vortex Generators (MVGs). A special type of MVGs, which has been recently introduced in the aerospace industry, is "Triangular Shape" MVGs and its impact on aerodynamic characteristics is the main interest of this study. This study will compare the effects of various configurations through which delay of the flow separation using boundary layer control will be analysed by experimental and theoretical approach. The experimental investigations have been conducted using subsonic wind tunnel and the theoretical analysis using ANSYS® 13.0 FLUENT of which the final results are compared with each other.

  8. Raman scattering enhanced within the plasmonic gap between an isolated Ag triangular nanoplate and Ag film

    NASA Astrophysics Data System (ADS)

    Li, Kuanguo; Jiang, Kang; Zhang, Lan; Wang, Yong; Mao, Lei; Zeng, Jie; Lu, Yonghua; Wang, Pei

    2016-04-01

    Enhanced electromagnetic field in the tiny gaps between metallic nanostructures holds great promise in optical applications. Herein, we report novel out-of-plane nanogaps composed of micrometer-sized Ag triangular nanoplates (AgTN) on Ag films. Notably, the new coupled plasmonic structure can dramatically enhance the surface-enhanced Raman scattering (SERS) by visible laser excitation, although the micrometer-sized AgTN has localized plasmon resonance at infrared wavelength. This enhancement is derived from the gap plasmon polariton between the AgTN and Ag film, which is excited via the antenna effect of the corner and edge of the AgTN. Systematic SERS studies indicated that the plasmon enhancement was on the order of corner > edge > face. These results were further verified by theoretical simulations. Our device paves the way for rational design of sensitive SERS substrates by judiciously choosing appropriate nanoparticles and optimizing the gap distance.

  9. Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island.

    PubMed

    Xu, Jinxia; Xiao, Xiangheng; Ren, Feng; Wu, Wei; Dai, Zhigao; Cai, Guangxu; Zhang, Shaofeng; Zhou, Juan; Mei, Fei; Jiang, Changzhong

    2012-01-01

    In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron-hole pair caused by the metal-semiconductor contact can also enhance the photocatalytic activity of the TiO2 film. PMID:22548875

  10. Quantum phases and phase transitions of frustrated hard-core bosons on a triangular ladder

    NASA Astrophysics Data System (ADS)

    Mishra, Tapan; Pai, Ramesh V.; Mukerjee, Subroto; Paramekanti, Arun

    2013-05-01

    Kinetically frustrated bosons at half filling in the presence of a competing nearest-neighbor repulsion support a wide supersolid regime on the two-dimensional triangular lattice. We study this model on a two-leg ladder using the finite-size density-matrix renormalization-group method, obtaining a phase diagram which contains three phases: a uniform superfluid (SF), an insulating charge density wave (CDW) crystal, and a bond ordered insulator (BO). We show that the transitions from SF to CDW and SF to BO are continuous in nature, with critical exponents varying continuously along the phase boundaries, while the transition from CDW to BO is found to be first order. The phase diagram is also found to contain an exactly solvable Majumdar Ghosh point, and reentrant SF to CDW phase transitions.

  11. Feature edge extraction from 3D triangular meshes using a thinning algorithm

    NASA Astrophysics Data System (ADS)

    Nomura, Masaru; Hamada, Nozomu

    2001-11-01

    Highly detailed geometric models, which are represented as dense triangular meshes are becoming popular in computer graphics. Since such 3D meshes often have huge information, we require some methods to treat them efficiently in the 3D mesh processing such as, surface simplification, subdivision surface, curved surface approximation and morphing. In these applications, we often extract features of 3D meshes such as feature vertices and feature edges in preprocessing step. An automatic extraction method of feature edges is treated in this study. In order to realize the feature edge extraction method, we first introduce the concavity and convexity evaluation value. Then the histogram of the concavity and convexity evaluation value is used to separate the feature edge region. We apply a thinning algorithm, which is used in 2D binary image processing. It is shown that the proposed method can extract appropriate feature edges from 3D meshes.

  12. Magnetic soft modes in the distorted triangular antiferromagnet -CaCr2O4

    SciTech Connect

    Toth, Sandor; Lake, Bella; Hradil, Klaudia; Rule, K; Stone, Matthew B; Islam, A. T. M. N.

    2012-01-01

    -CaCr2O4 is a spin-3/2, distorted triangular lattice antiferromagnet with a simple 120 spin structure that masks the complex pattern of exchange interactions. The magnetic excitation spectrum has been measured using inelastic neutron scattering on powder and single crystal samples. It reveals unusual low energy modes which can be explained by linear spin-wave theory assuming nearest and next-nearest neighbor interactions. The mode softening is due to the next-nearest neighbor interactions and indicates a new magnetic phase nearby as revealed by the phase diagram constructed for this system. The extracted direct exchange interactions correlate well with the Cr3+{Cr3+ distances and are in agreement with other chromium oxide delafossite compounds.

  13. Frustrated Ising chains on the triangular lattice in Sr3NiIrO6

    NASA Astrophysics Data System (ADS)

    Toth, S.; Wu, W.; Adroja, D. T.; Rayaprol, S.; Sampathkumaran, E. V.

    2016-05-01

    Inelastic neutron scattering study on the spin-chain compound Sr3NiIrO6 reveals gapped quasi-1D magnetic excitations. The observed one-magnon band between 29.5 and 39 meV consists of magnon modes of the Ni2 + ions. The fitting of the spin wave spectrum reveals strongly coupled Ising-like chains along the c axis that are weakly coupled into a frustrated triangular lattice in the a b plane. The magnetic excitations survive up to 200 K well above the magnetic ordering temperature of TN˜75 K, also indicating a quasi-1D nature of the magnetic interactions in Sr3NiIrO6 . Our microscopic model is in agreement with ab initio electronic structure calculations and explains the giant spin-flip field observed in bulk magnetization measurements.

  14. SFM-FDTD analysis of triangular-lattice AAA structure: Parametric study of the TEM mode

    NASA Astrophysics Data System (ADS)

    Hamidi, M.; Chemrouk, C.; Belkhir, A.; Kebci, Z.; Ndao, A.; Lamrous, O.; Baida, F. I.

    2014-05-01

    This theoretical work reports a parametric study of enhanced transmission through annular aperture array (AAA) structure arranged in a triangular lattice. The effect of the incidence angle in addition to the inner and outer radii values on the evolution of the transmission spectra is carried out. To this end, a 3D Finite-Difference Time-Domain code based on the Split Field Method (SFM) is used to calculate the spectral response of the structure for any angle of incidence. In order to work through an orthogonal unit cell which presents the advantage to reduce time and space of computation, special periodic boundary conditions are implemented. This study provides a new modeling of AAA structures useful for producing tunable ultra-compact devices.

  15. XY ring exchange model with frustrated Ising coupling on the triangular lattice

    NASA Astrophysics Data System (ADS)

    Owerre, S. A.

    2016-07-01

    We investigate the nature of a Z2-invariant XY ring-exchange interaction with a frustrated Ising coupling on the triangular lattice. Within the limits of pure XY ring-exchange interaction, we show that the classical ground state is degenerate resulting from the Z2-invariance of the Hamiltonian. Quantum fluctuations lift these classical degenerate ground states and produce an unusual state whose excitation spectrum exhibits a gapped maximum quadratic dispersion near k = 0 and vanishes at the midpoints of each side of the Brillouin zone. This result is in contrast to a gapless quadratic dispersion near k = 0 in the U(1)-invariant counterpart. We also study the effects of frustration when competing with a classically frustrated Ising interaction. We provide a glimpse into the possible quantum phases that could emerge. A comprehensive understanding of this Hamiltonian, however, cannot be elucidated analytically and requires an explicit numerical simulation.

  16. Spin superfluidity in the anisotropic XY model in the triangular lattice

    NASA Astrophysics Data System (ADS)

    Lima, L. S.

    2016-07-01

    We use the SU(3) Schwinger's boson theory to study the spin transport properties in the two-dimensional anisotropic frustrated Heisenberg model in the triangular lattice at T=0. We have investigated the behavior of the spin conductivity for this model which presents an single-ion anisotropy. We study the spin transport in the Bose-Einstein condensation regime where we have that the tz bosons are condensed and the following condition is valid: = < tz† > = t . Our results show a metallic spin transport for ω > 0 and a superfluid spin transport in the limit of DC conductivity, ω → 0 , where σ(ω) tends to infinity in this limit of ω.

  17. Stable motions around triangular libration points in the real Earth-Moon system

    NASA Astrophysics Data System (ADS)

    Hou, X. Y.; Xin, X.; Scheeres, D. J.; Wang, J.

    2015-12-01

    Stable motions around the triangular libration points (TLP) in the Earth-Moon system perturbed by Sun are described. Two special quasi-periodic orbits around each TLP (called dynamical substitutes in this paper) are given. They were previously described in the planar Sun-Earth-Moon system by Kamel and are numerically obtained in the spatial Sun-Earth-Moon system. Linearized motions around the dynamical substitute are described in a semi-analytical way. The size of the stable region around the substitute is described via a numerical approach, along with the resonance mechanisms that determine the boundary of the stable region. Possible temporary capture from the near Earth objects population is discussed. An observation algorithm to search permanent or temporarily captured objects in this region is given. Some potential applications of the TLPs of the Earth-Moon system in space missions are discussed.

  18. Kondo effects in a triangular triple quantum dot II: ground-state properties for deformed configurations

    NASA Astrophysics Data System (ADS)

    Oguri, Akira; Amaha, Shinichi; Nisikawa, Yunori; Hewson, A. C.; Tarucha, Seigo; Numata, Takahide

    2010-03-01

    We study transport through a triangular triple quantum dot (TTQD) connected to two noninteracting leads, using the numerical renormalization group. The system has been theoretically revealed to show a variety of Kondo effects depending on the electron filling of the triangle [1]. For instance, the SU(4) Kondo effect takes place at three-electron filling, and a two-stage Kondo screening of a high-spin S=1 Nagaoka state takes place at four-electron filling. Because of the enhanced freedom in the configurations, however, the large parameter space of the TTQD still has not been fully explored, especially for large deformations. We report the effects of the inhomogeneity in the inter-dot couplings and the level positions in a wide region of the filling. [1] T. Numata, Y. Nisikawa, A. Oguri, and A. C. Hewson: PRB 80, 155330 (2009).

  19. Experimental investigation of local heat transfer in the packing with triangular channels

    NASA Astrophysics Data System (ADS)

    Perepelitsa, B. V.

    2006-12-01

    Results of experimental studies on temperature distribution over the surface of a complex-shape heat exchanger like “Frenkel packing” are presented. Measurements were carried out with the airflow between two corrugated sheets with triangular crimps directed at 90° relative to each other. Microthermocouples glued on the outer surface of the heater were used for measurements. The effect of contact points, Reynolds number, and gap between corrugated sheets on temperature distribution over the heat exchanger surface is analysed under the turbulent mode of airflow. The main attention is paid to temperature distribution over the heating surface in an elementary cell. According to measurements performed, there is insignificant effect of contact points and gap on the type of temperature distribution over the perimeter of heated cell.

  20. On relative equilibria of mutually gravitating massive point and triangular rigid body

    NASA Astrophysics Data System (ADS)

    Nikonov, Vasily I.

    2014-07-01

    Planar motions of a triangular body and a massive point under the action of mutual Newtonian attraction are studied. For the first formulation the triangle is assumed to be composed of three massive points. For the second formulation it is constructed with three homogeneous rods. Some partial solutions are observed within the analysis of the geometry of mass distribution. The investigation is motivated by the problem of motion of spacecrafts near asteroid-like celestial objects possessing irregular mass distribution. Comparison of dynamical effects for two types of mass distribution is another goal of the research. Problems appearing because of irregularities in mass distributions have been known for a long time. Certain approaches to the description of motions under attraction as well as qualitative particulars of dynamics are discussed by Demin (1963), Burov & Karapetyan (1995), Buchin & Burov & Troger (2008), Burov & Guerman & Sulikashvili (2010), Kholshevnikov & Kuznetsov (2011), Beletsky & Rodnikov (2011) and Scheeres (2012).

  1. Accelerating the prediction-based lower triangular transform for data compression using Intel MIC

    NASA Astrophysics Data System (ADS)

    Wei, Shih-Chieh; Huang, Bormin

    2015-10-01

    With the same decorrelation and coding gain capabilities as the Karhunen-Loeve transform, the prediction-based lower triangular transform (PLT) can apply its perfect reconstruction property for lossless compression of ultraspectral sounder data. As the compression process requires computation of the covariance matrix, the LDU decomposition, and the transform kernel and coefficient matrices, it will be beneficial to introduce parallel processing technology in the PLT implementation. In this work, the recent Intel Many Integrated Core (MIC) architecture will be used which can exploit up to 60 cores with 4 hardware threads per core. Both threading and vectorization techniques will be explored for performance improvement. In our experiment, the total processing time of an AIRS granule can have a speedup of ~4.6x. With the offload mode, the MIC architecture provides a convenient and efficient tool for parallelization of the PLT compression scheme.

  2. Percolation in random sequential adsorption of extended objects on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Budinski-Petković, Lj.; Lončarević, I.; Petković, M.; Jakšić, Z. M.; Vrhovac, S. B.

    2012-06-01

    The percolation aspect of random sequential adsorption of extended objects on a triangular lattice is studied by means of Monte Carlo simulations. The depositing objects are formed by self-avoiding lattice steps on the lattice. Jamming coverage θjam, percolation threshold θp*, and their ratio θp*/θjam are determined for objects of various shapes and sizes. We find that the percolation threshold θp* may decrease or increase with the object size, depending on the local geometry of the objects. We demonstrate that for various objects of the same length, the threshold θp* of more compact shapes exceeds the θp* of elongated ones. In addition, we study polydisperse mixtures in which the size of line segments making up the mixture gradually increases with the number of components. It is found that the percolation threshold decreases, while the jamming coverage increases, with the number of components in the mixture.

  3. Chiral Spin Liquids in Triangular-Lattice SU (N ) Fermionic Mott Insulators with Artificial Gauge Fields

    NASA Astrophysics Data System (ADS)

    Nataf, Pierre; Lajkó, Miklós; Wietek, Alexander; Penc, Karlo; Mila, Frédéric; Läuchli, Andreas M.

    2016-10-01

    We show that, in the presence of a π /2 artificial gauge field per plaquette, Mott insulating phases of ultracold fermions with SU (N ) symmetry and one particle per site generically possess an extended chiral phase with intrinsic topological order characterized by an approximate ground space of N low-lying singlets for periodic boundary conditions, and by chiral edge states described by the SU(N ) 1 Wess-Zumino-Novikov-Witten conformal field theory for open boundary conditions. This has been achieved by extensive exact diagonalizations for N between 3 and 9, and by a parton construction based on a set of N Gutzwiller projected fermionic wave functions with flux π /N per triangular plaquette. Experimental implications are briefly discussed.

  4. Application of the control volume mixed finite element method to a triangular discretization

    USGS Publications Warehouse

    Naff, R.L.

    2012-01-01

    A two-dimensional control volume mixed finite element method is applied to the elliptic equation. Discretization of the computational domain is based in triangular elements. Shape functions and test functions are formulated on the basis of an equilateral reference triangle with unit edges. A pressure support based on the linear interpolation of elemental edge pressures is used in this formulation. Comparisons are made between results from the standard mixed finite element method and this control volume mixed finite element method. Published 2011. This article is a US Government work and is in the public domain in the USA. ?? 2012 John Wiley & Sons, Ltd. This article is a US Government work and is in the public domain in the USA.

  5. Controlling Orientational Order in 1-D Assemblies of Multivalent Triangular Prisms.

    PubMed

    Kohlstedt, Kevin L; Olvera de la Cruz, Monica; Schatz, George C

    2013-01-01

    Multivalent nanostructures are becoming an increasingly important player in the self-assembly of supramolecular lattices. Understanding the role that shape plays in the coordination of the assemblies is crucial for the functional response of the material. We develop a simple design rule for the assembly of multivalent Au triangular nanoprisms into 1-D ordered arrays based on both the length of the valent DNA and the aspect ratio of the prism. Using MD simulations, we describe an order parameter that captures the short-range order of the assembly controlled by the design parameters. The order parameter shows that even short chains (N = 4) of prisms have a high degree of orientational order that transitions to no orientational order when the DNA length is similar to the prism length. Unlike isotropic polyvalent assemblies, we find that the highly oriented chains of prisms lose orientational order in discrete steps during melting as the prisms in the arrays dissociate.

  6. Enhanced photocatalysis by coupling of anatase TiO2 film to triangular Ag nanoparticle island

    PubMed Central

    2012-01-01

    In order to overcome the low utilization ratio of solar light and high electron-hole pair recombination rate of TiO2, the triangular Ag nanoparticle island is covered on the surface of the TiO2 thin film. Enhancement of the photocatalytic activity of the Ag/TiO2 nanocomposite system is observed. The increase of electron-hole pair generation is caused by the enhanced near-field amplitudes of localized surface plasmon of the Ag nanoparticles. The efficiently suppressed recombination of electron-hole pair caused by the metal-semiconductor contact can also enhance the photocatalytic activity of the TiO2 film. PMID:22548875

  7. Magnetic Interaction in the Geometrically Frustrated Triangular LatticeAntiferromagnet CuFeO2

    SciTech Connect

    Ye, Feng; Fernandez-Baca, Jaime A; Fishman, Randy Scott; Ren, Y.; Kang, H. J.; Qiu, Y.; Kimura, T.

    2007-01-01

    The spin wave excitations of the geometrically frustrated triangular lattice antiferromagnet (TLA) CuFeO2 have been measured using high resolution inelastic neutron scattering. Antiferromagnetic interactions up to third nearest neighbors in the ab plane (J1, J2, J3, with J2=J1 0:44 and J3=J1 0:57), as well as out-of-plane coupling (Jz, with Jz=J1 0:29) are required to describe the spin wave dispersion relations, indicating a three dimensional character of the magnetic interactions. Two energy deeps in the spin wave dispersion occur at the incommensurate wavevectors associated with multiferroic phase, and can be interpreted as dynamic precursors to the magnetoelectric behavior in this system.

  8. Memory characteristics of flexible resistive switching devices with triangular-shaped silicon nanowire bottom electrodes

    NASA Astrophysics Data System (ADS)

    Park, Sukhyung; Cho, Kyoungah; Kim, Sangsig

    2015-05-01

    In this paper, we demonstrate the bipolar resistive switching characteristics of flexible resistive random access memory (ReRAM) devices, whose bottom electrodes are made of silicon nanowires (Si NWs) with a triangular structure, which offer preferential sites for the filaments. The temperature dependence of the low resistance state (LRS) of the resistive Al2O3/ZnO bilayers of ReRAM devices reveals that Ag filaments originating from the top Ag electrodes are responsible for bipolar resistive switching. With respect to the endurance characteristics of the LRS, resistance fluctuation is negligible because of the filaments generated at the specific sites of the vertices of the Si NW bottom electrodes. In addition, the resistive switching characteristics are maintained even after 1000 bending cycles.

  9. Localized surface plasmons in face to face dimer silver triangular prism nanoparticles

    NASA Astrophysics Data System (ADS)

    Azarian, Abas; Babaei, Ferydon

    2016-05-01

    Using the discrete dipole approximation method, all plasmonic bands in 80 nm silver face to face dimer triangular prism nanoparticles were reported. The characteristics of plasmonics peaks were investigated with variations of dimer gap and refractive index of the surrounding medium of dimer. We found that there are three and four plasmonic bands, respectively, for dimer separation 2 and 4 nm. The extinction spectra and electric field distribution showed that the dipole-dipole interaction creates strong plasmonic band, but the quadrupole-quadrupole interaction relates to weak plasmonic band. The results revealed that the strong plasmonic bands have high sensitivity factors with respect to weak plasmonic bands. This study may be used in the synthesis of asymmetric dimers made of metal nanoparticles with new plasmonics properties.

  10. Two-dimensional surface emitting photonic crystal laser with hybrid triangular-graphite structure.

    PubMed

    Martínez, Luis Javier; Alén, Benito; Prieto, Ivan; Galisteo-López, J F; Galli, Matteo; Andreani, Lucio Claudio; Seassal, Christian; Viktorovitch, Pierre; Postigo, Pablo Aitor

    2009-08-17

    We present laser emission of a compact surface-emitting micro laser, optical pumped and operating at 1.5 microm at room temperature. A two-dimensional photonic crystal lattice conformed in a hybrid triangular-graphite configuration is designed for vertical emission. The structures have been fabricated in an InP slab, including four InAsP quantum wells as active layer, on the top of a Si substrate SiO(2) wafer bonded. Laser emission with thresholds around 70 microW and quality factors (Qs) up to 12000 have been measured. The Bloch mode selected for the emission keeps a high Q (>or= 2 x 10(5)) around the Gamma point for a wide range of in-plane values k(||)

  11. Fabrication of triangular nanobeam waveguide networks in bulk diamond using single-crystal silicon hard masks

    SciTech Connect

    Bayn, I.; Mouradian, S.; Li, L.; Goldstein, J. A.; Schröder, T.; Zheng, J.; Chen, E. H.; Gaathon, O.; Englund, Dirk; Lu, M.; Stein, A.; Ruggiero, C. A.; Salzman, J.; Kalish, R.

    2014-11-24

    A scalable approach for integrated photonic networks in single-crystal diamond using triangular etching of bulk samples is presented. We describe designs of high quality factor (Q = 2.51 × 10{sup 6}) photonic crystal cavities with low mode volume (V{sub m} = 1.062 × (λ/n){sup 3}), which are connected via waveguides supported by suspension structures with predicted transmission loss of only 0.05 dB. We demonstrate the fabrication of these structures using transferred single-crystal silicon hard masks and angular dry etching, yielding photonic crystal cavities in the visible spectrum with measured quality factors in excess of Q = 3 × 10{sup 3}.

  12. A Revision Restoring Projection after Nipple Reconstruction by Burying Four Triangular Dermal Flaps

    PubMed Central

    Kim, Ji Hun

    2016-01-01

    Background Numerous techniques have been used to achieve long-term projection of the nipple following nipple-areola reconstruction. However, the reconstructed nipple loses projection over time. We describe a technique that uses local flaps to improve the lost projection of reconstructed nipples. Methods Between November 2013 and March 2015, nine patients (11 nipples) underwent revisional nipple reconstruction for lost projection. Only C–H nipple reconstructions were included in this study. The medical history of each patient was reviewed and photographs were taken in front and lateral views. All patients attended routine follow-up visits. Deepithelialized triangular flaps were made on all four sides of the nipple and buried in the opposite corners in order to augment the volume of the nipple. Anchoring sutures were used to attach each triangular flap on the side opposite their point of origin, and the resulting defects were closed directly. Results This procedure was used successfully in nine patients (11 nipples). Adequate projection was achieved in all patients and no complications occurred. The average nipple height was 3 mm before operation, 7 mm one day after operation, 5 mm at the six-month follow-up, and 5 mm at the 12-month follow-up. The average nipple-areolar angle was 164° before the operation, 111° one day after the operation, 130° at the six-month follow-up, and 133° at the 12-month follow-up. Conclusions The method described provides a solution to the loss of projection in reconstructed nipples. We recommend this technique because it leads to better projection, greater volume, and a more natural shape. PMID:27462566

  13. Superconducting correlations and thermodynamic properties in 2D square and triangular t-J model

    NASA Astrophysics Data System (ADS)

    Ogata, Masao

    2006-03-01

    Equal-time superconducting correlation functions of the two-dimensional t-J model on the square lattice are studied using high-temperature expansion method.[1] The sum of the pairing correlation, its spatial dependence and correlation length are obtained down to T ˜0.2t. By comparison of single-particle contributions in the correlation functions, we find effective attractive interactions between quasi-particles in dx^2-y^2-wave channel. It is shown that d-wave correlation grows rapidly at low temperatures for the doping 0.1 < δ< 0.5. The temperature for this growth is roughly scaled by J/2. This is in sharp contrast to the Hubbard model in a weak or intermediate coupling region, where there are few numerical evidences of superconductivity. We also study the possible d- and f-wave pairing in the triangular t-J model.[2] When t>0 with hole doping, a rapid growth of effective d-wave paring interaction is found that indicates the resonating-valence-bond superconductivity. In contrast, when t<0, where the ferromagnetic- and antiferromagnetic correlation compete, correlation lengths of the f-wave triplet paring tends to diverge around δ=0.6, although its effective interaction is small. This result is compared and discussed with the recently discovered superconductor, NaxCoO2.yH2O, where Co atoms form a triangular lattice. Specific heat in low temperatures are also obtained in the high-temperature expansion method. We will discuss that the doping dependence of the specific heat coefficient, γ, agrees with experimental data. [1] T. Koretsune and M. Ogata, J. Phys. Soc. Japan 74, 1390 (2005). [2] T. Koretsune and M. Ogata, Phys. Rev. Lett. 89, 116401 (2002), and Phys. Rev. B72, 134513 (2005).

  14. Extrahepatic Diseases and NAFLD: The Triangular Relationship between NAFLD, Type 2-Diabetes and Dysbiosis.

    PubMed

    Scorletti, Eleonora; Byrne, Christopher D

    2016-01-01

    Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of liver diseases from simple steatosis with hepatic lipid accumulation to end-stage liver disease with decompensated cirrhosis, liver failure and hepatocellular carcinoma. Recent data from the USA showed that in 2013, NAFLD was the second most frequent indication for liver transplantation behind hepatitis C. Since there are now effective treatments for hepatitis C and there is currently no licensed treatment for NAFLD, it has been predicted that over the next 10-15 years, NAFLD will replace hepatitis C as the most frequent indication for liver transplantation. Besides, increasing the risk of hepatocellular carcinoma and end-stage liver disease, it has recently become clear that NAFLD also increases risk of extrahepatic diseases such as type 2 diabetes mellitus (T2DM), cardiovascular disease, cardiac diseases and chronic kidney disease, to name but a few. Of each of these extrahepatic diseases, the evidence to date suggests that NAFLD is a strong risk factor for T2DM. When NAFLD occurs in combination with obesity and insulin resistance (as it frequently does), there is a marked increase in risk of incident T2DM with possible synergism occurring between liver fat accumulation, insulin resistance and obesity to further increase risk of development of T2DM. Thus, there is a reciprocal relationship between NAFLD as a risk factor for T2DM, and T2DM as a risk factor for liver disease progression in NAFLD. Moreover, recent evidence now points to the importance of perturbation of the intestinal microbiota (dysbiosis) in both T2DM and NAFLD. Consequently, there is a triangular relationship between dysbiosis and T2DM and NAFLD. This review will focus on T2DM as a key extrahepatic complication of NAFLD and will describe and discuss the triangular relationship between dysbiosis and T2DM and NAFLD and the factors and potential mechanisms underpinning this relationship. PMID:27548822

  15. Using adaptive sampling and triangular meshes for the processing and inversion of potential field data

    NASA Astrophysics Data System (ADS)

    Foks, Nathan Leon

    The interpretation of geophysical data plays an important role in the analysis of potential field data in resource exploration industries. Two categories of interpretation techniques are discussed in this thesis; boundary detection and geophysical inversion. Fault or boundary detection is a method to interpret the locations of subsurface boundaries from measured data, while inversion is a computationally intensive method that provides 3D information about subsurface structure. My research focuses on these two aspects of interpretation techniques. First, I develop a method to aid in the interpretation of faults and boundaries from magnetic data. These processes are traditionally carried out using raster grid and image processing techniques. Instead, I use unstructured meshes of triangular facets that can extract inferred boundaries using mesh edges. Next, to address the computational issues of geophysical inversion, I develop an approach to reduce the number of data in a data set. The approach selects the data points according to a user specified proxy for its signal content. The approach is performed in the data domain and requires no modification to existing inversion codes. This technique adds to the existing suite of compressive inversion algorithms. Finally, I develop an algorithm to invert gravity data for an interfacing surface using an unstructured mesh of triangular facets. A pertinent property of unstructured meshes is their flexibility at representing oblique, or arbitrarily oriented structures. This flexibility makes unstructured meshes an ideal candidate for geometry based interface inversions. The approaches I have developed provide a suite of algorithms geared towards large-scale interpretation of potential field data, by using an unstructured representation of both the data and model parameters.

  16. Anions Influence the Relaxation Dynamics of Mono-μ3-OH-Capped Triangular Dysprosium Aggregates.

    PubMed

    Zhang, Li; Zhang, Peng; Zhao, Lang; Wu, Jianfeng; Guo, Mei; Tang, Jinkui

    2015-06-01

    A family of four Dy3 triangular circular helicates, namely, [Dy3(HL)3(μ3-OH)(CH3OH)2(H2O)4]Cl1.5(OH)0.5·0.5H2O (1), [Dy3(HL)3(μ3-OH)(CH3OH)3(H2O)2Cl]Cl·CH3OH (2), [Dy3(HL)3(μ3-OH)(CH3OH)3(H2O)2(NO3)](NO3) (3), and [Dy3(HL)3(μ3-OH)(CH3OH)4(ClO4)](ClO4) (4), were assembled by the reaction of a new acylhydrazone ligand H3L [(3-hydroxy)-N'-((8-hydroxyquinolin-2-yl)methylene)picolinohydrazide] with different dysprosium(III) salts. These compounds represent the first examples of μ-Oacylhydrazone-bridged triangular Dy3 SMMs reported to date. Alternating-current magnetic susceptibility measurements revealed that compounds 1 and 2 show typical SMM behavior with the occurrence of multiple relaxation processes, whereas frequency-dependent relaxation signals without χ″ peaks were observed in 3 and 4 under zero dc field. Such distinct dynamic behaviors are attributed to the different sizes of the terminal coordination solvent/anions (H2O, Cl(-), NO3(-), and ClO4(-) for 1-4, respectively) at the Dy3 site. Here, similar deviations from the ideal monocapped square-antiprismatic (C4v) geometry defined by SHAPE software were observed around local Dy centers in 1 and 2, whereas the situation was completely different in 3 and 4 as a result of the presence of relatively large anions in the limited space defined by three intercrossing rigid hydrazone ligands. PMID:25984586

  17. Magnetic excitations in the triangular antiferromagnets Mn3Sn and Mn3Ge

    NASA Astrophysics Data System (ADS)

    Cable, J. W.; Wakabayashi, N.; Radhakrishna, P.

    1993-09-01

    Inelastic neutron scattering was used to study the magnetic excitations of the triangular antiferromagnets Mn3Sn and Mn3Ge. These compounds have itinerant d electrons and large magnetic moments localized at the Mn sites and may be regarded as materials that lie in the intermediate regime between local-moment and itinerant-electron systems. The spin-wave spectra exhibit steep dispersion and strong damping, which is characteristic behavior of itinerant-electron systems. Nevertheless, it is useful to analyze the data in terms of a local-moment model with anisotropy. We find the data are remarkably well described by this model with exchange parameters extending to fifth-nearest neighbors and with both axial- and basal-plane anisotropy. The axial-anisotropy parameters were determined from the uniform out-of-plane spin fluctuation, and the signs show that the spins are confined to the basal plane. The second-order basal-plane anisotropy constants were determined by satisfying both the magnitude of the weak basal-plane ferromagnetic moments and the observed splitting of a doubly degenerate acoustic-spin-wave branch. The sixth-order basal-plane anisotropy was determined by adjusting to the observed energy gap associated with spin fluctuations within the basal plane. The exchange parameters have the correct signs to stabilize the triangular antiferromagnetic structure but yield Néel temperatures that are higher than those observed by a factor of 3 or 4. This overestimation of the Néel temperature is not an uncommon result when a local moment model is applied to an itinerant-electron system.

  18. A 6-node co-rotational triangular elasto-plastic shell element

    NASA Astrophysics Data System (ADS)

    Li, Zhongxue; Xiang, Yu; Izzuddin, Bassam A.; Vu-Quoc, Loc; Zhuo, Xin; Zhang, Chuanjie

    2015-05-01

    A 6-node co-rotational triangular elasto-plastic shell element is developed. The local coordinate system of the element is defined by the vectors directing from one vertex to the other two vertices and their cross product. Based on such a co-rotational framework, the element rigid-body rotations are excluded in calculating the local nodal variables from the global nodal variables. The two smallest components of each nodal orientation vector are defined as rotational variables, resulting in the desired additive property for all nodal variables in a nonlinear incremental solution procedure. Different from other existing co-rotational finite element formulations, both the element tangent stiffness matrices in the local and in the global coordinate systems are symmetric owing to the commutativity of the nodal variables in calculating the second derivatives of the strain energy with respect to the local nodal variables and, through chain differentiation, with respect to the global nodal variables. For elasto-plastic analysis, the Maxwell-Huber-Hencky-von Mises yield criterion is employed together with the backward-Euler return-mapping method for the evaluation of the elasto-plastic stress state, where a consistent tangent modulus matrix is employed. To overcome locking problems, the assumed linear membrane strains and shear strains are obtained by using the line integration method proposed by MacNeal, and the assumed higher-order membrane strains are obtained by enforcing the stationarity of the mixed displacement-strain canonical functional, these assumed strains are then employed to replace the corresponding conforming strains. The reliability and convergence of the present 6-node triangular shell element formulation are verified through two elastic plate patch tests as well as two elastic and five elasto-plastic plate/shell problems undergoing large displacements and large rotations.

  19. Hydration-induced spin-glass state in a frustrated Na-Mn-O triangular lattice

    NASA Astrophysics Data System (ADS)

    Bakaimi, Ioanna; Brescia, Rosaria; Brown, Craig M.; Tsirlin, Alexander A.; Green, Mark A.; Lappas, Alexandros

    2016-05-01

    Birnessite compounds are stable across a wide range of compositions that produces a remarkable diversity in their physical, electrochemical, and functional properties. These are hydrated analogs of the magnetically frustrated, mixed-valent manganese oxide structures, with general formula, N axMn O2 . Here we demonstrate that the direct hydration of layered rock-salt type α-NaMn O2 , with the geometrically frustrated triangular lattice topology, yields the birnessite type oxide, N a0.36Mn O2.0.2 H2O , transforming its magnetic properties. This compound has a much-expanded interlayer spacing compared to its parent α-NaMn O2 compound. We show that while the parent α-NaMn O2 possesses a Néel temperature of 45 K as a result of broken symmetry in the M n3 + sublattice, the hydrated derivative undergoes collective spin freezing at 29 K within the M n3 +/M n4 + sublattice. Scaling-law analysis of the frequency dispersion of the ac susceptibility, as well as the temperature-dependent, low-field dc magnetization confirm a cooperative spin-glass state of strongly interacting spins. This is supported by complementary spectroscopic analysis [high-angle annular dark-field scanning transmission electron miscroscopy (TEM), energy-dispersive x-ray spectroscopy, and electron energy-loss spectroscopy] as well as by a structural investigation (high-resolution TEM, x-ray, and neutron powder diffraction) that yield insights into the chemical and atomic structure modifications. We conclude that the spin-glass state in birnessite is driven by the spin frustration imposed by the underlying triangular lattice topology that is further enhanced by the in-plane bond-disorder generated by the mixed-valent character of manganese in the layers.

  20. Kondo effects in a triangular triple quantum dot with lower symmetries

    NASA Astrophysics Data System (ADS)

    Oguri, A.; Amaha, S.; Nishikawa, Y.; Numata, T.; Shimamoto, M.; Hewson, A. C.; Tarucha, S.

    2011-05-01

    We study the low-energy properties and characteristic Kondo energy scale of a triangular triple quantum dot, connected to two non-interacting leads, in a wide parameter range of a gate voltage and distortions which lower the symmetry of an equilateral structure, using the numerical renormalization group approach. For large Coulomb interactions, the ground states with different characters can be classified according to the plateaus of Θ≡(δe-δo)(2/π), where δe and δo are the phase shifts for the even and odd partial waves. At these plateaus of Θ, both Θ and the occupation number Ntot≡(δe+δo)(2/π) take values close to integers, and thus the ground states can be characterized by these two integers. The Kondo effect with a local moment with total spin S=1 due to a Nagaoka mechanism appears on the plateau, which can be identified by Θ≃2.0 and Ntot≃4.0. For large distortions, however, the high-spin moment disappears through a singlet-triplet transition occurring within the four-electron region. It happens at a crossover to the adjacent plateaus for Θ≃0.0 and Θ≃4.0, and the two-terminal conductance has a peak in the transient regions. For weak distortions, the SU(4) Kondo effect also takes place for Ntot≃3.0. It appears as a sharp conductance valley between the S=1/2 Kondo ridges on both sides. We also find that the characteristic energy scale T* reflect these varieties of the Kondo effect. Particularly, T* is sensitive to the distribution of the charge and spin in the triangular triple dot.

  1. Coordinate Bethe ansatz computation for low temperature behavior of a triangular lattice of a spin-1 Heisenberg antiferromagnet

    SciTech Connect

    Shuaibu, A.; Rahman, M. M.

    2014-03-05

    We study the low temperature behavior of a triangular lattice quantum spin-1 Heisenberg antiferromagnet with single-site anisotropy by using coordinate Bethe ansatz method. We compute the standard two-particle Hermitian Hamiltonian, and obtain the eigenfunctions and eigenvalue of the system. The obtained results show a number of advantages in comparison with many results.

  2. Method for determining the elevation of a point on a work site represented in a triangular irregular network

    NASA Technical Reports Server (NTRS)

    Koehrsen, Craig L. (Inventor)

    2000-01-01

    A site database structure for storing elevation data for access by an application program being executed on a control system on a work machine. The data is stored in a Triangular Irregular Network (TIN). The elevation of a point on the work site based on the three points forming the triangle containing the point.

  3. Spin liquid state in the disordered triangular lattice Sc2Ga2CuO7 revealed by NMR

    NASA Astrophysics Data System (ADS)

    Khuntia, P.; Kumar, R.; Mahajan, A. V.; Baenitz, M.; Furukawa, Y.

    2016-04-01

    We present microscopic magnetic properties of a two-dimensional triangular lattice Sc2Ga2CuO7 , consisting of single and double triangular Cu planes. An antiferromagnetic (AFM) exchange interaction J /kB≈35 K between Cu2 + (S =1 /2 ) spins in the triangular biplane is obtained from the analysis of intrinsic magnetic susceptibility data. The intrinsic magnetic susceptibility, extracted from 71Ga NMR shift data, displays the presence of AFM short range spin correlations and remains finite down to 50 mK, suggesting a nonsinglet ground state. The nuclear spin-lattice relaxation rate (1 /T1 ) reveals a slowing down of Cu2 + spin fluctuations with decreasing T down to 100 mK. Magnetic specific heat (Cm) and 1 /T1 exhibit power law behavior at low temperatures, implying the gapless nature of the spin excitation spectrum. The absence of long range magnetic ordering down to ˜J /700 , nonzero spin susceptibility at low T , and the power law behavior of Cm and 1 /T1 suggest a gapless quantum spin liquid (QSL) state. Our results demonstrate that persistent spin dynamics induced by frustration maintain a quantum-disordered state at T →0 in this triangular lattice antiferromagnet. This suggests that the low energy modes are dominated by spinon excitations in the QSL state due to randomness engendered by disorder and frustration.

  4. Brief Report: Intimacy, Passion, and Commitment in Romantic Relationships--Validation of a "Triangular Love Scale" for Adolescents

    ERIC Educational Resources Information Center

    Overbeek, Geertjan; Ha, Thao; Scholte, Ron; de Kemp, Raymond; Engels, Rutger C. M. E.

    2007-01-01

    This study examined the psychometric properties of an adolescent version of the "triangular love scale" (TLS), which assesses three components of romantic relationships: intimacy, passion, and commitment. Using data from 435 Dutch adolescents aged 12-18 years, we found evidence for convergent validity, showing that dimensions of intimacy, passion,…

  5. Spin liquid state in the disordered triangular lattice Sc2Ga2CuO7 revealed by NMR

    DOE PAGES

    Khuntia, P.; Kumar, R.; Mahajan, A. V.; Baenitz, M.; Furukawa, Y.

    2016-04-18

    We present microscopic magnetic properties of a two-dimensional triangular lattice Sc2Ga2CuO7, consisting of single and double triangular Cu planes. An antiferromagnetic (AFM) exchange interaction J/kB ≈ 35 K between Cu2+ (S = 1/2) spins in the triangular biplane is obtained from the analysis of intrinsic magnetic susceptibility data. The intrinsic magnetic susceptibility, extracted from 71Ga NMR shift data, displays the presence of AFM short range spin correlations and remains finite down to 50 mK, suggesting a nonsinglet ground state. The nuclear spin-lattice relaxation rate (1/T1) reveals a slowing down of Cu2+ spin fluctuations with decreasing T down to 100 mK.more » Magnetic specific heat (Cm) and 1/T1 exhibit power law behavior at low temperatures, implying the gapless nature of the spin excitation spectrum. The absence of long range magnetic ordering down to ~J/700, nonzero spin susceptibility at low T, and the power law behavior of Cm and 1/T1 suggest a gapless quantum spin liquid (QSL) state. Our results demonstrate that persistent spin dynamics induced by frustration maintain a quantum-disordered state at T → 0 in this triangular lattice antiferromagnet. Furthermore, this suggests that the low energy modes are dominated by spinon excitations in the QSL state due to randomness engendered by disorder and frustration.« less

  6. High efficiency InGaN/GaN light emitting diodes with asymmetric triangular multiple quantum wells

    SciTech Connect

    Chang, Chiao-Yun; Li, Hen; Lu, Tien-Chang

    2014-03-03

    In this study, we demonstrated high efficiency InGaN/GaN light emitting diodes (LEDs) with asymmetric triangular multiple quantum wells (MQWs). Asymmetric triangular MQWs not only contribute to uniform carrier distribution in InGaN/GaN MQWs but also yield a low Auger recombination rate. In addition, asymmetric triangular MQWs with gallium face-oriented inclination band profiles can be immune from the polarization charge originating from typical c-plane InGaN/GaN quantum well structures. In the experiment, LEDs incorporated with asymmetric triangular MQWs with gallium face-oriented inclination band profiles exhibited a 60.0% external quantum efficiency at 20 mA and a 27.0% efficiency droop at 100 mA (corresponding to a current density of 69 A/cm{sup 2}), which accounted for an 11.7% efficiency improvement and a 31.1% droop reduction compared with symmetric square quantum well structure LEDs.

  7. 26 CFR 1.367(b)-10 - Acquisition of parent stock or securities for property in triangular reorganizations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... also includes— (A) A liability assumed by S to acquire the P stock or securities; and (B) S stock (or... paragraph (b) are illustrated by the following example: (i) Facts. P, a publicly traded domestic corporation..., this section applies to a triangular reorganization if P or S (or both) is a foreign corporation...

  8. 26 CFR 1.367(b)-10 - Acquisition of parent stock or securities for property in triangular reorganizations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... also includes— (A) A liability assumed by S to acquire the P stock or securities; and (B) S stock (or... paragraph (b) are illustrated by the following example: (i) Facts. P, a publicly traded domestic corporation..., this section applies to a triangular reorganization if P or S (or both) is a foreign corporation...

  9. 26 CFR 1.367(b)-10 - Acquisition of parent stock or securities for property in triangular reorganizations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... also includes— (A) A liability assumed by S to acquire the P stock or securities; and (B) S stock (or... paragraph (b) are illustrated by the following example: (i) Facts. P, a publicly traded domestic corporation..., this section applies to a triangular reorganization if P or S (or both) is a foreign corporation...

  10. NON-LINEAR VISCO-RESISTIVE COLLISIONAL TRANSPORT IN TOROIDAL ELLIPTICAL PLASMAS WITH TRIANGULARITY AND HOLE CURRENTS: A REVIEW

    SciTech Connect

    Martin, Pablo; Castro, Enrique; Puerta, Julio

    2009-07-26

    Non-linear plasma diffusion effects due to hole currents in tokamaks is analyzed in this work. Since the recent discovery of hole currents in tokamaks, this matter has become very important in confinement and instabilities in tokamaks plasmas. The analysis here presented includes non-linear flows as well as hole currents. In the case of low vorticity plasmas our treatment is performed using MHD equations, an it is more suitable for plasmas with very low levels of turbulence, as in the H-mode. The present treatment follows the lines of previous works, and some of the equations and results look like those obtained on these papers. However, the form of the family of the magnetic surfaces is very different to previous treatment, since the hole current modifies those families in a very important way. Elliptic plasmas with triangularity are considered. Pfirsch-Schlueter type currents are obtained for these generalized cases. Diffusion with and without holes are calculated and compared for several values of ellipticity and triangularity. Negative and positive triangularities are considered. In most of the calculations triangularity improves confinement, but the results are different for the positive than for the negative case.

  11. Increased chronic acceleration exposure enhances work capacity.

    PubMed

    Burton, R R; Smith, A H

    1997-10-01

    Adult male chickens adapted to 1.75 or 2.5 G from long term centrifugation, were maximally exercised on an animal treadmill at 1 g (Earth's gravity) and compared with the exercise capacities of control chickens raised at 1 g. The increased-G birds had statistically significantly greater exercise capacities than the controls during the first 3 weeks of the study after the initial exercise exposure. Thereafter however for the following two months of the study, there was no difference in either group's exercise capacities. This early increased work capacity was attributed to the increased-G birds improved ability to maximize their muscular strength with neurological adaptation. The increased-G birds lost body mass at a 31% greater rate during exercise than the controls although this difference was not statistically significant. This increased body mass loss was considered to have resulted from increased use of glycogen during exercise.

  12. Refinery Capacity Report

    EIA Publications

    2016-01-01

    Data series include fuel, electricity, and steam purchased for consumption at the refinery; refinery receipts of crude oil by method of transportation; and current and projected atmospheric crude oil distillation, downstream charge, and production capacities. Respondents are operators of all operating and idle petroleum refineries (including new refineries under construction) and refineries shut down during the previous year, located in the 50 states, the District of Columbia, Puerto Rico, the Virgin Islands, Guam, and other U.S. possessions. The Refinery Capacity Report does not contain working and shell storage capacity data. This data is now being collected twice a year as of March 31 and September 30 on the Form EIA-810, "Monthly Refinery Report", and is now released as a separate report Working and Net Available Shell Storage Capacity.

  13. Knudsen heat capacity

    SciTech Connect

    Babac, Gulru; Reese, Jason M.

    2014-05-15

    We present a “Knudsen heat capacity” as a more appropriate and useful fluid property in micro/nanoscale gas systems than the constant pressure heat capacity. At these scales, different fluid processes come to the fore that are not normally observed at the macroscale. For thermodynamic analyses that include these Knudsen processes, using the Knudsen heat capacity can be more effective and physical. We calculate this heat capacity theoretically for non-ideal monatomic and diatomic gases, in particular, helium, nitrogen, and hydrogen. The quantum modification for para and ortho hydrogen is also considered. We numerically model the Knudsen heat capacity using molecular dynamics simulations for the considered gases, and compare these results with the theoretical ones.

  14. Panama Canal capacity analysis

    SciTech Connect

    Bronzini, M.S.

    1995-04-27

    Predicting the transit capacities of the various Panama Canal alternatives required analyzing data on present Canal operations, adapting and extending an existing computer simulation model, performing simulation runs for each of the alternatives, and using the simulation model outputs to develop capacity estimates. These activities are summarized in this paper. A more complete account may be found in the project final report (TAMS 1993). Some of the material in this paper also appeared in a previously published paper (Rosselli, Bronzini, and Weekly 1994).

  15. Preeclampsia, biomarkers, syncytiotrophoblast stress, and placental capacity.

    PubMed

    Redman, Christopher W G; Staff, Anne Cathrine

    2015-10-01

    The maternal syndrome of preeclampsia is mediated by dysfunctional syncytiotrophoblast (STB). When this is stressed by uteroplacental malperfusion, its signaling to the mother changes, as part of a highly coordinated stress response. The STB signals are both proinflammatory and dysangiogenic such that the preeclamptic mother has a stronger vascular inflammatory response than normal, with an antiangiogenic bias. Angiogenic factors have limitations as preeclampsia biomarkers, especially for prediction and diagnosis of preeclampsia at term. However, if they are recognized as markers of STB stress, their physiological changes at term demonstrate that STB stress develops in all pregnancies. The biomarkers reveal that the duration of pregnancies is restricted by placental capacity, such that there is increasing placental dysfunction, at and beyond term. This capacity includes limitations imposed by the size of the uterus, the capacity of the uteroplacental circulation and, possibly, the supply of villous progenitor trophoblast cells. Limited placental capacity explains the increasing risks of postmaturity, including preeclampsia. Early-onset preeclampsia is predictable because STB stress and changes in its biomarkers are intrinsic to poor placentation, an early pregnancy pathology. Prediction of preeclampsia at term is not good because there is no early STB pathology. Moreover, biomarkers cannot accurately diagnose term preeclampsia against a background of universal STB dysfunction, which may or may not be clinically revealed before spontaneous or induced delivery. In this sense, postterm pregnancy is, at best, a pseudonormal state. However, the markers may prove useful in screening for women with more severe problems of postmaturity.

  16. Uncertainty in adaptive capacity

    NASA Astrophysics Data System (ADS)

    Adger, W. Neil; Vincent, Katharine

    2005-03-01

    The capacity to adapt is a critical element of the process of adaptation: it is the vector of resources that represent the asset base from which adaptation actions can be made. Adaptive capacity can in theory be identified and measured at various scales, from the individual to the nation. The assessment of uncertainty within such measures comes from the contested knowledge domain and theories surrounding the nature of the determinants of adaptive capacity and the human action of adaptation. While generic adaptive capacity at the national level, for example, is often postulated as being dependent on health, governance and political rights, and literacy, and economic well-being, the determinants of these variables at national levels are not widely understood. We outline the nature of this uncertainty for the major elements of adaptive capacity and illustrate these issues with the example of a social vulnerability index for countries in Africa. To cite this article: W.N. Adger, K. Vincent, C. R. Geoscience 337 (2005).

  17. Inattention and Impulsivity: Differential Impact on School Readiness Capacities

    ERIC Educational Resources Information Center

    Sasser, Tyler; Bierman, Karen

    2011-01-01

    Despite the conceptual link between self-regulation skills and school readiness capacities, questions remain regarding how distinct but related facets of self-regulation (i.e., attention regulation, behavior regulation) differentially impact the development of school readiness capacities during early childhood. Additionally, little is known about…

  18. Effects of Smoking on Respiratory Capacity and Control

    ERIC Educational Resources Information Center

    Awan, Shaheen N.; Alphonso, Vania A.

    2007-01-01

    The purpose of this study was to provide information concerning the possible early effects of smoking on measures of respiratory capacity and control in young adult female smokers vs. nonsmokers. In particular, maximum performance test results (vital capacity and maximum phonation time) and measures of air pressures and airflows during voiceless,…

  19. Triangular Fixation Technique for Bicolumn Restoration in Treatment of Distal Humerus Intercondylar Fracture

    PubMed Central

    Kang, Seung-Hoon; Jeong, Min; Lim, Hae-Seong

    2016-01-01

    Background Distal humerus intercondylar fractures are intra-articular and comminuted fractures involving soft tissue injury. As distal humerus is triangle-shaped, parallel plating coupled with articular fixation would be suitable for bicolumn restoration in treatment of distal humerus intercondylar fracture. Methods This study included 38 patients (15 males and 23 females) who underwent olecranon osteotomy, open reduction and internal fixation with the triangle-shaped cannulated screw and parallel locking plates (triangular fixation technique). Functional results were assessed with the visual analog scale (VAS) scores, Mayo elbow performance (MEP) scores and Disabilities of the Arm, Shoulder and Hand (DASH) questionnaires. Anteroposterior and lateral elbow radiographs were assessed for reduction, alignment, fracture union, posttraumatic arthrosis, and heterotopic ossification, and computed tomography (CT) scans were used to obtain more accurate measurements of articular discrepancy. Results All fractures healed primarily with no loss of reduction. The mean VAS, MEP, and DASH scores of the affected elbow were not significantly different from those of the unaffected elbow (p = 0.140, p = 0.090, and p = 0.262, respectively). The mean degree of flexion was significantly lower in the affected elbow than in the unaffected elbow, but was still considered as functional (p = 0.001, > 100° in 33 of 38 patients). Two cases of articular step-offs (> 2 mm) were seen on follow-up CT scans, but not significantly higher in the affected elbow than in the unaffected elbow (p = 0.657). Binary logistic regression analysis revealed that only Association for Osteosynthesis (AO) type C3 fractures correlated with good/excellent functional outcome (p = 0.012). Complications occurred in 12 of the 38 patients, and the overall reoperation rate for complications was 10.5% (4 of 38 patients). Conclusions Triangular fixation technique for bicolumn restoration was an effective and reliable

  20. Dual capacity reciprocating compressor

    DOEpatents

    Wolfe, R.W.

    1984-10-30

    A multi-cylinder compressor particularly useful in connection with northern climate heat pumps and in which different capacities are available in accordance with reversing motor rotation is provided with an eccentric cam on a crank pin under a fraction of the connecting rods, and arranged for rotation upon the crank pin between opposite positions 180[degree] apart so that with cam rotation on the crank pin such that the crank throw is at its normal maximum value all pistons pump at full capacity, and with rotation of the crank shaft in the opposite direction the cam moves to a circumferential position on the crank pin such that the overall crank throw is zero. Pistons whose connecting rods ride on a crank pin without a cam pump their normal rate with either crank rotational direction. Thus a small clearance volume is provided for any piston that moves when in either capacity mode of operation. 6 figs.

  1. Dual capacity reciprocating compressor

    DOEpatents

    Wolfe, Robert W.

    1984-01-01

    A multi-cylinder compressor 10 particularly useful in connection with northern climate heat pumps and in which different capacities are available in accordance with reversing motor 16 rotation is provided with an eccentric cam 38 on a crank pin 34 under a fraction of the connecting rods, and arranged for rotation upon the crank pin between opposite positions 180.degree. apart so that with cam rotation on the crank pin such that the crank throw is at its normal maximum value all pistons pump at full capacity, and with rotation of the crank shaft in the opposite direction the cam moves to a circumferential position on the crank pin such that the overall crank throw is zero. Pistons 24 whose connecting rods 30 ride on a crank pin 36 without a cam pump their normal rate with either crank rotational direction. Thus a small clearance volume is provided for any piston that moves when in either capacity mode of operation.

  2. Geothermal Plant Capacity Factors

    SciTech Connect

    Greg Mines; Jay Nathwani; Christopher Richard; Hillary Hanson; Rachel Wood

    2015-01-01

    The capacity factors recently provided by the Energy Information Administration (EIA) indicated this plant performance metric had declined for geothermal power plants since 2008. Though capacity factor is a term commonly used by geothermal stakeholders to express the ability of a plant to produce power, it is a term frequently misunderstood and in some instances incorrectly used. In this paper we discuss how this capacity factor is defined and utilized by the EIA, including discussion on the information that the EIA requests from operations in their 923 and 860 forms that are submitted both monthly and annually by geothermal operators. A discussion is also provided regarding the entities utilizing the information in the EIA reports, and how those entities can misinterpret the data being supplied by the operators. The intent of the paper is to inform the facility operators as the importance of the accuracy of the data that they provide, and the implications of not providing the correct information.

  3. Capacity Maximizing Constellations

    NASA Technical Reports Server (NTRS)

    Barsoum, Maged; Jones, Christopher

    2010-01-01

    Some non-traditional signal constellations have been proposed for transmission of data over the Additive White Gaussian Noise (AWGN) channel using such channel-capacity-approaching codes as low-density parity-check (LDPC) or turbo codes. Computational simulations have shown performance gains of more than 1 dB over traditional constellations. These gains could be translated to bandwidth- efficient communications, variously, over longer distances, using less power, or using smaller antennas. The proposed constellations have been used in a bit-interleaved coded modulation system employing state-ofthe-art LDPC codes. In computational simulations, these constellations were shown to afford performance gains over traditional constellations as predicted by the gap between the parallel decoding capacity of the constellations and the Gaussian capacity

  4. Proteomics: capacity versus utility.

    PubMed

    Harry, J L; Wilkins, M R; Herbert, B R; Packer, N H; Gooley, A A; Williams, K L

    2000-04-01

    Until recently scientists studied genes or proteins one at a time. With improvements in technology, new tools have become available to study the complex interactions that occur in biological systems. Global studies are required to do this, and these will involve genomic and proteomic approaches. High-throughput methods are necessary in each case because the number of genes and proteins in even the simplest of organisms are immense. In the developmental phase of genomics, the emphasis was on the generation and assembly of large amounts of nucleic acid sequence data. Proteomics is currently in a phase of technological development and establishment, and demonstrating the capacity for high throughput is a major challenge. However, funding bodies (both in the public and private sector) are increasingly focused on the usefulness of this capacity. Here we review the current state of proteome research in terms of capacity and utility.

  5. Triangular pulse generation using a dual-parallel Mach-Zehnder modulator driven by a single-frequency radio frequency signal.

    PubMed

    Zhang, Fangzheng; Ge, Xiaozhong; Pan, Shilong

    2013-11-01

    A simple scheme for the generation of full-duty-cycle triangular pulses is proposed and experimentally demonstrated using a dual-parallel Mach-Zehnder modulator driven by a single-frequency RF signal. By properly setting the bias voltages and the RF power, even-order harmonics in the optical intensity are suppressed, and the amplitude of the first-order harmonic is 9 times of that of the third-order harmonic. A periodical triangular pulse train is obtained in the time domain. 2.5, 5, and 10 GHz triangular pulse trains are experimentally generated, which verifies the feasibility of the proposed scheme.

  6. Preventing Early Learning Failure.

    ERIC Educational Resources Information Center

    Sornson, Bob, Ed.

    Noting that thousands of young children with the capacity to experience school success do not because they are unprepared for school learning activities, have experienced physical or emotional setbacks that cause them to be at risk for early learning failure, have never experienced limits on their behavior, or have mild sensory or motor deficits,…

  7. Heat transfer enhancement of laminar nanofluids flow in a triangular duct using vortex generator

    NASA Astrophysics Data System (ADS)

    Ahmed, H. E.; Mohammed, H. A.; Yusoff, M. Z.

    2012-09-01

    In this work, two dimensional laminar flow of different nanofluids flow inside a triangular duct with the existence of vortex generator is numerically investigated. The governing equations of mass, momentum and energy were solved using the finite volume method (FVM). The effects of type of the nanoparticles, particle concentrations, and Reynolds number on the heat transfer coefficient and pressure drop of nanofluids are examined. Reynolds number is ranged from 100 to 800. A constant surface temperature is assumed to be the thermal condition for the upper and lower heated walls. In the present work, three nanofluids are examined which are Al2O3, CuO and SiO2 suspended in the base fluid of ethylene glycol with nanoparticles concentrations ranged from 1 to 6%. The results show that for the case of SiO2-EG, at ϕ = 6% and Re = 800, it is found that the average Nusselt number is about 50.0% higher than the case of Re = 100.

  8. Highly Sensitive Homogeneous Immunoassays Based on Construction of Silver Triangular Nanoplates-Quantum Dots FRET System

    NASA Astrophysics Data System (ADS)

    Zeng, Qinghui; Li, Qin; Ji, Wenyu; Bin, Xue; Song, Jie

    2016-05-01

    With growing concerns about health issues worldwide, elegant sensors with high sensitivity and specificity for virus/antigens (Ag) detection are urgent to be developed. Homogeneous immunoassays (HIA) are an important technique with the advantages of small sample volumes requirement and pretreatment-free process. HIA are becoming more favorable for the medical diagnosis and disease surveillance than heterogeneous immunoassays. An important subset of HIA relies on the effect of fluorescence resonance energy transfer (FRET) via a donor-acceptor (D–A) platform, e.g., quantum dots (QDs) donor based FRET system. Being an excellent plasmonic material, silver triangular nanoplates (STNPs) have unique advantages in displaying surface plasmon resonance in the visible to near infrared spectral region, which make them a better acceptor for pairing with QDs in a FRET-based sensing system. However, the reported STNPs generally exhibited broad size distributions, which would greatly restrict their application as HIA acceptor for high detection sensitivity and specificity purpose. In this work, uniform STNPs and red-emitting QDs are firstly applied to construct FRET nanoplatform in the advanced HIA and further be exploited for analyzing virus Ag. The uniform STNPs/QDs nanoplatform based medical sensor provides a straightforward and highly sensitive method for Ag analysis in homogeneous form.

  9. Shape optimization of staggered ribs in a rotating equilateral triangular cooling channel

    NASA Astrophysics Data System (ADS)

    Moon, Mi-Ae; Park, Min-Jung; Kim, Kwang-Yong

    2014-04-01

    A rotating equilateral triangular cooling channel with staggered square ribs inside the leading edge of a turbine blade has been optimized in this work based on surrogate modeling. The fluid flow and heat transfer in the channel have been analyzed using three-dimensional Reynolds-averaged Navier-Stokes (RANS) equations under uniform heat flux condition. Shear stress transport turbulence model has been used as a turbulence closure. Computational results for area-averaged Nusselt number have been validated compared to the experimental data. The objectives related to the heat transfer rate and pressure drop has been linearly combined with a weighting factor to define the objective function. The angle of the rib, the rib pitch-to-hydraulic diameter ratio, and the rib width-to-hydraulic diameter ratio have been selected as the design variables. Twenty-two design points have been generated by Latin Hypercube sampling, and the values of the objective function have been calculated by the RANS analysis at these points. The surrogate model for the objective function has been constructed using the radial basis neural network method. Through the optimization, the objective function value has been improved by 21.5 % compared to that of the reference geometry.

  10. Semiclassical theory of the magnetization process of the triangular lattice Heisenberg model

    NASA Astrophysics Data System (ADS)

    Coletta, Tommaso; Tóth, Tamás A.; Penc, Karlo; Mila, Frédéric

    2016-08-01

    Motivated by the numerous examples of 1/3 magnetization plateaux in the triangular-lattice Heisenberg antiferromagnet with spins ranging from 1/2 to 5/2, we revisit the semiclassical calculation of the magnetization curve of that model, with the aim of coming up with a simple method that allows one to calculate the full magnetization curve and not just the critical fields of the 1/3 plateau. We show that it is actually possible to calculate the magnetization curve including the first quantum corrections and the appearance of the 1/3 plateau entirely within linear spin-wave theory, with predictions for the critical fields that agree to order 1 /S with those derived a long time ago on the basis of arguments that required going beyond linear spin-wave theory. This calculation relies on the central observation that there is a kink in the semiclassical energy at the field where the classical ground state is the collinear up-up-down structure and that this kink gives rise to a locally linear behavior of the energy with the field when all semiclassical ground states are compared to each other for all fields. The magnetization curves calculated in this way for spin 1/2, 1, and 5/2 are shown to be in good agreement with available experimental data.

  11. Aesthetic judgment of triangular shape: compactness and not the golden ratio determines perceived attractiveness

    PubMed Central

    Friedenberg, Jay

    2012-01-01

    Many studies over a period of more than a century have investigated the influence of the golden ratio on perceived geometric beauty. Surprisingly, very few of these studies used triangular shapes. In Experiment 1, we presented right triangles that differed in regard to their elongation determined by increasing the length of one side relative to another. Attractiveness ratings did not peak at the golden ratio, but there was a very strong influence of axis ratio overall. Participant ratings were a negative decreasing function of ratio. Triangles that pointed upward were judged as significantly more attractive than those that pointed down. We interpret these results according to a compactness hypothesis: triangles that are more compact are less likely to move or break and are thus considered more pleasing. Orientation also affects aesthetics. Upward-pointing triangles with a base parallel to the ground, regardless of their compactness, are also considered more perceptually stable and attractive. These findings were replicated across stimulus type in a second experiment with isosceles triangles and across testing procedure in a third experiment using a paired comparison technique. PMID:23145277

  12. Heat transfer on a naturally cross-driven ventilated triangular cavity with openings

    NASA Astrophysics Data System (ADS)

    Berli, M. E.; Di Paolo, J.; Saita, F. A.

    2009-05-01

    This work addresses the problem of heat transfer through the roof of a family home with the purpose of improving air-conditioning energy savings during hot summer days. To this end, the air natural convection in a right-angle triangular cavity, resembling an attic, is numerically analyzed. The air cavity is assumed as naturally ventilated through two openings that induce an external air-stream flowing into and out of the cavity. The governing equations for both flow and heat transfer are simultaneously solved with appropriate boundary conditions. Finite element technique is employed to transform the original set of differential equations into a non-linear discrete one, which is finally solved by Newton iteration. Two major assumptions are made, namely: radiation heat transfer is negligible and the air flow is in laminar regime; in addition, the usual Boussinesq approximation is employed. Under these assumptions the numerical predictions show that the amount of heat transferred through the ceiling rapidly diminishes as the flow through the cavity increases. Therefore; whether or not the ceiling is insulated, the energy transfer is reduced by more than 50% and energy savings are considerably improved.

  13. Innervation of the triangular fibrocartilage complex of the human wrist: quantitative immunohistochemical study.

    PubMed

    Shigemitsu, Toshio; Tobe, Masahiro; Mizutani, Kazuhiro; Murakami, Kunio; Ishikawa, Youichi; Sato, Fumi

    2007-09-01

    The distribution of neural elements in the triangular fibrocartilage complex (TFCC) of the human wrists was studied via immunohistochemical staining of protein gene product (PGP) 9.5 and calcitonin gene-related peptide (CGRP). Articular branches projecting to the TFCC arose from the dorsal branch of the ulnar nerve in all wrists examined. The TFCC is subdivided into the following six regions: the articular disc proper (ADP), meniscus homolog (MH), radio-ulnar ligament (RUL), loose part of ulnar collateral ligament (lUCL), dense part of ulnar collateral ligament (dUCL), and internal portion (IP). The IP consists of a mixture of dense and loose connective tissues enclosed by the ADP, MH, RUL, and UCL, and resides deep in the prestyloid recess, which is a pit in the MH. The densities of PGP 9.5-positive neural elements, including free nerve endings, single nerve fibers, nerve fascicles, and perivascular neural nets, were significantly higher in the IP than in other regions. Some of the neural elements except for the perivascular neural nets were positive for CGRP. The high density of neural elements in the IP suggests that sensory nerves projecting to the TFCC enter into the IP and from there distribute to adjacent regions such as the MH and RUL. Free nerve endings are responsible for pain transmission. The high density of free nerve endings in the IP suggests that the IP is a source of ulnar side wrist pain.

  14. Quantum phase transition from triangular to stripe charge order in NbSe2

    PubMed Central

    Soumyanarayanan, Anjan; Yee, Michael M.; He, Yang; van Wezel, Jasper; Rahn, Dirk J.; Rossnagel, Kai; Hudson, E. W.; Norman, Michael R.; Hoffman, Jennifer E.

    2013-01-01

    The competition between proximate electronic phases produces a complex phenomenology in strongly correlated systems. In particular, fluctuations associated with periodic charge or spin modulations, known as density waves, may lead to exotic superconductivity in several correlated materials. However, density waves have been difficult to isolate in the presence of chemical disorder, and the suspected causal link between competing density wave orders and high-temperature superconductivity is not understood. Here we used scanning tunneling microscopy to image a previously unknown unidirectional (stripe) charge-density wave (CDW) smoothly interfacing with the familiar tridirectional (triangular) CDW on the surface of the stoichiometric superconductor NbSe2. Our low-temperature measurements rule out thermal fluctuations and point to local strain as the tuning parameter for this quantum phase transition. We use this quantum interface to resolve two longstanding debates about the anomalous spectroscopic gap and the role of Fermi surface nesting in the CDW phase of NbSe2. Our results highlight the importance of local strain in governing phase transitions and competing phenomena, and suggest a promising direction of inquiry for resolving similarly longstanding debates in cuprate superconductors and other strongly correlated materials. PMID:23319646

  15. Aerodynamic Stabilization of Flexible Optical Disk with Triangularly Arranged Stabilizer System

    NASA Astrophysics Data System (ADS)

    Aman, Yasutomo; Onagi, Nobuaki; Murata, Shozo; Uchida, Keisuke

    2005-05-01

    We have developed a flexible optical disk (FOD) system comprising a flexible disk and stabilizer, which can achieve a small axial runout of the disk through simplified stabilizer control. The approach adopts a new stabilizer system made up of triangularly arranged stabilizers (TASs), which consists of one main stabilizer (MS) that stabilizes the pickup focus area on the disk and two auxiliary stabilizers (ASs) that control the balancing conditions around the MS. We experimentally demonstrated that the TAS system could effectively stabilize a flexible disk even under conditions with no active stabilizer adjustments, such as axial position control and tilt control, which could not be eliminated in our previous single-stabilizer system. The suppressed axial runout without active adjustments was sufficiently small of less than 5 μm at linear velocities from 5.7 to 13.0 m/s up to double the speed of Blu-ray disk system. The results indicated that the FOD system with the TASs, which is easily operated, could be implemented in high-density optical disk systems with a high numerical-aperture (NA) pickup.

  16. Highly Sensitive Homogeneous Immunoassays Based on Construction of Silver Triangular Nanoplates-Quantum Dots FRET System.

    PubMed

    Zeng, Qinghui; Li, Qin; Ji, Wenyu; Bin, Xue; Song, Jie

    2016-01-01

    With growing concerns about health issues worldwide, elegant sensors with high sensitivity and specificity for virus/antigens (Ag) detection are urgent to be developed. Homogeneous immunoassays (HIA) are an important technique with the advantages of small sample volumes requirement and pretreatment-free process. HIA are becoming more favorable for the medical diagnosis and disease surveillance than heterogeneous immunoassays. An important subset of HIA relies on the effect of fluorescence resonance energy transfer (FRET) via a donor-acceptor (D-A) platform, e.g., quantum dots (QDs) donor based FRET system. Being an excellent plasmonic material, silver triangular nanoplates (STNPs) have unique advantages in displaying surface plasmon resonance in the visible to near infrared spectral region, which make them a better acceptor for pairing with QDs in a FRET-based sensing system. However, the reported STNPs generally exhibited broad size distributions, which would greatly restrict their application as HIA acceptor for high detection sensitivity and specificity purpose. In this work, uniform STNPs and red-emitting QDs are firstly applied to construct FRET nanoplatform in the advanced HIA and further be exploited for analyzing virus Ag. The uniform STNPs/QDs nanoplatform based medical sensor provides a straightforward and highly sensitive method for Ag analysis in homogeneous form. PMID:27198713

  17. Analysis of triangular C-grid finite volume scheme for shallow water flows

    NASA Astrophysics Data System (ADS)

    Shirkhani, Hamidreza; Mohammadian, Abdolmajid; Seidou, Ousmane; Qiblawey, Hazim

    2015-08-01

    In this paper, a dispersion relation analysis is employed to investigate the finite volume triangular C-grid formulation for two-dimensional shallow-water equations. In addition, two proposed combinations of time-stepping methods with the C-grid spatial discretization are investigated. In the first part of this study, the C-grid spatial discretization scheme is assessed, and in the second part, fully discrete schemes are analyzed. Analysis of the semi-discretized scheme (i.e. only spatial discretization) shows that there is no damping associated with the spatial C-grid scheme, and its phase speed behavior is also acceptable for long and intermediate waves. The analytical dispersion analysis after considering the effect of time discretization shows that the Leap-Frog time stepping technique can improve the phase speed behavior of the numerical method; however it could not damp the shorter decelerated waves. The Adams-Bashforth technique leads to slower propagation of short and intermediate waves and it damps those waves with a slower propagating speed. The numerical solutions of various test problems also conform and are in good agreement with the analytical dispersion analysis. They also indicate that the Adams-Bashforth scheme exhibits faster convergence and more accurate results, respectively, when the spatial and temporal step size decreases. However, the Leap-Frog scheme is more stable with higher CFL numbers.

  18. Validation of an Adaptive Triangular Discontinuous Galerkin Shallow Water Model for the 2011 Tohoku Tsunami

    NASA Astrophysics Data System (ADS)

    Vater, Stefan; Behrens, Jörn

    2016-04-01

    We apply a tsunami simulation framework, which is based on depth-integrated hydrodynamic model equations, to the 2011 Tohoku tsunami event. While this model has been previously validated for analytic test cases and laboratory experiments, here it is applied to earthquake sources which are based on seismic inversion. Simulated wave heights and runup at the coast are compared to actual measurements. The discretization is based on a second-order Runge-Kutta discontinuous Galerkin (RKDG) scheme on triangular grids and features a robust wetting and drying scheme for the simulation of inundation events at the coast. Adaptive mesh refinement enables the efficient computation of large domains, while at the same time it allows for high local resolution and geometric accuracy. This work is part of the ASCETE (Advanced Simulation of Coupled Earthquake and Tsunami Events) project, which aims at an improved understanding of the coupling between the earthquake and the generated tsunami event. In this course, a coupled simulation framework has been developed which couples physics-based rupture generation with the presented hydrodynamic tsunami propagation and inundation model.

  19. A domain decomposition approach to finite volume solutions of the Euler equations on unstructured triangular meshes

    NASA Astrophysics Data System (ADS)

    Dolean, Victoria; Lanteri, Stéphane

    2001-11-01

    We report on our recent efforts on the formulation and the evaluation of a domain decomposition algorithm for the parallel solution of two-dimensional compressible inviscid flows. The starting point is a flow solver for the Euler equations, which is based on a mixed finite element/finite volume formulation on unstructured triangular meshes. Time integration of the resulting semi-discrete equations is obtained using a linearized backward Euler implicit scheme. As a result, each pseudo-time step requires the solution of a sparse linear system for the flow variables. In this study, a non-overlapping domain decomposition algorithm is used for advancing the solution at each implicit time step. First, we formulate an additive Schwarz algorithm using appropriate matching conditions at the subdomain interfaces. In accordance with the hyperbolic nature of the Euler equations, these transmission conditions are Dirichlet conditions for the characteristic variables corresponding to incoming waves. Then, we introduce interface operators that allow us to express the domain decomposition algorithm as a Richardson-type iteration on the interface unknowns. Algebraically speaking, the Schwarz algorithm is equivalent to a Jacobi iteration applied to a linear system whose matrix has a block structure. A substructuring technique can be applied to this matrix in order to obtain a fully implicit scheme in terms of interface unknowns. In our approach, the interface unknowns are numerical (normal) fluxes. Copyright

  20. Exponential characteristic nonlinear radiation transport method for unstructured grids of triangular cells

    SciTech Connect

    Mathews, K.A.; Brennan, C.R.

    1997-07-01

    The exponential characteristic (EC) method is one of a family of nonlinear spatial quadratures for discrete ordinates radiation transport that are positive and at least second-order accurate and provide accurate results for deep-penetration problems using coarse meshes. The authors use a split-cell methodology to adapt the method to unstructured grids of arbitrarily shaped and oriented triangular cells that provide efficient representation of curved surfaces. Exponential representations of the flux entering through a cell edge and of the scattering source within a cell are constructed to match average values and first moments passed from the adjacent cell (or from the boundary conditions) or obtained from the angular quadrature of the directional flux spatial moments in the previous iteration (or from an initial guess). The resulting one- and two-dimensional nonlinear rootsolving problems are efficiently solved using Newton`s method with an accurate starting approximation. Improved algorithms, presented here, have increased the efficiency of the method by a factor of 10 as compared to an initial report. The EC method now costs only twice as much per cell as does the linear characteristic method but can be accurate with many fewer cells. Numerical testing shows the EC method to be robust and effective.

  1. Arthroscopic-assisted repair of triangular fibrocartilage complex foveal avulsion in distal radioulnar joint injury

    PubMed Central

    Woo, Sung Jong; Jegal, Midum; Park, Min Jong

    2016-01-01

    Background: Disruption of the triangular fibrocartilage complex (TFCC) foveal insertion can lead to distal radioulnar joint (DRUJ) instability accompanied by ulnar-sided pain, weakness, snapping, and limited forearm rotation. We investigated the clinical outcomes of patients with TFCC foveal tears treated with arthroscopic-assisted repair. Materials and Methods: Twelve patients underwent foveal repair of avulsed TFCC with the assistance of arthroscopy between 2011 and 2013. These patients were followed up for an average of 19 months (range 14–25 months). The avulsed TFCC were reattached to the fovea using a transosseous pull-out suture or a knotless suture anchor. At the final followup, the range of motion, grip strength and DRUJ stability were measured as objective outcomes. Subjective outcomes were assessed using the Visual Analog Scale (VAS) for pain, patient rated wrist evaluation (PRWE), Disabilities of the Arm, Shoulder and Hand questionnaire (DASH score) and return to work. Results: Based on the DRUJ stress test, 5 patients had normal stability and 7 patients showed mild laxity as compared with the contralateral side. Postoperatively, the mean range of pronation supination increased from 141° to 166°, and the mean VAS score for pain decreased from 5.3 to 1.7 significantly. The PRWE and DASH questionnaires also showed significant functional improvement. All patients were able to return to their jobs. However, two patients complained of persistent pain. Conclusions: Arthroscopically assisted repair of TFCC foveal injury can provide significant pain relief, functional improvement and restoration of DRUJ stability. PMID:27293286

  2. Frustrated mixed spin-1/2 and spin-1 Ising ferrimagnets on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Žukovič, M.; Bobák, A.

    2015-05-01

    Mixed spin-1/2 and spin-1 Ising ferrimagnets on a triangular lattice with sublattices A, B, and C are studied for two spin-value distributions (SA,SB,SC) =(1 /2 ,1 /2 ,1 ) and (1 /2 ,1 ,1 ) by Monte Carlo simulations. The nonbipartite character of the lattice induces geometrical frustration in both systems, which leads to the critical behavior rather different from their ferromagnetic counterparts. We confirm second-order phase transitions belonging to the standard Ising universality class occurring at higher temperatures, however, in both models these change at tricritical points (TCP) to first-order transitions at lower temperatures. In the model (1 /2 ,1 /2 ,1 ) , TCP occurs on the boundary between paramagnetic and ferrimagnetic (±1 /2 ,±1 /2 ,∓1 ) phases. The boundary between two ferrimagnetic phases (±1 /2 ,±1 /2 ,∓1 ) and (±1 /2 ,∓1 /2 ,0 ) at lower temperatures is always first order and it is joined by a line of second-order phase transitions between the paramagnetic and the ferrimagnetic (±1 /2 ,∓1 /2 ,0 ) phases at a critical endpoint. The tricritical behavior is also confirmed in the model (1 /2 ,1 ,1 ) on the boundary between the paramagnetic and ferrimagnetic (0 ,±1 ,∓1 ) phases.

  3. Lower bounds of Copson type for the transposes of lower triangular matrices

    NASA Astrophysics Data System (ADS)

    Chen, Chang-Pao; Wang, Kuo-Zhong

    2008-05-01

    Let A=(an,k)n,k[greater-or-equal, slanted]0 be a non-negative matrix. Denote by Lp,q(A) the supremum of those L satisfying the following inequality: In this paper, we focus on the evaluation of Lp,p(At) for a lower triangular matrix A, where 0

  4. Microscopic model calculations for the magnetization process of layered triangular-lattice quantum antiferromagnets.

    PubMed

    Yamamoto, Daisuke; Marmorini, Giacomo; Danshita, Ippei

    2015-01-16

    Magnetization processes of spin-1/2 layered triangular-lattice antiferromagnets (TLAFs) under a magnetic field H are studied by means of a numerical cluster mean-field method with a scaling scheme. We find that small antiferromagnetic couplings between the layers give rise to several types of extra quantum phase transitions among different high-field coplanar phases. Especially, a field-induced first-order transition is found to occur at H≈0.7H_{s}, where H_{s} is the saturation field, as another common quantum effect of ideal TLAFs in addition to the well-established one-third plateau. Our microscopic model calculation with appropriate parameters shows excellent agreement with experiments on Ba_{3}CoSb_{2}O_{9} [T. Susuki et al., Phys. Rev. Lett. 110, 267201 (2013)]. Given this fact, we suggest that the Co^{2+}-based compounds may allow for quantum simulations of intriguing properties of this simple frustrated model, such as quantum criticality and supersolid states. PMID:25635561

  5. Critical behavior of a triangular lattice Ising AF/FM bilayer

    NASA Astrophysics Data System (ADS)

    Žukovič, M.; Bobák, A.

    2016-03-01

    We study a bilayer Ising spin system consisting of antiferromagnetic (AF) and ferromagnetic (FM) triangular planes, coupled by ferromagnetic exchange interaction, by standard Monte Carlo and parallel tempering methods. The AF/FM bilayer is found to display the critical behavior completely different from both the single FM and AF constituents as well as the FM/FM and AF/AF bilayers. Namely, by finite-size scaling (FSS) analysis we identify at the same temperature a standard Ising transition from the paramagnetic to FM state in the FM plane that induces a ferrimagnetic state with a finite net magnetic moment in the AF plane. At lower temperatures there is another phase transition, that takes place only in the AF plane, to different ferrimagnetic state with spins on two sublattices pointing parallel and on one sublattice antiparallel to the spins on the FM plane. FSS indicates that the corresponding critical exponents are close to the two-dimensional three-state ferromagnetic Potts model values.

  6. Response properties in the adsorption-desorption model on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Šćepanović, J. R.; Stojiljković, D.; Jakšić, Z. M.; Budinski-Petković, Lj.; Vrhovac, S. B.

    2016-06-01

    The out-of-equilibrium dynamical processes during the reversible random sequential adsorption (RSA) of objects of various shapes on a two-dimensional triangular lattice are studied numerically by means of Monte Carlo simulations. We focused on the influence of the order of symmetry axis of the shape on the response of the reversible RSA model to sudden perturbations of the desorption probability Pd. We provide a detailed discussion of the significance of collective events for governing the time coverage behavior of shapes with different rotational symmetries. We calculate the two-time density-density correlation function C(t ,tw) for various waiting times tw and show that longer memory of the initial state persists for the more symmetrical shapes. Our model displays nonequilibrium dynamical effects such as aging. We find that the correlation function C(t ,tw) for all objects scales as a function of single variable ln(tw) / ln(t) . We also study the short-term memory effects in two-component mixtures of extended objects and give a detailed analysis of the contribution to the densification kinetics coming from each mixture component. We observe the weakening of correlation features for the deposition processes in multicomponent systems.

  7. Cotunneling signatures of spin-electric coupling in frustrated triangular molecular magnets

    NASA Astrophysics Data System (ADS)

    Nossa, J. F.; Canali, C. M.

    2014-06-01

    The ground state of frustrated (antiferromagnetic) triangular molecular magnets is characterized by two total-spin S =1/2 doublets with opposite chirality. According to a group theory analysis [M. Trif et al., Phys. Rev. Lett. 101, 217201 (2008), 10.1103/PhysRevLett.101.217201], an external electric field can efficiently couple these two chiral spin states, even when the spin-orbit interaction (SOI) is absent. The strength of this coupling, d, is determined by an off-diagonal matrix element of the dipole operator, which can be calculated by ab initio methods [M. F. Islam et al., Phys. Rev. B 82, 155446 (2010), 10.1103/PhysRevB.82.155446]. In this work, we propose that Coulomb-blockade transport experiments in the cotunneling regime can provide a direct way to determine the spin-electric coupling strength. Indeed, an electric field generates a d-dependent splitting of the ground-state manifold, which can be detected in the inelastic cotunneling conductance. Our theoretical analysis is supported by master-equation calculations of quantum transport in the cotunneling regime. We employ a Hubbard-model approach to elucidate the relationship between the Hubbard parameters t and U, and the spin-electric coupling constant d. This allows us to predict the regime in which the coupling constant d can be extracted from experiment.

  8. Random-diluted triangular plaquette model: Study of phase transitions in a kinetically constrained model

    NASA Astrophysics Data System (ADS)

    Franz, Silvio; Gradenigo, Giacomo; Spigler, Stefano

    2016-03-01

    We study how the thermodynamic properties of the triangular plaquette model (TPM) are influenced by the addition of extra interactions. The thermodynamics of the original TPM is trivial, while its dynamics is glassy, as usual in kinetically constrained models. As soon as we generalize the model to include additional interactions, a thermodynamic phase transition appears in the system. The additional interactions we consider are either short ranged, forming a regular lattice in the plane, or long ranged of the small-world kind. In the case of long-range interactions we call the new model the random-diluted TPM. We provide arguments that the model so modified should undergo a thermodynamic phase transition, and that in the long-range case this is a glass transition of the "random first-order" kind. Finally, we give support to our conjectures studying the finite-temperature phase diagram of the random-diluted TPM in the Bethe approximation. This corresponds to the exact calculation on the random regular graph, where free energy and configurational entropy can be computed by means of the cavity equations.

  9. Random-diluted triangular plaquette model: Study of phase transitions in a kinetically constrained model.

    PubMed

    Franz, Silvio; Gradenigo, Giacomo; Spigler, Stefano

    2016-03-01

    We study how the thermodynamic properties of the triangular plaquette model (TPM) are influenced by the addition of extra interactions. The thermodynamics of the original TPM is trivial, while its dynamics is glassy, as usual in kinetically constrained models. As soon as we generalize the model to include additional interactions, a thermodynamic phase transition appears in the system. The additional interactions we consider are either short ranged, forming a regular lattice in the plane, or long ranged of the small-world kind. In the case of long-range interactions we call the new model the random-diluted TPM. We provide arguments that the model so modified should undergo a thermodynamic phase transition, and that in the long-range case this is a glass transition of the "random first-order" kind. Finally, we give support to our conjectures studying the finite-temperature phase diagram of the random-diluted TPM in the Bethe approximation. This corresponds to the exact calculation on the random regular graph, where free energy and configurational entropy can be computed by means of the cavity equations. PMID:27078408

  10. Convergence Analysis of Triangular MAC Schemes for Two Dimensional Stokes Equations

    PubMed Central

    Wang, Ming; Zhong, Lin

    2015-01-01

    In this paper, we consider the use of H(div) elements in the velocity–pressure formulation to discretize Stokes equations in two dimensions. We address the error estimate of the element pair RT0–P0, which is known to be suboptimal, and render the error estimate optimal by the symmetry of the grids and by the superconvergence result of Lagrange inter-polant. By enlarging RT0 such that it becomes a modified BDM-type element, we develop a new discretization BDM1b–P0. We, therefore, generalize the classical MAC scheme on rectangular grids to triangular grids and retain all the desirable properties of the MAC scheme: exact divergence-free, solver-friendly, and local conservation of physical quantities. Further, we prove that the proposed discretization BDM1b–P0 achieves the optimal convergence rate for both velocity and pressure on general quasi-uniform grids, and one and half order convergence rate for the vorticity and a recovered pressure. We demonstrate the validity of theories developed here by numerical experiments. PMID:26041948

  11. Superglass Phase of Interaction-Blockaded Gases on a Triangular Lattice

    NASA Astrophysics Data System (ADS)

    Angelone, Adriano; Mezzacapo, Fabio; Pupillo, Guido

    2016-04-01

    We investigate the quantum phases of monodispersed bosonic gases confined to a triangular lattice and interacting via a class of soft-shoulder potentials. The latter correspond to soft-core potentials with an additional hard-core onsite interaction. Using exact quantum Monte Carlo simulations, we show that the low temperature phases for weak and strong interactions following a temperature quench are a homogeneous superfluid and a glass, respectively. The latter is an insulating phase characterized by inhomogeneity in the density distribution and structural disorder. Remarkably, we find that for intermediate interaction strengths a superglass occurs in an extended region of the phase diagram, where glassy behavior coexists with a sizable finite superfluid fraction. This glass phase is obtained in the absence of geometrical frustration or external disorder and is a result of the competition of quantum fluctuations and cluster formation in the corresponding classical ground state. For high enough temperature, the glass and superglass turn into a floating stripe solid and a supersolid, respectively. Given the simplicity and generality of the model, these phases should be directly relevant for state-of-the-art experiments with Rydberg-dressed atoms in optical lattices.

  12. Spin-orbit interactions in two-dimensional holes in quasi-triangular wells: variational calculations

    NASA Astrophysics Data System (ADS)

    Marcellina, Elizabeth; Hamilton, Alex; Winkler, Roland; Culcer, Dimitrie; UNSW Collaboration; NIU Collaboration

    Spin-orbit (SO) interactions in semiconductors are key to the realization of semiconductor spintronic devices and quantum information processing. Low-dimensional holes are strongly SO-coupled systems, as such, they offer the promise of all-electrical spin control which can lead to more efficient electronic devices. However the spin properties of holes are highly complex, and heavily influencd by the nature of the confining potential. So far, calculations on two-dimensional holes in semiconductor heterojunctions have mostly been numerical and material-specific. In this work, we develop variational-based methods, which are easy to use and applicable to various materials, to quantify SO interactions in two-dimensional holes confined in self-consistent quasi-triangular wells. In particular, we calculate the SO hole spin-splittings and effective masses in common semiconductor materials such as GaAs, Ge, InSb, InAs, and Si. Our results show that the strength of SO interactions is very sensitive to the material type and that in zincblende materials with a bulk inversion asymmetry (BIA), the dominant contribution to the SO interaction is still the structure inversion asymmetry (SIA) term corresponding to the confinement potential.

  13. Tricriticality of the Blume-Emery-Griffiths model in thin films of stacked triangular lattices

    NASA Astrophysics Data System (ADS)

    El Hog, Sahbi; Diep, H. T.

    2016-03-01

    We study in this paper the Blume-Emery-Griffiths model in a thin film of stacked triangular lattices. The model is described by three parameters: bilinear exchange interaction between spins J, quadratic exchange interaction K and single-ion anisotropy D. The spin Si at the lattice site i takes three values (-1, 0, +1). This model can describe the mixing phase of He-4 (Si = +1,-1) and He-3 (Si = 0) at low temperatures. Using Monte Carlo simulations, we show that there exists a critical value of D below (above) which the transition is of second-(first-)order. In general, the temperature dependence of the concentrations of He-3 is different from layer by layer. At a finite temperature in the superfluid phase, the film surface shows a deficit of He-4 with respect to interior layers. However, effects of surface interaction parameters can reverse this situation. Effects of the film thickness on physical properties will be also shown as functions of temperature.

  14. Simulation study of anisotropic random sequential adsorption of extended objects on a triangular lattice

    NASA Astrophysics Data System (ADS)

    Budinski-Petković, Lj.; Lončarević, I.; Jakšić, Z. M.; Vrhovac, S. B.; Švrakić, N. M.

    2011-11-01

    The properties of the anisotropic random sequential adsorption (RSA) of objects of various shapes on a two-dimensional triangular lattice are studied numerically by means of Monte Carlo simulations. The depositing objects are formed by self-avoiding lattice steps, whereby the first step determines the orientation of the object. Anisotropy is introduced by positing unequal probabilities for orientation of depositing objects along different directions of the lattice. This probability is equal p or (1-p)/2, depending on whether the randomly chosen orientation is horizontal or not, respectively. Approach of the coverage θ(t) to the jamming limit θjam is found to be exponential θjam-θ(t)∝exp(-t/σ), for all probabilities p. It was shown that the relaxation time σ increases with the degree of anisotropy in the case of elongated and asymmetrical shapes. However, for rounded and symmetrical shapes, values of σ and θjam are not affected by the presence of anisotropy. We finally analyze the properties of the anisotropic RSA of polydisperse mixtures of k-mers. Strong dependencies of the parameter σ and the jamming coverage θjam on the degree of anisotropy are obtained. It is found that anisotropic constraints lead to the increased contribution of the longer k-mers in the total coverage fraction of the mixture.

  15. RKKY interaction and local density of states for a triangular triple quantum dot system

    NASA Astrophysics Data System (ADS)

    Xiong, Yong-Chen; Wang, Wei-Zhong; Luo, Shi-Jun; Yang, Jun-Tao; Huang, Hai-Ming

    2016-02-01

    By means of the numerical renormalization group technique, we study the local density of states (LDOS) for a triangular triple quantum dot system, with two dots connected in parallel to the conduction leads. We find the location of the Ruderman-Kittel-Kasuya-Yosida (RKKY) peak identified in the LDOS could be illustrated as JRKKY = aΓ2 / U +bt22 / U, with U being the on-site Coulomb repulsion, Γ the dot-lead coupling, and t2 the hopping between the connected dots and the side dot. When the hopping between two connected dots t1 turns on, the spectrum weight of the RKKY peaks decreases due to the competition between the direct and the RKKY interactions. As t1 increases beyond a critical point t1c, two connected dots form a spin singlet, and decouple from both the side dot and the conduction leads, thus the Kondo and RKKY peaks could not be found. For t1 1 ≥t1 c, it drops to zero.

  16. Phase diagram and low temperature scenario for a triangular triple dot system

    NASA Astrophysics Data System (ADS)

    Xiong, Yong-Chen; Wang, Wei-Zhong; Yang, Jun-Tao; Luo, Shi-Jun

    2016-01-01

    We present a triangular triple quantum dot (TTQD) system with two dots connected parallelly to one conduction lead, and investigate the phase diagram, the electric transport, and the temperature-dependent magnetic moment at half filling. When the hopping between two connected dots t12 = 0, and those between the connected dots and the side dot are symmetric t13 = t23, two connected dots form a spin triplet due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction mediated by the dot-lead coupling and/or the hopping t13 (t23). For t13 = 0, the triplet is partially screened by the conduction leads at low temperature. Both the connected dots and the side dot contribute to the magnetic moment of the system. For any definite t13, the triplet is totally screened by the conduction leads and the side dot, and the two-stage Kondo effect occurs. When t12 increases beyond a critical t12c, two connected dots form a spin singlet and decouple from the side dot. In this case, the Kondo peak is strongly suppressed, indicating zero conductance, and only the localized side dot contribute to the magnetic moment at low temperature. When t13 ≠ t23, we find a crossover as t12 increases, contrast to the first order transition of the symmetric case. Numerical renormalization group technique and physical arguments are used to obtain a detailed understanding of these problems.

  17. Quantum electrical dipole in triangular systems: A model for spontaneous polarity in metal clusters

    SciTech Connect

    Allen, Philip B.; Abanov, Alexander G.; Requist, Ryan

    2005-04-01

    Triangular symmetric molecules with mirror symmetry perpendicular to the threefold axis are forbidden to have a fixed electrical dipole moment. However, if the ground state is orbitally degenerate and lacks inversion symmetry, then a 'quantum' dipole moment does exist. The system of three electrons in D{sub 3h} symmetry is our example. This system is realized in triatomic molecules like Na{sub 3}. Unlike the fixed dipole of a molecule like water, the quantum moment does not point in a fixed direction, but lies in the plane of the molecule and takes quantized values {+-}{mu}{sub 0} along any direction of measurement in the plane. An electric field F-vector in the plane leads to a linear Stark splitting {+-}{mu}{sub 0} vertical bar F-vector vertical bar. We introduce a toy model to study the effect of Jahn-Teller distortions on the quantum dipole moment. We find that the quantum dipole property survives when the dynamic Jahn-Teller effect is included if the distortion of the molecule is small. Linear Stark splittings are suppressed in low fields by molecular rotation, just as the linear Stark shift of water is suppressed, but will be revealed in moderately large applied fields and low temperatures. Coulomb correlations also give a partial suppression.

  18. Quantum electrical dipole in triangular systems: A model for spontaneous polarity in metal clusters

    NASA Astrophysics Data System (ADS)

    Allen, Philip B.; Abanov, Alexander G.; Requist, Ryan

    2005-04-01

    Triangular symmetric molecules with mirror symmetry perpendicular to the threefold axis are forbidden to have a fixed electrical dipole moment. However, if the ground state is orbitally degenerate and lacks inversion symmetry, then a “quantum” dipole moment does exist. The system of three electrons in D3h symmetry is our example. This system is realized in triatomic molecules like Na3 . Unlike the fixed dipole of a molecule like water, the quantum moment does not point in a fixed direction, but lies in the plane of the molecule and takes quantized values ±μ0 along any direction of measurement in the plane. An electric field F⃗ in the plane leads to a linear Stark splitting ±μ0∣F⃗∣ . We introduce a toy model to study the effect of Jahn-Teller distortions on the quantum dipole moment. We find that the quantum dipole property survives when the dynamic Jahn-Teller effect is included if the distortion of the molecule is small. Linear Stark splittings are suppressed in low fields by molecular rotation, just as the linear Stark shift of water is suppressed, but will be revealed in moderately large applied fields and low temperatures. Coulomb correlations also give a partial suppression.

  19. Geometric frustration on a 1/9th site depleted triangular lattice

    NASA Astrophysics Data System (ADS)

    Hopkinson, John; Beck, Jarrett

    2013-03-01

    In the searches both for new spin liquid and spin ice (artificial and macroscopic) candidates, geometrically frustrated two-dimensional spin systems have played a prominent role. Here we present a study of the classical antiferromagnetic Ising (AFI) model on the sorrel net, a 1/9th site depleted and 1/7th bond depleted triangular lattice. The AFI model on this corner-shared triangle net is found to have a large residual entropy per spin S/N = 0 . 48185 +/- 0 . 00008 , indicating the sorrel net is highly geometrically frustrated. Anticipating that it may be difficult to achieve perfect bond depletion, we investigate the physics resulting from turning back on the depleted bonds (J2). We present the phase diagram, analytic expressions for the long range partially ordered ground state spin structure for antiferromagnetic J2 and the short range ordered ground state spin structure for ferromagnetic J2, the magnetic susceptibility and the static structure factor. We briefly comment on the possibility that artificial spin ice on the sorrel lattice could by made, and on a recent report [T. D. Keene et al., Dalton Trans. 40 2983 (2011)] of the creation of a 1/9th depleted cobalt hydroxide oxalate. This work was supported by NSERC (JMH) and NSERC USRA (JJB)

  20. Triangular Alignment (TAME). A Tensor-based Approach for Higher-order Network Alignment

    SciTech Connect

    Mohammadi, Shahin; Gleich, David F.; Kolda, Tamara G.; Grama, Ananth

    2015-11-01

    Network alignment is an important tool with extensive applications in comparative interactomics. Traditional approaches aim to simultaneously maximize the number of conserved edges and the underlying similarity of aligned entities. We propose a novel formulation of the network alignment problem that extends topological similarity to higher-order structures and provide a new objective function that maximizes the number of aligned substructures. This objective function corresponds to an integer programming problem, which is NP-hard. Consequently, we approximate this objective function as a surrogate function whose maximization results in a tensor eigenvalue problem. Based on this formulation, we present an algorithm called Triangular AlignMEnt (TAME), which attempts to maximize the number of aligned triangles across networks. We focus on alignment of triangles because of their enrichment in complex networks; however, our formulation and resulting algorithms can be applied to general motifs. Using a case study on the NAPABench dataset, we show that TAME is capable of producing alignments with up to 99% accuracy in terms of aligned nodes. We further evaluate our method by aligning yeast and human interactomes. Our results indicate that TAME outperforms the state-of-art alignment methods both in terms of biological and topological quality of the alignments.

  1. Calculation of the elastic properties of a triangular cell core for lightweight composite mirrors

    NASA Astrophysics Data System (ADS)

    Penado, F. Ernesto; Clark, James H., III; Walton, Joshua P.; Romeo, Robert C.; Martin, Robert N.

    2007-09-01

    The use of composite materials in the fabrication of optical telescope mirrors offers many advantages over conventional methods, including lightweight, portability and the potential for lower manufacturing costs. In the construction of the substrate for these mirrors, sandwich construction offers the advantage of even lower weight and higher stiffness. Generally, an aluminum or Nomex honeycomb core is used in composite applications requiring sandwich construction. However, the use of a composite core offers the potential for increased stiffness and strength, low thermal distortion compatible with that of the facesheets, the absence of galvanic corrosion and the ability to readily modify the core properties. In order to design, analyze and optimize these mirrors, knowledge of the mechanical properties of the core is essential. In this paper, the mechanical properties of a composite triangular cell core (often referred to as isogrid) are determined using finite element analysis of a representative unit cell. The core studied offers many advantages over conventional cores including increased thermal and dimensional stability, as well as low weight. Results are provided for the engineering elastic moduli of cores made of high stiffness composite material as a function of the ply layup and cell size. Finally, in order to illustrate the use of these properties in a typical application, a 1.4-m diameter composite mirror is analyzed using the finite element method, and the resulting stiffness and natural frequencies are presented.

  2. Spin effects in transport through triangular quantum dot molecule in different geometrical configurations

    NASA Astrophysics Data System (ADS)

    Wrześniewski, Kacper; Weymann, Ireneusz

    2015-07-01

    We analyze the spin-resolved transport properties of a triangular quantum dot molecule weakly coupled to external ferromagnetic leads. The calculations are performed by using the real-time diagrammatic technique up to the second-order of perturbation theory, which enables a description of both the sequential and cotunneling processes. We study the behavior of the current and differential conductance in the parallel and antiparallel magnetic configurations, as well as the tunnel magnetoresistance (TMR) and the Fano factor in both the linear and nonlinear response regimes. It is shown that the transport characteristics depend greatly on how the system is connected to external leads. Two specific geometrical configurations of the device are considered—the mirror one, which possesses the reflection symmetry with respect to the current flow direction and the fork one, in which this symmetry is broken. In the case of first configuration we show that, depending on the bias and gate voltages, the system exhibits both enhanced TMR and super-Poissonian shot noise. On the other hand, when the system is in the second configuration, we predict a negative TMR and a negative differential conductance in certain transport regimes. The mechanisms leading to those effects are thoroughly discussed.

  3. Highly Sensitive Homogeneous Immunoassays Based on Construction of Silver Triangular Nanoplates-Quantum Dots FRET System

    PubMed Central

    Zeng, Qinghui; Li, Qin; Ji, Wenyu; Bin, Xue; Song, Jie

    2016-01-01

    With growing concerns about health issues worldwide, elegant sensors with high sensitivity and specificity for virus/antigens (Ag) detection are urgent to be developed. Homogeneous immunoassays (HIA) are an important technique with the advantages of small sample volumes requirement and pretreatment-free process. HIA are becoming more favorable for the medical diagnosis and disease surveillance than heterogeneous immunoassays. An important subset of HIA relies on the effect of fluorescence resonance energy transfer (FRET) via a donor-acceptor (D–A) platform, e.g., quantum dots (QDs) donor based FRET system. Being an excellent plasmonic material, silver triangular nanoplates (STNPs) have unique advantages in displaying surface plasmon resonance in the visible to near infrared spectral region, which make them a better acceptor for pairing with QDs in a FRET-based sensing system. However, the reported STNPs generally exhibited broad size distributions, which would greatly restrict their application as HIA acceptor for high detection sensitivity and specificity purpose. In this work, uniform STNPs and red-emitting QDs are firstly applied to construct FRET nanoplatform in the advanced HIA and further be exploited for analyzing virus Ag. The uniform STNPs/QDs nanoplatform based medical sensor provides a straightforward and highly sensitive method for Ag analysis in homogeneous form. PMID:27198713

  4. Preparation of metallic triangular nanoparticle array with controllable interparticle distance and its application in surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Jing; Xu, Rongqing; Yan, Zhendong; Tang, Chaojun; Chen, Zhuo; Wang, Zhenlin

    2013-10-01

    This paper reports a facile method for fabricating metallic triangular nanoparticle array with controllable interparticle distance, based on a combination of nanosphere lithography, reactive ion etching and physical sputtering technique. Light transmission spectra of the metallic triangular nanoparticle arrays with a series of interparticle distances are measured, which show a surface plasmon resonance whose position is observed to shift to longer wavelength for the polarization direction parallel to the long particle pair axis with decreasing the interparticle distance. With this structure as surface-enhanced Raman scattering substrate, the Raman signal is strongly enhanced and shows high dependence on the interparticle distance. The controllable interparticle distance and large-area ordered array of the substrate suggest its promising application in surface-enhanced Raman spectroscopy.

  5. Analytical Study of a Pin-Loaded Hole in Unidirectional Laminated Composites With Triangular and Circular Fibers.

    PubMed

    Robati, Hossein; Mahdi Attar, Mohammad

    2013-03-01

    The problem of stress concentrations in the vicinity of pin-loaded holes is of particular importance in the design of multilayered composite structures made of triangular or circular glass fibers. It is assumed that all of the fibers in the laminate lie in one direction while loaded by a force p0 at infinity, parallel to the direction of the fibers. According to the shear lag model, equilibrium equations are derived for both types of fibers. A rectangular arrangement is postulated in either case. Upon the proper use of boundary and bondness conditions, stress fields are derived within the laminate, along with the surrounding pinhole. The analytical results are compared to those of the finite element values. A very good agreement is observed between the two methods. According to the results, composite structures made of triangular glass fibers result in lower values of stress concentrations around the pin, as opposed to those of circular glass fibers. PMID:24891727

  6. Exact duality of the dissipative Hofstadter model on a triangular lattice: T-duality and noncommutative algebra

    NASA Astrophysics Data System (ADS)

    Lee, Taejin

    2016-09-01

    We study the dissipative Hofstadter model on a triangular lattice, making use of the O(2, 2; R) T-dual transformation of string theory. The O(2, 2; R) dual transformation transcribes the model in a commutative basis into the model in a noncommutative basis. In the zero-temperature limit, the model exhibits an exact duality, which identifies equivalent points on the two-dimensional parameter space of the model. The exact duality also defines magic circles on the parameter space, where the model can be mapped onto the boundary sine-Gordon on a triangular lattice. The model describes the junction of three quantum wires in a uniform magnetic field background. An explicit expression of the equivalence relation, which identifies the points on the two-dimensional parameter space of the model by the exact duality, is obtained. It may help us to understand the structure of the phase diagram of the model.

  7. Quantum Monte Carlo study of long-range transverse-field Ising models on the triangular lattice

    NASA Astrophysics Data System (ADS)

    Humeniuk, Stephan

    2016-03-01

    Motivated by recent experiments with a Penning ion trap quantum simulator, we perform numerically exact Stochastic Series Expansion quantum Monte Carlo simulations of long-range transverse-field Ising models on a triangular lattice for different decay powers α of the interactions. The phase boundary for the ferromagnet is obtained as a function of α . For antiferromagnetic interactions, there is strong indication that the transverse field stabilizes a clock ordered phase with sublattice magnetization (M ,-M/2 ,-M/2 ) with unsaturated M <1 in a process known as "order by disorder" similar to the nearest-neighbor antiferromagnet on the triangular lattice. Connecting the known limiting cases of nearest-neighbor and infinite-range interactions, a semiquantitative phase diagram is obtained. Magnetization curves for the ferromagnet for experimentally relevant system sizes and with open boundary conditions are presented.

  8. Reconstruction of three-dimensional occluded object using optical flow and triangular mesh reconstruction in integral imaging.

    PubMed

    Jung, Jae-Hyun; Hong, Keehoon; Park, Gilbae; Chung, Indeok; Park, Jae-Hyeung; Lee, Byoungho

    2010-12-01

    We proposed a reconstruction method for the occluded region of three-dimensional (3D) object using the depth extraction based on the optical flow and triangular mesh reconstruction in integral imaging. The depth information of sub-images from the acquired elemental image set is extracted using the optical flow with sub-pixel accuracy, which alleviates the depth quantization problem. The extracted depth maps of sub-image array are segmented by the depth threshold from the histogram based segmentation, which is represented as the point clouds. The point clouds are projected to the viewpoint of center sub-image and reconstructed by the triangular mesh reconstruction. The experimental results support the validity of the proposed method with high accuracy of peak signal-to-noise ratio and normalized cross-correlation in 3D image recognition.

  9. Pseudogap opening and localization in disordered graphene: frustration effects at the Fermi energy due to the underlying triangular symmetry

    NASA Astrophysics Data System (ADS)

    Barrios-Vargas, Eduardo; Naumis, Gerardo G.

    2014-03-01

    An intuitive explanation of the increase in localization observed near the Dirac point in doped graphene is presented. To do this, we renormalize the tight binding Hamiltonian in such a way that the honeycomb lattice maps into a triangular one. Then, we investigate the frustration effects that emerge in this Hamiltonian. In this doped triangular lattice, the eigenstates have a bonding and antibonding contribution near the Dirac point, and thus there is a kind of Lifshitz tail. The increase in frustration is related to an increase in localization, since the number of frustrated bonds decreases with disorder, while the frustration contribution raises. Then we show that states have a multifractal nature, with a fractal spectrum that approaches freezing as disorder increases. We compute exacty the first spectral moments of the DOS using statistical averages and counting paths. Finally, the number of states at the Dirac point is obtained using a configurational counting. Apdo. Postal 20-364, 01000, México DF.

  10. On the stability of triangular points in the relativistic R3BP with oblate primaries and bigger radiating

    NASA Astrophysics Data System (ADS)

    Bello, Nakone; Singh, Jagadish

    2016-01-01

    We consider a version of the relativistic R3BP which includes the effects of oblateness of the primaries and radiation of the bigger primary as well on the stability of triangular points. We observe that the positions of the triangular points and their stability are affected by the relativistic effect apart from the radiation and oblateness of the primaries. It is further seen for these points that the range of stability region increases or decreases according as the part of the critical mass value, depending upon relativistic terms, radiation and oblateness coefficients, is positive or negative. A numerical exploration shows that in the Sun-Saturn, Sun-Uranus, Sun-Neptune systems, the oblateness has no influence on their positions and range of stability region; whereas it has a little influence on the Sun-Mars, Sun-Jupiter systems. On the other hand, we found that radiation pressure has an observable effect on the solar system.

  11. The Moral Capacity Profile

    ERIC Educational Resources Information Center

    Wilks, Duffy; Ratheal, Juli D'Ann

    2011-01-01

    Effective counseling practice continues to be inevitably linked to underlying theories of behavioral causality. In this article, the authors present the Moral Capacity Profile of an individual from the perspective of the Amoral, Moral, Quasi-Moral/Quasi-Immoral, and Immoral Model of Behavior, a model that uniquely expands counseling's theoretical…

  12. Flood Bypass Capacity Optimization

    NASA Astrophysics Data System (ADS)

    Siclari, A.; Hui, R.; Lund, J. R.

    2015-12-01

    Large river flows can damage adjacent flood-prone areas, by exceeding river channel and levee capacities. Particularly large floods are difficult to contain in leveed river banks alone. Flood bypasses often can efficiently reduce flood risks, where excess river flow is diverted over a weir to bypasses, that incur much less damage and cost. Additional benefits of bypasses include ecosystem protection, agriculture, groundwater recharge and recreation. Constructing or expanding an existing bypass costs in land purchase easements, and levee setbacks. Accounting for such benefits and costs, this study develops a simple mathematical model for optimizing flood bypass capacity using benefit-cost and risk analysis. Application to the Yolo Bypass, an existing bypass along the Sacramento River in California, estimates optimal capacity that economically reduces flood damage and increases various benefits, especially for agriculture. Land availability is likely to limit bypass expansion. Compensation for landowners could relax such limitations. Other economic values could affect the optimal results, which are shown by sensitivity analysis on major parameters. By including land geography into the model, location of promising capacity expansions can be identified.

  13. Start-to-end beam dynamics simulation of double triangular current profile generation in Argonne Wakefield Accelerator

    SciTech Connect

    Ha, G.; Power, J.; Kim, S. H.; Gai, W.; Kim, K.-J.; Cho, M. H.; Namkung, W.

    2012-12-21

    Double triangular current profile (DT) gives a high transformer ratio which is the determining factor of the performance of collinear wakefield accelerator. This current profile can be generated using the emittance exchange (EEX) beam line. Argonne Wakefield Accelerator (AWA) facility plans to generate DT using the EEX beam line. We conducted start-to-end simulation for the AWA beam line using PARMELA code. Also, we discuss requirements of beam parameters for the generation of DT.

  14. 26 CFR 1.367(b)-14T - Acquisition of parent stock for property in triangular reorganizations (temporary).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 26 Internal Revenue 4 2010-04-01 2010-04-01 false Acquisition of parent stock for property in... § 1.367(b)-14T Acquisition of parent stock for property in triangular reorganizations (temporary). (a... Securities and Exchange Act of 1934 (15 U.S.C. 78n(d)(1)) and Regulation 14(D) (17 CFR 240.14d-1 through...

  15. Novel local symmetries and chiral-symmetry-broken phases in S = 1/2 triangular-lattice Heisenberg model

    NASA Technical Reports Server (NTRS)

    Baskaran, G.

    1989-01-01

    Using a nonmean-field approach the triangular-lattice S = 1/2 Heisenberg antiferromagnet with nearest- and next-nearest-neighbor couplings is shown undergo an Ising-type phase transition into a chiral-symmetry-broken phase (Kalmeyer-Laughlin-like state) at small T. Removal of next-nearest-neighbor coupling introduces a local Z2 symmetry, thereby suppressing any finite-T chiral order.

  16. Upper triangular flap method for primary repairs of incomplete unilateral cleft lip patients: minor to two-thirds way defects.

    PubMed

    Koh, Kyung S; Oh, Tae Suk; Song, Jin Woo

    2015-03-01

    Incomplete unilateral cleft lips show a wide range of deformities, ranging from microform to near-complete clefts. Because there are different amounts and qualities of tissue present on the cleft and non-cleft sides, surgical approaches should make distinctions based on the remnant tissue. A new procedure using an upper triangular flap that combines characteristics of both rotation advancement and straight line repair was applied and the surgical results were reviewed. Between June 2007 and April 2011, 28 patients with minor to two-thirds way unilateral cleft lips [minor (n = 12), one-third (n = 2), halfway (n = 11), and two-thirds way (n = 3)] were subjected to the upper triangular flap method. The patients ranged in age from 62 days to 6 years (mean, 9 months). The average follow-up period was 25 months (range, 12-60 months). The repairs were successful in all 28 patients without complications. The scar was acceptable because it ran along the vertical philtral columns. During the follow-up period, long lip deformities and Cupid bow drooping were not observed in any of the patients. However, misalignment of the white skin roll was observed due to insufficient rotation at the cleft side in 1 patient. The repairs of minor to two-thirds way unilateral cleft lips using the upper triangular flap method allowed for a symmetric Cupid bow and philtrum. Moreover, this method allowed for satisfactory nostril sill reconstruction with acceptable scarring. The upper triangular flap method is recommended as an alternative to conventional methods for repair of minor to two-thirds way incomplete unilateral cleft lips.

  17. A topological semimetal model with f-wave symmetry in a non-Abelian triangular optical lattice

    NASA Astrophysics Data System (ADS)

    Li, Ling; Bai, Zhiming; Hao, Ningning; Liu, Guocai

    2016-08-01

    We demonstrate that an chiral f-wave topological semimetal can be induced in a non-Abelian triangular optical lattice. We show that the f-wave symmetry topological semimetal is characterized by the topological invariant, i.e., the winding number W, with W=3 and is different from the semimetal with W=1 and 2 which have the p-wave and d-wave symmetry, respectively.

  18. Low-Speed Static Stability and Control Characteristics of a Model of a Right Triangular Pyramid Reentry Configuration

    NASA Technical Reports Server (NTRS)

    Paulson, John W.

    1959-01-01

    An investigation of the low-speed static stability and control characteristics of a model of a right triangular pyramid reentry configuration has been made in the Langley free-flight tunnel. The investigation showed that the model had generally satisfactory longitudinal and lateral static stability characteristics. The maximum lift-drag ratio was increased from about 3 to 5 by boattailing the base of the model.

  19. Early nerve ending rescue from oxidative damage and energy failure by L: -carnitine as post-treatment in two neurotoxic models in rat: recovery of antioxidant and reductive capacities.

    PubMed

    Elinos-Calderón, Diana; Robledo-Arratia, Yolanda; Pérez-De La Cruz, Verónica; Pedraza-Chaverrí, José; Ali, Syed F; Santamaría, Abel

    2009-08-01

    Cell rescue is a primary need during acute and chronic insults to the central nervous system. Functional preservation during the early stages of toxicity in a given degenerative event may represent a significant amelioration of detrimental processes linked to neuronal cell loss. Excitotoxicity and depleted cellular energy are toxic events leading to cell death in several neurodegenerative disorders. In this work, the effects of the well-known antioxidant and energy precursor, L: -carnitine (L: -CAR), were tested as a post-treatment in two neurotoxic models under in vitro and in vivo conditions. The experimental models tested included: (1) a typical excitotoxic and pro-oxidant inducer, quinolinic acid (QUIN); and (2) a mitochondrial energy inhibitor, 3-nitropropionic acid (3-NP). For in vitro studies, increasing concentrations of L: -CAR (10-1,000 microM) were added to the isolated brain synaptosomes at different times (1, 3 and 6 h) after the incubation with toxins (100 microM QUIN and 1 mM 3-NP), and 30 min later, lipid peroxidation (LP) and mitochondrial dysfunction (MD) were evaluated. For in vivo purposes, L: -CAR (100 mg/kg, i.p.) was given to rats either as a single administration 120 min after the intrastriatal infusion of QUIN (240 nmol/microl) or 3-NP (500 nmol/microl), or for 7 consecutive days (starting 120 min post-lesion). LP and MD were evaluated 4 h and 7 days post-lesions in isolated striatal synaptosomes. Our results show that, despite some variations depending on the toxic model tested, the time of exposure, or the biomarker evaluated, nerve ending protection can be mostly achieved by L: -CAR within the first hours after the toxic insults started, suggesting that targeting the ongoing oxidative damage and/or energy depletion during the first stages of neurotoxic events is essential to rescue nerve endings.

  20. Magnetism and multiferroicity of an isosceles triangular lattice antiferromagnet Sr3NiNb2O9.

    PubMed

    Lee, M; Choi, E S; Ma, J; Sinclair, R; Dela Cruz, C R; Zhou, H D

    2016-11-30

    Various experimental measurements were performed to complete the phase diagram of a weakly distorted triangular lattice system, Sr3NiNb2O9 with Ni(2+) , spin-1 magnetic ions. This compound possesses an isosceles triangular lattice with two shorter bonds and one longer bond. It shows a two-step magnetic phase transition at [Formula: see text] K and [Formula: see text] K at zero magnetic field, characteristic of an easy-axis anisotropy. In the magnetization curves, a series of magnetic phase transitions was observed such as an up-up-down phase at [Formula: see text] T with 1/3 of the saturation magnetization (M sat) and an oblique phase at [Formula: see text] T with [Formula: see text]/3 M sat. Intriguingly, the magnetic phase transition below T N2 is in tandem with the ferroelectricity, which demonstrates multiferroic behaviors. Moreover, the multiferroic phase persists in all magnetically ordered phases regardless of the spin structure. The comparison between the phase diagrams of Sr3NiNb2O9 and its sister compound with an equilateral triangular lattice antiferromagnet Ba3NiNb2O9 (Hwang et al 2012 Phys. Rev. Lett. 109 257205), illustrates how a small imbalance among exchange interactions change the magnetic ground states of the TLAFs. PMID:27661860

  1. Magnetism and multiferroicity of an isosceles triangular lattice antiferromagnet Sr3NiNb2O9.

    PubMed

    Lee, M; Choi, E S; Ma, J; Sinclair, R; Dela Cruz, C R; Zhou, H D

    2016-11-30

    Various experimental measurements were performed to complete the phase diagram of a weakly distorted triangular lattice system, Sr3NiNb2O9 with Ni(2+) , spin-1 magnetic ions. This compound possesses an isosceles triangular lattice with two shorter bonds and one longer bond. It shows a two-step magnetic phase transition at [Formula: see text] K and [Formula: see text] K at zero magnetic field, characteristic of an easy-axis anisotropy. In the magnetization curves, a series of magnetic phase transitions was observed such as an up-up-down phase at [Formula: see text] T with 1/3 of the saturation magnetization (M sat) and an oblique phase at [Formula: see text] T with [Formula: see text]/3 M sat. Intriguingly, the magnetic phase transition below T N2 is in tandem with the ferroelectricity, which demonstrates multiferroic behaviors. Moreover, the multiferroic phase persists in all magnetically ordered phases regardless of the spin structure. The comparison between the phase diagrams of Sr3NiNb2O9 and its sister compound with an equilateral triangular lattice antiferromagnet Ba3NiNb2O9 (Hwang et al 2012 Phys. Rev. Lett. 109 257205), illustrates how a small imbalance among exchange interactions change the magnetic ground states of the TLAFs.

  2. Air forces and moments on triangular and related wings with subsonic leading edges oscillating in supersonic potential flow

    NASA Technical Reports Server (NTRS)

    Watkins, Charles E; Berman, Julian N

    1952-01-01

    This analysis treats the air forces and moments in supersonic potential flow on oscillating triangular wings and a series of sweptback and arrow wings with subsonic leading edges and supersonic trailing edges. For the wings undergoing sinusoidal torsional oscillations simultaneously with vertical translations, the linearized velocity potential is derived in the form of a power series in terms of a frequency parameter. This method can be useful for treatment of similar problems for other plan forms and for wings undergoing other sinusoidal motions. For triangular wings, as many terms of such a series expansion as may be derived can be determined; however, the terms after the first few become very cumbersome. Closed expressions that include the reduced frequency to the fifth power, an order which is sufficient for a large class of practical application, are given for the velocity potential and for the components of chordwise section force and moment coefficients. These wings are found to exhibit the possibility of undamped torsional oscillations for certain ranges of Mach number and locations of the axis of rotation. The ranges of these parameters are delineated for triangular wings.

  3. Magnetism and multiferroicity of an isosceles triangular lattice antiferromagnet Sr3NiNb2O9

    NASA Astrophysics Data System (ADS)

    Lee, M.; Choi, E. S.; Ma, J.; Sinclair, R.; Dela Cruz, C. R.; Zhou, H. D.

    2016-11-01

    Various experimental measurements were performed to complete the phase diagram of a weakly distorted triangular lattice system, Sr3NiNb2O9 with Ni2+ , spin-1 magnetic ions. This compound possesses an isosceles triangular lattice with two shorter bonds and one longer bond. It shows a two-step magnetic phase transition at {{T}\\text{N1}}∼ 5.1 K and {{T}\\text{N2}}∼ 5.5 K at zero magnetic field, characteristic of an easy-axis anisotropy. In the magnetization curves, a series of magnetic phase transitions was observed such as an up-up-down phase at {μ0}{{H}c1}∼ 10.5 T with 1/3 of the saturation magnetization (M sat) and an oblique phase at {μ0}{{H}c2}∼ 16 T with \\sqrt{3} /3 M sat. Intriguingly, the magnetic phase transition below T N2 is in tandem with the ferroelectricity, which demonstrates multiferroic behaviors. Moreover, the multiferroic phase persists in all magnetically ordered phases regardless of the spin structure. The comparison between the phase diagrams of Sr3NiNb2O9 and its sister compound with an equilateral triangular lattice antiferromagnet Ba3NiNb2O9 (Hwang et al 2012 Phys. Rev. Lett. 109 257205), illustrates how a small imbalance among exchange interactions change the magnetic ground states of the TLAFs.

  4. LIFT: a nested decomposition algorithm for solving lower block triangular linear programs. Report AMD-859. [In PL/I for IBM 370

    SciTech Connect

    Ament, D; Ho, J; Loute, E; Remmelswaal, M

    1980-06-01

    Nested decomposition of linear programs is the result of a multilevel, hierarchical application of the Dantzig-Wolfe decomposition principle. The general structure is called lower block-triangular, and permits direct accounting of long-term effects of investment, service life, etc. LIFT, an algorithm for solving lower block triangular linear programs, is based on state-of-the-art modular LP software. The algorithmic and software aspects of LIFT are outlined, and computational results are presented. 5 figures, 6 tables. (RWR)

  5. Heat Capacity Mapping Mission

    NASA Technical Reports Server (NTRS)

    Nilsson, C. S.; Andrews, J. C.; Scully-Power, P.; Ball, S.; Speechley, G.; Latham, A. R. (Principal Investigator)

    1980-01-01

    The Tasman Front was delineated by airborne expendable bathythermograph survey; and an Heat Capacity Mapping Mission (HCMM) IR image on the same day shows the same principal features as determined from ground-truth. It is clear that digital enhancement of HCMM images is necessary to map ocean surface temperatures and when done, the Tasman Front and other oceanographic features can be mapped by this method, even through considerable scattered cloud cover.

  6. Community Capacity Building:

    PubMed Central

    Goytia, Crispin N.; Todaro-Rivera, Lea; Brenner, Barbara; Shepard, Peggy; Piedras, Veronica; Horowitz, Carol

    2013-01-01

    Background: Successful community–academic research partnerships require building the capacity of both community-based organizations (CBOs) and academics to conduct collaborative research of mutual interest and benefit. Yet, information about the needs and goals of research-interested CBOs is lacking. Our partnership aimed to conduct a community research needs assessment and to use results to develop future capacity-building programs for CBOs. Methods: Based on our review of the literature, informal interviews with research-interested CBOs and community-engaged research groups locally and nationally, we developed a needs assessment survey. Key domains of this survey included history and experience with research collaboration, interest in specific research topics, and preference for learning format and structure. We trained community health workers (CHWs) to recruit senior leaders from CBOs in New York City (NYC) and encourage them to complete an on-line survey. Results: Fully 54% (33/61) of CBOs completed the needs assessment. Most (69%) reported involvement with research or evaluation in the last 2 years and 33% had some funding for research. Although 75% had collaborated with academic institutions in the past, 58% did not rate this experience well. The four areas respondents prioritized for skills building were program evaluation, developing needs assessments, building surveys, and understanding statistical analyses. They were less interested in learning to build collaborations with academics. Conclusions: A formal needs assessment of research training and educational needs of CBOs revealed that most had experience, albeit negative, with academic collaborations. CBO leaders wanted to build skills to conduct and analyze assessments and program evaluations. Our community–academic partnership is using these findings to develop a research capacity-building course. Other partnerships should consider conducting such assessments to transform the capacity of CBOs to

  7. CSTI High Capacity Power

    NASA Technical Reports Server (NTRS)

    Winter, Jerry M.

    1989-01-01

    The SP-100 program was established in 1983 by DOD, DOE, and NASA as a joint program to develop the technology necessary for space nuclear power systems for military and civil application. During FY-86 and 87, the NASA SP-100 Advanced Technology Program was devised to maintain the momentum of promising technology advancement efforts started during Phase 1 of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for future space applications. In FY-88, the Advanced Technology Program was incorporated into NASA's new Civil Space Technology Initiative (CSTI). The CSTI Program was established to provide the foundation for technology development in automation and robotics, information, propulsion, and power. The CSTI High Capacity Power Program builds on the technology efforts of the SP-100 program, incorporates the previous NASA SP-100 Advanced Technology project, and provides a bridge to NASA Project Pathfinder. The elements of CSTI High Capacity Power development include Conversion Systems, Thermal Management, Power Management, System Diagnostics, and Environmental Interactions. Technology advancement in all areas, including materials, is required to assure the high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall program will develop and demonstrate the technology base required to provide a wide range of modular power systems as well as allowing mission independence from solar and orbital attitude requirements. Several recent advancements in CSTI High Capacity power development will be discussed.

  8. CSTI high capacity power

    SciTech Connect

    Winter, J.M.

    1994-09-01

    The SP-100 program was established in 1983 by DOD, DOE, and NASA as a joint program to develop the technology necessary for space nuclear power systems for military and civil application. During FY86 and 87, the NASA SP-100 Advanced Technology Program was devised to maintain the momentum of promising technology advancement efforts started during Phase I of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for future space applications. In FY88, the Advanced Technology Program was incorporated into NASA`s new Civil Space Technology Initiative (CSTI). The CSTI Program was established to provide the foundation for technology development in automation and robotics, information, propulsion, and power. The CSTI High Capacity Power Program builds on the technology efforts of the SP-100 program, incorporates the previous NASA SP-100 Advanced Technology project, and provides a bridge to NASA Project Pathfinder. The elements of CSTI High Capacity Power development include Conversion Systems, Thermal Management, Power Management, System Diagnostics, and Environmental Interactions. Technology advancement in all areas, including materials, is required to assure the high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall program will develop and demonstrate the technology base required to provide a wide range of modular power systems as well as allowing mission independence from solar and orbital attitude requirements. Several recent advancements in CSTI High Capacity power development will be discussed.

  9. Fluorescence Visualization of Hypersonic Flow Past Triangular and Rectangular Boundary-layer Trips

    NASA Technical Reports Server (NTRS)

    Danehy, Paul M.; Garcia, A. P.; Borg, Stephen E.; Dyakonov, Artem A.; Berry, Scott A.; Inman, Jennifer A.; Alderfer, David W.

    2007-01-01

    Planar laser-induced fluorescence (PLIF) flow visualization has been used to investigate the hypersonic flow of air over surface protrusions that are sized to force laminar-to-turbulent boundary layer transition. These trips were selected to simulate protruding Space Shuttle Orbiter heat shield gap-filler material. Experiments were performed in the NASA Langley Research Center 31-Inch Mach 10 Air Wind Tunnel, which is an electrically-heated, blowdown facility. Two-mm high by 8-mm wide triangular and rectangular trips were attached to a flat plate and were oriented at an angle of 45 degrees with respect to the oncoming flow. Upstream of these trips, nitric oxide (NO) was seeded into the boundary layer. PLIF visualization of this NO allowed observation of both laminar and turbulent boundary layer flow downstream of the trips for varying flow conditions as the flat plate angle of attack was varied. By varying the angle of attack, the Mach number above the boundary layer was varied between 4.2 and 9.8, according to analytical oblique-shock calculations. Computational Fluid Dynamics (CFD) simulations of the flowfield with a laminar boundary layer were also performed to better understand the flow environment. The PLIF images of the tripped boundary layer flow were compared to a case with no trip for which the flow remained laminar over the entire angle-of-attack range studied. Qualitative agreement is found between the present observed transition measurements and a previous experimental roughness-induced transition database determined by other means, which is used by the shuttle return-to-flight program.

  10. DC characterization and 3D modelling of a triangular, epoxy-impregnated high temperature superconducting coil

    NASA Astrophysics Data System (ADS)

    Hu, D.; Ainslie, M. D.; Rush, J. P.; Durrell, J. H.; Zou, J.; Raine, M. J.; Hampshire, D. P.

    2015-06-01

    The direct current (dc) characterization of high temperature superconducting (HTS) coils is important for applications, such as electric machines, superconducting magnetic energy storage and transformers. In this paper, the dc characterization of a triangular-shaped, epoxy-impregnated HTS coil wound with YBCO coated conductor intended for use in an axial-flux HTS motor is presented. Voltage was measured at several points along the coil to provide detailed information of its dc characteristics. The coil is modelled based on the H -formulation using a new three-dimensional (3D) technique that utilizes the real superconducting layer thickness, and this model allows simulation of the actual geometrical layout of the HTS coil structure. Detailed information on the critical current density’s dependence on the magnitude and orientation of the magnetic flux density, Jc(B,θ), determined from experimental measurement of a short sample of the coated conductor comprising the coil is included directly in the numerical model by a two-variable direct interpolation to avoid developing complicated equations for data fitting and greatly improve the computational speed. Issues related to meshing the finite elements of the real thickness 3D model are also discussed in detail. Based on a comparison of the measurement and simulation results, it is found that non-uniformity along the length exists in the coil, which implies imperfect superconducting properties in the coated conductor, and hence, coil. By evaluating the current-voltage (I-V) curves using the experimental data, and after taking into account a more practical n value and critical current for the non-uniform region, the modelling results show good agreement with the experimental results, validating this model as an appropriate tool to estimate the dc I-V relationship of a superconducting coil. This work provides a further step towards effective and efficient 3D modelling of superconducting devices for large

  11. Spin liquid nature in the Heisenberg J1-J2 triangular antiferromagnet

    NASA Astrophysics Data System (ADS)

    Iqbal, Yasir; Hu, Wen-Jun; Thomale, Ronny; Poilblanc, Didier; Becca, Federico

    2016-04-01

    We investigate the spin-1/2 Heisenberg model on the triangular lattice in the presence of nearest-neighbor J1 and next-nearest-neighbor J2 antiferromagnetic couplings. Motivated by recent findings from density-matrix renormalization group (DMRG) claiming the existence of a gapped spin liquid with signatures of spontaneously broken lattice point group symmetry [Zhu and White, Phys. Rev. B 92, 041105 (2015), 10.1103/PhysRevB.92.041105 and Hu, Gong, Zhu, and Sheng, Phys. Rev. B 92, 140403 (2015), 10.1103/PhysRevB.92.140403], we employ the variational Monte Carlo (VMC) approach to analyze the model from an alternative perspective that considers both magnetically ordered and paramagnetic trial states. We find a quantum paramagnet in the regime 0.08 ≲J2/J1≲0.16 , framed by 120∘ coplanar (stripe collinear) antiferromagnetic order for smaller (larger) J2/J1 . By considering the optimization of spin-liquid wave functions of a different gauge group and lattice point group content as derived from Abrikosov mean-field theory, we obtain the gapless U(1 ) Dirac spin liquid as the energetically most preferable state in comparison to all symmetric or nematic gapped Z2 spin liquids so far advocated by DMRG. Moreover, by the application of few Lanczos iterations, we find the energy to be the same as the DMRG result within error bars. To further resolve the intriguing disagreement between VMC and DMRG, we complement our methodological approach by the pseudofermion functional renormalization group (PFFRG) to compare the spin structure factors for the paramagnetic regime calculated by VMC, DMRG, and PFFRG. This model promises to be an ideal test bed for future numerical refinements in tracking the long-range correlations in frustrated magnets.

  12. Implications of mountain shading on calculating energy for snowmelt using unstructured triangular meshes

    NASA Astrophysics Data System (ADS)

    Marsh, C.; Pomeroy, J. W.; Spiteri, R.

    2012-12-01

    In many parts of the world, the snowmelt energy balance is dominated by net solar shortwave radiation. This is the case in the Canadian Rocky Mountains, where clear skies dominate the winter and spring. In mountainous regions, irradiance at the snow surface is not only affected by solar angles, atmospheric transmittance, and the slope and aspect of immediate topography, but also by horizon-shadows, i.e., shadows from surrounding terrain. Many hydrological models do not consider such horizon-shadows and the accumulation of errors in estimating solar irradiance by neglecting horizon-shadows may lead to significant errors in calculating the timing and rate of snowmelt due to the seasonal storage of internal energy in the snowpack. An unstructured triangular-mesh-based horizon-shading model is compared to standard self-shading algorithms in the Marmot Creek Research Basin (MCRB), Alberta, Canada. A systematic basin-wide over-prediction (basin mean expressed as phase change mass (assumed constant albedo of 0.8): 14 mm, maximum: 200 mm) in net shortwave radiation is observed when only self-shading is considered. The horizon-shadow model is run at a point scale at three sites throughout the MCRB to investigate the effects of topographic scale on the model results. In addition, the model results are compared to measurements of mountain shadows via orthorectified timelapse digital photographs and measured surface irradiance. The horizon-model irradiance data are used to drive a point-scale energy balance model, SNOBAL, via The Cold Regions Hydrological Model, an HRU-based hydrologic model. Melt timing is shown to differ by up to four days by neglecting horizon-shadows. It is further hypothesized that the errors might be much larger in basins with more rugged topography. Finally, a consideration of the intersection of unstructured-mesh and HRU landscape representations is discussed.

  13. Visual determination of trace cysteine based on promoted corrosion of triangular silver nanoplates by sodium thiosulfate.

    PubMed

    Hou, Xin Yan; Chen, Shu; Tang, Jian; Long, Yun Fei

    2014-05-01

    In this study, triangular silver nanoplates (TAg-NPs) were used to detect trace Cysteine concentration in the presence of sodium thiosulfate (Na2S2O3). Study showed that the TAg-NPs could be gently etched by Cysteine with the concentration of 1.0×10(-7) mol L(-1) through forming Ag-S covalent bond at the three corners. However, in the presence of Na2S2O3 (only 3.0×10(-6) mol L(-1)), the corrosion of Cysteine on TAg-NPs can be promoted significantly. It was also found that the color, morphology, and the maximum absorption wavelength of TAg-NPs change clearly with the concentrations of Cysteine as low as 2.5×10(-8) mol L(-1). Furthermore, the wavelength shift values (Δλ) of TAg-NPs solution were proportional to the concentrations of Cysteine in the range of 1.0×10(-9)-1.0×10(-7) mol L(-1), and the linear regression equation is Δλ=-0.89+319.94 c (c, μM, n=5) with the correlation coefficient of 0.990. At the same time, the color change of the TAg-NPs solution could be observed clearly by the naked eyes with increasing Cysteine concentrations in the range of 2.5×10(-8)-1.0×10(-7) mol L(-1). Thus, a novel method for the detection of Cysteine by either UV-vis spectrophotometry detection or naked eyes observation is established. It allows determination of Cysteine content in compound amino acid injection sample of 18AA-V.

  14. Triangular Titanium Implants for Minimally Invasive Sacroiliac Joint Fusion: A Prospective Study

    PubMed Central

    Duhon, Bradley S.; Cher, Daniel J.; Wine, Kathryn D.; Kovalsky, Don A.; Lockstadt, Harry

    2015-01-01

    Study Design Prospective multicenter single-arm interventional clinical trial. Objective To determine the degree of improvement in sacroiliac (SI) joint pain, disability related to SI joint pain, and quality of life in patients with SI joint dysfunction who undergo minimally invasive SI joint fusion using triangular-shaped titanium implants. Methods Subjects (n = 172) underwent minimally invasive SI joint fusion between August 2012 and January 2014 and completed structured assessments preoperatively and at 1, 3, 6, and 12 months postoperatively, including a 100-mm SI joint and back pain visual analog scale (VAS), Oswestry Disability Index (ODI), Short Form-36 (SF-36), and EuroQOL-5D. Patient satisfaction with surgery was assessed at 6 and 12 months. Results Mean SI joint pain improved from 79.8 at baseline to 30.0 and 30.4 at 6 and 12 months, respectively (mean improvements of 49.9 and 49.1 points, p < 0.0001 each). Mean ODI improved from 55.2 at baseline to 32.5 and 31.4 at 6 and 12 months (improvements of 22.7 and 23.9 points, p < 0.0001 each). SF-36 physical component summary improved from 31.7 at baseline to 40.2 and 40.3 at 6 and 12 months (p < 0.0001). At 6 and 12 months, 93 and 87% of subjects, respectively, were somewhat or very satisfied and 92 and 91%, respectively, would have the procedure again. Conclusions Minimally invasive SI joint fusion resulted in improvement of pain, disability, and quality of life in patients with SI joint dysfunction due to degenerative sacroiliitis and SI joint disruption. PMID:27099817

  15. Magnetostatic dipolar domain-wall pinning in chains of permalloy triangular rings.

    SciTech Connect

    Vavassori, P.; Bisero, D.; Bonanni, V.; Busato, A.; Grimsditch, M.; Lebecki, K. M.; Metlushko, V.; Ilic, B.; Materials Science Division; CIC nanoGUNE Consolider; Univ. di Ferrara; CNR-INFM National Research Centre; Polish Academy of Science; Univ. of Illinois at Chicago; Cornell Univ.

    2008-01-01

    In a combined experimental and numerical study, we investigated the details of the motion and pinning of domain walls in isolated and interacting permalloy triangular rings (side 2 {micro}m, width 250 nm, and thickness 25 nm). To induce interaction between the rings, they were arranged either in vertical chains with an apex of each triangle in proximity to the edge center of the triangle above it or in horizontal chains where the proximity is between the adjacent corners of the triangles. Using longitudinal and diffraction magneto-optic Kerr effects, magnetic force microscopy, and micromagnetic simulations, we determined the field dependence of the spin structure in the rings. In all cases the remnant state of each ring is an 'onion' state characterized by two domain walls - one head to head the other tail to tail - pinned at the apexes. In isolated rings the magnetization reversal occurs between two onion states via the formation of an intermediate vortex state, which arises from the motion and annihilation of the two domain walls. In the case of the horizontal chains the reversal mechanism is unchanged except that the dipolar interaction affects the field range in which the rings are in the vortex state. In the case of vertical chains an additional intermediate state is observed during reversal. The new state involves a domain wall pinned at the center of the edge that is in close proximity to the apex of its neighbor. We show that the domain-wall motion in this last case can be modeled by a triple potential well. Because the new state requires that a domain wall be pinned at the neighboring apex, our observations can be viewed as a very elementary form of magnetic logic.

  16. Highly sensitive detection of bovine serum albumin based on the aggregation of triangular silver nanoplates

    NASA Astrophysics Data System (ADS)

    Zhang, Ling Ling; Ma, Fang Fang; Kuang, Yang Fang; Cheng, Shu; Long, Yun Fei; Xiao, Qiu Guo

    2016-02-01

    A simple, fast and highly sensitive spectrophotometric method for the determination of bovine serum albumin (BSA) has been developed based on the interactions between triangular silver nanoplates (TAgNPs) and BSA in the presence of Britton-Robison buffer solution (BR). Particularly, the wavelength of absorption maximum (λmax) of TAgNPs is red shifted in the presence of BSA together with Britton-Robinson buffer solution (BR, pH = 2.56), and the color of the solution changed from blue to light blue. This may be due to the interactions between BSA molecules on the surface of TAgNPs through electrostatic forces, hydrogen bonds, hydrophobic effects and van der Waals forces at pH 2.56, which leads to the aggregation of TAgNPs. The determination of BSA was achieved by measuring the change of λmax corresponding to localized surface plasmon resonance (LSPR) from UV-visible spectrophotometry. It was found that the shift value in the wavelength of absorption maximum (Δλ, the difference in absorption maxima of the TAgNPs/BSA/BR mixture and the TAgNPs/BR mixture) was proportionate to the concentration of BSA in the range of 1.0 ng mL- 1 to 100.0 ng mL- 1 with the correlation coefficient of r = 0.9969. The detection limit (3 σ/k) for BSA was found to be as low as 0.5 ng mL- 1.

  17. Thickness effects on the plastic collapse of perforated plates with triangular penetration patterns

    SciTech Connect

    Gordon, J.L.; Jones, D.P.; Holliday, J.E.

    2000-03-01

    This paper investigates the effects of plate thickness on the accuracy of limit load solutions obtained using an elastic-perfectly plastic [EPP] equivalent solid [EQS] procedure for flat perforated plates with a triangular array of penetrations. The EQS approach for limit loads is based on an EQS collapse surface that is valid for generalized plane strain. This assumption is applicable for very thick plates but is known to be less reasonable for very thin plates where plane stress may be a better assumption. The limits of applicability of the generalized plane strain assumption are investigated by obtaining limit load solutions for perforated plates of various thicknesses that are subjected to in-plane and bending loads. Plastic limit load solutions obtained using three-dimensional EPP finite element analysis [FEA] of models which include each penetration explicitly are compared with solutions obtained using the EQS approximation. The penetration pattern chosen for this study has a ligament efficiency (ligament width-to-pitch ratio, h/P) of 0.32. For plates thicker than the pitch, the limit load calculated using the EQS method for both in-plane and bending loads is shown to be very accurate (within 4%) of the limit load calculated for the explicit model. On the other hand, for thin plates (t/P< 2), the EQS limit load is 5% greater than the explicit limit load for bending and 8% greater than the explicit limit load for in-plane loads. For thinner plates, the collapse surface is tied to the local geometry deformation and, hence, an equivalent solid plate representation of plastic collapse is a function of deformation mode and thickness.

  18. Lead toxicity, defense strategies and associated indicative biomarkers in Talinum triangulare grown hydroponically.

    PubMed

    Kumar, Abhay; Prasad, M N V; Sytar, Oksana

    2012-11-01

    Talinum species have been used to investigate a variety of environmental problems for e.g. determination of metal pollution index and total petroleum hydrocarbons in roadside soils, stabilization and reclamation of heavy metals (HMs) in dump sites, removal of HMs from storm water-runoff and green roof leachates. Species of Talinum are popular leaf vegetables having nutrient antinutrient properties. In this study, Talinum triangulare (Jacq.) Willd (Ceylon spinach) grown hydroponically were exposed to different concentrations of lead (Pb) (0, 0.25, 0.5, 0.75, 1.0 and 1.25 mM) to investigate the biomarkers of toxicity and tolerance mechanisms. Relative water content, cell death, photosynthetic pigments, sulphoquinovosyldiacylglycerol (SQDG), anthocyanins, α-tocopherol, malondialdehyde (MDA), reactive oxygen species (ROS) glutathione (GSH and GSSG) and elemental analysis have been investigated. The results showed that Pb in roots and shoots gradually increased as the function of Pb exposure; however Pb concentration in leaves was below detectable level. Chlorophylls and SQDG contents increased at 0.25 mM of Pb treatment in comparison to control at all treated durations, thereafter decreased. Levels of carotenoid, anthocyanins, α-tocopherol, and lipid peroxidation increased in Pb treated plants compared to control. Water content, cells death and elemental analysis suggested the damage of transport system interfering with nutrient transport causing cell death. The present study also explained that Pb imposed indirect oxidative stress in leaves is characterized by decreases in GSH/GSSG ratio with increased doses of Pb treatment. Lead-induced oxidative stress was alleviated by carotenoids, anthocyanins, α-tocopherol and glutathione suggesting that these defense responses as potential biomarkers for detecting Pb toxicity.

  19. Six new inorganic-organic hybrids based on rigid triangular ligands: Syntheses, structures and properties

    NASA Astrophysics Data System (ADS)

    Li, Na; Huang, Rudan

    2016-01-01

    Six new inorganic-organic hybrids based on rigid triangular N-containing ligands, NaCuI2(tib)4(H2O)4[H2PWVWVI11O40][H2PWVI12O40]·6H2O (1), CuII3(tib)4Cl4[H2PWVI12O40]2·4H2O (2), Co(tib)2[PWV3WVI9O38]·5H2O (3), CuII3(tib)2[P2MoVI5O22(O2)]·4H2O (4), Mn(pytpy)2MoVI4O13 (5) and Co(pytpy)2MoVI4O13 (6) (tib=1,3,5-tris(1-imidazolyl)benzene, pytpy=4'-(4"-pyridyl)2,4':6',4"-terpyridine), have been hydrothermally synthesized. Single crystal X-ray diffraction studies revealed that compounds 1-4 display two-dimensional (2D) layered structures, and in compounds 1-3, the adjacent Keggin anions link with each other by W-O-W covalent interactions to form 1D inorganic chains. Compounds 5-6 are 3D "pillar-layer" frameworks based on bimetal-oxide layers pillared by the pytpy ligands. The compounds have been characterized by elemental analysis, powder X-ray diffraction, X-ray photoelectron spectroscopy and thermo gravimetric analyses. Moreover, the electrochemical and catalytic properties of compound 1 have been investigated as well.

  20. Flow-induced oscillations of a prism with triangular cross-section placed in water

    NASA Astrophysics Data System (ADS)

    Carlson, Daniel; Seyed-Aghazadeh, Banafsheh; Modarres-Sadeghi, Yahya

    2015-11-01

    Flow-induced oscillations of a prism with a triangular cross-section was studied experimentally. The cylinder had one-degree-of-freedom to oscillate in the crossflow direction. The response of the cylinder in terms of the amplitudes of oscillations as well as the flow forces were studied at varying angles of attack in the range of α = 0° -60° and a reduced velocity range of U* =4-22. Depending on the angle of attack and the reduced velocity, the cylinder experienced either VIV or galloping. For small angles of attack of α<30°, the cylinder did not oscillate while for larger angles of α = 30° and 35°, the cylinder underwent VIV in a range of reduced velocities (U* =7-14.5) and galloping at higher reduced velocities (U* =19.5-22). The conducted dye flow visualization as well as the measured flow forces confirmed the existence of lock-in as well as galloping-type response. For larger angles of attack of α>35°, the amplitude of oscillations increased monotonically with increasing reduced velocity and the cylinder underwent galloping. Several different vortex shedding patterns were observed in the wake of the cylinder at different angles of attack and flow velocities. New, high-frequency shedding patterns with their corresponding high harmonic shedding frequencies in the flow force FFTs were observed in the regions where galloping occurred. This work is partially supported by the NSF-sponsored IGERT: Offshore Wind Energy Engineering, Environmental Science, and Policy (Grant Number 1068864).

  1. A role for TRIANGULAR HULL1 in fine-tuning spikelet morphogenesis in rice.

    PubMed

    Sato, Dai-Suke; Ohmori, Yoshihiro; Nagashima, Haruka; Toriba, Taiyo; Hirano, Hiro-Yuki

    2014-01-01

    The lemma and palea, which enclose the pistil, stamens, and lodicules, are the most conspicuous organs in the rice spikelet. We isolated a mutant line (ng6569) in which the lemma and palea were narrower than those of the wild type, and found that the mutant had a defect in TRIANGULAR HULL1 (TH1), which encodes a nuclear protein with an ALOG domain. Detailed morphological analysis indicated that the th1 mutation caused a reduction in the size of tubercles, which are convex structures on the surface of the lemma and palea. This reduction was more pronounced in the apical region of the lemma than in the basal region, resulting in the formation of a beak-like spikelet. By contrast, the number of tubercle rows and their spatial distribution on the lemma were not affected in the th1 mutant. Thus, the TH1 gene seems to be involved in fine-tuning the morphogenesis of the lemma and palea. In situ hybridization analysis revealed that TH1 was highly expressed in the primordia of the lemma and palea, but only weakly expressed in the primordia of the sterile lemma and rudimentary glume. We then examined the effect of th1 mutation on the lemma-like structure formed in the long sterile lemma/glume1 (g1) and extra glume1 (eg1) mutants. The result showed that the th1 mutation strongly affected the morphology of the extra lemma of eg1, but had no significant effect on the transformed lemma of g1. PMID:25224972

  2. Highly sensitive detection of bovine serum albumin based on the aggregation of triangular silver nanoplates.

    PubMed

    Zhang, Ling Ling; Ma, Fang Fang; Kuang, Yang Fang; Cheng, Shu; Long, Yun Fei; Xiao, Qiu Guo

    2016-02-01

    A simple, fast and highly sensitive spectrophotometric method for the determination of bovine serum albumin (BSA) has been developed based on the interactions between triangular silver nanoplates (TAgNPs) and BSA in the presence of Britton-Robison buffer solution (BR). Particularly, the wavelength of absorption maximum (λ(max)) of TAgNPs is red shifted in the presence of BSA together with Britton-Robinson buffer solution (BR, pH=2.56), and the color of the solution changed from blue to light blue. This may be due to the interactions between BSA molecules on the surface of TAgNPs through electrostatic forces, hydrogen bonds, hydrophobic effects and van der Waals forces at pH2.56, which leads to the aggregation of TAgNPs. The determination of BSA was achieved by measuring the change of λ(max) corresponding to localized surface plasmon resonance (LSPR) from UV-visible spectrophotometry. It was found that the shift value in the wavelength of absorption maximum (Δλ, the difference in absorption maxima of the TAgNPs/BSA/BR mixture and the TAgNPs/BR mixture) was proportionate to the concentration of BSA in the range of 1.0 ng mL(-1) to 100.0 ng mL(-1) with the correlation coefficient of r=0.9969. The detection limit (3 σ/k) for BSA was found to be as low as 0.5 ng mL(-1). PMID:26519916

  3. Methane storage in homogeneous armchair open-ended single-walled boron nitride nanotube triangular arrays: a grand canonical Monte Carlo simulation study.

    PubMed

    Mahdizadeh, Sayyed Jalil; Tayyari, Sayyed Faramarz

    2012-06-01

    The physisorption of methane in homogeneous armchair open-ended SWBNNT triangular arrays was evaluated using grand canonical ensemble Monte Carlo simulation for tubes 11.08, 13.85, 16.62, and 19.41 Å [(8,8), (10,10), (12,12), and (14,14), respectively] in diameter, at temperatures of 273, 298, 323, and 373 K, and at fugacities of 0.5-9.0 Mpa. The intermolecular forces were modeled using the Lennard-Jones potential model. The absolute, excess, and delivery adsorption isotherms of methane were calculated for the various boron nitride nanotube arrays. The specific surface areas and the isosteric heats of adsorption, Q(st), were also studied, different isotherm models were fitted to the simulated adsorption data, and the model parameters were correlated. According to the results, it is possible to reach 108% and 140% of the US Department of Energy's target for CH(4) storage (180 v/v at 298 K and 35 bar) using the SWBNNT array with nanotubes 16.62 and 19.41 Å in diameter, respectively, as adsorbent. The results show that for a van der Waals gap of 3.4 Å, there is no interstitial adsorption except for arrays containing nanotubes with diameters of >15.8 Å. Multilayer adsorption starts to occur in arrays containing nanotubes with diameters of >16.62 Å, and the minimum pressure required for multilayer adsorption is 1.0 MPa. A brief comparison of the methane adsorption capacities of single-walled carbon and boron nitride nanotube arrays was also performed. PMID:22102208

  4. Quantum reading capacity

    NASA Astrophysics Data System (ADS)

    Pirandola, Stefano; Lupo, Cosmo; Giovannetti, Vittorio; Mancini, Stefano; Braunstein, Samuel L.

    2011-11-01

    The readout of a classical memory can be modelled as a problem of quantum channel discrimination, where a decoder retrieves information by distinguishing the different quantum channels encoded in each cell of the memory (Pirandola 2011 Phys. Rev. Lett. 106 090504). In the case of optical memories, such as CDs and DVDs, this discrimination involves lossy bosonic channels and can be remarkably boosted by the use of nonclassical light (quantum reading). Here we generalize these concepts by extending the model of memory from single-cell to multi-cell encoding. In general, information is stored in a block of cells by using a channel-codeword, i.e. a sequence of channels chosen according to a classical code. Correspondingly, the readout of data is realized by a process of ‘parallel’ channel discrimination, where the entire block of cells is probed simultaneously and decoded via an optimal collective measurement. In the limit of a large block we define the quantum reading capacity of the memory, quantifying the maximum number of readable bits per cell. This notion of capacity is nontrivial when we suitably constrain the physical resources of the decoder. For optical memories (encoding bosonic channels), such a constraint is energetic and corresponds to fixing the mean total number of photons per cell. In this case, we are able to prove a separation between the quantum reading capacity and the maximum information rate achievable by classical transmitters, i.e. arbitrary classical mixtures of coherent states. In fact, we can easily construct nonclassical transmitters that are able to outperform any classical transmitter, thus showing that the advantages of quantum reading persist in the optimal multi-cell scenario.

  5. Effect of adsorbent particle size on the relative merits of a non-triangular and a triangular separation region in the optimal design of a three-zone simulated moving bed chromatography for binary separation with linear isotherms.

    PubMed

    Mun, Sungyong

    2016-06-24

    The design approaches for a three-zone simulated moving bed (SMB) chromatography with linear isotherms can be classified into two categories, depending on whether the SMB design is based on a classical region (i.e., triangular region of the triangle theory) in the first quadrant (m2, m3) plane or on a non-triangular separation region in the third quadrant (m2, m3) plane. The SMBs based on the classical and the non-triangular design approaches, which are named here as (m(+))_SMB and (m(-))_SMB respectively, are compared in this study using the Pareto solutions from the simultaneous optimization of throughput and desorbent usage under the constraints on product purities and pressure drop. The results showed that the (m(-))_SMB approach led to significantly lower desorbent usage than the (m(+))_SMB approach, which was due to the fact that the flow-rate-ratios from the (m(-))_SMB approach are extremely lower than those from the (m(+))_SMB approach. This factor also enables the (m(-))_SMB to have a significantly lower pressure drop, thereby making its throughput less restricted by a pressure-drop constraint. Due to such advantage of the (m(-))_SMB, it can make a further substantial improvement in throughput by modulating its adsorbent particle size properly. This issue was investigated using a model separation system containing succinic acid and acetic acid. It was confirmed that if the adsorbent particle size corresponding to the boundary between a mass-transfer limiting region and a pressure-drop limiting region is adopted, the (m(-))_SMB can lead to 82% higher throughput and 73% lower desorbent usage than the (m(+))_SMB.

  6. Effect of adsorbent particle size on the relative merits of a non-triangular and a triangular separation region in the optimal design of a three-zone simulated moving bed chromatography for binary separation with linear isotherms.

    PubMed

    Mun, Sungyong

    2016-06-24

    The design approaches for a three-zone simulated moving bed (SMB) chromatography with linear isotherms can be classified into two categories, depending on whether the SMB design is based on a classical region (i.e., triangular region of the triangle theory) in the first quadrant (m2, m3) plane or on a non-triangular separation region in the third quadrant (m2, m3) plane. The SMBs based on the classical and the non-triangular design approaches, which are named here as (m(+))_SMB and (m(-))_SMB respectively, are compared in this study using the Pareto solutions from the simultaneous optimization of throughput and desorbent usage under the constraints on product purities and pressure drop. The results showed that the (m(-))_SMB approach led to significantly lower desorbent usage than the (m(+))_SMB approach, which was due to the fact that the flow-rate-ratios from the (m(-))_SMB approach are extremely lower than those from the (m(+))_SMB approach. This factor also enables the (m(-))_SMB to have a significantly lower pressure drop, thereby making its throughput less restricted by a pressure-drop constraint. Due to such advantage of the (m(-))_SMB, it can make a further substantial improvement in throughput by modulating its adsorbent particle size properly. This issue was investigated using a model separation system containing succinic acid and acetic acid. It was confirmed that if the adsorbent particle size corresponding to the boundary between a mass-transfer limiting region and a pressure-drop limiting region is adopted, the (m(-))_SMB can lead to 82% higher throughput and 73% lower desorbent usage than the (m(+))_SMB. PMID:27208988

  7. Heat Capacity in Proteins

    NASA Astrophysics Data System (ADS)

    Prabhu, Ninad V.; Sharp, Kim A.

    2005-05-01

    Heat capacity (Cp) is one of several major thermodynamic quantities commonly measured in proteins. With more than half a dozen definitions, it is the hardest of these quantities to understand in physical terms, but the richest in insight. There are many ramifications of observed Cp changes: The sign distinguishes apolar from polar solvation. It imparts a temperature (T) dependence to entropy and enthalpy that may change their signs and which of them dominate. Protein unfolding usually has a positive ΔCp, producing a maximum in stability and sometimes cold denaturation. There are two heat capacity contributions, from hydration and protein-protein interactions; which dominates in folding and binding is an open question. Theoretical work to date has dealt mostly with the hydration term and can account, at least semiquantitatively, for the major Cp-related features: the positive and negative Cp of hydration for apolar and polar groups, respectively; the convergence of apolar group hydration entropy at T ≈ 112°C; the decrease in apolar hydration Cp with increasing T; and the T-maximum in protein stability and cold denaturation.

  8. Working memory's workload capacity.

    PubMed

    Heathcote, Andrew; Coleman, James R; Eidels, Ami; Watson, Jason M; Houpt, Joseph; Strayer, David L

    2015-10-01

    We examined the role of dual-task interference in working memory using a novel dual two-back task that requires a redundant-target response (i.e., a response that neither the auditory nor the visual stimulus occurred two back versus a response that one or both occurred two back) on every trial. Comparisons with performance on single two-back trials (i.e., with only auditory or only visual stimuli) showed that dual-task demands reduced both speed and accuracy. Our task design enabled a novel application of Townsend and Nozawa's (Journal of Mathematical Psychology 39: 321-359, 1995) workload capacity measure, which revealed that the decrement in dual two-back performance was mediated by the sharing of a limited amount of processing capacity. Relative to most other single and dual n-back tasks, performance measures for our task were more reliable, due to the use of a small stimulus set that induced a high and constant level of proactive interference. For a version of our dual two-back task that minimized response bias, accuracy was also more strongly correlated with complex span than has been found for most other single and dual n-back tasks.

  9. A density-controlled triangular and quadrilateral element mesh automatic generation system

    NASA Astrophysics Data System (ADS)

    Sun, L.; Yeh, G.; Lin, F.; Zhao, G.

    2013-12-01

    We made an intensive study to develop an automatic mesh generation system based on the theory of Voronoi diagram and front advancing. The objective of this system is to create meshes for numerical modeling of practical engineering problems in the fields of geomechanics, hydrology, hydraulics, and water resources. The input data of the system is a set of given points to form the boundary contour of the analyzed geometry, containing the coordinates, the connections and the point spacing specified by users. Boundary points are generated by recursively inserting midpoints according to the spacing of the input points. For the curved boundaries, B-splines are constructed to interpolate midpoints. For the geometries with concave features and long thin domains, boundary loss problem may occur after generating the Voronoi diagram of boundary points. This problem is resolved by recursively inserting pseudo-points at the midpoints of the missing edges until all the original boundary edges are fully described. In order to ensure the curvature accuracy of curved boundaries, pseudo-points should be eliminated again by corresponding modes. Two criteria for selecting removal modes are employed, the Jacobian and minimum angle. Two methods are used to generate interior points. One is direct method and the other is pre-test method. A comparison of the two methods is also made. Laplacian method is used to smooth the interior points of triangles. For the geometries with several sub-domains, it is required to ensure the conformity of the elements and points on the intersecting boundaries between adjacent sub-domains. We establish corresponding methods to treat the overlapped boundary edges and implement the reasonable distribution and excellent conformity of the triangles and points on the overlapped boundaries. On the basis of the triangular mesh created by Delaunay triangulation, a front-advancing method is used to further generate quadrilateral mesh by combining two connected

  10. Stepwise formation of organometallic macrocycles and triangular prisms containing 2,2'-bisbenzimidazole ligands.

    PubMed

    Wu, Tong; Lin, Yue-Jian; Jin, Guo-Xin

    2013-01-01

    A series of organometallic macrocycles have been constructed by an efficient “bottom-up” assembly methodology at ambient temperature. Treatment of [Cp*MCl2]2 (1a: M = Ir, 1b: M = Rh) with pyrazine or 4,4′-bipyridine (bpy) (1:1; Cp* = pentamethylcyclopentadienyl) at room temperature resulted in the formation of binuclear complexes [Cp*MCl2]2(pyrazine) and [Cp*MCl2]2(bpy) (M = Ir or Rh), which were then further reacted with AgOTf (Tf = O2SCF3) and 2,2′-bisbenzimidazole ligand (BiBzIm). Four organometallic macrocyclic complexes formulated as [Cp*4Ir4(BiBzIm)2(pyrazine)2](OTf)4 (2a), [Cp*4Rh4(BiBzIm)2(pyrazine)2](OTf)4 (2b), [Cp*4Ir4(BiBzIm)2(bpy)2](OTf)4 (2c) and [Cp*4Rh4(BiBzIm)2(bpy)2](OTf)4 (2d) each bearing 2,2′-bisbenzimidazole ligand and the half-sandwich Ir, Rh fragments were finally obtained in good yields. In a similar process, if a rigid ligand L (3-pyridyl-bian) was used as the linker, two novel metallacycles (3a and 3b) which enchased a silver atom in the centre were obtained. Organometallic triangular prisms 4a were synthesized via methods similar to those of the rectangles. [Cp*IrCl2]2 reacted with tridentate ligand 2,4,6-tri(4-pyridyl)-1,3,5-triazine (tpt) to give the corresponding trinuclear complexes [Cp*IrCl2]3(tpt), then further reacted with AgOTf and 2,2′-bisbenzimidazole ligand, leading to the formation of the prism-like complexes formulated as [Cp*6M6(BiBzIm)6(tpt)2](OTf)6 (3a: M = Ir, 3b: M = Rh). All complexes were well characterized by 1H NMR and IR spectroscopy, as well as elemental analyses. The molecular structures of 2a, 2b, 2c, 3a, 3b and 4a were characterized by single-crystal X-ray crystallography. We found that the prism-like hexanuclear complexes 4a displayed interesting host–guest chemistry.

  11. The triangular voltage sweep method as a performance metric for diffusion barrier evaluation in copper metallization

    NASA Astrophysics Data System (ADS)

    Kumar, Kaushik Arun

    Increasing demands on computer chip technology require exploration of novel materials, deposition techniques and characterization methods. Copper-based interconnects have been implemented in advanced microprocessor designs owing to copper's low resistivity (1.7 muO-cm). Copper interconnects require a barrier layer to prevent diffusion into the dielectric layer. Traditionally, a technique known as bias-thermal-stress-capacitance-voltage (BTS) has been used to quantify barrier reliability against Cu diffusion. Triangular voltage sweep (TVS) is a new method for quantifying barrier reliability against Cu diffusion, whose advantage lies in its ability to discriminate between various mobile charges based on their mobilities in an insulator. In the first phase of this work, physical vapor deposited (PVD) tantalum nitride (TaN) was first used as a baseline barrier to establish and understand the performance metrics of TVS. The development and optimization of PVD TaN employed a design of experiment (DOE) approach. The optimization resulted in stoichiometric TaN films with a resistivity of 250 muO-cm for 50 nm thick films. The films were polycrystalline and exhibited a zone "T" type microstructure. TVS was used to characterize these films. Pertinent results, including possible failure mechanisms, are presented in the document. As the device sizes shrink to 100 nm and below, diffusion barrier thickness is expected to fall to less than 10 nm. One potential material for the barrier layer in the sub-100 nm technology is tungsten nitride (WNx) deposited by chemical vapor deposition (CVD). Tungsten nitride is expected to perform well as a barrier because of its refractory nature and excellent thermal, chemical, and mechanical properties. In addition, it can be deposited in amorphous form. Amorphous materials have no grain boundaries, thereby avoiding grain boundary diffusion, which is a fast path diffusion mechanism. Additionally, a low-dielectric constant material, such as Si

  12. Herringbone and triangular patterns of dislocations in Ag, Au, and AgAu alloy films on Ru(0001).

    SciTech Connect

    Thayer, Gayle Echo; de la Figuera, Juan; Bartelt, Norman Charles; Carter, C. Barrington; Hwang, R. Q.; Thurmer, Konrad; Ling, W. L.; Hamilton, John C.; McCarty, Kevin F.

    2008-10-01

    We have studied the dislocation structures that occur in films of Ag, Au, and Ag{sub 0.5}Au{sub 0.5} alloy on a Ru(0001) substrate. Monolayer (ML) films form herringbone phases while films two or more layers thick contain triangular patterns of dislocations. We use scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) to determine how the film composition affects the structure and periodicity of these ordered structures. One layer of Ag forms two different herringbone phases depending on the exact Ag coverage and temperature. Low-energy electron microscopy (LEEM) establishes that a reversible, first-order phase transition occurs between these two phases at a certain temperature. We critically compare our 1 ML Ag structures to conflicting results from an X-ray scattering study [H. Zajonz et al., Phys. Rev. B 67 (2003) 155417]. Unlike Ag, the herringbone phases of Au and AgAu alloy are independent of the exact film coverage. For two layer films in all three systems, none of the dislocations in the triangular networks thread into the second film layer. In all three systems, the in-plane atomic spacing of the second film layer is nearly the same as in the bulk. Film composition does, however, affect the details of the two layer structures. Ag and Au films form interconnected networks of dislocations, which we refer to as 'trigons.' In 2 ML AgAu alloy, the dislocations form a different triangular network that shares features of both trigon and moire structures. Yet another well-ordered structure, with square symmetry, forms at the boundaries of translational trigon domains in 2 ML Ag films but not in Au films.

  13. Thermo-Elastic Triangular Sandwich Element for the Complete Stress Field Based on a Single-Layer Theory

    NASA Technical Reports Server (NTRS)

    Das, M.; Barut, A.; Madenci, E.; Ambur, D. R.

    2004-01-01

    This study presents a new triangular finite element for modeling thick sandwich panels, subjected to thermo-mechanical loading, based on a {3,2}-order single-layer plate theory. A hybrid energy functional is employed in the derivation of the element because of a C interelement continuity requirement. The single-layer theory is based on five weighted-average field variables arising from the cubic and quadratic representations of the in-plane and transverse displacement fields, respectively. The variations of temperature and distributed loading acting on the top and bottom surfaces are non-uniform. The temperature varies linearly through the thickness.

  14. Design of triangular core LMA-PCF with low-bending loss and low non-linearity for laser application

    NASA Astrophysics Data System (ADS)

    Kabir, Sumaiya; Khandokar, Md. Rezwanul Haque; Khan, Muhammad Abdul Goffar

    2016-07-01

    In this paper we characterize the design of a simple large-mode area photonic crystal fiber (LMA-PCF) with low bending loss and low non-linearity. The finite element method (FEM) with perfectly matched boundary layer (PML) is used to investigate the guiding properties. According to simulation the characterized four ring fluorine doped triangular core LMA-PCF achieves 1500 μm2 effective mode area with a low bending loss of 10-5dB/km at the wavelength of 1.064 μm and at a bending radius of 40 cm which is suitable for high power fiber laser.

  15. Effect of bismuth surfactant on InP-based highly strained InAs/InGaAs triangular quantum wells

    SciTech Connect

    Gu, Y.; Zhang, Y. G. Chen, X. Y.; Xi, S. P.; Du, B.; Ma, Y. J.

    2015-11-23

    We report the effect of Bi surfactant on the properties of highly strained InAs/InGaAs triangular quantum wells grown on InP substrates. Reduced surface roughness, improved heterostructure interfaces and enhanced photoluminescence intensity at 2.2 μm are observed by moderate Bi-mediated growth. The nonradiative processes are analysed based on temperature-dependent photoluminescence. It is confirmed that Bi incorporation is insignificant in the samples, whereas excessive Bi flux during the growth results in deteriorated performance. The surfactant effect of Bi is promising to improve InP-based highly strained structures while the excess of Bi flux needs to be avoided.

  16. Verification of Three Dimensional Triangular Prismatic Discrete Ordinates Transport Code ENSEMBLE-TRIZ by Comparison with Monte Carlo Code GMVP

    NASA Astrophysics Data System (ADS)

    Homma, Yuto; Moriwaki, Hiroyuki; Ohki, Shigeo; Ikeda, Kazumi

    2014-06-01

    This paper deals with verification of three dimensional triangular prismatic discrete ordinates transport calculation code ENSEMBLE-TRIZ by comparison with multi-group Monte Carlo calculation code GMVP in a large fast breeder reactor. The reactor is a 750 MWe electric power sodium cooled reactor. Nuclear characteristics are calculated at beginning of cycle of an initial core and at beginning and end of cycle of equilibrium core. According to the calculations, the differences between the two methodologies are smaller than 0.0002 Δk in the multi-plication factor, relatively about 1% in the control rod reactivity, and 1% in the sodium void reactivity.

  17. Binary classification SVM-based algorithms with interval-valued training data using triangular and Epanechnikov kernels.

    PubMed

    Utkin, Lev V; Chekh, Anatoly I; Zhuk, Yulia A

    2016-08-01

    Classification algorithms based on different forms of support vector machines (SVMs) for dealing with interval-valued training data are proposed in the paper. L2-norm and L∞-norm SVMs are used for constructing the algorithms. The main idea allowing us to represent the complex optimization problems as a set of simple linear or quadratic programming problems is to approximate the Gaussian kernel by the well-known triangular and Epanechnikov kernels. The minimax strategy is used to choose an optimal probability distribution from the set and to construct optimal separating functions. Numerical experiments illustrate the algorithms. PMID:27179616

  18. Control of optical bistability and third-order nonlinearity via tunneling induced quantum interference in triangular quantum dot molecules

    SciTech Connect

    Tian, Si-Cong Tong, Cun-Zhu Zhang, Jin-Long; Shan, Xiao-Nan; Fu, Xi-Hong; Zeng, Yu-Gang; Qin, Li; Ning, Yong-Qiang; Wan, Ren-Gang

    2015-06-15

    The optical bistability of a triangular quantum dot molecules embedded inside a unidirectional ring cavity is studied. The type, the threshold and the hysteresis loop of the optical bistability curves can be modified by the tunneling parameters, as well as the probe laser field. The linear and nonlinear susceptibilities of the medium are also studied to interpret the corresponding results. The physical interpretation is that the tunneling can induce the quantum interference, which modifies the linear and the nonlinear response of the medium. As a consequence, the characteristics of the optical bistability are changed. The scheme proposed here can be utilized for optimizing and controlling the optical switching process.

  19. Spin Nematics, Valence-Bond Solids, and Spin Liquids in SO(N) Quantum Spin Models on the Triangular Lattice.

    PubMed

    Kaul, Ribhu K

    2015-10-01

    We introduce a simple model of SO(N) spins with two-site interactions which is amenable to quantum Monte Carlo studies without a sign problem on nonbipartite lattices. We present numerical results for this model on the two-dimensional triangular lattice where we find evidence for a spin nematic at small N, a valence-bond solid at large N, and a quantum spin liquid at intermediate N. By the introduction of a sign-free four-site interaction, we uncover a rich phase diagram with evidence for both first-order and exotic continuous phase transitions. PMID:26550748

  20. Modified spin-wave theory and spin-liquid behavior of cold bosons on an inhomogeneous triangular lattice

    NASA Astrophysics Data System (ADS)

    Celi, Alessio; Grass, Tobias; Ferris, Andrew J.; Padhi, Bikash; Raventós, David; Simonet, Juliette; Sengstock, Klaus; Lewenstein, Maciej

    2016-08-01

    Ultracold bosons in a triangular lattice are a promising candidate for observing quantum spin liquid behavior. Here we investigate, for such system, the role of a harmonic trap giving rise to an inhomogeneous density. We construct a modified spin-wave theory for arbitrary filling and predict the breakdown of order for certain values of the lattice anisotropy. These regimes, identified with the spin liquid phases, are found to be quite robust upon changes in the filling factor. This result is backed by an exact diagonalization study on a small lattice.