Vulnerability to Climate Change in Rural Saskatchewan: Case Study of the Rural Municipality of Rudy No. 284

ERIC Educational Resources Information Center

Pittman, Jeremy; Wittrock, Virginia; Kulshreshtha, Surendra; Wheaton, Elaine

2011-01-01

With the likelihood of future changes in climate and climate variability, it is important to understand how human systems may be vulnerable. Rural communities in Saskatchewan having agricultural-based economies are particularly dependent on climate and could be among the most vulnerable human systems in Canada. Future changes in climate are likely…

Ecological interpretations of the leaf anatomy of amphibious species of Aeschynomene L. (Leguminosae - Papilionoideae).

PubMed

Leme, F M; Scremin-Dias, E

2014-02-01

We present the leaf anatomy of seven amphibious species of Aeschynomene L. (Papilionoideae, Leguminosae), interpreting their structures and ecological functions, and also, providing information on which their taxonomy can be based, especially of morphologically similar species. We evaluated Aeschynomene americana, A. ciliata, A. evenia, A. denticulata, A. fluminensis, A. rudis and A. sensitiva. The anatomy corroborates the separation of the series Americanae, Fluminenses, Indicae and Sensitivae, with the shape of the petiole, types of trichomes and quantity of vascular units in the petiole as main characteristics to delimit the species. The petiole shape varies from cylindric in A. americana, A. sensitiva and A. fluminensis, to triangular in A. evenia and quadrangular in A. rudis, A. denticulata and A. ciliata. We observed four types of trichomes: hydathode trichome, long conic trichome, short conic trichome and bulb-based trichome. The hydathode trichome was the most common, except for A. americana and A. fluminensis. Species with higher affinity with water share similar adaptive characteristics, including hydathode trichomes described for the first time for the genus. This article adds unseen descriptions for the genus and on the adaptation factors of the amphibious species.

A Quantitative Model for Assessing Visual Simulation Software Architecture

DTIC Science & Technology

2011-09-01

Software Engineering Arnold Buss Research Associate Professor of MOVES LtCol Jeff Boleng, PhD Associate Professor of Computer Science U.S. Air Force Academy... science (operating and programming systems series). New York, NY, USA: Elsevier Science Ltd. Henry, S., & Kafura, D. (1984). The evaluation of software...Rudy Darken Professor of Computer Science Dissertation Supervisor Ted Lewis Professor of Computer Science Richard Riehle Professor of Practice

Inheritance of Mesotrione Resistance in an Amaranthus tuberculatus (var. rudis) Population from Nebraska, USA

PubMed Central

Oliveira, Maxwel C.; Gaines, Todd A.; Jhala, Amit J.; Knezevic, Stevan Z.

2018-01-01

A population of Amaranthus tuberculatus (var. rudis) evolved resistance to 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitor herbicides (mesotrione, tembotrione, and topramezone) in Nebraska. The level of resistance was the highest to mesotrione, and the mechanism of resistance in this population is metabolism-based likely via cytochrome P450 enzymes. The increasing number of weeds resistant to herbicides warrants studies on the ecology and evolutionary factors contributing for resistance evolution, including inheritance of resistance traits. In this study, we investigated the genetic control of mesotrione resistance in an A. tuberculatus population from Nebraska, USA. Results showed that reciprocal crosses in the F1 families exhibited nuclear inheritance, which allows pollen movement carrying herbicide resistance alleles. The mode of inheritance varied from incomplete recessive to incomplete dominance depending upon the F1 family. Observed segregation patterns for the majority of the F2 and back-cross susceptible (BC/S) families did not fit to a single major gene model. Therefore, multiple genes are likely to confer metabolism-based mesotrione resistance in this A. tuberculatus population from Nebraska. The results of this study aid to understand the genetics and inheritance of a non-target-site based mesotrione resistant A. tuberculatus population from Nebraska, USA. PMID:29456544

Civitas: Toward a Secure Voting System

DTIC Science & Technology

2008-05-01

voting, we believe that remote vot- ing is the right problem to solve. One of our goals was therefore to strike a reasonable compromise between enabling...versions of this work. References [1] Ben Adida . Advances in Cryptographic Voting Systems. PhD thesis, MIT, Aug. 2006. [2] Roberto Araújo, Sébastien...3] Association for Computing Machinery. SIG elections. http://www.acm.org/sigs/elections, 2007. [4] Jonathan Bannet, David W. Price , Algis Rudys

Geolocation of Source Interference from a Single Satellite with Multiple Antennas

DTIC Science & Technology

2014-03-01

Newman , Rudy Panholzer, and Al Scott for volunteering your time to “murder board” this thesis. Your suggestions and critiques have significantly...components must belong to a Parent object. This concept summarizes the description of this section thus far. In order for these scalar...the Parent object of the Data Element scalar calculation. 64 D. THE GRAPHICAL PROCESS All of the STK calculations in Part C provided the ground

Workshop on Diffuse Discharge Opening Switches (January 13-15, 1982).

DTIC Science & Technology

1982-04-23

Chairman) Peter Bletzinger Air Force Wright Aeronautical Laboratory Frank DeLucia Duke University Albert Engelhardt Los Alamos National Laboratory...and other gas discharge plasmas," J. Opt. Soc. Am., 68, 352 (1978). 9. P. Camus , M. Dieulin and C. Morillon, "Optogalvanic detection of barium high...Parkway Wright-Patterson AFB, OH 45433 Everett, MA 02149 513/255-2923 617/389-3000 ext. 36 ext. 568 Rudy Buser Albert G. Engelhardt Night Vision and

Kernel ADA Programming Support Environment (KAPSE) Interface Team Public Report. Volume 4.

DTIC Science & Technology

1984-04-30

the document until further discussion has taken place among the group metbers. RACWG announced their editor, Reed Kotler . The RACWG plans to narrow...KRUTAR, Rudy NRL *LAPLANT, Bill HQ USAF LOPER, Warren NOSC *MAGLIERI, Lucas Canadian National Defense HQ MILLER, Jo NWC MYERS, Gil NOSC *MYERS, Philip ...HUMPHREY, Dianna Control Data Corp. JOHNSON, Ron Boeing Aerospace Co. KERNER, Judy Norden Systems KOTLER , Reed Lockheed Missiles & Space LAMB, J. Eli

The new normal. Avoiding financial risk and boosting transparency and governance are all emphasized in the wake of September 2008's meltdown.

PubMed

Evans, Melanie; Galloro, Vince

2009-09-21

A year after the financial sector's meltdown, hospitals are still adjusting to the economic landscape. Where once they overlooked potential balance sheet stress from debt portfolios and the riskiness of their investments, they now obsess about risk and how to minimize it. "Systems are spending a lot more time on this than they were a year ago," says Kerry Rudy, of Ziegler Capital Markets.

Biophysical Coupling Between Turbulence, Veliger Behavior, and Larval Supply

DTIC Science & Technology

2005-09-01

the freedom to pursue this research, and for being such an excellent role model. Thanks also to my committee, Mike Neubert, Rudy Scheltema, Glenn...Flierl, Danny Griinbaum, and Scott Gallager for all of their helpful suggestions. I’m grateful to Mike for his encouragement and for showing me how math...appreciation for statistics. Thanks to Hal Caswell, Mike Neubert, and everyone in their labs for letting me attend lab meetings and Nantucket retreats; I

Joint Force Quarterly. Issue 56, 1st Quarter, January 2010

DTIC Science & Technology

2010-01-01

He opines that “building a rudi- mentary state, even a flawed one that is able to provide a modicum of security and gover - nance to its people, is...as its ethos to balance tribal elites and powerbrokers that often remain wedded to benefiting their peers. Third, the concept of official gover ...American approach. A renewed U.S. commitment to funding grassroots development and gover - nance must accompany the influx of troops. The Afghan

Ceramics for High Power Lasers

DTIC Science & Technology

2013-07-01

139-144 (Wiley, 2009). [22] M.F. Becker, D.J. Kuizenga, A.E. Siegman , “Harmonic Mode Locking of the Nd:YAG Laser ,” IEEE Journal of Quantum...AFRL-OSR-VA-TR-2013-0347 Ceramics for High Power Lasers R.L. Byer, R.M. Gaume, R.K. Route, C. Rudy Stanford University July...To) 05-15-2010 to 05-15-2013 4. TITLE AND SUBTITLE Ceramics for High Power Lasers 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-10-1-0227

Heart Fibrillation and Parallel Supercomputers

NASA Technical Reports Server (NTRS)

Kogan, B. Y.; Karplus, W. J.; Chudin, E. E.

1997-01-01

The Luo and Rudy 3 cardiac cell mathematical model is implemented on the parallel supercomputer CRAY - T3D. The splitting algorithm combined with variable time step and an explicit method of integration provide reasonable solution times and almost perfect scaling for rectilinear wave propagation. The computer simulation makes it possible to observe new phenomena: the break-up of spiral waves caused by intracellular calcium and dynamics and the non-uniformity of the calcium distribution in space during the onset of the spiral wave.

ALONE, UNARMED, AND UNAFRAID OVER CUBA: THE STORY OF MAJOR RUDY ANDERSON

DTIC Science & Technology

2017-06-01

Junior. Major Anderson was a U-2 pilot during the Cuban Missile Crisis and was shot down on 27 October 1962 while conducting a reconnaissance...the SA-2 Guideline). Two and a half years earlier one of his friends, Francis Gary Powers, flying a similarly configured U-2, was shot down over... shot down the first US reconnaissance flight on 8 April 1950.8 The Soviets were frustrated by the continual US overflights and wanted to put an

Fly with Eagles

NASA Astrophysics Data System (ADS)

Brown, G. E.

My training in many areas of research in theoretical physics derived from what I learned from the "eagles" I flew with. Let me enumerate them. First of all, when the Navy sent me to the University of Wisconsin in January 1944 to become an electrical engineering officer, I met Gregory Breit, who practically adopted me as a son. I learned from him to drag a problem bleeding through the street until it cried for help and gave up. My political indiscretions during my young life forced me to flee to England from Joe McCarthy, where I ended up in the inspiring theory group of Rudi Peierls. Peierls taught us to drive immediately to fundamentals. When I began collaborating with Hans Bethe, the first thing I learned was why he had never had long-term collaborators. I had to wait until he was more than 70 years old in order to have any chance of keeping up with him. He worked like a bulldozer, heading directly for the light at the end of the tunnel. Most important is confidence. He starts each day with a pile of white paper in the upper left-hand corner of his desk and fills it with calculations at a more or less even rate, although he's happy to stop for lunch. I found this to be an amazingly effective procedure to imitate. From my training with Rudi Peierls, his closest friend, I was well prepared to work with Hans. The twenty-odd years I've collaborated with him have been exciting and productive.

Design of an Automatic Octave Sound Analyzer and Recorder

DTIC Science & Technology

1942-11-21

e Fredric Flader Henry K. Growald Mr. A. E. Raymond Mr. E. P. Wheaton El Segundo, California Mr. Paul Dennis Fairchild Aircraft Division...Dr. E. B« I-’oots Dr. R. H. Nichols, Jr\\ Mr. H. ■v. RudiTiose Mr. R. L. Wallace , Jr. Dr. P. M. Wiener Mr. H. F. Dienel Mr. H. L. Eri c :J on Mr...25 43 I / Recorder Motor "ON-OFF Switch^//’] \\ ^ti Indexing Switch Mazda 47 B j MUT Pilot Light -Jjv k4: 10A. \\A Start Switch ch

Program Code Generator for Cardiac Electrophysiology Simulation with Automatic PDE Boundary Condition Handling

PubMed Central

Punzalan, Florencio Rusty; Kunieda, Yoshitoshi; Amano, Akira

2015-01-01

Clinical and experimental studies involving human hearts can have certain limitations. Methods such as computer simulations can be an important alternative or supplemental tool. Physiological simulation at the tissue or organ level typically involves the handling of partial differential equations (PDEs). Boundary conditions and distributed parameters, such as those used in pharmacokinetics simulation, add to the complexity of the PDE solution. These factors can tailor PDE solutions and their corresponding program code to specific problems. Boundary condition and parameter changes in the customized code are usually prone to errors and time-consuming. We propose a general approach for handling PDEs and boundary conditions in computational models using a replacement scheme for discretization. This study is an extension of a program generator that we introduced in a previous publication. The program generator can generate code for multi-cell simulations of cardiac electrophysiology. Improvements to the system allow it to handle simultaneous equations in the biological function model as well as implicit PDE numerical schemes. The replacement scheme involves substituting all partial differential terms with numerical solution equations. Once the model and boundary equations are discretized with the numerical solution scheme, instances of the equations are generated to undergo dependency analysis. The result of the dependency analysis is then used to generate the program code. The resulting program code are in Java or C programming language. To validate the automatic handling of boundary conditions in the program code generator, we generated simulation code using the FHN, Luo-Rudy 1, and Hund-Rudy cell models and run cell-to-cell coupling and action potential propagation simulations. One of the simulations is based on a published experiment and simulation results are compared with the experimental data. We conclude that the proposed program code generator can be used to generate code for physiological simulations and provides a tool for studying cardiac electrophysiology. PMID:26356082

Quadratic adaptive algorithm for solving cardiac action potential models.

PubMed

Chen, Min-Hung; Chen, Po-Yuan; Luo, Ching-Hsing

2016-10-01

An adaptive integration method is proposed for computing cardiac action potential models accurately and efficiently. Time steps are adaptively chosen by solving a quadratic formula involving the first and second derivatives of the membrane action potential. To improve the numerical accuracy, we devise an extremum-locator (el) function to predict the local extremum when approaching the peak amplitude of the action potential. In addition, the time step restriction (tsr) technique is designed to limit the increase in time steps, and thus prevent the membrane potential from changing abruptly. The performance of the proposed method is tested using the Luo-Rudy phase 1 (LR1), dynamic (LR2), and human O'Hara-Rudy dynamic (ORd) ventricular action potential models, and the Courtemanche atrial model incorporating a Markov sodium channel model. Numerical experiments demonstrate that the action potential generated using the proposed method is more accurate than that using the traditional Hybrid method, especially near the peak region. The traditional Hybrid method may choose large time steps near to the peak region, and sometimes causes the action potential to become distorted. In contrast, the proposed new method chooses very fine time steps in the peak region, but large time steps in the smooth region, and the profiles are smoother and closer to the reference solution. In the test on the stiff Markov ionic channel model, the Hybrid blows up if the allowable time step is set to be greater than 0.1ms. In contrast, our method can adjust the time step size automatically, and is stable. Overall, the proposed method is more accurate than and as efficient as the traditional Hybrid method, especially for the human ORd model. The proposed method shows improvement for action potentials with a non-smooth morphology, and it needs further investigation to determine whether the method is helpful during propagation of the action potential. Copyright © 2016 Elsevier Ltd. All rights reserved.

KSC-2012-2767

NASA Image and Video Library

2012-05-14

CAPE CANAVERAL, Fla. – Outside the Operations and Checkout Building, Rudy Werlink gives students a first-hand look at the workings of the cryogenics lab. The 26 honor students in chemistry and biology and their teachers got a chance to visit a number of high-tech labs at Kennedy Space Center as part of an effort to encourage students in the areas of science, technology, engineering and math. The tenth and eleventh grade students from Terry Parker High School in Jacksonville, Fla., visited a number of vastly different labs during their one-day tour. The group's visit to Kennedy was hosted by the Education Office as part of a nationwide effort by the National Lab Network to help introduce the nation's students to science careers. Photo credit: NASA/Jim Grossmann

In the limelight of stars. Einstein, Mandl, and the origins of gravitational lens research (German Title: Im Rampenlicht der Sterne. Einstein, Mandl und die Ursprünge der Gravitationslinsenforschung)

NASA Astrophysics Data System (ADS)

Renn, Jürgen; Sauer, Tilman

Einstein's paper on gravitational lensing from 1936 was published only as a result of insistent prodding by the Czech amateur scientist Rudi Mandl. We discuss Mandl's role for the publication history of Einstein's paper and point out striking similarities between Mandl's situation in 1936 and Einstein's own position in 1912. At that time, Einstein himself had already considered the idea of gravitational lensing, as had been discovered some years ago through the identification of research notes from that period. Other early discussions of gravitational lensing by Lodge, Chwolson, Tikhov, Zwicky, Russell, and others were either only perceived or only written after Mandl had succeeded to persuade Einstein into publication.

KSC-2012-2769

NASA Image and Video Library

2012-05-14

CAPE CANAVERAL, Fla. – Inside the Operations and Checkout Building, Rudy Werlink gives students a first-hand look at the workings of the sound testing area of cryogenics lab. The 26 honor students in chemistry and biology and their teachers got a chance to visit a number of high-tech labs at Kennedy Space Center as part of an effort to encourage students in the areas of science, technology, engineering and math. The tenth and eleventh grade students from Terry Parker High School in Jacksonville, Fla., visited a number of vastly different labs during their one-day tour. The group's visit to Kennedy was hosted by the Education Office as part of a nationwide effort by the National Lab Network to help introduce the nation's students to science careers. Photo credit: NASA/Jim Grossmann

KSC-2012-2768

NASA Image and Video Library

2012-05-14

CAPE CANAVERAL, Fla. – Inside the Operations and Checkout Building, Rudy Werlink gives students a first-hand look at the workings of the sound testing area of cryogenics lab. The 26 honor students in chemistry and biology and their teachers got a chance to visit a number of high-tech labs at Kennedy Space Center as part of an effort to encourage students in the areas of science, technology, engineering and math. The tenth and eleventh grade students from Terry Parker High School in Jacksonville, Fla., visited a number of vastly different labs during their one-day tour. The group's visit to Kennedy was hosted by the Education Office as part of a nationwide effort by the National Lab Network to help introduce the nation's students to science careers. Photo credit: NASA/Jim Grossmann

Genetically engineered cardiac pacemaker: Stem cells transfected with HCN2 gene and myocytes—A model

NASA Astrophysics Data System (ADS)

Kanani, S.; Pumir, A.; Krinsky, V.

2008-01-01

One of the successfully tested methods to design genetically engineered cardiac pacemaker cells consists in transfecting a human mesenchymal stem cell (hMSC) with a HCN2 gene and connecting it to a myocyte. We develop and study a mathematical model, describing a myocyte connected to a hMSC transfected with a HCN2 gene. The cardiac action potential is described both with the simple Beeler Reuter model, as well as with the elaborate dynamic Luo Rudy model. The HCN2 channel is described by fitting electrophysiological records, in the spirit of Hodgkin Huxley. The model shows that oscillations can occur in a pair myocyte-stem cell, that was not observed in the experiments yet. The model predicted that: (1) HCN pacemaker channels can induce oscillations only if the number of expressed I channels is low enough. At too high an expression level of I channels, oscillations cannot be induced, no matter how many pacemaker channels are expressed. (2) At low expression levels of I channels, a large domain of values in the parameter space (n, N) exists, where oscillations should be observed. We denote N the number of expressed pacemaker channels in the stem cell, and n the number of gap junction channels coupling the stem cell and the myocyte. (3) The expression levels of I channels observed in ventricular myocytes, both in the Beeler Reuter and in the dynamic Luo Rudy models are too high to allow to observe oscillations. With expression levels below ˜1/4 of the original value, oscillations can be observed. The main consequence of this work is that in order to obtain oscillations in an experiment with a myocyte-stem cell pair, increasing the values of n, N is unlikely to be helpful, unless the expression level of I has been reduced enough. The model also allows us to explore levels of gene expression not yet achieved in experiments, and could be useful to plan new experiments, aimed at improving the robustness of the oscillations.

Modeling the response of normal and ischemic cardiac tissue to electrical stimulation

NASA Astrophysics Data System (ADS)

Kandel, Sunil Mani

Heart disease, the leading cause of death worldwide, is often caused by ventricular fibrillation. A common treatment for this lethal arrhythmia is defibrillation: a strong electrical shock that resets the heart to its normal rhythm. To design better defibrillators, we need a better understanding of both fibrillation and defibrillation. Fundamental mysteries remain regarding the mechanism of how the heart responds to a shock, particularly anodal shocks and the resultant hyperpolarization. Virtual anodes play critical roles in defibrillation, and one cannot build better defibrillators until these mechanisms are understood. We are using mathematical modeling to numerically simulate observed phenomena, and are exploring fundamental mechanisms responsible for the heart's electrical behavior. Such simulations clarify mechanisms and identify key parameters. We investigate how systolic tissue responds to an anodal shock and how refractory tissue reacts to hyperpolarization by studying the dip in the anodal strength-interval curve. This dip is due to electrotonic interaction between regions of depolarization and hyperpolarization following a shock. The dominance of the electrotonic mechanism over calcium interactions implies the importance of the spatial distribution of virtual electrodes. We also investigate the response of localized ischemic tissue to an anodal shock by modeling a regional elevation of extracellular potassium concentration. This heterogeneity leads to action potential instability, 2:1 conduction block (alternans), and reflection-like reentry at the boarder of the normal and ischemic regions. This kind of reflection (reentry) occurs due to the delay between proximal and distal segments to re-excite the proximal segment. Our numerical simulations are based on the bidomain model, the state-of-the-art mathematical description of how cardiac tissue responds to shocks. The dynamic LuoRudy model describes the active properties of the membrane. To model ischemia, the Luo-Rudy model is modified by adding ischemic-related ion currents and concentrations to mimic conditions during the initial phase of ischemia. The stimulus is applied through a unipolar electrode that induces a complicated spatial distribution of transmembrane potential, including adjacent regions of depolarization and hyperpolarization. This research is significant because it uncovers basic properties of excitation that are fundamental for understanding cardiac pacing and defibrillation.

The blowflies of the Madeira Archipelago: species diversity, distribution and identification (Diptera, Calliphoridae s. l.)

PubMed Central

Prado e Castro, Catarina; Szpila, Krzysztof; Martínez-Sánchez, Anabel; Rego; Silva, Isamberto; Serrano, Artur R.M.; Boieiro, Mário

2016-01-01

Abstract Knowledge on the taxonomic diversity and distribution of blowflies from the Madeira Archipelago is updated. New and interesting findings are reported for poorly studied islands and islets of this archipelago, together with a brief analysis of the diversity of Macaronesian Calliphoridae s. l. Seven blowfly species were collected during this study, including the first records of Calliphora vicina Robineau-Desvoidy, 1830, Chrysomya albiceps (Wiedemann, 1819), Lucilia sericata (Meigen, 1826), Pollenia rudis (Fabricius, 1794) and Stomorhina lunata (Fabricius, 1805) from Porto Santo, and of Calliphora vicina, Lucilia sericata and Stomorhina lunata from Desertas Islands. The presence of Calliphora loewi Enderlein, 1903 in Madeira Laurisilva forest is discussed and its first instar larva is redescribed, revealing important differences in relation to its original description. An identification key to the adult Madeiran blowflies is provided for the first time. PMID:27917052

Distributed computing for membrane-based modeling of action potential propagation.

PubMed

Porras, D; Rogers, J M; Smith, W M; Pollard, A E

2000-08-01

Action potential propagation simulations with physiologic membrane currents and macroscopic tissue dimensions are computationally expensive. We, therefore, analyzed distributed computing schemes to reduce execution time in workstation clusters by parallelizing solutions with message passing. Four schemes were considered in two-dimensional monodomain simulations with the Beeler-Reuter membrane equations. Parallel speedups measured with each scheme were compared to theoretical speedups, recognizing the relationship between speedup and code portions that executed serially. A data decomposition scheme based on total ionic current provided the best performance. Analysis of communication latencies in that scheme led to a load-balancing algorithm in which measured speedups at 89 +/- 2% and 75 +/- 8% of theoretical speedups were achieved in homogeneous and heterogeneous clusters of workstations. Speedups in this scheme with the Luo-Rudy dynamic membrane equations exceeded 3.0 with eight distributed workstations. Cluster speedups were comparable to those measured during parallel execution on a shared memory machine.

KSC-2011-6564

NASA Image and Video Library

2011-07-21

VANDENBERG AIR FORCE BASE, Calif. -- At Vandenberg Air Force Base in California, the interstage of the United Launch Alliance Delta II that will carry NASA's National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) satellite into space is lifted up the side of NASA's Space Launch Complex-2. The interstage provides an interface between the launch vehicle's first and second stages. NPP represents a critical first step in building the next-generation of Earth-observing satellites. NPP will carry the first of the new sensors developed for this satellite fleet, now known as the Joint Polar Satellite System (JPSS) to be launched in 2016. NPP is the bridge between NASA's Earth Observing System (EOS) satellites and the forthcoming series of JPSS satellites. The mission will test key technologies and instruments for the JPSS missions. For more information, visit http://www.nasa.gov/NPP. Photo credit: NASA/VAFB, Rudy Bledsoe

KSC-2011-6563

NASA Image and Video Library

2011-07-21

VANDENBERG AIR FORCE BASE, Calif. -- At Vandenberg Air Force Base in California, the interstage of the United Launch Alliance Delta II that will carry NASA's National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) satellite into space is lifted up the side of NASA's Space Launch Complex-2. The interstage provides an interface between the launch vehicle's first and second stages. NPP represents a critical first step in building the next-generation of Earth-observing satellites. NPP will carry the first of the new sensors developed for this satellite fleet, now known as the Joint Polar Satellite System (JPSS) to be launched in 2016. NPP is the bridge between NASA's Earth Observing System (EOS) satellites and the forthcoming series of JPSS satellites. The mission will test key technologies and instruments for the JPSS missions. For more information, visit http://www.nasa.gov/NPP. Photo credit: NASA/VAFB, Rudy Bledsoe

KSC-2011-6560

NASA Image and Video Library

2011-07-21

VANDENBERG AIR FORCE BASE, Calif. -- At NASA's Space Launch Complex-2 on Vandenberg Air Force Base in California, spacecraft technicians prepare to attach the interstage of the United Launch Alliance Delta II that will carry NASA's National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) satellite into space to a lifting device. The interstage provides an interface between the launch vehicle's first and second stages. NPP represents a critical first step in building the next-generation of Earth-observing satellites. NPP will carry the first of the new sensors developed for this satellite fleet, now known as the Joint Polar Satellite System (JPSS) to be launched in 2016. NPP is the bridge between NASA's Earth Observing System (EOS) satellites and the forthcoming series of JPSS satellites. The mission will test key technologies and instruments for the JPSS missions. For more information, visit http://www.nasa.gov/NPP. Photo credit: NASA/VAFB, Rudy Bledsoe

KSC-2011-6558

NASA Image and Video Library

2011-07-21

VANDENBERG AIR FORCE BASE, Calif. -- At Vandenberg Air Force Base in California, preparations are under way to lift the interstage of the United Launch Alliance Delta II that will carry NASA's National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) satellite into space at NASA's Space Launch Complex-2. The interstage provides an interface between the launch vehicle's first and second stages. NPP represents a critical first step in building the next-generation of Earth-observing satellites. NPP will carry the first of the new sensors developed for this satellite fleet, now known as the Joint Polar Satellite System (JPSS) to be launched in 2016. NPP is the bridge between NASA's Earth Observing System (EOS) satellites and the forthcoming series of JPSS satellites. The mission will test key technologies and instruments for the JPSS missions. For more information, visit http://www.nasa.gov/NPP. Photo credit: NASA/VAFB, Rudy Bledsoe

Propagation of Electrical Excitation in a Ring of Cardiac Cells: A Computer Simulation Study

NASA Technical Reports Server (NTRS)

Kogan, B. Y.; Karplus, W. J.; Karpoukhin, M. G.; Roizen, I. M.; Chudin, E.; Qu, Z.

1996-01-01

The propagation of electrical excitation in a ring of cells described by the Noble, Beeler-Reuter (BR), Luo-Rudy I (LR I), and third-order simplified (TOS) mathematical models is studied using computer simulation. For each of the models it is shown that after transition from steady-state circulation to quasi-periodicity achieved by shortening the ring length (RL), the action potential duration (APD) restitution curve becomes a double-valued function and is located below the original ( that of an isolated cell) APD restitution curve. The distributions of APD and diastolic interval (DI) along a ring for the entire range of RL corresponding to quasi-periodic oscillations remain periodic with the period slightly different from two RLs. The 'S' shape of the original APD restitution curve determines the appearance of the second steady-state circulation region for short RLs. For all the models and the wide variety of their original APD restitution curves, no transition from quasi-periodicity to chaos was observed.

Valsaria and the Valsariales

PubMed Central

Fournier, J.; Dai, D. Q.; Hyde, K. D.; Voglmayr, H.

2016-01-01

More than 100 recent collections of Valsaria sensu lato mostly from Europe were used to elucidate the species composition within the genus. Multigene phylogeny based on SSU, LSU, ITS, rpb2 and tef1 sequences revealed a monophyletic group of ten species within the Dothideomycetes, belonging to three morphologically similar genera. This group could not be accommodated in any known family and are thus classified in the new family Valsariaceae and the new order Valsariales. The genus Valsaria sensu stricto comprises V. insitiva, V. robiniae, V. rudis, V. spartii, V. lopadostomoides sp. nov. and V. neotropica sp. nov., which are phylogenetically well-defined, but morphologically nearly indistinguishable species. The new monotypic genus Bambusaria is introduced to accommodate Valsaria bambusae. Munkovalsaria rubra and Valsaria fulvopruinata are combined in Myrmaecium, a genus traditionally treated as a synonym of Valsaria, which comprises three species, with M. rubricosum as its generic type. This work is presented as a basis for additional species to be detected in future. PMID:27274717

KSC-2012-3731

NASA Image and Video Library

2012-07-09

CAPE CANAVERAL, Fla. – Near the Hypergolic Maintenance Facility at NASA’s Kennedy Space Center in Florida, a groundbreaking ceremony was held to mark the location of the Ground Operations Demonstration Unit Liquid Hydrogen, or GODU LH2, test site. From left, are Johnny Nguyen, Fluids Test and Technology Development branch chief Emily Watkins, engineering intern Jeff Walls, Engineering Services Contract, or ESC, Cryogenics Test Lab engineer Kelly Currin, systems engineer Stephen Huff and Rudy Werlink partially hidden, cryogenics engineers Angela Krenn, systems engineer Doug Hammond, command and control engineer in the electrical division William Notardonato, GODU LH2 project manager and Kevin Jumper, ESC Cryogenics Test Lab manager. The GODU LH2 test site is one of the projects in NASA’s Advanced Exploration Systems Program. The site will be used to demonstrate advanced liquid hydrogen systems that are cost and energy efficient ways to store and transfer liquid hydrogen during process, loading, launch and spaceflight. The main components of the site will be a storage tank and a cryogenic refrigerator. Photo credit: NASA/Dimitri Gerondidakis

KSC-2012-3732

NASA Image and Video Library

2012-07-09

CAPE CANAVERAL, Fla. – Near the Hypergolic Maintenance Facility at NASA’s Kennedy Space Center in Florida, a groundbreaking ceremony was held to mark the location of the Ground Operations Demonstration Unit Liquid Hydrogen, or GODU LH2, test site. From left, are Johnny Nguyen, Fluids Test and Technology Development branch chief Emily Watkins, engineering intern Jeff Walls, Engineering Services Contract, or ESC, Cryogenics Test Lab engineer Kelly Currin, systems engineer Stephen Huff and Rudy Werlink partially hidden, cryogenics engineers Angela Krenn, systems engineer Doug Hammond, command and control engineer in the electrical division William Notardonato, GODU LH2 project manager and Kevin Jumper, ESC Cryogenics Test Lab manager. The GODU LH2 test site is one of the projects in NASA’s Advanced Exploration Systems Program. The site will be used to demonstrate advanced liquid hydrogen systems that are cost and energy efficient ways to store and transfer liquid hydrogen during process, loading, launch and spaceflight. The main components of the site will be a storage tank and a cryogenic refrigerator. Photo credit: NASA/Dimitri Gerondidakis

Generation Mechanism of Alternans in Luo-Rudy Model

NASA Astrophysics Data System (ADS)

Kitajima, Hiroyuki; Ioka, Eri; Yazawa, Toru

Electrical alternans is the alternating amplitude from beat to beat in the action potential of the cardiac cell. It has been associated with ventricular arrhythmias in many clinical studies; however, its dynamical mechanisms remain unknown. The reason is that we do not have realistic network models of the heart system. Recently, Yazawa clarified the network structure of the heart and the central nerve system in the crustacean heart. In this study, we construct a simple model of the heart system based on Yazawa’s experimental data. Using this model, we clarify that two parameters (the conductance of sodium ions and free concentration of potassium ions in the extracellular compartment) play the key roles of generating alternans. In particular, we clarify that the inactivation gate of the time-independent potassium channel is the most important parameter. Moreover, interaction between the membrane potential and potassium ionic currents is significant for generating alternate rhythms. This result indicates that if the muscle cell has problems such as channelopathies, there is great risk of generating alternans.

Effects of pacing magnitudes and forms on bistability width in a modeled ventricular tissue

NASA Astrophysics Data System (ADS)

Huang, Xiaodong; Liu, Xuemei; Zheng, Lixian; Mi, Yuanyuan; Qian, Yu

2013-07-01

Bistability in periodically paced cardiac tissue is relevant to cardiac arrhythmias and its control. In the present paper, one-dimensional tissue of the phase I Luo-Rudy model is numerically investigated. The effects of various parameters of pacing signals on bistability width are studied. The following conclusions are obtained: (i) Pacing can be classified into two types: pulsatile and sinusoidal types. Pulsatile pacing reduces bistability width as its magnitude is increased. Sinusoidal pacing increases the width as its amplitude is increased. (ii) In a pacing period the hyperpolarizing part plays a more important role than the depolarizing part. Variations of the hyperpolarizing ratio in a period evidently change the width of bistability and its variation tendency. (iii) A dynamical mechanism is proposed to qualitatively explain the phenomena, which reveals the reason for the different effects of pulsatile and sinusoidal pacing on bistability. The methods for changing bistability width by external pacing may help control arrhythmias in cardiology.

Isolation of Cryptococcus neoformans var. gattii from Eucalyptus camaldulensis in India.

PubMed Central

Chakrabarti, A; Jatana, M; Kumar, P; Chatha, L; Kaushal, A; Padhye, A A

1997-01-01

Cryptococcus neoformans var. gattii has an ecological association with five Eucalyptus species: E. blakelyi, E. camaldulensis, E. gomphocephala, E. rudis, and E. tereticornis. After human infections due to C. neoformans var. gattii were diagnosed in the states of Punjab, Himachal Pradesh, and Karnataka, India, a study was undertaken to investigate the association of C. neoformans var. gattii with Indian eucalypts, especially in the state of Punjab. A total of 696 specimens collected from E. camaldulensis, E. citriodora and E. tereticornis (hybrid) trees were examined for the presence of C. neoformans var. gattii. Flowers from two trees of E. camaldulensis in the Chak Sarkar forest and one from the village of Periana near the Ferozepur area yielded five isolates of C. neoformans var. gattii. The origin of the trees could be traced to Australia, thus providing evidence that the distribution of E. camaldulensis correlated with the distribution of human cryptococcosis cases caused by C. neoformans var. gattii in northern India. PMID:9399553

Domain-domain interactions determine the gating, permeation, pharmacology, and subunit modulation of the IKs ion channel.

PubMed

Zaydman, Mark A; Kasimova, Marina A; McFarland, Kelli; Beller, Zachary; Hou, Panpan; Kinser, Holly E; Liang, Hongwu; Zhang, Guohui; Shi, Jingyi; Tarek, Mounir; Cui, Jianmin

2014-12-23

Voltage-gated ion channels generate electrical currents that control muscle contraction, encode neuronal information, and trigger hormonal release. Tissue-specific expression of accessory (β) subunits causes these channels to generate currents with distinct properties. In the heart, KCNQ1 voltage-gated potassium channels coassemble with KCNE1 β-subunits to generate the IKs current (Barhanin et al., 1996; Sanguinetti et al., 1996), an important current for maintenance of stable heart rhythms. KCNE1 significantly modulates the gating, permeation, and pharmacology of KCNQ1 (Wrobel et al., 2012; Sun et al., 2012; Abbott, 2014). These changes are essential for the physiological role of IKs (Silva and Rudy, 2005); however, after 18 years of study, no coherent mechanism explaining how KCNE1 affects KCNQ1 has emerged. Here we provide evidence of such a mechanism, whereby, KCNE1 alters the state-dependent interactions that functionally couple the voltage-sensing domains (VSDs) to the pore.

Domain–domain interactions determine the gating, permeation, pharmacology, and subunit modulation of the IKs ion channel

PubMed Central

Zaydman, Mark A; Kasimova, Marina A; McFarland, Kelli; Beller, Zachary; Hou, Panpan; Kinser, Holly E; Liang, Hongwu; Zhang, Guohui; Shi, Jingyi; Tarek, Mounir; Cui, Jianmin

2014-01-01

Voltage-gated ion channels generate electrical currents that control muscle contraction, encode neuronal information, and trigger hormonal release. Tissue-specific expression of accessory (β) subunits causes these channels to generate currents with distinct properties. In the heart, KCNQ1 voltage-gated potassium channels coassemble with KCNE1 β-subunits to generate the IKs current (Barhanin et al., 1996; Sanguinetti et al., 1996), an important current for maintenance of stable heart rhythms. KCNE1 significantly modulates the gating, permeation, and pharmacology of KCNQ1 (Wrobel et al., 2012; Sun et al., 2012; Abbott, 2014). These changes are essential for the physiological role of IKs (Silva and Rudy, 2005); however, after 18 years of study, no coherent mechanism explaining how KCNE1 affects KCNQ1 has emerged. Here we provide evidence of such a mechanism, whereby, KCNE1 alters the state-dependent interactions that functionally couple the voltage-sensing domains (VSDs) to the pore. DOI: http://dx.doi.org/10.7554/eLife.03606.001 PMID:25535795

Scroll wave dynamics in a three-dimensional cardiac tissue model: roles of restitution, thickness, and fiber rotation.

PubMed Central

Qu, Z; Kil, J; Xie, F; Garfinkel, A; Weiss, J N

2000-01-01

Scroll wave (vortex) breakup is hypothesized to underlie ventricular fibrillation, the leading cause of sudden cardiac death. We simulated scroll wave behaviors in a three-dimensional cardiac tissue model, using phase I of the Luo-Rudy (LR1) action potential model. The effects of action potential duration (APD) restitution, tissue thickness, filament twist, and fiber rotation were studied. We found that APD restitution is the major determinant of scroll wave behavior and that instabilities arising from APD restitution are the main determinants of scroll wave breakup in this cardiac model. We did not see a "thickness-induced instability" in the LR1 model, but a minimum thickness is required for scroll breakup in the presence of fiber rotation. The major effect of fiber rotation is to maintain twist in a scroll wave, promoting filament bending and thus scroll breakup. In addition, fiber rotation induces curvature in the scroll wave, which weakens conduction and further facilitates wave break. PMID:10827961

Underground Lead-Zinc Mine Production Planning Using Fuzzy Stochastic Inventory Policy / Planowanie Wydobycia Cynku I Ołowiu W Kopalniach Podziemnych Z Wykorzystaniem Podejścia Stochastycznego Z Elementami Logiki Rozmytej Do Określania Niezbędnego Poziomu Zapasów

NASA Astrophysics Data System (ADS)

Gligoric, Zoran; Beljic, Cedomir; Gluscevic, Branko; Cvijovic, Cedomir

2015-03-01

Methodology for long-term underground lead-zinc mine planning based on fuzzy inventory theory is presented in this paper. We developed a fuzzy stochastic model of inventory control problem for planning lead-zinc ore production under uncertainty. The final purpose of this article is to find the optimal quantity of mined ore that should be stockpiled, in order to enable "feeding" of mineral processing plant in cases when the production in underground mine is interrupted, by using Possibilistic mean value of fuzzy number for defuzzing the fuzzy total annual inventory costs, and by using Extension of the Lagrangean method for solving inequality constrain problem. The different types of costs involved in mined ore inventory problems affect the efficiency of production scheduling. Dynamic nature of lead and zinc metal price is described by Ornstein-Uhlenbeck stochastic mean reverting process. The model is illustrated with a numerical example. W pracy przedstawiono metodologię długoterminowego wydobycia cynku i ołowiu w kopalniach podziemnych z wykorzystaniem podejścia stochastycznego z elementami logiki rozmytej do określania wymaganego poziomu zapasów. Opracowaliśmy model stochastyczny z wykorzystaniem elementów logiki rozmytej do kontroli zapasów w planowaniu wydobycia cynku i ołowiu w warunkach niepewności. Celem końcowym pracy jest określenie optymalnej ilości wydobywanej rudy, którą należy zachować jako zapas tak aby zapewnić odpowiednie jej dostawy do zakładu przeróbczego nawet w przypadku przerwania wydobycia w kopalni podziemnej, opierając się na posybilistycznej wartości średniej liczby rozmytej i wyostrzeniu całkowitych rocznych kosztów zapasów. Wykorzystano także rozszerzenie metody Lagrange'a do rozwiązywania problemu więzów w nierówności. Różnorakie koszty związane ze składowaniem zapasów wydobywanej rudy mają wpływ na wydajność planowanej produkcji. Dynamiczne zmiany cen cynku i ołowiu zostały określone z wykorzystaniem rewersji średniej stochastycznej, w pracy Ornsteina-Uhlenbecka. Zaprezentowano przykład numeryczny jako ilustrację modelu.

Modelling far field pacing for terminating spiral waves pinned to ischaemic heterogeneities in cardiac tissue

PubMed Central

Boccia, E.; Luther, S.

2017-01-01

In cardiac tissue, electrical spiral waves pinned to a heterogeneity can be unpinned (and eventually terminated) using electric far field pulses and recruiting the heterogeneity as a virtual electrode. While for isotropic media the process of unpinning is much better understood, the case of an anisotropic substrate with different conductivities in different directions still needs intensive investigation. To study the impact of anisotropy on the unpinning process, we present numerical simulations based on the bidomain formulation of the phase I of the Luo and Rudy action potential model modified due to the occurrence of acute myocardial ischaemia. Simulating a rotating spiral wave pinned to an ischaemic heterogeneity, we compare the success of sequences of far field pulses in the isotropic and the anisotropic case for spirals still in transient or in steady rotation states. Our results clearly indicate that the range of pacing parameters resulting in successful termination of pinned spiral waves is larger in anisotropic tissue than in an isotropic medium. This article is part of the themed issue ‘Mathematical methods in medicine: neuroscience, cardiology and pathology’. PMID:28507234

Terrestrial arthropods of Steel Creek, Buffalo National River, Arkansas. II. Sawflies (Insecta: Hymenoptera: "Symphyta")

PubMed Central

Smith, David R.; Fisher, Danielle M.; Dowling, Ashley P.G.

2016-01-01

Abstract Background This is the second in a series of papers detailing the terrestrial arthropods collected during an intensive survey of a site near Steel Creek campground along the Buffalo National River in Arkansas. The survey was conducted over a period of eight and a half months using twelve trap types – Malaise traps, canopy traps (upper and lower collector), Lindgren multifunnel traps (black, green, and purple), pan traps (blue, purple, red, white, and yellow), and pitfall traps – and Berlese-Tullgren extraction of leaf litter. New information We provide collection records for 47 species of "Symphyta" (Insecta: Hymenoptera), 30 of which are new state records for Arkansas: (Argidae) Sterictiphora serotina; (Cimbicidae) Abia americana; (Diprionidae) Monoctenus fulvus; (Orussidae) Orussus terminalis; (Pamphiliidae) Onycholyda luteicornis, Pamphilius ocreatus, P. persicum, P. rileyi; (Pergidae) Acordulecera dorsalis, A. mellina, A. pellucida; (Tenthredinidae) Caliroa quercuscoccineae, Empria coryli, Hoplocampa marlatti, Macrophya cassandra, Monophadnoides conspiculatus, Monophadnus bakeri, Nematus abbotii, Neopareophora litura, Pachynematus corniger, Paracharactus rudis, Periclista marginicollis, Pristiphora banski, P. chlorea, Strongylogaster impressata, S. remota, Taxonus epicera, Thrinax albidopictus, T. multicinctus, Zaschizonyx montana; (Xiphydriidae) Xiphydria tibialis. PMID:27222635

Modelling far field pacing for terminating spiral waves pinned to ischaemic heterogeneities in cardiac tissue

NASA Astrophysics Data System (ADS)

Boccia, E.; Luther, S.; Parlitz, U.

2017-05-01

In cardiac tissue, electrical spiral waves pinned to a heterogeneity can be unpinned (and eventually terminated) using electric far field pulses and recruiting the heterogeneity as a virtual electrode. While for isotropic media the process of unpinning is much better understood, the case of an anisotropic substrate with different conductivities in different directions still needs intensive investigation. To study the impact of anisotropy on the unpinning process, we present numerical simulations based on the bidomain formulation of the phase I of the Luo and Rudy action potential model modified due to the occurrence of acute myocardial ischaemia. Simulating a rotating spiral wave pinned to an ischaemic heterogeneity, we compare the success of sequences of far field pulses in the isotropic and the anisotropic case for spirals still in transient or in steady rotation states. Our results clearly indicate that the range of pacing parameters resulting in successful termination of pinned spiral waves is larger in anisotropic tissue than in an isotropic medium. This article is part of the themed issue `Mathematical methods in medicine: neuroscience, cardiology and pathology'.

The Application of Modern Techniques and Measurement Devices for Identification of Copper Ore Types and Their Properties / Wykorzystanie nowoczesnych technik i urządzeń pomiarowych do identyfikacji typów rud miedzi i ich właściwości

NASA Astrophysics Data System (ADS)

Krawczykowska, Aldona; Trybalski, Kazimierz; Krawczykowski, Damian

2013-06-01

The paper concerns the application of modern methods and research techniques for investigations of copper ore properties. It presents the procedure and tools which, when put together, can constitute a source of information on properties of different products of processing and, simultaneously, can be used in the process control and optimization. The copper ore of one of the branches of the KHGM Polska Miedz plc was investigated. The ore samples represented each of the three lithological types occurring in the Polish deposits, i.e. carbonate, shale and sandstone ores. The paper presents the results of microscopic analyses, image analysis of scanning photographs and application procedures of the obtained information for the identification of ore types (application of neuron networks to the recognition of lithological compositions). The present publication will present sample results of modelling of classification identifying two types of ores, i.e. carbonate-shale and sandstone. Summing up the predictions of ore type fractions in respective mixtures for the considered problem of classification it can be stated that the prediction results are good and confirm the lithological predominance of certain ore types in the investigated mixtures. The experimental part comprised the determination of mineralogical and lithological composition of ores (optical microscope) and also elemental composition in the microareas of analysed samples (scanning microscope). Next, the image analysis was performed and subsequently the models classifying the ore types were made. W rudzie miedzi przerabianej w zakładach wzbogacania O/ZWR KGHM Polska Miedź S.A. można wyróżnić trzy typy litologiczne: rudę węglanową, łupkową i piaskowcową. Typy te różnią się właściwościami między innymi takimi jak: rodzaj i zawartość minerałów miedzi, rodzaj minerałów nieużytecznych, zawartość miedzi, twardość i podatność na rozdrabnianie, ale także wielkością i kształtem ziaren minerałów miedzionośnych oraz rodzajem ich skupień i wpryśnięć. Niezwykle istotne jest właściwe rozpoznanie rudy pod względem petrograficzno-mineralogicznym. Znajomość właściwości przerabianej rudy pozwala na pełniejsze jej wykorzystanie poprzez właściwe prowadzenie i sterowanie procesami, dobór ich parametrów takich m.in. jak: czas mielenia, parametry klasyfikacji, rodzaj odczynników flotacyjnych, czas flotacji. W artykule przedstawiono wyniki przeprowadzonych analiz mikroskopowych, analizy obrazów zdjęć skaningowych oraz procedury wykorzystania otrzymanych informacji do identyfikacji typów rud (zastosowanie sieci neuronowych do rozpoznawania składów litologicznych). W badaniach wykorzystano rudę miedzi, pochodzącą z jednego z zakładów górniczych KGHM Polska Miedź S.A. Pobrane próbki rudy reprezentowały każdy z trzech typów litologicznych występujących w krajowych złożach: węglanową, łupkową oraz piaskowcową. Przeprowadzono ilościową analizę mineralogiczno-petrograficzną przy pomocy mikroskopu optycznego w świetle odbitym, a wyniki przedstawiono w tabelach 1 i 2. Wyniki te określają ilościowo stopień uwolnienia i zrosty dla jednego rodzaju minerału. Pokazano także przykładowe zdjęcia mikroskopowe zgładów poszczególnych typów litologicznych rud oraz próbek proszkowych tych typów (rys. 1 i 2). W kolejnym etapie badań wykorzystano skaningowy mikroskop elektronowy. Zdjęcia morfologii próbek uzyskane z mikroskopu elektronowego (obrazy SEM) były przedmiotem komputerowej analizy obrazu, umożliwiającej mikrostrukturalną klasyfikację ilościową typów rud. Analizowano wszystkie próbki poszczególnych typów litologicznych rudy miedzi: węglanowej, łupkowej i piaskowcowej oraz mieszanki tych typów w trzech klasach ziarnowych: 0÷45 μm, 45÷71 μm i 71÷100 μm. Celem przekształceń wykorzystanych w procedurze komputerowej analizy obrazu jest otrzymanie poprawnie posegmentowanego obrazu binarnego, który umożliwiałby wyróżnienie badanych obiektów - pojedynczych (poszczególnych) ziaren oraz tła, a następnie wykonanie pomiarów parametrów zbinaryzowanych obiektów. Spośród dużej ilości parametrów dostępnych w używanym oprogramowaniu do identyfikacji typów rud wybrano najważniejsze z punktu widzenia opisu ziaren. Obok parametrów opisujących podstawowe właściwości geometryczne tj. pole powierzchni, wysokość, szerokość, średnice Feret'a, oraz opisujących kształt ziaren, np. współczynniki wypełnienia, kolistości, wybrano parametry szarości obiektów. W tabeli 3 podano wartości statystyczne zmiennych wykorzystywanych w obliczeniach modelowych, dla jednego z materiałów. Do analizy uzyskanych danych wykorzystano sieci neuronowe. W niniejszej publikacji przedstawiono przykładowe wyniki modelowania dla zagadnienia klasyfikacji identyfikującego dwa typy rud: węglanowo-łupkową i piaskowcową. Połączenie rud: węglanowej i łupkowej w jeden typ ma swoje technologiczne uzasadnienie. Obliczenia modelujące wykonano przy użyciu komputerowego programu do modelowania Statistica Neural Networks firmy StatSoft. W tabeli 4 i 5 przedstawiono charakterystyki ostatecznych najskuteczniejszych modeli sieci neuronowych klasyfikujących typy rud. Ogólnie modele sieci neuronowych, realizujące zagadnienie klasyfikacji typów rud, charakteryzowały się wysoką jakością działania oraz małymi błędami sieci dla poszczególnych podzbiorów danych (uczącego, walidacyjnego i testowego). Świadczy to o ich wysokiej stabilności i pewności działania w przypadku uruchamiania sieci na nowych zbiorach danych. Weryfikacja zdolności predykcyjnych najskuteczniejszych modeli sieci neuronowych polegała na uruchomieniu sieci na nowych danych charakterystycznych dla poszczególnych mieszanek, oraz na porównaniu i ocenie uzyskanych przewidywań z rzeczywistymi udziałami poszczególnych typów rud miedzi w analizowanych mieszankach. Na rysunkach 6 i 7 przedstawiono wyniki przewidywań udziałów odmian litologicznych rud miedzi w mieszankach. Podsumowując przewidywania udziałów typów rud w poszczególnych mieszankach dla rozważanego zagadnienia klasyfikacji można stwierdzić, że wyniki przewidywań są dobre i potwierdzają przewagę litologiczną określonych odmian rud w badanych mieszankach. Szczególnie istotny z technologicznego punktu widzenia jest wysoki stopień trafności przewidywań typów rud dla szerokiej klasy ziarnowej, która odpowiada zazwyczaj rzeczywistemu składowi ziarnowemu nadawy do procesu flotacji. Trafność tych przewidywań jest większa dla mieszanek z przewagą rudy piaskowcowej.

Nonlinear effects in subthreshold virtual electrode polarization.

PubMed

Sambelashvili, Aleksandre T; Nikolski, Vladimir P; Efimov, Igor R

2003-06-01

Introduction of the virtual electrode polarization (VEP) theory suggested solutions to several century-old puzzles of heart electrophysiology including explanation of the mechanisms of stimulation and defibrillation. Bidomain theory predicts that VEPs should exist at any stimulus strength. Although the presence of VEPs for strong suprathreshold pulses has been well documented, their existence at subthreshold strengths during diastole remains controversial. We studied cardiac membrane polarization produced by subthreshold stimuli in 1) rabbit ventricular muscle using high-resolution fluorescent imaging with the voltage-sensitive dye pyridinium 4-[2-[6-(dibutylamino)-2-naphthalenyl]-ethenyl]-1-(3-sulfopropyl)hydroxide (di-4-ANEPPS) and 2) an active bidomain model with Luo-Rudy ion channel kinetics. Both in vitro and in numero models show that the common dog-bone-shaped VEP is present at any stimulus strength during both systole and diastole. Diastolic subthreshold VEPs exhibited nonlinear properties that were expressed in time-dependent asymmetric reversal of membrane polarization with respect to stimulus polarity. The bidomain model reveals that this asymmetry is due to nonlinear properties of the inward rectifier potassium current. Our results suggest that active ion channel kinetics modulate the transmembrane polarization pattern that is predicted by the linear bidomain model of cardiac syncytium.

How does an inventor find an investor or partner? Raising funds to start a company.

PubMed

Mazzocchi, Rudy A

2017-05-01

Rudy Mazzocchi has over 25 years of senior executive management, technology and intellectual property development, and financing experience in the medical-technology/biotechnology industries. He serves currently as cofounder/chief executive officer of ELENZA, Inc, an ophthalmology company that has developed an electro-active, autofocusing, implantable lens; executive chairman of Establishment Labs; executive chairman of LAFORGE Optical; and executive chairman of OptiSTENT, Inc. He served previously as managing director of Accuitive Medical Ventures and The Innovation Factory; cofounder/chief executive officer of Image-Guided NEUROLOGICS, acquired by Medtronic in 2005; and founding chief executive officer of MICROVENA Corporation, which became "eV3," acquired by Covidien. He was formerly cofounder/director of Vascular Science, acquired by St Jude Medical in 1996, and cofounder/chairman of CytoGenesis, one of the first United States stem cell companies that was merged with BresaGen and listed on the Australian public exchange. He is the recipient of the Technology Leadership Award, the Businessman of the Year Award, the Ernst & Young Entrepreneur of the Year Award in Healthcare, and Global Entrepreneur of the Year Award. He has also authored more than 70 patents; 2 published, award-winning novels (medical thrillers); and a top-selling business book on entrepreneurism. Copyright © 2016 Elsevier Inc. All rights reserved.

A generalised individual-based algorithm for modelling the evolution of quantitative herbicide resistance in arable weed populations.

PubMed

Liu, Chun; Bridges, Melissa E; Kaundun, Shiv S; Glasgow, Les; Owen, Micheal Dk; Neve, Paul

2017-02-01

Simulation models are useful tools for predicting and comparing the risk of herbicide resistance in weed populations under different management strategies. Most existing models assume a monogenic mechanism governing herbicide resistance evolution. However, growing evidence suggests that herbicide resistance is often inherited in a polygenic or quantitative fashion. Therefore, we constructed a generalised modelling framework to simulate the evolution of quantitative herbicide resistance in summer annual weeds. Real-field management parameters based on Amaranthus tuberculatus (Moq.) Sauer (syn. rudis) control with glyphosate and mesotrione in Midwestern US maize-soybean agroecosystems demonstrated that the model can represent evolved herbicide resistance in realistic timescales. Sensitivity analyses showed that genetic and management parameters were impactful on the rate of quantitative herbicide resistance evolution, whilst biological parameters such as emergence and seed bank mortality were less important. The simulation model provides a robust and widely applicable framework for predicting the evolution of quantitative herbicide resistance in summer annual weed populations. The sensitivity analyses identified weed characteristics that would favour herbicide resistance evolution, including high annual fecundity, large resistance phenotypic variance and pre-existing herbicide resistance. Implications for herbicide resistance management and potential use of the model are discussed. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Mutualism between co-introduced species facilitates invasion and alters plant community structure

PubMed Central

Prior, Kirsten M.; Robinson, Jennifer M.; Meadley Dunphy, Shannon A.; Frederickson, Megan E.

2015-01-01

Generalized mutualisms are often predicted to be resilient to changes in partner identity. Variation in mutualism-related traits between native and invasive species however, can exacerbate the spread of invasive species (‘invasional meltdown’) if invasive partners strongly interact. Here we show how invasion by a seed-dispersing ant (Myrmica rubra) promotes recruitment of a co-introduced invasive over native ant-dispersed (myrmecochorous) plants. We created experimental communities of invasive (M. rubra) or native ants (Aphaenogaster rudis) and invasive and native plants and measured seed dispersal and plant recruitment. In our mesocosms, and in laboratory and field trials, M. rubra acted as a superior seed disperser relative to the native ant. By contrast, previous studies have found that invasive ants are often poor seed dispersers compared with native ants. Despite belonging to the same behavioural guild, seed-dispersing ants were not functionally redundant. Instead, native and invasive ants had strongly divergent effects on plant communities: the invasive plant dominated in the presence of the invasive ant and the native plants dominated in the presence of the native ant. Community changes were not due to preferences for coevolved partners: variation in functional traits of linked partners drove differences. Here, we show that strongly interacting introduced mutualists can be major drivers of ecological change. PMID:25540283

Differential calcium sensitivity in NaV 1.5 mixed syndrome mutants.

PubMed

Abdelsayed, Mena; Baruteau, Alban-Elouen; Gibbs, Karen; Sanatani, Shubhayan; Krahn, Andrew D; Probst, Vincent; Ruben, Peter C

2017-09-15

SCN5a mutations may express gain-of-function (Long QT Syndrome-3), loss-of-function (Brugada Syndrome 1) or both (mixed syndromes), depending on the mutation and environmental triggers. One such trigger may be an increase in cytosolic calcium, accompanying exercise. Many mixed syndromes mutants, including ∆KPQ, E1784K, 1795insD and Q1909R, are found in calcium-sensitive regions. Elevated cytosolic calcium attenuates gain-of-function properties in ∆KPQ, 1795insD and Q1909R, but not in E1784K. By contrast, elevated cytosolic calcium further exacerbates gain-of-function in E1784K by destabilizing slow inactivation. Action potential modelling, using a modified O'Hara Rudy model, suggests that elevated heart rate rescues action potential duration in ∆KPQ, 1795insD and Q1909R, but not in E1784K. Action potential simulations suggest that E1784K carriers have an increased intracellular sodium-to-calcium ratio under bradycardia and tachycardia conditions. Elevated cytosolic calcium, which is common during high heart rates, ameliorates or exacerbates the mixed syndrome phenotype depending on the genetic signature. Inherited arrhythmias may arise from mutations in the gene for SCN5a, which encodes the cardiac voltage-gated sodium channel, Na V 1.5. Mutants in Na V 1.5 result in Brugada Syndrome (BrS1), Long-QT Syndrome (LQT3) or mixed syndromes (an overlap of BrS1/LQT3). Exercise is a potential arrhythmogenic trigger in mixed syndromes. We aimed to determine the effects of elevated cytosolic calcium, which is common during exercise, in mixed syndrome Na V 1.5 mutants. We used whole-cell patch clamp to assess the biophysical properties of Na V 1.5 wild-type (WT), ∆KPQ, E1784K, 1795insD and Q1909R mutants in human embryonic kidney 293 cells transiently transfected with the Na V 1.5 α subunit (WT or mutants), β1 subunit and enhanced green fluorescent protein. Voltage-dependence and kinetics were measured at cytosolic calcium levels of approximately 0, 500 and 2500 nm. In silico, action potential (AP) model simulations were performed using a modified O'Hara Rudy model. Elevated cytosolic calcium attenuates the late sodium current in ∆KPQ, 1795insD and Q1909R, but not in E1784K. Elevated cytosolic calcium restores steady-state slow inactivation (SSSI) to the WT-form in Q1909R, but depolarized SSSI in E1784K. Our AP simulations showed a frequency-dependent reduction of AP duration in ∆KPQ, 1795insD and Q1909R carriers. In E1784K, AP duration is relatively prolonged at both low and high heart rates, resulting in a sodium overload. Cellular perturbations during exercise may affect BrS1/LQT3 patients differently depending on their individual genetic signature. Thus, exercise may be therapeutic or may be an arrhythmogenic trigger in some SCN5a patients. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

Simulation of action potentials from metabolically impaired cardiac myocytes. Role of ATP-sensitive K+ current.

PubMed

Ferrero, J M; Sáiz, J; Ferrero, J M; Thakor, N V

1996-08-01

The role of the ATP-sensitive K+ current (IK-ATP) and its contribution to electrophysiological changes that occur during metabolic impairment in cardiac ventricular myocytes is still being discussed. The aim of this work was to quantitatively study this issue by using computer modeling. A model of IK-ATP is formulated and incorporated into the Luo-Rudy ionic model of the ventricular action potential. Action potentials under different degrees of activation of IK-ATP are simulated. Our results show that in normal ionic concentrations, only approximately 0.6% of the KATP channels, when open, should account for a 50% reduction in action potential duration. However, increased levels of intracellular Mg2+ counteract this shortening. Under conditions of high [K+]0, such as those found in early ischemia, the activation of only approximately 0.4% of the KATP channels could account for a 50% reduction in action potential duration. Thus, our results suggest that opening of IK-ATP channels should play a significant role in action potential shortening during hypoxic/ischemic episodes, with the fraction of open channels involved being very low ( < 1%). However, the results of the model suggest that activation of IK-ATP alone does not quantitatively account for the observed K+ efflux in metabolically impaired cardiac myocytes. Mechanisms other than KATP channel activation should be responsible for a significant part of the K+ efflux measured in hypoxic/ischemic situations.

Change of short-term memory effect in acute ischemic ventricular myocardium: a computational study.

PubMed

Mei, Xi; Wang, Jing; Zhang, Hong; Liu, Zhi-cheng; Zhang, Zhen-xi

2014-02-01

The ionic mechanism of change in short-term memory (STM) during acute myocardial ischemia has not been well understood. In this paper, an advanced guinea pig ventricular model developed by Luo and Rudy was used to investigate STM property of ischemic ventricular myocardium. STM response was calculated by testing the time to reach steady-state action potential duration (APD) after an abrupt shortening of basic cycling length (BCL) in the pacing protocol. Electrical restitution curves (RCs), which can simultaneously visualize multiple aspects of APD restitution and STM, were obtained from dynamic and local S1S2 restitution portrait (RP), which consist of a longer interval stimulus (S1) and a shorter interval stimulus (S2). The angle between dynamic RC and local S1S2 RC reflects the amount of STM. Our results indicated that compared with control (normal) condition, time constant of STM response in the ischemic condition decreased significantly. Meanwhile the angle which reflects STM amount is less in ischemic model than that in control model. By tracking the effect of ischemia on intracellular ion concentration and membrane currents, we declared that changes in membrane currents caused by ischemia exert subtle influences on STM; it is only the decline of intracellular calcium concentration that give rise to the most decrement of STM. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Pathways, Networks and Systems Medicine Conferences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nadeau, Joseph H.

The 6th Pathways, Networks and Systems Medicine Conference was held at the Minoa Palace Conference Center, Chania, Crete, Greece (16-21 June 2008). The Organizing Committee was composed of Joe Nadeau (CWRU, Cleveland), Rudi Balling (German Research Centre, Brauschweig), David Galas (Institute for Systems Biology, Seattle), Lee Hood (Institute for Systems Biology, Seattle), Diane Isonaka (Seattle), Fotis Kafatos (Imperial College, London), John Lambris (Univ. Pennsylvania, Philadelphia),Harris Lewin (Univ. of Indiana, Urbana-Champaign), Edison Liu (Genome Institute of Singapore, Singapore), and Shankar Subramaniam (Univ. California, San Diego). A total of 101 individuals from 21 countries participated in the conference: USA (48), Canada (5),more » France (5), Austria (4), Germany (3), Italy (3), UK (3), Greece (2), New Zealand (2), Singapore (2), Argentina (1), Australia (1), Cuba (1), Denmark (1), Japan (1), Mexico (1), Netherlands (1), Spain (1), Sweden (1), Switzerland (1). With respect to speakers, 29 were established faculty members and 13 were graduate students or postdoctoral fellows. With respect to gender representation, among speakers, 13 were female and 28 were male, and among all participants 43 were female and 58 were male. Program these included the following topics: Cancer Pathways and Networks (Day 1), Metabolic Disease Networks (Day 2), Day 3 ? Organs, Pathways and Stem Cells (Day 3), and Day 4 ? Inflammation, Immunity, Microbes and the Environment (Day 4). Proceedings of the Conference were not published.« less

Pollen-mediated gene flow from glyphosate-resistant common waterhemp (Amaranthus rudis Sauer): consequences for the dispersal of resistance genes

PubMed Central

Sarangi, Debalin; Tyre, Andrew J.; Patterson, Eric L.; Gaines, Todd A.; Irmak, Suat; Knezevic, Stevan Z.; Lindquist, John L.; Jhala, Amit J.

2017-01-01

Gene flow is an important component in evolutionary biology; however, the role of gene flow in dispersal of herbicide-resistant alleles among weed populations is poorly understood. Field experiments were conducted at the University of Nebraska-Lincoln to quantify pollen-mediated gene flow (PMGF) from glyphosate-resistant (GR) to -susceptible (GS) common waterhemp using a concentric donor-receptor design. More than 130,000 common waterhemp plants were screened and 26,199 plants were confirmed resistant to glyphosate. Frequency of gene flow from all distances, directions, and years was estimated with a double exponential decay model using Generalized Nonlinear Model (package gnm) in R. PMGF declined by 50% at <3 m distance from the pollen source, whereas 90% reduction was found at 88 m (maximum) depending on the direction of the pollen-receptor blocks. Amplification of the target site gene, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), was identified as the mechanism of glyphosate resistance in parent biotype. The EPSPS gene amplification was heritable in common waterhemp and can be transferred via PMGF, and also correlated with glyphosate resistance in pseudo-F2 progeny. This is the first report of PMGF in GR common waterhemp and the results are critical in explaining the rapid dispersal of GR common waterhemp in Midwestern United States. PMID:28327669

FPGA in-the-loop simulations of cardiac excitation model under voltage clamp conditions

NASA Astrophysics Data System (ADS)

Othman, Norliza; Adon, Nur Atiqah; Mahmud, Farhanahani

2017-01-01

Voltage clamp technique allows the detection of single channel currents in biological membranes in identifying variety of electrophysiological problems in the cellular level. In this paper, a simulation study of the voltage clamp technique has been presented to analyse current-voltage (I-V) characteristics of ion currents based on Luo-Rudy Phase-I (LR-I) cardiac model by using a Field Programmable Gate Array (FPGA). Nowadays, cardiac models are becoming increasingly complex which can cause a vast amount of time to run the simulation. Thus, a real-time hardware implementation using FPGA could be one of the best solutions for high-performance real-time systems as it provides high configurability and performance, and able to executes in parallel mode operation. For shorter time development while retaining high confidence results, FPGA-based rapid prototyping through HDL Coder from MATLAB software has been used to construct the algorithm for the simulation system. Basically, the HDL Coder is capable to convert the designed MATLAB Simulink blocks into hardware description language (HDL) for the FPGA implementation. As a result, the voltage-clamp fixed-point design of LR-I model has been successfully conducted in MATLAB Simulink and the simulation of the I-V characteristics of the ionic currents has been verified on Xilinx FPGA Virtex-6 XC6VLX240T development board through an FPGA-in-the-loop (FIL) simulation.

Contributions to the Content Analysis of Gender Roles: An Introduction to a Special Issue

PubMed Central

Popova, Lucy; Linz, Daniel G.

2011-01-01

This special issue on gender-related content analysis is the second of two parts (see Rudy et al. 2010b). The current special issue is more diverse than was the first in the number of countries that are represented and in the variety of media genres and content types that are included. The primary aim of this paper is to outline some of the contributions of the individual papers in this second special issue. Some of these advancements and innovations include (a) examining underresearched measures, countries, time spans, sexual orientations, and individual media programs; (b) addressing both international and intranational differences in gender-role portrayals; (c) comparing multiple content formats within the same media unit; (d) updating past findings to take into consideration the current media landscape; (e) employing established measures in novel ways and novel contexts; (f) uncovering limitations in established intercultural measures and media-effects theories; (g) suggesting variables that could predict additional differences in gender-role portrayals; (h) adopting virtually identical methods and measures across distinct content categories in order to facilitate comparisons; (i) conducting multiple tests of a given hypothesis; (j) examining, from multiple perspectives, the implications of racial differences in gender portrayals; and (k) examining the implications of underrepresentation of women and the perspectives that women hold. In addition to the original content-analytical research presented in this special issue, two reviews, one methodological and the other analytical, offer recommendations of procedures and perspectives to be implemented in future research. PMID:21423330

Effects of Na(+) and K(+) channel blockade on vulnerability to and termination of fibrillation in simulated normal cardiac tissue.

PubMed

Qu, Zhilin; Weiss, James N

2005-10-01

Na(+) and K(+) channel-blocking drugs have anti- and proarrhythmic effects. Their effects during fibrillation, however, remain poorly understood. We used computer simulation of a two-dimensional (2-D) structurally normal tissue model with phase I of the Luo-Rudy action potential model to study the effects of Na(+) and K(+) channel blockade on vulnerability to and termination of reentry in simulated multiple-wavelet and mother rotor fibrillation. Our main findings are as follows: 1) Na(+) channel blockade decreased, whereas K(+) channel blockade increased, the vulnerable window of reentry in heterogeneous 2-D tissue because of opposing effects on dynamical wave instability. 2) Na(+) channel blockade increased the cycle length of reentry more than it increased refractoriness. In multiple-wavelet fibrillation, Na(+) channel blockade first increased and then decreased the average duration or transient time () of fibrillation. In mother rotor fibrillation, Na(+) channel blockade caused peripheral fibrillatory conduction block to resolve and the mother rotor to drift, leading to self-termination or sustained tachycardia. 3) K(+) channel blockade increased dynamical instability by steepening action potential duration restitution. In multiple-wavelet fibrillation, this effect shortened because of enhanced wave instability. In mother rotor fibrillation, this effect converted mother rotor fibrillation to multiple-wavelet fibrillation, which then could self-terminate. Our findings help illuminate, from a theoretical perspective, the possible underlying mechanisms of termination of different types of fibrillation by antiarrhythmic drugs.

Mechanical perturbation control of cardiac alternans

NASA Astrophysics Data System (ADS)

Hazim, Azzam; Belhamadia, Youssef; Dubljevic, Stevan

2018-05-01

Cardiac alternans is a disturbance in heart rhythm that is linked to the onset of lethal cardiac arrhythmias. Mechanical perturbation control has been recently used to suppress alternans in cardiac tissue of relevant size. In this control strategy, cardiac tissue mechanics are perturbed via active tension generated by the heart's electrical activity, which alters the tissue's electric wave profile through mechanoelectric coupling. We analyze the effects of mechanical perturbation on the dynamics of a map model that couples the membrane voltage and active tension systems at the cellular level. Therefore, a two-dimensional iterative map of the heart beat-to-beat dynamics is introduced, and a stability analysis of the system of coupled maps is performed in the presence of a mechanical perturbation algorithm. To this end, a bidirectional coupling between the membrane voltage and active tension systems in a single cardiac cell is provided, and a discrete form of the proposed control algorithm, that can be incorporated in the coupled maps, is derived. In addition, a realistic electromechanical model of cardiac tissue is employed to explore the feasibility of suppressing alternans at cellular and tissue levels. Electrical activity is represented in two detailed ionic models, the Luo-Rudy 1 and the Fox models, while two active contractile tension models, namely a smooth variant of the Nash-Panfilov model and the Niederer-Hunter-Smith model, are used to represent mechanical activity in the heart. The Mooney-Rivlin passive elasticity model is employed to describe passive mechanical behavior of the myocardium.

Contributions to the Content Analysis of Gender Roles: An Introduction to a Special Issue.

PubMed

Rudy, Rena M; Popova, Lucy; Linz, Daniel G

2011-02-01

This special issue on gender-related content analysis is the second of two parts (see Rudy et al. 2010b). The current special issue is more diverse than was the first in the number of countries that are represented and in the variety of media genres and content types that are included. The primary aim of this paper is to outline some of the contributions of the individual papers in this second special issue. Some of these advancements and innovations include (a) examining underresearched measures, countries, time spans, sexual orientations, and individual media programs; (b) addressing both international and intranational differences in gender-role portrayals; (c) comparing multiple content formats within the same media unit; (d) updating past findings to take into consideration the current media landscape; (e) employing established measures in novel ways and novel contexts; (f) uncovering limitations in established intercultural measures and media-effects theories; (g) suggesting variables that could predict additional differences in gender-role portrayals; (h) adopting virtually identical methods and measures across distinct content categories in order to facilitate comparisons; (i) conducting multiple tests of a given hypothesis; (j) examining, from multiple perspectives, the implications of racial differences in gender portrayals; and (k) examining the implications of underrepresentation of women and the perspectives that women hold. In addition to the original content-analytical research presented in this special issue, two reviews, one methodological and the other analytical, offer recommendations of procedures and perspectives to be implemented in future research.

simBio: a Java package for the development of detailed cell models.

PubMed

Sarai, Nobuaki; Matsuoka, Satoshi; Noma, Akinori

2006-01-01

Quantitative dynamic computer models, which integrate a variety of molecular functions into a cell model, provide a powerful tool to create and test working hypotheses. We have developed a new modeling tool, the simBio package (freely available from ), which can be used for constructing cell models, such as cardiac cells (the Kyoto model from Matsuoka et al., 2003, 2004 a, b, the LRd model from Faber and Rudy, 2000, and the Noble 98 model from Noble et al., 1998), epithelial cells (Strieter et al., 1990) and pancreatic beta cells (Magnus and Keizer, 1998). The simBio package is written in Java, uses XML and can solve ordinary differential equations. In an attempt to mimic biological functional structures, a cell model is, in simBio, composed of independent functional modules called Reactors, such as ion channels and the sarcoplasmic reticulum, and dynamic variables called Nodes, such as ion concentrations. The interactions between Reactors and Nodes are described by the graph theory and the resulting graph represents a blueprint of an intricate cellular system. Reactors are prepared in a hierarchical order, in analogy to the biological classification. Each Reactor can be composed or improved independently, and can easily be reused for different models. This way of building models, through the combination of various modules, is enabled through the use of object-oriented programming concepts. Thus, simBio is a straightforward system for the creation of a variety of cell models on a common database of functional modules.

Mobile Geochemistry Instrument Package Facility (MGIPF) for In Situ Mineralogical and Chemical Analysis of Planetary Surface Material

NASA Astrophysics Data System (ADS)

Klingelhöfer, G.; Romstedt, J.; Henkel, H.; Michaelis, H.; Brückner, J.; D'Uston, C.

A first order requirement for any spacecraft mission to land on a solid planetary or moon surface is instrumentation for in-situ mineralogical and chemical analysis 2 Such analysis provide data needed for primary classification and characterization of surface materials present We will discuss a mobile instrument package we have developed for in-situ investigations under harsh environmental conditions like on Mercury or Mars This Geochemistry Instrument Package Facility is a compact box also called payload cab containing three small advanced geochemistry mineralogy instruments the chemical spectrometer APXS the mineralogical M o ssbauer spectrometer MIMOS II 3 and a textural imager close-up camera The payload cab is equipped with two actuating arms with two degrees of freedom permitting precision placement of all instruments at a chosen sample This payload cab is the central part of the small rover Nanokhod which has the size of a shoebox 1 The Nanokhod rover is a tethered system with a typical operational range of sim 100 m Of course the payload cab itself can be attached by means of its arms to any deployment device of any other rover or deployment device 1 Andre Schiele Jens Romstedt Chris Lee Sabine Klinkner Rudi Rieder Ralf Gellert G o star Klingelh o fer Bodo Bernhardt Harald Michaelis The new NANOKHOD Engineeering model for extreme cold environments 8th International symposium on Artificial Intelligence Robotics and Automation in Space 5 - 9 September 2005

What can we Expect of High-Resolution Spectroscopies on Carbohydrates?

NASA Astrophysics Data System (ADS)

Cocinero, Emilio J.; Ecija, Patricia; Uriarte, Iciar; Usabiaga, Imanol; Fernández, José A.; Basterretxea, Francisco J.; Lesarri, Alberto; Davis, Benjamin G.

2015-06-01

Carbohydrates are one of the most multifaceted building blocks, performing numerous roles in living organisms. We present several structural investigations on carbohydrates exploiting an experimental strategy which combines microwave (MW) and laser spectroscopies in high-resolution. Laser spectroscopy offers high sensitivity coupled to mass and conformer selectivity, making it ideal for polysaccharides studies. On the other hand, microwave spectroscopy provides much higher resolution and direct access to molecular structure of monosaccharides. This combined approach provides not only accurate chemical insight on conformation, structure and molecular properties, but also benchmarking standards guiding the development of theoretical calculations. In order to illustrate the possibilities of a combined MW-laser approach we present results on the conformational landscape and structural properties of several monosaccharides and oligosaccharides including microsolvation and molecular recognition processes of carbohydrates. E.J. Cocinero, A. Lesarri, P. écija, F.J. Basterretxea, J.-U. Grabow, J.A. Fernández and F. Casta {n}o Angew. Chem. Int. Ed. 51, 3119-3124, 2012. E.J. Cocinero, A. Lesarri, P. écija, Á. Cimas, B.G. Davis, F.J. Basterretxea, J.A. Fernández and F. Casta {n}o J. Am. Chem. Soc. 135, 2845-2852, 2013. E.J. Cocinero, P. Çarçabal, T.D. Vaden, J.P. Simons and B.G. Davis Nature 469, 76-80, 2011. C.S. Barry, E.J. Cocinero, P. Çarçabal, D.P. Gamblin, E.C. Stanca-Kaposta, S. M. Fernández-Alonso, S. Rudić, J.P. Simons and B.G. Davis J. Am. Chem. Soc. 135, 16895-16903, 2013.

Modeling the effect of climate change on the distribution of oak and pine species of Mexico.

PubMed

Gómez-Mendoza, Leticia; Arriaga, Laura

2007-12-01

We examined the vulnerability of 34 species of oaks (Quercus) and pines (Pinus) to the effects of global climate change in Mexico. We regionalized the HadCM2 model of climate change with local climatic data (mean annual temperature and rainfall) and downscaled the model with the inverse distance-weighted method. Databases of herbaria specimens, genetic algorithms (GARP), and digital covers of biophysical variables that affect oaks and pines were used to project geographic distributions of the species under a severe and conservative scenario of climate change for the year 2050. Starting with the current average temperature of 20.2 degrees C and average precipitation of 793 mm, under the severe warming scenario mean temperature and precipitation changed to 22.7 degrees C and 660 mm, respectively, in 2050. For the conservative warming scenario, these variables shifted to 21.8 degrees C and 721 mm. Responses to the different scenarios of climate change were predicted to be species-specific and related to each species climate affinity. The current geographic distribution of oaks and pines decreased 7-48% and 0.2-64%, respectively. The more vulnerable pines were Pinus rudis, P. chihuahuana, P. oocarpa, and P. culminicola, and the most vulnerable oaks were Quercus crispipilis, Q. peduncularis, Q. acutifolia, and Q. sideroxyla. In addition to habitat conservation, we think sensitive pine and oak species should be looked at more closely to define ex situ strategies (i.e., seed preservation in germplasm banks) for their long-term conservation. Modeling climatic-change scenarios is important to the development of conservation strategies.

A CellML simulation compiler and code generator using ODE solving schemes

PubMed Central

2012-01-01

Models written in description languages such as CellML are becoming a popular solution to the handling of complex cellular physiological models in biological function simulations. However, in order to fully simulate a model, boundary conditions and ordinary differential equation (ODE) solving schemes have to be combined with it. Though boundary conditions can be described in CellML, it is difficult to explicitly specify ODE solving schemes using existing tools. In this study, we define an ODE solving scheme description language-based on XML and propose a code generation system for biological function simulations. In the proposed system, biological simulation programs using various ODE solving schemes can be easily generated. We designed a two-stage approach where the system generates the equation set associating the physiological model variable values at a certain time t with values at t + Δt in the first stage. The second stage generates the simulation code for the model. This approach enables the flexible construction of code generation modules that can support complex sets of formulas. We evaluate the relationship between models and their calculation accuracies by simulating complex biological models using various ODE solving schemes. Using the FHN model simulation, results showed good qualitative and quantitative correspondence with the theoretical predictions. Results for the Luo-Rudy 1991 model showed that only first order precision was achieved. In addition, running the generated code in parallel on a GPU made it possible to speed up the calculation time by a factor of 50. The CellML Compiler source code is available for download at http://sourceforge.net/projects/cellmlcompiler. PMID:23083065

Evaluation of bait traps as a means to predict initial blow fly (Diptera: Calliphoridae) communities associated with decomposing swine remains in New Jersey, USA.

PubMed

Weidner, Lauren M; Gemmellaro, M Denise; Tomberlin, Jeffery K; Hamilton, George C

2017-09-01

Information about blow fly (Diptera: Calliphoridae) species distributions can be valuable for criminal investigations, with regards to determining movement of remains from one location to another and time of colonization estimates, making these data extremely useful. Past work has been conducted on initial species community structure across New Jersey, USA using traps baited with beef liver; however, if these same species frequent vertebrate carrion remains unclear. In order to evaluate these data, piglet carcasses were placed out once every two weeks for a year in New Brunswick, New Jersey, USA. The same methods were implemented as those used for traps baited with beef liver, with length of collections being based on ADD values. Seven calliphorid species, Calliphora vicina (Robineau-Desvoidy), Lucilia sericata (Meigen), Lucilia coeruleiviridis (Macquart), Phormia regina (Meigen), Pollenia pediculata Macquart, Pollenia rudis (F.) and Protophormia terraenovae (Robineau-Desvoidy) were collected from the carcasses. During this experiment L. sericata, L. coeruleiviridis and P. regina were the dominant adult blow flies captured, totaling 38.2%, 29.2% and 29.2% respectively of all adults caught. All three species colonized the carcasses as well, although not all were dominant colonizers. C. vicina was recorded ovipositing in December, while the piglet was submerged in approximately 5cm of snow. All species that totaled at least 1% of the total collection (adults captured and larvae reared) were the same across baited traps and carcasses. This study supports the use of beef liver baits for surveying forensically important blow flies and the application of such information to forensic investigations. Copyright © 2017 Elsevier B.V. All rights reserved.

Origin and characteristics of high Shannon entropy at the pivot of locally stable rotors: insights from computational simulation.

PubMed

Ganesan, Anand N; Kuklik, Pawel; Gharaviri, Ali; Brooks, Anthony; Chapman, Darius; Lau, Dennis H; Roberts-Thomson, Kurt C; Sanders, Prashanthan

2014-01-01

Rotors are postulated to maintain cardiac fibrillation. Despite the importance of bipolar electrograms in clinical electrophysiology, few data exist on the properties of bipolar electrograms at rotor sites. The pivot of a spiral wave is characterized by relative uncertainty of wavefront propagation direction compared to the periphery. The bipolar electrograms used in electrophysiology recording encode information on both direction and timing of approaching wavefronts. To test the hypothesis that bipolar electrograms from the pivot of rotors have higher Shannon entropy (ShEn) than electrograms recorded at the periphery due to the spatial dynamics of spiral waves. We studied spiral wave propagation in 2-dimensional sheets constructed using a simple cell automaton (FitzHugh-Nagumo), atrial (Courtemanche-Ramirez-Nattel) and ventricular (Luo-Rudy) myocyte cell models and in a geometric model spiral wave. In each system, bipolar electrogram recordings were simulated, and Shannon entropy maps constructed as a measure of electrogram information content. ShEn was consistently highest in the pivoting region associated with the phase singularity of the spiral wave. This property was consistently preserved across; (i) variation of model system (ii) alterations in bipolar electrode spacing, (iii) alternative bipolar electrode orientation (iv) bipolar electrogram filtering and (v) in the presence of rotor meander. Directional activation plots demonstrated that the origin of high ShEn at the pivot was the directional diversity of wavefront propagation observed in this location. The pivot of the rotor is consistently associated with high Shannon entropy of bipolar electrograms despite differences in action potential model, bipolar electrode spacing, signal filtering and rotor meander. Maximum ShEn is co-located with the pivot for rotors observed in the bipolar electrogram recording mode, and may be an intrinsic property of spiral wave dynamic behaviour.

Simulations of the cardiac action potential based on the Hodgkin-Huxley kinetics with the use of Microsoft Excel spreadsheets.

PubMed

Wu, Sheng-Nan

2004-03-31

The purpose of this study was to develop a method to simulate the cardiac action potential using a Microsoft Excel spreadsheet. The mathematical model contained voltage-gated ionic currents that were modeled using either Beeler-Reuter (B-R) or Luo-Rudy (L-R) phase 1 kinetics. The simulation protocol involves the use of in-cell formulas directly typed into a spreadsheet. The capability of spreadsheet iteration was used in these simulations. It does not require any prior knowledge of computer programming, although the use of the macro language can speed up the calculation. The normal configuration of the cardiac ventricular action potential can be well simulated in the B-R model that is defined by four individual ionic currents, each representing the diffusion of ions through channels in the membrane. The contribution of Na+ inward current to the rate of depolarization is reproduced in this model. After removal of Na+ current from the model, a constant current stimulus elicits an oscillatory change in membrane potential. In the L-R phase 1 model where six types of ionic currents were defined, the effect of extracellular K+ concentration on changes both in the time course of repolarization and in the time-independent K+ current can be demonstrated, when the solutions are implemented in Excel. Using the simulation protocols described here, the users can readily study and graphically display the underlying properties of ionic currents to see how changes in these properties determine the behavior of the heart cell. The method employed in these simulation protocols may also be extended or modified to other biological simulation programs.

Optimal design of gene knockout experiments for gene regulatory network inference

PubMed Central

Ud-Dean, S. M. Minhaz; Gunawan, Rudiyanto

2016-01-01

Motivation: We addressed the problem of inferring gene regulatory network (GRN) from gene expression data of knockout (KO) experiments. This inference is known to be underdetermined and the GRN is not identifiable from data. Past studies have shown that suboptimal design of experiments (DOE) contributes significantly to the identifiability issue of biological networks, including GRNs. However, optimizing DOE has received much less attention than developing methods for GRN inference. Results: We developed REDuction of UnCertain Edges (REDUCE) algorithm for finding the optimal gene KO experiment for inferring directed graphs (digraphs) of GRNs. REDUCE employed ensemble inference to define uncertain gene interactions that could not be verified by prior data. The optimal experiment corresponds to the maximum number of uncertain interactions that could be verified by the resulting data. For this purpose, we introduced the concept of edge separatoid which gave a list of nodes (genes) that upon their removal would allow the verification of a particular gene interaction. Finally, we proposed a procedure that iterates over performing KO experiments, ensemble update and optimal DOE. The case studies including the inference of Escherichia coli GRN and DREAM 4 100-gene GRNs, demonstrated the efficacy of the iterative GRN inference. In comparison to systematic KOs, REDUCE could provide much higher information return per gene KO experiment and consequently more accurate GRN estimates. Conclusions: REDUCE represents an enabling tool for tackling the underdetermined GRN inference. Along with advances in gene deletion and automation technology, the iterative procedure brings an efficient and fully automated GRN inference closer to reality. Availability and implementation: MATLAB and Python scripts of REDUCE are available on www.cabsel.ethz.ch/tools/REDUCE. Contact: rudi.gunawan@chem.ethz.ch Supplementary information: Supplementary data are available at Bioinformatics online. PMID:26568633

Safety and efficacy of polymer-free biolimus-eluting stents in all-comer patients: the RUDI-FREE study.

PubMed

Sardella, Gennaro; Stefanini, Giulio G; Briguori, Carlo; Tamburino, Corrado; Fabbiocchi, Franco; Rotolo, Francesco; Tomai, Fabrizio; Paggi, Anita; Lombardi, Mario; Gioffrè, Gaetano; Sclafani, Rocco; Rolandi, Andrea; Sciahbasi, Alessandro; Scardaci, Francesco; Signore, Nicola; Calcagno, Simone; Mancone, Massimo; Chiarito, Mauro; Giordano, Arturo

2018-05-21

Polymer-free biolimus-eluting stents (PF-BES) have been shown superior to bare metal stents in high bleeding risk (HBR) patients treated with 1-month dual antiplatelet therapy (DAPT). However, limited evidence is available on PF-BES in non-HBR patients. We aim to evaluate the safety and efficacy of PF-BES in all-comer patients undergoing percutaneous coronary interventions (PCI). Patients with stable coronary artery disease or acute coronary syndromes (ACS) undergoing PCI with PF-BES in routine clinical practice were included in a multicenter, prospective registry. DAPT duration was left at the discretion of the operator. The primary endpoint was the composite of cardiovascular death, myocardial infarction (MI), and definite/probable stent thrombosis (ST) at 1 year. Overall, 1,104 consecutive patients treated with PF-BES were included at 16 Italian centers. Mean age was 68.7±11.2 years, 77.2% of patients were men, 30% had diabetes, 15.1% had chronic kidney disease, and 40.5% had ACS at baseline. Mean CRUSADE score was 24.1±13.1, and 83.7% of patients did not have high bleeding risk features. At 1-year, the primary endpoint occurred in 4.1% of patients, cardiovascular death in 2.4%, MI in 1.8%, and definite/probable ST in 1.1%. With respect to efficacy, target-lesion revascularization occurred in 1.2% of patients. This is the first study providing clinical evidence on the use of PF-BES in all-comer patients irrespective of HBR status. Our findings suggest that PF-BES has a favorable safety and efficacy profile in a real world clinical setting. Further investigation in randomised clinical trials against new-generation DES is warranted.

Convergence of models of human ventricular myocyte electrophysiology after global optimization to recapitulate clinical long QT phenotypes.

PubMed

Mann, Stefan A; Imtiaz, Mohammad; Winbo, Annika; Rydberg, Annika; Perry, Matthew D; Couderc, Jean-Philippe; Polonsky, Bronislava; McNitt, Scott; Zareba, Wojciech; Hill, Adam P; Vandenberg, Jamie I

2016-11-01

In-silico models of human cardiac electrophysiology are now being considered for prediction of cardiotoxicity as part of the preclinical assessment phase of all new drugs. We ask the question whether any of the available models are actually fit for this purpose. We tested three models of the human ventricular action potential, the O'hara-Rudy (ORD11), the Grandi-Bers (GB10) and the Ten Tusscher (TT06) models. We extracted clinical QT data for LQTS1 and LQTS2 patients with nonsense mutations that would be predicted to cause 50% loss of function in I Ks and I Kr respectively. We also obtained clinical QT data for LQTS3 patients. We then used a global optimization approach to improve the existing in silico models so that they reproduced all three clinical data sets more closely. We also examined the effects of adrenergic stimulation in the different LQTS subsets. All models, in their original form, produce markedly different and unrealistic predictions of QT prolongation for LQTS1, 2 and 3. After global optimization of the maximum conductances for membrane channels, all models have similar current densities during the action potential, despite differences in kinetic properties of the channels in the different models, and more closely reproduce the prolongation of repolarization seen in all LQTS subtypes. In-silico models of cardiac electrophysiology have the potential to be tremendously useful in complementing traditional preclinical drug testing studies. However, our results demonstrate they should be carefully validated and optimized to clinical data before they can be used for this purpose. Copyright © 2016 Elsevier Ltd. All rights reserved.

A reliability analysis of cardiac repolarization time markers.

PubMed

Scacchi, S; Franzone, P Colli; Pavarino, L F; Taccardi, B

2009-06-01

Only a limited number of studies have addressed the reliability of extracellular markers of cardiac repolarization time, such as the classical marker RT(eg) defined as the time of maximum upslope of the electrogram T wave. This work presents an extensive three-dimensional simulation study of cardiac repolarization time, extending the previous one-dimensional simulation study of a myocardial strand by Steinhaus [B.M. Steinhaus, Estimating cardiac transmembrane activation and recovery times from unipolar and bipolar extracellular electrograms: a simulation study, Circ. Res. 64 (3) (1989) 449]. The simulations are based on the bidomain - Luo-Rudy phase I system with rotational fiber anisotropy and homogeneous or heterogeneous transmural intrinsic membrane properties. The classical extracellular marker RT(eg) is compared with the gold standard of fastest repolarization time RT(tap), defined as the time of minimum derivative during the downstroke of the transmembrane action potential (TAP). Additionally, a new extracellular marker RT90(eg) is compared with the gold standard of late repolarization time RT90(tap), defined as the time when the TAP reaches 90% of its resting value. The results show a good global match between the extracellular and transmembrane repolarization markers, with small relative mean discrepancy (or=0.92), ensuring a reasonably good global match between the associated repolarization sequences. However, large local discrepancies of the extracellular versus transmembrane markers may ensue in regions where the curvature of the repolarization front changes abruptly (e.g. near front collisions) or is negligible (e.g. where repolarization proceeds almost uniformly across fiber). As a consequence, the spatial distribution of activation-recovery intervals (ARI) may provide an inaccurate estimate of (and weakly correlated with) the spatial distribution of action potential durations (APD).

Biogeographic patterns in the cartilaginous fauna (Pisces: Elasmobranchii and Holocephali) in the southeast Pacific Ocean

PubMed Central

Vargas-Caro, Carolina; Bennett, Michael B.

2014-01-01

The abundance and species richness of the cartilaginous fish community of the continental shelf and slope off central Chile is described, based on fishery-independent trawl tows made in 2006 and 2007. A total of 194,705 specimens comprising 20 species (9 sharks, 10 skates, 1 chimaera) were caught at depths of 100–500 m along a 1,000 km transect between 29.5°S and 39°S. Sample site locations were grouped to represent eight geographical zones within this latitudinal range. Species richness fluctuated from 1 to 6 species per zone. There was no significant latitudinal trend for sharks, but skates showed an increased species richness with latitude. Standardised catch per unit effort (CPUE) increased with increasing depth for sharks, but not for skates, but the observed trend for increasing CPUE with latitude was not significant for either sharks or skates. A change in community composition occurred along the depth gradient with the skates, Psammobatis rudis, Zearaja chilensis and Dipturus trachyderma dominating communities between 100 and 300 m, but small-sized, deep-water dogfishes, such as Centroscyllium spp. dominated the catch between 300 and 500 m. Cluster and ordination analysis identified one widespread assemblage, grouping 58% of sites, and three shallow-water assemblages. Assemblages with low diversity (coldspots) coincided with highly productive fishing grounds for demersal crustaceans and bony fishes. The community distribution suggested that the differences between assemblages may be due to compensatory changes in mesopredator species abundance, as a consequence of continuous and unselective species removal. Distribution patterns and the quantitative assessment of sharks, skates and chimaeras presented here complement extant biogeographic knowledge and further the understanding of deep-water ecosystem dynamics in relation to fishing activity in the south-east Pacific Ocean. PMID:24918036

Biogeographic patterns in the cartilaginous fauna (Pisces: Elasmobranchii and Holocephali) in the southeast Pacific Ocean.

PubMed

Bustamante, Carlos; Vargas-Caro, Carolina; Bennett, Michael B

2014-01-01

The abundance and species richness of the cartilaginous fish community of the continental shelf and slope off central Chile is described, based on fishery-independent trawl tows made in 2006 and 2007. A total of 194,705 specimens comprising 20 species (9 sharks, 10 skates, 1 chimaera) were caught at depths of 100-500 m along a 1,000 km transect between 29.5°S and 39°S. Sample site locations were grouped to represent eight geographical zones within this latitudinal range. Species richness fluctuated from 1 to 6 species per zone. There was no significant latitudinal trend for sharks, but skates showed an increased species richness with latitude. Standardised catch per unit effort (CPUE) increased with increasing depth for sharks, but not for skates, but the observed trend for increasing CPUE with latitude was not significant for either sharks or skates. A change in community composition occurred along the depth gradient with the skates, Psammobatis rudis, Zearaja chilensis and Dipturus trachyderma dominating communities between 100 and 300 m, but small-sized, deep-water dogfishes, such as Centroscyllium spp. dominated the catch between 300 and 500 m. Cluster and ordination analysis identified one widespread assemblage, grouping 58% of sites, and three shallow-water assemblages. Assemblages with low diversity (coldspots) coincided with highly productive fishing grounds for demersal crustaceans and bony fishes. The community distribution suggested that the differences between assemblages may be due to compensatory changes in mesopredator species abundance, as a consequence of continuous and unselective species removal. Distribution patterns and the quantitative assessment of sharks, skates and chimaeras presented here complement extant biogeographic knowledge and further the understanding of deep-water ecosystem dynamics in relation to fishing activity in the south-east Pacific Ocean.

Spatial problem-solving in a wheel-shaped maze: quantitative and qualitative analyses of the behavioural changes following damage to the hippocampus in the rat.

PubMed

Buhot, M C; Chapuis, N; Scardigli, P; Herrmann, T

1991-07-01

The behaviour of sham-operated rats and rats with damage to the dorsal hippocampus was compared in a complex spatial problem-solving task using a 'hub-spoke-rim' wheel type maze. Compared to the classical Olton 8-arm radial maze and Morris water maze, this apparatus presents the animal with a series of possible alternative routes both direct and indirect to the goal (food). The task included 3 main stages: exploration, feeding and testing, as do the classic problem-solving tasks. During exploration, hippocampal rats were found to be more active than sham rats. Nevertheless, they displayed habituation and a relatively efficient circumnavigation, though, in both cases, different from those of sham rats. During test trials, hippocampal rats were characterized as being less accurate, making more errors than sham rats. Nevertheless, both groups increased their accuracy of first choices over trials. The qualitative analyses of test trial performance indicated that hippocampal rats were less accurate in terms of the initial error's deviation from the goal, and less efficient in terms of corrective behaviour than sham rats which used either the periphery or the spokes to attain economically the goal. Surprisingly, hippocampal rats were not limited to a taxon type orientation but learned to use the periphery, a tendency which developed over time. Seemingly, for sham rats, the problem-solving process took the form of updating information during transit. For hippocampal rats, the use of periphery reflected both an ability to discriminate its usefulness in reaching the goal via a taxis type behaviour, and some sparing of ability to generalize the closeness and the location of the goal. These results, especially the strategic correction patterns, are discussed in the light of Sutherland and Rudy's 'configurational association theory'.

New species of leaf-mining Nepticulidae (Lepidoptera) from the Neotropical and Ando-Patagonian regions, with new data on host plants.

PubMed

Stonis, Jonas R; Remeikis, Andrius; Diškus, Arūnas; Megoran, Nick

2017-05-26

The paper treats fifteen species of leaf-mining pygmy moths (Insecta, Lepidoptera, Nepticulidae) discovered in the Neotropics (British Virgin Islands, Belize, Costa Rica, Venezuela, and Ecuador), and Ando-Patagonian region (Argentina and Chile). Except for two species, all belong to Stigmella Schrank. Twelve species are new, and are named and described in the current paper: Stigmella apicibrunella Diškus & Stonis, sp. nov.; S. decora Diškus & Stonis, sp. nov.; S. unicaudata Remeikis & Stonis, sp. nov.; S. sanmartini Remeikis & Stonis, sp. nov.; S. patula Remeikis & Stonis, sp. nov.; S. torosa Remeikis & Stonis, sp. nov.; S. monstrata Remeikis & Stonis, sp. nov.; S. huahumi Remeikis & Stonis, sp. nov.; S. venezuelica Remeikis & Stonis, sp. nov.; S. virginica Remeikis & Stonis, sp. nov.; Fomoria miranda Diškus & Stonis, sp. nov.; and Hesperolyra robinsoni Stonis, sp. n. Newly discovered variation of male genitalia of the Andean Stigmella rudis Puplesis & Robinson, 2000 is briefly discussed, and the formerly poorly understood Stigmella hylomaga (Meyrick, 1931) is redescribed and documented with photographs for the first time. We also present more photographs and add some addtional information on Stigmella gallicola van Nieukerken & Nishida, a recently described gall-maker from Costa Rica.The paper also provides new host-plant data: some of the described (or redescribed) species are reported for the first time as leaf-miners on plants belonging to Euphorbiaceae (Acalypha padifolia Kunth), Salicaceae (Azara microphylla Hook. f.), Fabaceae (Inga spectabilis (Vahl) Willd. or I. edulis Mart.), Rhamnaceae (Colletia spinosissima J. F. Gmel.), Geraniaceae or Vivianiaceae (Rhynchotheca spinosa Ruiz & Pav.), and Asteraceae (Mutisia decurrens Cav.). All species treated in the paper are illustrated with photographs of the adults and genitalia, a distribution map, and also photographs of the leaf-mines and host plants when available.

A Quantitative Comparison of the Behavior of Human Ventricular Cardiac Electrophysiology Models in Tissue

PubMed Central

Elshrif, Mohamed M.; Cherry, Elizabeth M.

2014-01-01

Numerical integration of mathematical models of heart cell electrophysiology provides an important computational tool for studying cardiac arrhythmias, but the abundance of available models complicates selecting an appropriate model. We study the behavior of two recently published models of human ventricular action potentials, the Grandi-Pasqualini-Bers (GPB) and the O'Hara-Virág-Varró-Rudy (OVVR) models, and compare the results with four previously published models and with available experimental and clinical data. We find the shapes and durations of action potentials and calcium transients differ between the GPB and OVVR models, as do the magnitudes and rate-dependent properties of transmembrane currents and the calcium transient. Differences also occur in the steady-state and S1–S2 action potential duration and conduction velocity restitution curves, including a maximum conduction velocity for the OVVR model roughly half that of the GPB model and well below clinical values. Between single cells and tissue, both models exhibit differences in properties, including maximum upstroke velocity, action potential amplitude, and minimum diastolic interval. Compared to experimental data, action potential durations for the GPB and OVVR models agree fairly well (although OVVR epicardial action potentials are shorter), but maximum slopes of steady-state restitution curves are smaller. Although studies show alternans in normal hearts, it occurs only in the OVVR model, and only for a narrow range of cycle lengths. We find initiated spiral waves do not progress to sustained breakup for either model. The dominant spiral wave period of the GPB model falls within clinically relevant values for ventricular tachycardia (VT), but for the OVVR model, the dominant period is longer than periods associated with VT. Our results should facilitate choosing a model to match properties of interest in human cardiac tissue and to replicate arrhythmia behavior more closely. Furthermore, by indicating areas where existing models disagree, our findings suggest avenues for further experimental work. PMID:24416228

Origin and Characteristics of High Shannon Entropy at the Pivot of Locally Stable Rotors: Insights from Computational Simulation

PubMed Central

Gharaviri, Ali; Brooks, Anthony; Chapman, Darius; Lau, Dennis H.; Roberts-Thomson, Kurt C.; Sanders, Prashanthan

2014-01-01

Background Rotors are postulated to maintain cardiac fibrillation. Despite the importance of bipolar electrograms in clinical electrophysiology, few data exist on the properties of bipolar electrograms at rotor sites. The pivot of a spiral wave is characterized by relative uncertainty of wavefront propagation direction compared to the periphery. The bipolar electrograms used in electrophysiology recording encode information on both direction and timing of approaching wavefronts. Objective To test the hypothesis that bipolar electrograms from the pivot of rotors have higher Shannon entropy (ShEn) than electrograms recorded at the periphery due to the spatial dynamics of spiral waves. Methods and Results We studied spiral wave propagation in 2-dimensional sheets constructed using a simple cell automaton (FitzHugh-Nagumo), atrial (Courtemanche-Ramirez-Nattel) and ventricular (Luo-Rudy) myocyte cell models and in a geometric model spiral wave. In each system, bipolar electrogram recordings were simulated, and Shannon entropy maps constructed as a measure of electrogram information content. ShEn was consistently highest in the pivoting region associated with the phase singularity of the spiral wave. This property was consistently preserved across; (i) variation of model system (ii) alterations in bipolar electrode spacing, (iii) alternative bipolar electrode orientation (iv) bipolar electrogram filtering and (v) in the presence of rotor meander. Directional activation plots demonstrated that the origin of high ShEn at the pivot was the directional diversity of wavefront propagation observed in this location. Conclusions The pivot of the rotor is consistently associated with high Shannon entropy of bipolar electrograms despite differences in action potential model, bipolar electrode spacing, signal filtering and rotor meander. Maximum ShEn is co-located with the pivot for rotors observed in the bipolar electrogram recording mode, and may be an intrinsic property of spiral wave dynamic behaviour. PMID:25401331

Computational modeling for cardiac safety pharmacology analysis: Contribution of fibroblasts.

PubMed

Gao, Xin; Engel, Tyler; Carlson, Brian E; Wakatsuki, Tetsuro

2017-09-01

Drug-induced proarrhythmic potential is an important regulatory criterion in safety pharmacology. The application of in silico approaches to predict proarrhythmic potential of new compounds is under consideration as part of future guidelines. Current approaches simulate the electrophysiology of a single human adult ventricular cardiomyocyte. However, drug-induced proarrhythmic potential can be different when cardiomyocytes are surrounded by non-muscle cells. Incorporating fibroblasts in models of myocardium is important particularly for predicting a drugs cardiac liability in the aging population - a growing population who take more medications and exhibit increased cardiac fibrosis. In this study, we used computational models to investigate the effects of fibroblast coupling on the electrophysiology and response to drugs of cardiomyocytes. A computational model of cardiomyocyte electrophysiology and ion handling (O'Hara, Virag, Varro, & Rudy, 2011) is coupled to a passive model of fibroblast electrophysiology to test the effects of three compounds that block cardiomyocyte ion channels. Results are compared to model results without fibroblast coupling to see how fibroblasts affect cardiomyocyte action potential duration at 90% repolarization (APD 90 ) and propensity for early after depolarization (EAD). Simulation results show changes in cardiomyocyte APD 90 with increasing concentration of three drugs that affect cardiac function (dofetilide, vardenafil and nebivolol) when no fibroblasts are coupled to the cardiomyocyte. Coupling fibroblasts to cardiomyocytes markedly shortens APD 90 . Moreover, increasing the number of fibroblasts can augment the shortening effect. Coupling cardiomyocytes and fibroblasts are predicted to decrease proarrhythmic susceptibility under dofetilide, vardenafil and nebivolol block. However, this result is sensitive to parameters which define the electrophysiological function of the fibroblast. Fibroblast membrane capacitance and conductance (C FB and G FB ) have less of an effect on APD 90 than the fibroblast resting membrane potential (E FB ). This study suggests that in both theoretical models and experimental tissue constructs that represent cardiac tissue, both cardiomyocytes and non-muscle cells should be considered when testing cardiac pharmacological agents. Copyright © 2017 Elsevier Inc. All rights reserved.

THE COLUMN DENSITY DISTRIBUTION AND CONTINUUM OPACITY OF THE INTERGALACTIC AND CIRCUMGALACTIC MEDIUM AT REDSHIFT (z) = 2.4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudie, Gwen C.; Steidel, Charles C.; Shapley, Alice E.

2013-06-01

We present new high-precision measurements of the opacity of the intergalactic and circumgalactic medium (IGM; CGM) at (z) = 2.4. Using Voigt profile fits to the full Ly{alpha} and Ly{beta} forests in 15 high-resolution high-S/N spectra of hyperluminous QSOs, we make the first statistically robust measurement of the frequency of absorbers with H I column densities 14{approx}< log (N{sub H{sub I}}/cm{sup -2}){approx}<17.2. We also present the first measurements of the frequency distribution of H I absorbers in the volume surrounding high-z galaxies (the CGM, 300 pkpc), finding that the incidence of absorbers in the CGM is much higher than inmore » the IGM. In agreement with Rudie et al., we find that there are fractionally more high-N{sub H{sub I}} absorbers than low-N{sub H{sub I}} absorbers in the CGM compared to the IGM, leading to a shallower power law fit to the CGM frequency distribution. We use these new measurements to calculate the total opacity of the IGM and CGM to hydrogen-ionizing photons, finding significantly higher opacity than most previous studies, especially from absorbers with log (N{sub H{sub I}}/cm{sup -2}) < 17.2. Reproducing the opacity measured in our data as well as the incidence of absorbers with log (N{sub H{sub I}}/cm{sup -2})>17.2 requires a broken power law parameterization of the frequency distribution with a break near N{sub H{sub I}} Almost-Equal-To 10{sup 15} cm{sup -2}. We compute new estimates of the mean free path ({lambda}{sub mfp}) to hydrogen-ionizing photons at z{sub em} = 2.4, finding {lambda}{sub mfp} = 147 {+-} 15 Mpc when considering only IGM opacity. If instead, we consider photons emanating from a high-z star-forming galaxy and account for the local excess opacity due to the surrounding CGM of the galaxy itself, the mean free path is reduced to {lambda}{sub mfp} = 121 {+-} 15 Mpc. These {lambda}{sub mfp} measurements are smaller than recent estimates and should inform future studies of the metagalactic UV background and of ionizing sources at z Almost-Equal-To 2-3.« less

Intramural activation and repolarization sequences in canine ventricles. Experimental and simulation studies.

PubMed

Taccardi, Bruno; Punske, Bonnie B; Sachse, Frank; Tricoche, Xavier; Colli-Franzone, Piero; Pavarino, Luca F; Zabawa, Christine

2005-10-01

There are no published data showing the three-dimensional sequence of repolarization and the associated potential fields in the ventricles. Knowledge of the sequence of repolarization has medical relevance because high spatial dispersion of recovery times and action potential durations favors cardiac arrhythmias. In this study we describe measured and simulated 3-D excitation and recovery sequences and activation-recovery intervals (ARIs) (measured) or action potential durations (APDs) (simulated) in the ventricular walls. We recorded from 600 to 1400 unipolar electrograms from canine ventricular walls during atrial and ventricular pacing at 350-450 ms cycle length. Measured excitation and recovery times and ARIs were displayed as 2-D maps in transmural planes or 3-D maps in the volume explored, using specially developed software. Excitation and recovery sequences and APD distributions were also simulated in parallelepipedal slabs using anisotropic monodomain or bidomain models based on the Lou-Rudy version 1 model with homogeneous membrane properties. Simulations showed that in the presence of homogeneous membrane properties, the sequence of repolarization was similar but not identical to the excitation sequence. In a transmural plane perpendicular to epicardial fiber direction, both activation and recovery pathways starting from an epicardial pacing site returned toward the epicardium at a few cm distance from the pacing site. However, APDs were not constant, but had a dispersion of approximately 14 ms in the simulated domain. The maximum APD value was near the pacing site and two minima appeared along a line perpendicular to fiber directions, passing through the pacing site. Electrical measurements in dog ventricles showed that, for short cycle lengths, both excitation and recovery pathways, starting from an epicardial pacing site, returned toward the epicardium. For slower pacing rates, pathways of recovery departed from the pathway of excitation. Highest ARI values were observed near the pacing site in part of the experiments. In addition, maps of activation-recovery intervals showed mid-myocardial clusters with activation-recovery intervals that were slightly longer than ARIs closer to the epi- or endocardium, suggesting the presence of M cells in those areas. Transmural dispersion of measured ARIs was on the order of 20-25 ms. Potential distributions during recovery were less affected by myocardial anisotropy than were excitation potentials.

The update of resist outgas testing for metal containing resists at EIDEC

NASA Astrophysics Data System (ADS)

Shiobara, Eishi; Mikami, Shinji

2017-10-01

The metal containing resist is one of the candidates for high sensitivity resists. EIDEC has prepared the infrastructure for outgas testing in hydrogen environment for metal containing resists at High Power EUV irradiation tool (HPEUV). We have experimentally obtained the preliminary results of the non-cleanable metal contamination on witness sample using model material by HPEUV [1]. The metal contamination was observed at only the condition of hydrogen environment. It suggested the generation of volatile metal hydrides by hydrogen radicals. Additionally, the metal contamination on a witness sample covered with Ru was not removed by hydrogen radical cleaning. The strong interaction between the metal hydride and Ru was confirmed by the absorption simulation. Recently, ASML announced a resist outgassing barrier technology using Dynamic Gas Lock (DGL) membrane located between projection optics and wafer stage [2], [3]. DGL membrane blocks the diffusion of all kinds of resist outgassing to the projection optics and prevents the reflectivity loss of EUV mirrors. The investigation of DGL membrane for high volume manufacturing is just going on. It extends the limitation of material design for EUV resists. However, the DGL membrane has an impact for the productivity of EUV scanners due to the transmission loss of EUV light and the necessity of periodic maintenance. The well understanding and control of the outgassing characteristics of metal containing resists may help to improve the productivity of EUV scanner. We consider the outgas evaluation for the resists still useful. For the improvement of resist outgas testing by HPEUV, there are some issues such as the contamination limited regime, the optimization of exposure dose to obtain the measurable contamination film thickness and the detection of minimum amount of metal related outgas species generated. The investigation and improvement for these issues are ongoing. The updates will be presented in the conference. This work was supported by Ministry of Economy, Trade and Industry (METI) and New Energy and Industrial Technology Development Organization (NEDO). [1] Eishi Shiobara, Shinji Mikami, Satoshi Tanaka, International Symposium on EUV Lithography, Hiroshima, Japan, P-RE-01, (2016). [2] Mark van de Kerkhof, Hans Jasper, Leon Levasier, Rudy Peeters, Roderik van Es, Jan-Willem Bosker, Alexander Zdravkov, Egbert Lenderink, Fabrizio Evangelista, Par Broman, Bartosz Bilski, Thorsten Last, Proc. of SPIE Vol. 10143, 101430D (2017). [3] Oktay Yildirim, Elizabeth Buitrago, Rik Hoefnagels, Marieke Meeuwissen, Sander Wuister, Gijsbert Rispens, Anton van Oosten, Paul Derks, Jo Finders, Michaela Vockenhuber, Yasin Ekinci, Proc. of SPIE Vol. 10143, 101430Q (2017).

The Column Density Distribution and Continuum Opacity of the Intergalactic and Circumgalactic Medium at Redshift langzrang = 2.4

NASA Astrophysics Data System (ADS)

Rudie, Gwen C.; Steidel, Charles C.; Shapley, Alice E.; Pettini, Max

2013-06-01

We present new high-precision measurements of the opacity of the intergalactic and circumgalactic medium (IGM; CGM) at langzrang = 2.4. Using Voigt profile fits to the full Lyα and Lyβ forests in 15 high-resolution high-S/N spectra of hyperluminous QSOs, we make the first statistically robust measurement of the frequency of absorbers with H I column densities 14 \\lesssim log (N_H\\,\\scriptsize{ I}/ {cm}^{-2}) \\lesssim 17.2. We also present the first measurements of the frequency distribution of H I absorbers in the volume surrounding high-z galaxies (the CGM, 300 pkpc), finding that the incidence of absorbers in the CGM is much higher than in the IGM. In agreement with Rudie et al., we find that there are fractionally more high-N H I absorbers than low-N H I absorbers in the CGM compared to the IGM, leading to a shallower power law fit to the CGM frequency distribution. We use these new measurements to calculate the total opacity of the IGM and CGM to hydrogen-ionizing photons, finding significantly higher opacity than most previous studies, especially from absorbers with log (N_H\\,\\scriptsize{ I}/ {cm}^{-2}) < 17.2. Reproducing the opacity measured in our data as well as the incidence of absorbers with log (N_H\\,\\scriptsize{ I}/ {cm}^{-2}) \\gt 17.2 requires a broken power law parameterization of the frequency distribution with a break near N H I ≈1015 cm-2. We compute new estimates of the mean free path (λmfp) to hydrogen-ionizing photons at z em = 2.4, finding λmfp = 147 ± 15 Mpc when considering only IGM opacity. If instead, we consider photons emanating from a high-z star-forming galaxy and account for the local excess opacity due to the surrounding CGM of the galaxy itself, the mean free path is reduced to λmfp = 121 ± 15 Mpc. These λmfp measurements are smaller than recent estimates and should inform future studies of the metagalactic UV background and of ionizing sources at z ≈ 2-3. Based on data obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W. M. Keck Foundation.

Determining the Optimum Cut-Off Grades in Sulfide Copper Deposits / Określanie Optymalnej Wartości Odcięcia Zawartości Procentowej Pierwiastka Użytecznego W Złożach Siarczku Miedzi

NASA Astrophysics Data System (ADS)

Rahimi, Esmaeil; Oraee, Kazem; Shafahi, Zia Aldin; Ghasemzadeh, Hasan

2015-03-01

Optimum cut-off grades determination in mining life affects production planning and ultimate pit limit and it is also important from social, economical and environmental aspects. Calculation of optimum cut-off grades has been less considered for mines containing various mineral processing methods. In this paper, an optimization technique is applied to obtain optimum cut-off grades for both concentration and heap leaching processes. In this technique, production costs and different recoveries of heap leaching method directed into modeling different annual cash flows in copper mines. Considering the governing constraints, the Lagrange multiplier method is practiced to optimize the cut-off grades in which the objective function is supposed to maximize Net Present Value. The results indicate the effect of heap leaching process on the optimum cut-off grades of primary and secondary sulfide deposits. Określanie optymalnego poziomu odcięcia dla zawartości procentowej pierwiastka użytecznego ma poważny wpływ na planowanie produkcji, określanie ostatecznych limitów zasobów złoża; jest to także ważna kwestia z punktu widzenia kwestii społecznych, ekonomicznych i środowiskowych. Obliczanie optymalnego poziomu odcięcia dla zawartości procentowej pierwiastka użytecznego nie było zwykle szeroko rozważane w przypadku kopalni prowadzących ciągły system przeróbki. W pracy tej przedstawiono technikę optymalizacji określania poziomu zawartości procentowej pierwiastka użytecznego z uwzględnieniem zarówno procesów koncentracji jak i ługowania. W metodzie uwzględniono koszty produkcji i różne wskaźniki odzysku rudy, wielkości te wykorzystane zostały do modelowania rocznych przepływów gotówki w kopalniach miedzi. Uwzględniając narzucone ograniczenia, zastosowano metodę mnożników Lagrange'a w celu optymalizacji określania poziomu zawartości procentowej pierwiastka użytecznego, gdzie przyjętą funkcją celu jest maksymalizacja wartości bieżącej netto. Wyniki wskazują wpływ procesów ługowania na zawartość procentową pierwiastka użytecznego w rudzie pochodzącej z pierwotnych lub wtórnych złóż siarczku miedzi.

Chandra Fellows Named

NASA Astrophysics Data System (ADS)

1999-02-01

Six scientists have been chosen as Fellows of the second annual Chandra X-ray Observatory Postdoctoral Fellowship Program. The fellowships are open to recent astronomy and astrophysics graduates worldwide. This year's winners will work for three years at a host astronomical institution in the United States where they will research problems broadly related to the scientific mission of the Chandra Observatory. The Chandra X-ray Observatory Fellowship Program is a joint venture between NASA and the Chandra X-ray Observatory Center in cooperation with the host institutions. The 1999 Fellows are: Markus Boettcher, a graduate of Bonn University, whose host institution will be Rice University; Jimmy Irwin, a graduate of the University of Virginia, will be hosted by the University of Michigan; Kristen Menou, a graduate of the University of Paris, will be hosted by Princeton University; Eliot Quataert, a graduate of Harvard University, will be hosted by the Institute for Advanced Study; Rudy Wijnands, a graduate of the University of Amsterdam, will be hosted by MIT; and Amy Barger, a graduate of Cambridge University, is a Fellow at large at the University of Hawaii Institute for Astronomy. The Chandra Fellowship Program attracted forty-five applicants from eleven countries. A member of the review panel commented, "I found it extremely difficult to choose between the many excellent entries." "We are very pleased with the response to the program, and I am confident that the work of these fellows will enhance our understanding of the scientific problems to be explored by the Chandra X-ray Observatory," said Nancy Remage Evans, coordinator of the Fellowship Program. NASA's Chandra X-ray Observatory, formerly know as AXAF, will provide stunning new images and data of the extremely hot, active regions in the universe. Such regions exist where stars have exploded, where matter is swirling into black holes, and where clusters of galaxies are merging. A tentative launch date of July 9, 1999 has been set by NASA for the Chandra X-ray Observatory. The Space Shuttle Columbia mission STS-93, commanded by astronaut Eileen Collins will carry the telescope into a low circular orbit of Earth. There the astronauts will deploy the Chandra spacecraft, which will then fire two Boeing Inertial Upper Stage solid motors in succession to place Chandra in a highly elliptical orbit. This orbit will be fine-tuned by the spacecraft's integral propulsion system made by TRW, until it reaches its final height of 10,000 km by 140,000 km. Further information about the Chandra X-ray Observatory is available at the World Wide Web at http://chandra.harvard.edu/. Further information about the Fellowship program is available at http://asc.harvard.edu/fellows/

Application of Concentration-Number and Concentration-Volume Fractal Models to Recognize Mineralized Zones in North Anomaly Iron Ore Deposit, Central Iran / Zastosowanie Modeli Fraktalnych Typu K-L (Koncentracja-Liczba), Oraz K-O (Koncentracja Objętość) Do Rozpoznawania Stref Występowania Surowców Mineralnych W Regionie Złóż Rud Żelaza North Anomaly, W Środkowym Iranie

NASA Astrophysics Data System (ADS)

Afzal, Peyman; Ghasempour, Reza; Mokhtari, Ahmad Reza; Haroni, Hooshang Asadi

2015-09-01

Identification of various mineralized zones in an ore deposit is essential for mine planning and design. This study aims to distinguish the different mineralized zones and the wall rock in the Central block of North Anomaly iron ore deposit situated in Bafq (Central Iran) utilizing the concentration-number (C-N) and concentration-volume (C-V) fractal models. The C-N model indicates four mineralized zones described by Fe thresholds of 8%, 21%, and 50%, with zones <8% and >50% Fe representing wall rocks and highly mineralized zone, respectively. The C-V model reveals geochemical zones defined by Fe thresholds of 12%, 21%, 43% and 57%, with zones <12% Fe demonstrating wall rocks. Both the C-N and C-V models show that highly mineralized zones are situated in the central and western parts of the ore deposit. The results of validation of the fractal models with the geological model show that the C-N fractal model of highly mineralized zones is better than the C-V fractal model of highly mineralized zones based on logratio matrix. Identyfikacja stref występowania surowców mineralnych jest kwestia kluczową przy planowaniu wydobycia i projektowaniu kopalni. Celem pracy jest rozróżnienie stref o różnej zawartości surowców mineralnych oraz pasma skalnego w środkowej części zagłębia Bafq (środkowa cześć Iranu) przy wykorzystaniu modeli fraktalnych typu koncentracja-liczba i koncentracja-objętość. Model koncentracja-liczba pozwala na wyróżnienie czterech stref występowania surowca, definiowanych poprzez progową zawartość żelaza w rudzie na poziomie 8%, 21%, i 50% oraz strefy <8% i >50% zawartości żelaza, co odpowiada pasmu skalnemu oraz strefie o wysokim stopniu zawartości rudy. Model koncentracja-objętość wskazuje na istnienie stref geochemicznych określonych poprzez progowe wartości zawartości żelaza: 12%, 21%, 43% i 57 % oraz strefy <12%, co odpowiada ścianie skalnej. Obydwa modele stwierdzają obecność stref o wysokim stopniu zawartości surowca w środkowej i zachodniej części złoża. Wyniki walidacji modeli fraktalnych przy użyciu modeli geologicznych wskazują, ze model fraktalny koncentracja-liczba lepiej odwzorowuje obecność stref o wysokiej zawartości rud niż model fraktalny typu koncentracja-objętość.

Value of Geological Information in Exploitation Management: the Case of Exploitation Units of the Polkowice-Sieroszowice Mine

NASA Astrophysics Data System (ADS)

Krzak, Mariusz; Panajew, Paweł

2014-03-01

The application of mathematical techniques of management is particularly significant in managing mineral deposits as well as generally in the mining industry, in which the execution of geological-mining projects is usually time-consuming and expensive. Such projects are usually undertaken in conditions of uncertainty, and the incurred expenses do not always generate satisfactory revenues. Mineral deposit management requires close cooperation between the geologist providing necessary information about the deposit and the miner conducting exploitation work. A real decision-making problem was undertaken, in which three exploitation divisions of a certain area in the Polkowice-Sieroszowice mine, differing in ore quality, could be developed in an order which would guarantee maximisation of income. First, the ore price was calculated with the NSR formula; next, the decision-making problem was presented as a kind of game between the geologist (the mine) and states of Nature. Projekty geologiczno-górnicze (surowcowe) różnią się znacznie od innych form aktywności gospodarczej człowieka, ponieważ wiedza o przedmiocie zainteresowań opiera się głównie na ocenach, zaś samo złoże kopalin jest obiektem przyrodniczym i trudno jest jednoznacznie przewidzieć rzeczywiste efekty jego odkrycia. Geologiczna niepewność związana z modelem złoża i jego zasobami znajduje odzwierciedlenie w technicznych planach kopalni i przygotowaniu rozcinki złoża odpowiednim systemem i sposobem eksploatacji. Kwantyfikacja, ocena i zarządzanie niepewnością geologiczną jest kluczowe w strategicznym planowaniu działania kopalni. Podstawowym celem, dla którego wykonuje się wyrobiska udostępniające jest przygotowanie złoża do eksploatacji górniczej. Wyrobiska udostępniające stanowią główne drogi transportu ludzi i urobku oraz spływu wód kopalnianych. Część z nich stanowi drogi jezdne i wentylacyjne, na innych zostaje ulokowany przenośnik taśmowy, a jeszcze innymi podprowadzone są niezbędne media. W celu zabezpieczenia wyrobisk w ich bezpośrednim sąsiedztwie wydzielane są ochronne filary oporowe (rys. 1) mające różną szerokość (100-260 m) w zależności od parametrów wytrzymałościowych otaczających je skał. W trakcie drążenia wyrobisk udostępniających i przygotowawczych duże znaczenie ma prawidłowe rozpoznanie geologiczne nowo rozcinanych obszarów złoża. Do głównych zadań służby geologicznej w kopalniach rud w tym zakresie należą: - prawidłowe opróbowanie serii złożowej, - kartowanie wyrobisk podziemnych i dokumentowanie wszelkiego typu zjawisk nietypowych, - rozpoznanie złoża otworami wyprzedzającymi z wyrobisk podziemnych. Podczas prac udostępniających gromadzona jest informacja o parametrach serii złożowej, która potem zostaje wykorzystana w prowadzeniu właściwej gospodarki złożem. O przydatności i użyteczności informacji decyduje wiele cech, niemniej za najbardziej istotne należy uznać jej aktualność, dokładność, dostępność, elastyczność i kompletność. Niebagatelne są także koszty jej pozyskania. Bardziej precyzyjna informacja wymaga często znacznych, dodatkowych wydatków. W górnictwie, w kwestii oceny warunków bezpieczeństwa pracy taka konieczność jest nieodzowna. Kompletna informacja umożliwia podejmowanie właściwych decyzji, przekłada się na sposób wykorzystania posiadanych środków i możliwości, zapewnia większą elastyczność w dopasowaniu do bieżących realiów rynkowych, technologicznych i in. Zagadnienie dostępu do informacji jest problemem szerokim i dotyczy wielu aspektów rzeczywistości. Zdobywanie kolejnych informacji, służących zmniejszaniu ryzyka, jest zwykle kosztowne. Zdarza się, że pozyskanie kolejnych informacji jest od pewnego momentu nieopłacalne. Dodatkowa informacja jest potrzebna tylko do momentu, gdy oczekiwane korzyści z jej uzyskania przewyższają koszty z jej zdobywania. Wiąże się z tym problem wyceny informacji. Informacja, adekwatna do problemu, dla którego jest pozyskiwana, zwiększa zasób wiedzy podmiotu gospodarującego, jednak rosnąca jej ilość stwarza możliwość dezinformacji. Instrumentów analizy posiadanej przez decydenta informacji dostarczają m.in. narzędzia teoria gier. W teorii gier informacja modelowana jest zazwyczaj z wykorzystaniem koncepcji zbiorów informacyjnych (rys. 2). Zwykle uczestnicy gry nie dysponują pełną informacją, co implikuje fakt, ze sytuacja decyzyjna rozgrywa się w warunkach niepewności. Działalność operacyjna kopalni zmierzająca do udostępnienia i eksploatacji poszczególnych części złoża realizowana jest etapami. Nieodzownym staje się zatem podejmowanie decyzji i wybór optymalnej strategii na każdym z nich. Dążeniem kopalni może być uzyskanie najkorzystniejszych wypłat, niezależnie od zaistniałych warunków otoczenia. Działanie takowe zaprezentowano na przykładzie trzech parcel eksploatacyjnych A, B i C uruchamianych w obrębie ZG Polkowice-Sieroszowice. Charakterystykę parcel zestawiono w tabelach 1, 2 i 3, a schematyczne przekroje zmienności zobrazowano na figurach 3, 4 oraz 5. Na podstawie formuły NSR (3) obliczono ceny rudy w parcelach. Bazując na analogii określono prawdopodobieństwa napotkania konkretnych układów wskaźników jakościowych rudy w parcelach. Zestawiając oczekiwane przychody w odniesieniu do możliwych dwóch stanów natury zdefiniowano macierz gry (4). Wygenerowany problem decyzyjny sprowadzony został do modelu gry koordynacji, a rozstrzygano w nim, które z parcel należy poddać eksploatacji. Opierając się na zakresie informacji o parametrach złoża we wszystkich parcelach będącej w posiadaniu geologa nadzorującego postęp frontu eksploatacyjnego, przeanalizowano dostępne struktury informacyjne, wskazując te optymalne. Oczekiwane średnie wielkości przychodów dla poddawanych ocenie struktur zestawiono w tabelach 4, 5 oraz 6.

New Curculionoidea (Coleoptera) records for Canada

PubMed Central

Douglas, Hume; Bouchard, Patrice; Anderson, Robert S.; de Tonnancour, Pierre; Vigneault, Robert; Webster, Reginald P.

2013-01-01

Abstract The following species of Curculionoidea are recorded from Canada for the first time, in ten cases also representing new records at the generic level: Ischnopterapion (Ischnopterapion) loti (Kirby, 1808); Stenopterapion meliloti (Kirby, 1808) (both Brentidae); Atrichonotus taeniatulus (Berg, 1881); Barinus cribricollis (LeConte, 1876); Caulophilus dubius (Horn, 1873); Cionus scrophulariae (Linnaeus, 1758); Cryptorhynchus tristis LeConte, 1876; Cylindrocopturus furnissi Buchanan, 1940; Cylindrocopturus quercus (Say, 1832); Desmoglyptus crenatus (LeConte, 1876); Pnigodes setosus LeConte, 1876; Pseudopentarthrum parvicollis (Casey, 1892); Sibariops confinis (LeConte, 1876); Sibariops confusus (Boheman, 1836); Smicronyx griseus LeConte, 1876; Smicronyx lineolatus Casey, 1892; Euwallacea validus (Eichhoff, 1875); Hylocurus rudis (LeConte, 1876); Lymantor alaskanus Wood, 1978; Phloeotribus scabricollis (Hopkins, 1916); Scolytus oregoni Blackman, 1934; Xyleborus celsus Eichhoff, 1868; Xyleborus ferrugineus (Fabricius, 1801); Xylosandrus crassiusculus (Motschulsky, 1866) (all Curculionidae). In addition the following species were recorded for the first time from these provinces and territories: Yukon – Dendroctonus simplex LeConte, 1868; Phloetribus piceae Swaine, 1911 (both Curculionidae); Northwest Territories – Loborhynchapion cyanitinctum (Fall, 1927) (Brentidae); Nunavut – Dendroctonus simplex LeConte, 1868 (Curculionidae); Alberta – Anthonomus tectus LeConte, 1876; Promecotarsus densus Casey, 1892; Dendroctonus ponderosae Hopkins, 1902; Hylastes macer LeConte, 1868; Rhyncolus knowltoni (Thatcher, 1940); Scolytus schevyrewi Semenov Tjan-Shansky, 1902 (all Curculionidae); Saskatchewan – Phloeotribus liminaris (Harris, 1852); Rhyncolus knowltoni (Thatcher, 1940); Scolytus schevyrewi Semenov Tjan-Shansky, 1902 (all Curculionidae); Manitoba – Cosmobaris scolopacea Germar, 1819; Listronotus maculicollis (Kirby, 1837); Listronotus punctiger LeConte, 1876; Scolytus schevyrewi Semenov Tjan-Shansky, 1902; Tyloderma foveolatum (Say, 1832); (all Curculionidae); Ontario – Trichapion nigrum (Herbst, 1797); Nanophyes marmoratus marmoratus (Goeze, 1777) (both Brentidae); Asperosoma echinatum (Fall, 1917); Micracis suturalis LeConte, 1868; Orchestes alni (Linnaeus, 1758); Phloeosinus pini Swaine, 1915; Scolytus schevyrewi Semenov Tjan-Shansky, 1902; Xyleborinus attenuatus (Blandford, 1894) (all Curculionidae); Quebec – Trigonorhinus alternatus (Say, 1826); Trigonorhinus tomentosus tomentosus (Say, 1826) (both Anthribidae); Trichapion nigrum (Herbst, 1797); Trichapion porcatum (Boheman, 1839); Nanophyes marmoratus marmoratus (Goeze, 1777) (all Brentidae); Lissorhoptrus oryzophilus Kuschel, 1952 (Brachyceridae); Acalles carinatus LeConte, 1876; Ampeloglypter ampelopsis (Riley, 1869); Anthonomus rufipes LeConte, 1876; Anthonomus suturalis LeConte, 1824; Ceutorhynchus hamiltoni Dietz, 1896; Curculio pardalis (Chittenden, 1908); Cyrtepistomus castaneus (Roelofs, 1873); Larinus planus (Fabricius, 1792); Mecinus janthinus (Germar, 1821); Microhyus setiger LeConte, 1876; Microplontus campestris (Gyllenhal, 1837); Orchestes alni (Linnaeus, 1758); Otiorhynchus ligustici (Linnaeus, 1758); Rhinusa neta (Germar, 1821); Trichobaris trinotata (Say, 1832); Tychius liljebladi Blatchley, 1916; Xyleborinus attenuatus (Blandford, 1894); Xyleborus affinis Eichhoff, 1868 (all Curculionidae); Sphenophorus incongruus Chittenden, 1905 (Dryophthoridae); New Brunswick – Euparius paganus Gyllenhal, 1833; Allandrus populi Pierce, 1930; Gonotropis dorsalis (Thunberg, 1796); Euxenus punctatus LeConte, 1876 (all Anthribidae); Loborhynchapion cyanitinctum (Fall, 1927) (Brentidae); Pseudanthonomus seriesetosus Dietz, 1891; Curculio sulcatulus (Casey, 1897); Lignyodes bischoffi (Blatchley, 1916); Lignyodes horridulus (Casey, 1892); Dietzella zimmermanni (Gyllenhal, 1837); Parenthis vestitus Dietz, 1896; Pelenomus squamosus LeConte, 1876; Psomus armatus Dietz, 1891; Rhyncolus macrops Buchanan, 1946; Magdalis inconspicua Horn, 1873; Magdalis salicis Horn, 1873 (all Curculionidae); Nova Scotia – Dryocoetes autographus (Ratzeburg, 1837); Ips perroti Swaine, 1915; Xyleborinus attenuatus (Blandford, 1894) (all Curculionidae); Prince Edward Island – Dryocoetes caryi Hopkins, 1915 (Curculionidae); Newfoundland – Scolytus piceae (Swaine, 1910) (Curculionidae). Published records of Dendroctonus simplex LeConte, 1868 from Northwest Territories should be reassigned to Nunavut, leaving no documented record for NWT. Collection data are provided for eight provincial and national records published without further information previously. PMID:23794927

Evaluation, Proposed Solution and Current Status of the Crater Lake Breakout Problem, Mount Pinatubo, Philippines

NASA Astrophysics Data System (ADS)

Bornas, M. A.

2001-12-01

Rapid rise of Mount Pinatubo's crater lake and recent geological assessments of the crater's lowest point, the Maraunot Notch, raised concern about a breakout lahar down the northwestern slope of the volcano. Three factors indicated a serious hazard. First, the lake rose about 50 m from May 98-August 2001 and was expected to overtop the Maraunot Notch within the last trimester 2001. Overtopping might well have occurred at the height of a strong typhoon or under heavy monsoonal rainstorms. Second, the uppermost 10-20 m of "dam" was erodible ash and poorly indurated coarse breccia, susceptible to failure by overtopping and erosion as at many landslide and other natural dams. Third, the volumes of lake discharge corresponding to 10 and 20 m of erosion would have been 28 and 55 million m3; peak discharges at a breach could have been as high as 3,200 m3/sec to 11,000 m3/sec, respectively. These discharges would have eroded 1991 pyroclastic and lahar material on the volcano's slopes, increased the flow volume by 3-6x, and entered the Bucao River as a large-magnitude lahar. The Municipality of Botolan (pop. ca. 40,000) lies on the delta of the Bucao River valley some 40 km downriver from the notch, and could have been at great risk. Given this potential risk, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) in early August 2001 advocated three actions. (1) An intentional breaching of the Maraunot Notch by the construction of a spillway or canal, by the Department of Public Works and Highways (DPWH). Early breaching would limit further rise of the lake and thus reduce the magnitude of potential flood. Also, breaching would be scheduled during good weather to eliminate the danger of overtopping at an unknown time and/or under typhoon/rainstorm conditions. (2) An information campaign in Botolan in order to educate and prepare residents for breaching. (3) Evacuation of people at risk, one day before the scheduled breaching. A spillway was excavated by as many as 70 men with picks and shovels, and the specter of a wholly uncontrolled breach through the most erodible debris was averted. Early flow through the spillway was gentle and evacuees quickly returned home. However, 10-15 m of poorly indurated breccia still remains, lake level is still rising slowly, and we are watching to see whether outflow after heavy rains will armor the spillway or catastrophically erode the remaining dam. Insufficient communication between scientists and engineers led DPWH to design for less scouring than expected by PHIVOLCS, and politics and liability concerns at several levels halted digging before the trench could be deepened and outflow increased. Perhaps this is just as well. An inherent conflict arose between short- and long-term risk mitigation. Short-term risk was minimized; long-term risk was reduced but remains a concern. Complete breaching of the dam and thus elimination of long-term risk would have sharply increased short-term risk to Botolan. *Quick Response Team Members: Mabel Abigania, Rene Arante, Onie Arboleda, Maricar Arpa, Mariton Bornas, Edwin dela Cruz, Jojo Cordon, Toti Corpuz, Art Daag, Elmer Gabinete, Del Garcia, Lito Gelido, Lito de Guzman, Sheila Insauriga, Dindo Javier, Rudy Lacson, Bong Luis, Rey Lumbang, Danny Martinez, Mylene Martinez-Villegas, Chris Newhall, Jed Paladio-Melosantos, Mel Pagtalunan, Myla Panol, Jack Puertollano, Raymundo Punongbayan, Gina Quiambao, Andoy Ramos, July Sabit, Noli Sexon, Jimmy Sincioco, Opet Villacorte.

Scleractinian corals from the upper Berriasian of central Europe and comparison with contemporaneous coral assemblages.

PubMed

Baron-Szabo, Rosemarie Christine

2018-02-22

Scleractinian coral faunas from the upper Berriasian part of the Oehrli Formation of western Austria (Vorarlberg) and eastern Switzerland (Canton of Appenzell) are taxonomically described for the first time. Furthermore, scleractinian corals of the upper Berriasian part of the Oehrli Formation of the Swiss Cantons of Nidwalden and Uri are revised based on the study of type material. Lectotypes are designated for the species Dimorphocoeniopsis alpina (Koby, 1896) and Pleurophyllia tobleri (Koby, 1896). Sixty-one species belonging to 43 genera and 18 families were identified, making the coral fauna of the upper Oehrli Formation by far the most diverse among the Berriasian assemblages: Actinastrea pseudominima (Koby), A. sp., Adelocoenia bulgarica (Toula)(new combination), A. hexaphyllia (d'Orbigny)(new combination), A. radisensis (d'Orbigny)(new combination), Allocoeniopsis luciensis (d'Orbigny), Amphiaulastrea sp., Astraeofungia cf. decipiens (Michelin), Cladophyllia conybearei Milne Edwards Haime, Columnocoenia ksiazkiewiczi Morycowa, Comoseris jireceki Toula, Complexastrea seriata Turnšek, C. lobata Geyer, Cycloria mariscali (Felix)(new combination), Dermosmilia capitata (Koby), D. simplex Koby, Dimorphastrea excavata d'Orbigny, D. explanata De Fromentel, Dimorphocoeniopsis alpina (Koby), Ellipsocoenia lorioli (Koby), Enallhelia compressa (Münster), E. rathieri d'Orbigny, Epistreptophyllum cf. densum Roniewicz, Fungiastraea moeschi (Koby), Heliocoenia corallina Koby, H. humberti Étallon, H. minima Sikharulidze, Heterocoenia cf. inflexa (Eichwald), Latiphyllia neocomiensis De Fromentel, Latiastrea mucronata Sikharulidze, Latomeandra sp., Meandrastrea rudis (De Fromentel)(new combination), M. cf. lamberti (Bataller), Meandrophyllia corrugata (Michelin), Microsolena major (Ferry), M. cf. subexcavata Eguchi, Mitrodendron cf. modicum Eliášová, Mixastraea polyseptata Morycowa, Montlivaltia arcuata Beauvais, M. kaufmanni Koby, M. truncata (Defrance, 1817), Myriophyllia cf. propria Sikharulidze, Paraclausastrea vorarlbergensis Baron-Szabo, Peplosmilia stutzi (Koby), Placocoenia heimi (Koby)(new combination), Placophyllia dianthus (Goldfuss), Plesiomontlivaltia paucisepta (Koby)(new combination), Pleurophyllia schmidti (Koby)(new combination), P. tobleri (Koby), Polyphylloseris icaunensis (d'Orbigny, 1850), Rhipidogyra cf. minima Koby, Stylangia cf. laddi Wells, Stylina pleionantha Meneghini, S. decipiens Étallon, S. cf. sparsa Trautschold, Stylosmilia alpina Koby, S. yabei Eguchi, Thecosmilia dichotoma (Koby), Th. sp., Trigerastraea gourdani (De Fromentel), and Vallimeandra cf. explanata (De Fromentel). Furthermore, five additional Berriasian coral faunas are reviewed and compared with the coral fauna of the upper Oehrli Formation. These five assemblages are from southern Ukraine (2 assemblages, consisting of five and 12 species, respectively), northern Tunisia (13 species), southern Spain (23 species), and central Tibet (11 species). Except for the faunas from central Tibet and northern Tunisia, the Berriasian coral assemblages are distinctly dominated by colonial species (70-95%); they represent largely isolated populations of mostly endemic species; and consist largely of genera that had already appeared in the Upper Jurassic (80-100%). On the species-level, however, with the exception of the coral assemblage of Spain, the Beriasian coral faunas are dominated by or completely consist of taxa that have their first occurrence in the Berriasian (54-100%). The Berriasian fauna of the upper Oehrli Formation described in this work contains nearly three times more species than found in the contemporaneous fauna of southern Spain which up to now was the largest known Berriasian fauna. Two of the upper Berriasian taxa described in the current work (Cycloria and Placocoenia) may be the first representatives of lineages that still occur today (Mussidae and Montastraeidae, respectively) as suggested by a recent study of the cox1 Intron in modern corals.

PREFACE: IUPAP C20 Conference on Computational Physics (CCP 2011)

NASA Astrophysics Data System (ADS)

Troparevsky, Claudia; Stocks, George Malcolm

2012-12-01

Increasingly, computational physics stands alongside experiment and theory as an integral part of the modern approach to solving the great scientific challenges of the day on all scales - from cosmology and astrophysics, through climate science, to materials physics, and the fundamental structure of matter. Computational physics touches aspects of science and technology with direct relevance to our everyday lives, such as communication technologies and securing a clean and efficient energy future. This volume of Journal of Physics: Conference Series contains the proceedings of the scientific contributions presented at the 23rd Conference on Computational Physics held in Gatlinburg, Tennessee, USA, in November 2011. The annual Conferences on Computational Physics (CCP) are dedicated to presenting an overview of the most recent developments and opportunities in computational physics across a broad range of topical areas and from around the world. The CCP series has been in existence for more than 20 years, serving as a lively forum for computational physicists. The topics covered by this conference were: Materials/Condensed Matter Theory and Nanoscience, Strongly Correlated Systems and Quantum Phase Transitions, Quantum Chemistry and Atomic Physics, Quantum Chromodynamics, Astrophysics, Plasma Physics, Nuclear and High Energy Physics, Complex Systems: Chaos and Statistical Physics, Macroscopic Transport and Mesoscopic Methods, Biological Physics and Soft Materials, Supercomputing and Computational Physics Teaching, Computational Physics and Sustainable Energy. We would like to take this opportunity to thank our sponsors: International Union of Pure and Applied Physics (IUPAP), IUPAP Commission on Computational Physics (C20), American Physical Society Division of Computational Physics (APS-DCOMP), Oak Ridge National Laboratory (ORNL), Center for Defect Physics (CDP), the University of Tennessee (UT)/ORNL Joint Institute for Computational Sciences (JICS) and Cray, Inc. We are grateful to the committees that helped put the conference together, especially the local organizing committee. Particular thanks are also due to a number of ORNL staff who spent long hours with the administrative details. We are pleased to express our thanks to the conference administrator Ann Strange (ORNL/CDP) for her responsive and efficient day-to-day handling of this event, Sherry Samples, Assistant Conference Administrator (ORNL), Angie Beach and the ORNL Conference Office, and Shirley Shugart (ORNL) and Fern Stooksbury (ORNL) who created and maintained the conference website. Editors: G Malcolm Stocks (ORNL) and M Claudia Troparevsky (UT) http://ccp2011.ornl.gov Chair: Dr Malcolm Stocks (ORNL) Vice Chairs: Adriana Moreo (ORNL/UT) James Guberrnatis (LANL) Local Program Committee: Don Batchelor (ORNL) Jack Dongarra (UTK/ORNL) James Hack (ORNL) Robert Harrison (ORNL) Paul Kent (ORNL) Anthony Mezzacappa (ORNL) Adriana Moreo (ORNL) Witold Nazarewicz (UT) Loukas Petridis (ORNL) David Schultz (ORNL) Bill Shelton (ORNL) Claudia Troparevsky (ORNL) Mina Yoon (ORNL) International Advisory Board Members: Joan Adler (Israel Institute of Technology, Israel) Constantia Alexandrou (University of Cyprus, Cyprus) Claudia Ambrosch-Draxl (University of Leoben, Austria) Amanda Barnard (CSIRO, Australia) Peter Borcherds (University of Birmingham, UK) Klaus Cappelle (UFABC, Brazil) Giovanni Ciccotti (Università degli Studi di Roma 'La Sapienza', Italy) Nithaya Chetty (University of Pretoria, South Africa) Charlotte Froese-Fischer (NIST, US) Giulia A. Galli (University of California, Davis, US) Gillian Gehring (University of Sheffield, UK) Guang-Yu Guo (National Taiwan University, Taiwan) Sharon Hammes-Schiffer (Penn State, US) Alex Hansen (Norweigan UST) Duane D. Johnson (University of Illinois at Urbana-Champaign, US) David Landau (University of Georgia, US) Joaquin Marro (University of Granada, Spain) Richard Martin (UIUC, US) Todd Martinez (Stanford University, US) Bill McCurdy (Lawrence Berkeley National Laboratory, US) Ingrid Mertig (Martin Luther University, Germany) Alejandro Muramatsu (Universitat Stuttgart, Germany) Richard Needs (Cavendish Laboratory, UK) Giuseppina Orlandini (University of Trento, Italy) Martin Savage (University of Washington, US) Thomas Schulthess (ETH, Switzerland) Dzidka Szotek (Daresbury Laboratory, UK) Hideaki Takabe (Osaka University, Japan) William M. Tang (Princeton University, US) James Vary (Iowa State, US) Enge Wang (Chinese Academy of Science, China) Jian-Guo Wang (Institute of Applied Physics and Computational Mathematics, China) Jian-Sheng Wang (National University, Singapore) Dan Wei (Tsinghua University, China) Tony Williams (University of Adelaide, Australia) Rudy Zeller (Julich, Germany) Conference Administrator: Ann Strange (ORNL)

Star in Deep Freeze Chills Theory, MIT Researchers Report

NASA Astrophysics Data System (ADS)

2001-09-01

CAMBRIDGE, Mass. -- Like a frozen turkey that just won't thaw, a strange star near the center of the Milky Way is surprising MIT experts and colleagues with its remarkably low temperature. The odd behavior is chilling current theories of stellar physics. A famously battered neutron star named KS 1731-260 appears no hotter than some of its tranquil brethren, despite enduring the heat of constant thermonuclear explosions with the force of billions of hydrogen bombs every second across a region only a few miles wide for the past 12 years. Dr. Rudi Wijnands, an astrophysicist at MIT's Center for Space Research, used the Chandra X-ray Observatory to measure the temperature of the neutron star at a very opportune moment, only months after the nuclear war apparently ended and the smoke cleared. He presented his team's findings September 5 in Washington, D.C. at a scientific conference entitled "Two Years of Science with Chandra." "Twelve years of constant thermonuclear explosions: One would think that would heat things up," said Wijnands. "This leaves us wondering whether some neutron stars are in the freezer for a much longer time than previously thought and consequently take a long time to heat up, or whether they cool down incredibly fast. Either explanation has profound implications for our field." Neutron stars are the dense, core remains of stars once many times more massive than our Sun. They are created in dazzling supernovas, in which the outer shell of the star explodes into space, and the core, containing about as much mass as the Sun, implodes and collapses into a sphere no wider than Cambridge, Massachusetts. Despite their tiny size, neutron stars are visible in several ways. One is through accretion. Neutron stars are a strong source of gravity. When they exist in binary star systems, such as KS 1731-260, they can attract the gas from what is often a "healthy" hydrogen-burning companion star (although the nature of KS 1731-260's companion is not clear.) Gas spirals around the neutron star and comes crashing down onto its surface, leading to nuclear explosions. The fury glows predominantly in X-ray radiation. Neutron star binaries can experience varying periods of active accretion. KS 1731-260's period was particularly prolonged, lasting from mid-1988 to the end of 2000. Other systems flare from week to week or year to year. When the stars are in quiescence, they are harder to detect. Chandra has the resolution and photon-collecting power and is in the right energy range to detect neutron stars glowing dimly in quiescence. KS 1731-260 is the first neutron star enduring such prolonged accretion to enter into quiescence during Chandra's reign. Other systems only dump matter onto the neutron star for a short period at a time, so no one expects much heating. The Chandra observation provided the first chance to test the theory of neutron star heating and cooling for a system with such prolonged episodes of accretion. The team found KS 1731-260 to be at least 10 times cooler than expected, a mere 3.5 million degrees. This is about the same temperature as neutron stars that get only a week's or month's worth of dumping. KS 1731-260 therefore appears to be much too cool, assuming that this and the other neutron stars have accretion episodes at roughly similar time intervals. So what happened to the heat? There are complicated models of neutrino cooling to explain rapid temperature decreases. But maybe KS 1731-260 was in a relative deep freeze before 1988 and took 12 years just to get to the temperature it is today. According to the popular model of neutron star heating and cooling, Wijnands calculated that KS 1731-260 would need to have been dormant (that is, no accretion) for over a thousand years to get so cold that 12 years of fury would only raise it to its current temperature. "Neutron stars in such close binaries are not known to stop accreting for periods longer that about 100 years," said Walter Lewin, a professor of physics also at MIT. "We may have identified a new type of neutron star system that can lie dormant for thousands of years. If so, there could be hundreds of these systems in our Galaxy." The next step is to use Chandra to take the temperature of scores of other neutron stars experiencing various phases of accretion and quiescence. Other members of the observation team include Jon Miller of MIT, Craig Markwardt from NASA Goddard Space Flight Center, and Michiel van der Klis from the University of Amsterdam. The observation was made with Chandra's Advanced CCD Imaging Spectrometer, which was conceived and developed for NASA by Pennsylvania State University and MIT.

Obituary: Norman Hodgson Baker, Jr., 1931-2005

NASA Astrophysics Data System (ADS)

Helfand, David J.

2005-12-01

Norman H. Baker, a key contributor to the foundation of modern stellar pulsation theory and former editor of the "Astronomical Journal", died on 11 October 2005 in Watertown, New York near his beloved summer home in Natural Bridge. He succumbed to complications of Waldenstrom's macroglobulinemia, a bone marrow lymphoma that he had successfully surmounted for twenty-two years. Norm, as he was known to all, was born 23 October 1931 in Fergus Falls, Minnesota to Norman Hodgson and Jeannette (née Lieber) Baker. He attended the University of Minnesota where he met the first of many lifelong astronomical friends, Bill Erickson. He received his BA in 1952. He went on to do his PhD, "Radiation from Particle Interactions which Create Current," at Cornell University under Phil Morrison. He then moved to a postdoctoral position at the Max Planck Institut für Physik und Astrophysik in München with the intent of pursuing his work in plasma physics with Ludwig Biermann and Arnulf Schlüter. However, Rudolf (Rudi) Kippenhan snatched him away to pursue what became his lifelong interest, stellar physics. This was the dawn of the era in which electronic computers were becoming practical for scientific calculations, and Norm immediately adopted this new tool. Indeed, he remained at the forefront of computing technology throughout his life: He was certainly the first member of the Astronomy Department at Columbia to buy a Mac, and was undoubtedly one of the few emeritus professors in the world known by all the administrative staff as the first person to turn to when stumped by a computer problem. Following his first paper with Kippenhan on stellar rotation, Norm turned his attention to stellar pulsations, a topic he would pursue throughout his career. His 1962 paper in "Zeitschrift für Astrophysik" on pulsational models of Cepheids (Baker and Kippenhan 1962, 54, 155) is a classic in the field. The first figure displays the three dimensional model of the atmospheric absorption coefficient as a function of log P and log T. Sophisticated three-dimensional computer images being many years in the future, it was contructed from a folded and bent sheet of grid paper which was subsequently photographed. Using extensive numerical analysis, the paper showed that stars in the δ Cephei region of the H-R diagram were ``pulsationally unstable due to the destabilizing effect of the He+ region.'' This paper, along with those of Zhevakin, Cox, and Christy, established our modern understanding of pulsational instability in horizontal branch stars. His second paper with Kippenhan the following year brought convection into the problem; this topic became another lifelong theme of Norm's research that he subsequently pursued with Douglas Gough. His most cited work, carried out a decade later with van Albada, was an attempt to understand the properties of horizontal branch stars. It synthesized for the first time stellar evolution theory and the insights gained from studies of stellar pulsations. Between 1961 and 1965, Norm held no fewer than five positions. After a year on the west coast at the Convair Science Research Lab in San Diego, he landed in the New York area to pursue pulsations, oscillating among the Goddard Institute for Space Studies, the Institute for Advanced Study in Princeton, Yale, and New York University. In 1965, he was hired as an Assistant Professor in the Department of Astronomy at Columbia University by Lo Woltjer, and remained at Columbia until he retired in 2003. As a teacher, he was deeply appreciated by undergraduate and graduate students alike for lectures that were models of clarity, for his out-of-class assistance which was generous and unstinting, and for incorporating into his courses modern numerical techniques which served the students well throughout their careers. In 1975 when Woltjer returned to Europe, Norm took over the editorship of the "Astronomical Journal", a position he held (shared in the last few years with Leon Lucy) for a decade. His scrupulous integrity and forthright honesty served him, and the Society, well. Despite his scathing intolerance for administrative stupidity, he also managed to complete successfully a term as Chair of the Department of Astronomy. (This author, who currently holds the Chair and shares the intolerance, has yet to fathom the gracious equanimity Norm displayed.) His early interest in brewing beer during graduate school at Cornell (where he co-founded the Old Undershirt Brewing Company) was transformed in later life into an expertise in German wines. The precision that marked his research extended to every aspect of his private life. I had the distinct pleasure of subletting his apartment during my first year on the faculty at Columbia while he was on leave in Europe. We spent most of the year trying to imagine how we could ever restore it to the state of perfect organization in which we found it. Norm is survived by his wife and constant companion of thirty years, psychiatrist Doris Blum Nagel, by his sister Dr. Jean Trousdale, and brother Dr. Richard C. Baker, two nieces, three nephews, and by several generations of undergraduates, graduate students, postdocs, and colleagues who hold fond memories of his patience, kindness, humor, and quiet "joie de vivre".

Europe goes to Mars - preparations are well under way

NASA Astrophysics Data System (ADS)

2001-04-01

Under the umbrella of the European Space Agency, at least 25 companies from 15 European countries are building hardware or software for the spacecraft, or otherwise contributing their expertise; and more than 200 scientists from research institutes in all ESA member states and beyond are contributing towards the scientific payload. "The Mars Express project is providing about 1000 jobs throughout Europe," estimates Rudi Schmidt, Mars Express Project Manager at ESTEC, the European Space Agency's technical centre in the Netherlands. Preparations are well under way and on schedule for a May/June 2003 launch sending the spacecraft on its six-month voyage. The structure is taking shape under the guidance of the prime contractor Astrium, Toulouse (France), and the scientific teams are on target with scientific instrument development. Water and life ESA's Mars Express mission consists of an orbiter, carrying seven scientific experiments, and a lander, Beagle 2. The two vehicles will play key roles in an international Mars exploration programme spanning the next two decades. The instruments on board the orbiter will provide remote sensing of the atmosphere, the surface and up to 5km below the surface, to a degree of accuracy never before achieved. The information gleaned will help answer many questions outstanding about Mars. One concerns the fate of water that once flowed freely on the planet’s surface; another is whether life ever evolved on Mars. Beagle-2 will be the first lander since NASA’s two Viking probes in the 1970s to look specifically for evidence of past or present life on Mars. No other Mars probe planned so far is making exobiology so central to its mission. When the spacecraft arrives at the Red Planet around Christmas 2003, the Mars Express orbiter will jettison Beagle 2 and then move into a near-polar orbit from which it will observe the whole planet over the next Martian year (equivalent to two Earth years). The lander will make its own way to a carefully selected site on Isidis Planitia, a plain just north of the equator near where the ancient, cratered southern highlands meet the younger, smooth northern lowlands. Beagle 2 will complete its mission in about six months. The Mars Express orbiter instruments will: * Image the entire surface at high resolution (10m/pixel) and selected areas at super resolution (2m/pixel) (HRSC instrument) * Produce a map of the mineral composition of the surface at 100m resolution (OMEGA instrument) * Map the composition of the atmosphere and determine its global circulation (PFS instrument) * Determine the structure of the sub-surface to a depth of a few kilometres (MARSIS instrument) * Determine the water vapour and ozone in the atmosphere (SPICAM instrument) * Determine the interaction of the atmosphere with the solar wind (ASPERA instrument and MaRS experiment) (see below for list of full instrument names, acronyms and Principal Investigators) The Beagle 2 lander will: * Determine the geology and the mineral and chemical composition of the landing site * Search for life signatures (exobiology) * Study the weather and climate Mars Express will provide unique investigations that will contribute to an understanding of many of the unknowns about Mars. Here are a few: * If Mars really was warm and wet during its early history, where did the water go? Some may have been lost to space and some may be buried underground. ASPERA will measure water loss to space and MARSIS is the only instrument planned for any mission with the capability of looking for water or ice down to a depth of a few kilometres. The presence of underground water would have a considerable impact on the prospects for future manned missions to the planet. * If there was water could there have been, or still be, life? Beagle 2 will scoop up soil and rock samples and analyse them there and then for some of the key chemical signatures of life. The results will be far more telling than anything yet found in Martian meteorites on Earth, as the chances of contamination by biological specimens from Earth will be virtually eliminated. * What is the surface of Mars made of and what can its composition tell us about the history of the planet, in particular about the history of water there? OMEGA will map surface mineral composition more accurately than ever before. In particular, it will look for carbonates, which no previous mission has found, but which should be present if water was once abundant on Mars. * The thin Martian atmosphere is thought to be very oxidising - it turns the plentiful iron in the surface rocks and dust into rust, hence the planet's red colour. SPICAM will help to determine precisely how the atmosphere has this effect. Such understanding will ultimately have implications for designing space suits and life support system for visiting astronauts! * Was there an ancient ocean over the northern plains of Mars? The evidence revealed by previous missions has been ambiguous. The HRSC's contiguous 3D imaging in full colour has the best chance yet of revealing an ancient shoreline, if one exists. Over the next few months, the European Space Agency in collaboration with national organisations will be holding press conferences about Mars Express at different locations across Europe. Further information will follow as soon as it is available. In the meantime, background information and regular updates on the progress of the project are available at ESA's Mars Express website, at http://sci.esa.int/marsexpress Instrument and Principal Investigator ASPERA (Energetic Neutral Atoms Analyser) Rickard Lundin, Swedish Institute of Space Physics, Kiruna, Sweden (presently on sabbatical in Toulouse). Contact: Dr Stas Barabash (Co-PI), Swedish Institute of Space Physics, Box 812 98128, Kiruna, Sweden, tel. +46-980-79122, Fax: +46-980-79050, e-mail: stas@irf.se BEAGLE-2 (Geochemical Lander) Colin Pillinger, Open University, Milton Keynes, UK, tel. +44 1908 652119, fax.+44 1908 655910, e-mail: psri@open.ac.uk HRSC (High/Super Resolution Stereo Camera), Gerhard Neukum, DLR, Institut für Planetenerkundung, Berlin, Germany, tel. +49 30 67055 300, fax. +49 30 67055 303, e-mail: gerhard.neukum@dlr.de MaRS (Radio Science Experiment), Martin Pätzold, University of Cologne, Germany, tel. +49 221 4703385, fax. +49 221 4705198, e-mail: paetzold@geo.uni-koeln.de MARSIS (Subsurface Sounding Radar/Altimeter), Giovanni Picardi, University of Rome, Italy, tel. +39 06 44585455, fax. +39 06 4873300, e-mail: picar@infocom.ing.uniroma1.it OMEGA (IR Mineralogical Mapping Spectrometer), Jean-Pierre Bibring, Institut d'Astrophysique Spatiale, Orsay, France, tel. +33 1 69858686, fax. +33 1 69858675, e-mail: bibring@ias.u-psud.fr PFS (Planetary Fourier Spectrometer), Vittorio Formisano, Istituto Fisica Spazio Interplanetario, Rome, Italy, tel. +39 6 49934362, fax. +39 6 49934383, e-mail: formisan@nike.ifsi.rm.cnr.it SPICAM (UV and IR Atmospheric Spectrometer), Jean-Loup Bertaux, Service d'Aéronomie, Verrières-le-Buisson, France, tel. +33 1 64474251, fax. +33 1 6920299, e-mail: jean-loup.bertaux@aerov.jussieu.fr. Additional contact: Christian Muller, Belgian Institute for Space Aeronomy. B.USOC earth observations coordination, Avenue Circulaire, 3, B-1180 Brussels, Belgium, tel. +32-2-3730372, fax: +32-2-3748423, e- mail: Christian.Muller@oma.be

Mars Express — how to be fastest to the Red Planet

NASA Astrophysics Data System (ADS)

2003-05-01

Mars Express is the first example of ESA’s new style of developing scientific missions: faster, smarter and more cost-effective, but without compromising reliability and quality - there have been no cuts in tests or pre-launch preparations. Mars Express will face demanding technical challenges during its trip to the Red Planet and ESA engineers have worked hard to make sure it meets them. "With Mars Express, Europe is building its own expertise in many fields. This ranges from the development of science experiments and new technologies - new for European industry - to the control of a mission that includes landing on another planet. We have never done this before,” says Rudi Schmidt, Mars Express Project Manager. Quicker, smarter…safe! Mars Express’s design and development phase has taken about four years, compared with about six years for previous similar missions. And its cost, 300 million euros, is much less than other comparable planetary missions. The ‘magic’ lies in the new managerial approach being used. This new approach includes the reuse of existing hardware and instruments. Also, the mission was developed by a smaller ESA team, who gave more responsibility to industry. Mars Express has been built by a consortium of 24 companies from ESA’s 15 Member States and the United States, led by Astrium as prime contractor. However, mission safety was never compromised. “Although we were under heavy pressure towards the end of the project, we did not drop any of the planned tests to save time. I call this a fast design phase, followed by thorough testing activity,” says Schmidt. This new streamlined development method will continue with Venus Express and probably other future missions. Launch Mars Express will be launched on 2 June on board a Soyuz-Fregat rocket from the Baikonur Cosmodrome in Kazakhstan. The mission consists of an orbiter and a lander, called Beagle 2. In its launch configuration, Mars Express is a honeycombed aluminium box that measures 1.5 by 1.8 by 1.4 metres (excluding solar panels), and weighs 1223 kilograms in total. The Beagle-2 lander travels attached to one side of the spacecraft, folded up rather like a very large pocket watch. Arrival at Mars is scheduled for late December this year, when Beagle 2 will land while the orbiter is entering its orbit around Mars. The last activities of an intense launch campaign are taking place in Baikonur at this very moment. Mars Express arrived at the Cosmodrome on 20 March. The spacecraft, fuelled with 457 kilograms of propellant, was mounted on the Soyuz launcher on 24 May in a process that the Russians call ‘marriage’. The whole structure was rolled out to the launch pad on 29 May, four days before launch. The fastest possible trip to Mars One of the reasons scientists had to develop Mars Express so quickly arises from the fact that, this summer, Mars and the Earth will be especially close to each other. Although launch opportunities to go to Mars occur every 26 months - when the Sun, Earth and Mars form a straight line - this year the planets will be at their closest, which happens every 15 to 17 years. On top of that, calculations had shown that the best combination of fuel expenditure and travel time could only be achieved by launching in the period between 23 May and 21 June. The Mars Express team had to work very hard to meet this launch window. As a tribute from one European high-tech organisation to another, Mars Express is carrying a small container of Ferrari red paint to the Red Planet. After the launch Mars Express will separate from the Soyuz Fregat upper stage 90 minutes after liftoff. Then the solar arrays will open and the spacecraft will make contact with ESA’s ground station in New Norcia, Western Australia. Mars Express will be travelling away from Earth at a speed of 3 kilometres per second. A crucial operation at this early stage of the trip will be to release the Beagle-2 launch clamps three days after launch. These clamps are extra gears to make sure that the lander stays securely attached to the spacecraft during the launch, but once in space they are not needed any more. A pyrotechnic device will be activated to release them. This will be a key step, necessary so that Beagle 2 can be ejected when the spacecraft arrives at Mars. Every effort has been made to ensure that things go smoothly. Schmidt says: “We have tested all aspects of the mission well enough to be confident that there will be no errors or trivial mistakes. Mars Express has been developed in record time, but there have been no compromises on testing, including the ground segment." Orbiting and landing on Mars Six days before arrival at Mars, the lander will be released. This operation is regarded as one of the most complex of the Mars Express mission. Beagle 2, which weighs only 65 kilograms, is too light to carry a steering mechanism and is not designed to receive commands during cruise and landing. So Beagle 2 can only reach its planned landing site by relying on the orbiter to put it into the correct trajectory and drop it at a very precise point in space and at a specified speed. The ground control team at the European Space Operations Centre (ESOC) in Darmstadt, Germany, will guide this manoeuvre. To be ready for the approach to Mars and the ejection operations, engineers have been training for months with simulators that resemble sophisticated computer games. Tests will continue after Mars Express’s launch. Approaching Mars, the orbiter will eject the lander and then be left on a collision course with the planet. In another key manoeuvre, ground controllers will have to adjust its trajectory, reducing its speed to 1.8 kilometres per second. At that speed, the planet’s gravity will be able to ‘capture’ the Mars Express orbiter and put it into Mars orbit. Ground controllers will still have to perform several manoeuvres to get the spacecraft into its final operational state - a highly elliptical polar orbit - from where the scientific observations can begin. In the meantime, Beagle 2 will have landed on Mars. The landing area covers a large ellipsis, 300 kilometres long and 150 kilometres wide, on an equatorial region called Isidis Planitia. It was chosen in the light of the strong Martian winds and the relatively smooth surface of the site. The lander will deploy parachutes, and then large gas-filled bags will protect it as it bounces to a halt on the surface. Once landed, Beagle 2 will emit a ‘beep’, a signal that will tell operators at the United Kingdom’s Jodrell Bank radio telescope station that it has touched down safely. This 9-note call sign was composed for the Beagle-2 team by the British pop group, Blur. Mars Express will investigate the Martian surface, subsurface, and atmosphere for at least two years. The lander will operate on the surface for about six Earth months, relaying its data to Earth through the orbiter. Mars Express will help answer fundamental questions about Mars, such as the presence and quantity of water, and possible signs of present or past life. In the worldwide effort to explore the Red Planet in recent years, the European Mars Express mission represents the most thorough investigation of Mars attempted so far.

EDITORIAL: A tribute to Zhores Ivanovitch Alferov, a pioneer who changed our way of daily life A tribute to Zhores Ivanovitch Alferov, a pioneer who changed our way of daily life

NASA Astrophysics Data System (ADS)

Bimberg, Dieter

2011-01-01

Can you think of living without the World Wide Web, e-mail, DVDs, CD-ROMs, the bar code scanner, mobile phones or high-efficiency solar cells? I cannot. These systems are part of the backbone of our modern civilization. And they have something in common: they are all devices based on the double heterostructure. Zhores Alferov (and independently Herbert Krömer) proposed its concept and its usefulness for semiconductor lasers in 1962, two years after the first demonstration of the first (solid-state) laser. InP-based double heterostructure lasers are today, and have been for more than 20 years, the enabling light sources for optical fiber communication, sending their photonic bits around the globe at enormous and ever-increasing rates. In 2009, 61% of the 500+ billion world market for laser systems was based on semiconductor lasers. Obviously a straightforward success story? Not really at the beginning, rather the kind of survival story of somebody who was producing an enormous number of ideas and trying to make them reality; his production of ideas has not yet stopped after 60 years of professional life. Let's have a look back at how it started. Zhores Alferov was born 80 years ago on 15 March 1930 in Vitebsk in eastern Byelorussia, an area where 47 years before him the famous painter Marc Chagall had been born. His parents believed in socialism and named him after the French socialist Jean Jaurès, the author of J'accuse. The war came when he was an adolescent and his admired older and only brother was killed in 1944 at the battle of Stalingrad. Despite the turmoil of war and post-war times he finished school successfully on time, was admitted to the V I Uljanov Electrotechnical Institute in Leningrad, studied physics and graduated there in 1952. In 1953 he started work at the Physico-Technical Institute in Leningrad, founded by Abraham Ioffe, the first PhD student of Conrad Rèntgen in Munich. Ioffe had initiated systematic studies of semiconductors at this institute in the thirties, leading to many important discoveries such as the metal-semiconductor contact, work that Ioffe did together with Frenkel. Seven years later, in 1960, another completely different direction of research created excitement and interest across the world, including for Zhores Alferov. The first demonstration of laser action in ruby by Theodore Maiman, verifying Einstein's prediction of stimulated emission (1917), was followed within 18 months by the demonstration of gas lasers and semiconductor diode lasers based on GaAs homojunctions. Solid-state and gas lasers from the very beginning operated at room temperature (RT), but semiconductor lasers did not. They operated only at the temperature of liquid He, at 4 K. Gas and solid-state lasers very quickly found a wide range of applications. Not so semiconductor lasers, being judged at that time to be useless. The whole world however, recognized at once how important it would be to have RT semiconductor lasers. Teams at Bell Labs, IBM, RCA etc. entered the race, but failed for a long time. The problem—as we now know—was the p-n homojunction. In a forward-biased homojunction the charge carriers are widely spread in space at room temperature with low peak carrier density. In addition, there are enormous losses of the light emitted in the junction. At that time a new subject appeared in the life of Zhores Alferov: the heterojunctions. Heterojunctions had already appeared on the horizon in the early days of electronics, starting in 1951 with theoretical proposals for improved transistors by Shockley, Krömer and others. Single heterostructures were tried for laser action and the temperature limit was pushed up to 77 K, an enormous progression compared with 4 K, but still completely academic. In 1963, Zhores Alferov and Rudi Kazarinov in a patent application, and Herbert Krömer in a publication, proposed independently of each other to confine carriers in a double heterostructure, leading to an increase of carrier density by several orders of magnitude in the confinement layer. Alferov and Kazarinov called it the superinjection effect. But there was no practical realization. The advantages of such a structure, as pointed out a little later by Zhores Alferov in 1966, would be efficient injection and localization of charge carriers in a material having a narrower energy gap surrounded by wide-gap material, and additionally, guidance of the emitted light by index of refraction steps at the heterojunction. The proposal was a theoretical one and the first attempts at experimental realization went in an unsuccessful direction, as may happen to any of us: the combination of indirect semiconductors with direct ones to form a heterostructure. Alferov and Kazarinov's patent was then considered by some in the community as paperwork. Then suddenly, material science and device physics merged. Zhores Alferov became aware that other researchers at Ioffe had successfully grown the ternary compound AlGaAs, lattice-matched to GaAs, but with a larger band gap. He had the instinct to realize how important that progress was. Ideally perfect AlGaAs/GaAs/AlGaAs double heterostructures were grown on his initiative by liquid-phase epitaxy, lasers were processed and were observed to operate suddenly at RT. In 1968, results on the first double heterostructure laser operating at RT were submitted to Soviet Physics-Semiconductors. That was the breakthrough which ignited an explosion of work on many different applications of semiconductor lasers, which diffused, year by year, more and more into our daily life. Often, we do not realize that the same strategic principle exists, here the double heterostructure, which makes many completely different devices and systems work. Already in 1967, Zhores Alferov had started to discuss the first applications of such structures for electronic devices. A hetero-bipolar transistor was realized in 1973, nowadays a high-power and frequency-enabling device, e.g. for satellite telephones, in some ways continuing his work for the candidate degree when he had developed power rectifiers based on Ge and Si. Then, in 1970, he presented the first solar cells with efficiency >30% based on heterojunctions. Soon the Soviet Space Administration became aware of these results, and in 1986 the Soviet space station MIR was partially powered by solar cells developed by Alferov and Andre'ev. Finally in 1992, a joint research program between the author of this Editorial and Zhores Alferov, being both guest scientists at the same time at the University of California, on semiconductor quantum dots for the active zone of (nowadays many different) optoelectronic devices was proposed and inaugurated. Quantum dot lasers today have the lowest threshold current density of any semiconductor lasers. They are far superior to quantum wells as amplifiers, and their nonlinear optical applications such as cross-gain modulation in local area networks, present the basis for novel types of solar cells, nanoflash memories, single q-bit emitters for quantum cryptography etc. The story of inventing a concept and inventing applications seems to repeat in some way. This Semiconductor Science and Technology special edition presents contributions from about 100 researchers around the globe, who use in their work concepts invented by Zhores Alferov during his long active scientific life spanning six decades. They would like to pay a tribute to him and honour him on the occasion of his 80th birthday. This very personal way of saying thank you thus adds to the many prizes he has received during the past 40 years, starting with the Ballantine Gold Medal of the Franklin Institute, via the Nobel Prize for Physics 2000 to many honorary doctorates from institutes around the world.