bluuebunny/crossref_metadata_2025 huggingface dataset:
When East Meets West: New Technology From Romania Reduces Fuel Consumption and Emissions With Virtually No Capital Costs
Authors: Barnes William
Published: October 2008

Wouldn’t it be nice to have plug and play technology for your boilers just like on your home computer? Wouldn’t it be great if this technology could give you instant and measurable reductions of 5 percent or more in fuel consumption? Well, in the modern era, this technology has arrived. A small Romanian company has developed a technology that treats combustion air that significantly increases fuel efficiency and lowers emissions on furnaces and boilers by interacting with the fuel at the combustion stage. This technology has the potential to reduce emissions of CO2 by 2–20%, NOx by 5–30%, SOx by 20–60% and emissions that negatively affect human health like acid mists (SO3), dioxins, benzenes, and VOC by as much as 90%. With over a million hours of testing on over 100 boilers and furnaces this economical technology holds great promise. The best part of the technology is that there is limited capital investment or operational costs, and use of the specialty aerosol injection will reduce wear and corrosion in your combustion box regardless of the fuel burned. It reduces costs across the board. Avogadro Environmental Corporation in Easton, PA is working with our partners, Opris Engineering and Kubik in Romania to make this technology available in the United States. The technology has a long proven record of performance and has been fully tested in the U.S. for efficiency improvements and emissions reductions. The technology has received the support of USEPA and state agencies. We are looking for plant operators interested in reducing their emissions and at the same time saving 5–25% in operating and maintenance costs. We just completed two full scale tests of the technology here in the US. The first site was a 90-day test at a 450 MMBtu/hr waste coal-fired electric utility boiler in Pennsylvania. The second site was a 60-day test at a 1,500 MMBtu/hr coal-fired electric utility boiler in the Southeast US.
Estimating HP-IP Mid-Span Packing Leakage in Combined Cycles
Authors: Fiadjoe Tsatsu
Published: October 2008

When a turbine has combined High Pressure (HP) and Intermediate Pressure (IP) sections, there is a steam flow path between the sections. In Combined Cycle steam turbines this internal leakage flow rate needs to be determined for the steam turbine performance calculations. However, since the leakage is internal to the turbine, it cannot be measured directly. One method which has been employed in determining the Mid-packing leakage flow rate is the Variation of Initial and/or Reheat Temperature method. This method is described in the paper “Estimating The Leakage From HP To IP Turbine Sections” presented by J.A. Booth and D.E. Kautzmann. It involves using the convergence of IP efficiency plots from multiple test runs to estimate the HP-IP leakage flow rate. Although this method has been employed successfully in large steam applications, it has generally not produced consistent results for Combined Cycle steam turbines. The lack of convergence for Combined Cycles may be due to the fact that some of the assumptions made in applying the method to large steam applications are not valid for Combined Cycle applications. Some of the assumptions which need to be reviewed and modified for Combined Cycle application are as follows: • Constant IP efficiency for all test runs; • Constant throttle flow during all test runs; • Constant section pressure ratios for all test runs; • No influence of external cooling or admission flows. This paper reviews the modifications to the traditional Initial and/or Reheat temperature variation method to make the Mid-Packing leakage calculations more consistent for Combined Cycle applications. Some data has shown that incorporating these additional changes improves the convergence of Mid-packing leakage determination.
Homogeneous Charge Compression Ignition (HCCI) Engine Fueled With Natural Gas for Stationary Power Generation Applications
Authors: Kweon Chol-Bum M. , Pratapas John M. , Foster David E.
Published: October 2008

In this study, a single-cylinder HCCI engine was used to study the technical feasibility of HCCI engines for stationary power generation applications. The compression ratio (CR) of the engine was set at 13.8:1 considering a hybrid system with diesel micro-pilot injection. The engine was operated under various loads at a rated speed of 1800 rpm. Intake manifold temperature of the air/fuel mixture was used to control the start of combustion (SOC) of the HCCI engine. Oil and coolant temperatures were set at 100°C. Location of peak in-cylinder pressure (PPL) was maintained within 6∼9°ATDC in order to obtain maximum thermal efficiency by initiating the SOC between 2∼4°BTDC. Intake boost was increased up to 2.5 bar absolute to increase engine power output. Results of the HCCI combustion were also compared with those of diesel and diesel micro-pilot natural gas combustion. The results showed that the required intake temperature ranged from 149°C to 261°C depending on engine loads. The highest net mean effective pressure (NMEP) was about 10.6 bar. Higher intake boost pressure would increase NMEP even higher. Maximum indicated thermal efficiency (ITE) was about 49% at the excess air ratio (λ) of 3.2 and maximum combustion efficiency was about 94% at λ = 2.6. Oxides of nitrogen (NOx) emissions were below 10 ppm when λ was above 3. At these excess air ratios, in the good HCCI operating regimes, carbon monoxide (CO), total hydrocarbons (THC), and methane (CH4) were equivalent to those of conventional natural gas engines.
Analysis of Vibration of the Turbine Blades Using Non-Intrusive Stress Measurement System
Authors: Joung Kyu-Kang , Kang Suk-Chul , Paeng Ki-Seok , Park No-Gill , Choi Ho-Jin , You Young-Jun , von Flotow Andy
Published: October 2008

A Non-intrusive Stress Measurement (NSMS) was developed to measure coupled vibration on turbine blades. These systems can report the actual stresses seen on the blades; detect synchronous resonances that are the source of High Cycle Fatigue (HCF) in blades; measure individual blade mistuning and even help separate complicated, coupled resonances in bladed disks. Tests were successfully performed at high temperature and measured both tip timing and tip clearance of all blades. Non-Intrusive Stress Measurement Systems (NSMS) was used successfully in measuring bladed disk vibration, and was consistent over many runs. The SDOF curve fit and Circumferential Fourier fit were used to identify resonance amplitudes, resonance RPM and damping for all blades. The results of the two data-reduction methods matched well. Because tip deflection for every blade can be obtained with NSMS system, it might be possible to reduce the fatigue margin relative to the fatigue margin based upon strain gage data from a few blades.
Manufacturing and Testing of Welded Stainless Steel Tubing: You Have a Choice
Authors: Janikowski Daniel S. , Roth Ron
Published: October 2008

A tubing manufacturer has many alternatives for manufacturing and testing stainless steel tubing for feedwater heater and condenser applications. ASTM specifications are fairly generic in nature and only specify the basic requirements needed for supplying a tube. These may not be sufficient for providing the appropriate quality tube for a critical power plant application. This paper summarizes many of the options in welding, cold working, heat treating and testing of tubing. It identifies the advantages and disadvantages of each and provides suggestions on what should be specified to ensure a reliable cost-effective tube for your application.
On Identifying Condenser Design Deficiencies
Authors: Harpster Joseph W.
Published: October 2008

How well a condenser is performing is shown to be difficult to determine. The result obtained by using defined measurements in this determination is sometimes biased by shell side conditions that are often not well understood, leading to gross error in calculated condenser performance parameters. This paper describes some of these conditions, identified through recent research findings, and introduces methods to minimize the extent of the error. The discussion addresses how these condenser operating conditions have impact on calculated condenser performance parameters and how they may be properly understood by making use of relatively new measurements or through the application of comprehensive knowledge of the water vapor and noncondensable gas mixture dynamics. Such conditions as measured air in-leakage, and knowledge of no or very low tube fouling based on recent cleaning, are important for the purpose of quantifying the impact of design deficiencies on calculated condenser performance parameters. With proper condenser monitoring, telltale indicators of these deficiencies are clearly observed and will be presented. An investigation program that identifies the amount of performance loss, and the recoverable portion through condenser modifications, is discussed.
Development of a Technology Roadmap for the Energy and Water Nexus
Authors: Ho Clifford K. , Hightower M. Michael , Pate Ronald C. , Einfeld Wayne , Cameron Christopher P. , Hernandez Jacquelynne , O’Leary Marilyn C. , McMahon James E. , Mulligan Conrad
Published: October 2008

Energy and water are critical resources that are inextricably and reciprocally linked. The production of energy requires large volumes of water, and the treatment and distribution of water depends upon readily available, low-cost energy. For example, electricity production from thermoelectric power plants can use ∼140,000 million gallons of water per day for cooling—accounting for 39% of all freshwater withdrawals in the nation, second only to agriculture in the United States (Figure 1). Significant amounts of water are also needed for hydropower, extraction/refining of minerals for energy, and bio-fuel production. Electrical energy, on the other hand, is needed for water treatment (e.g., desalination, wastewater), pumping, and distribution. The amount of electricity used in water and wastewater industries is equivalent to the amount used in chemical, petroleum refining, and paper industries. These interdependencies, coupled with increasing demands for energy and diminishing availability of freshwater supplies, pose significant challenges to ensure the sustainability of these two critical resources. Examples of the interrelationships between energy and water use are shown in Figure 2.
Construction of a Lab-Scale Reverse Osmosis (RO) System for Organic/Biological Fouling Research
Authors: Jin Yujie , Huang Frank
Published: October 2008

New Mexico ranks 2nd in natural gas production of all producing states and the Gulf Coast region. A significant amount of produced water can be generated during gas production. In 2002, around 3.8 million barrels of produced water were generated during gas production in the San Juan Basin. While obviously not drinkable at the wellhead due to the presence of salts, trace organics, and heavy metals, produced water may be treated for agricultural and industrial purposes. Reclaiming produced water for industrial processes would then free up freshwater resources for other beneficial uses. Membrane separation is a viable option for produced water desalinization; however, its large-scale implementation has been plagued by the recurring fouling of the membranes and the associated high operating costs. The paper describes the components and layout of a bench-scale reverse osmosis (RO) system used to study membrane fouling from the desalination of produced water.
QUANTUM CONFINEMENT EFFECTS IN STRAINED SILICON MOSFETS
Authors: KUMAR M. JAGADESH , SINGH TARUN VIR
Published: October 2008

In this paper, we have examined the effect of quantum confinement of carriers on the threshold voltage of strained-silicon (s- Si ) nanoscale Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). Using results from quantum theory and two-dimensional simulation, we show that strain-induced threshold voltage roll-off in s- Si nanoscale MOSFETs can be overcome by decreasing s- Si layer thickness. Based on our simulation study, we provide an optimization between threshold voltage, strain and s- Si layer thickness.
STRANGE EFFECT OF DISORDER ON ELECTRON TRANSPORT THROUGH A THIN FILM
Authors: MAITI SANTANU K.
Published: October 2008

A novel feature of electron transport is explored through a thin film of varying impurity density with the distance from its surface. The film, attached to two metallic electrodes, is described by simple tight-binding model and its coupling to the electrodes is treated through Newns–Anderson chemisorption theory. It is observed that in the strong disorder regime the amplitude of the current passing through the film increases with the increase of the disorder strength, while it decreases in the weak disorder regime. This anomalous behavior is completely opposite to that of conventional disordered systems. Our results also predict that the electron transport is significantly influenced by the finite size of the thin film.
FABRICATION AND CHARACTERIZATION OF MWCNT/THERMOPLASTIC MICROSPHERE NANOCOMPOSITE FOAMS
Authors: RANGARI VIJAYA K. , JEELANI MOHAMMAD I. , ZHOU YUANXIN , JEELANI SHAIK
Published: October 2008

A novel sonochemical method is developed to coat multi-walled carbon nanotubes (MWCNTs) on expandable thermoplastic (acrylonitrile and methylacrylonitrile polymer) microspheres (Expancel). These polymeric thermoplastic microspheres were further fabricated in a form of foam panels using a compression molding technique. The test coupons were cut precisely from the as-prepared panels and characterized by scanning electron microscopy (SEM), X-ray diffraction, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The SEM studies have shown that the MWCNTs are well dispersed over the entire volume of the matrix with minimal agglomeration. The foam cell structures are well-ordered, spherical in shape, and uniform in size. The TGA and DSC analyses indicate that the nanocomposite foam samples are thermally more stable than the corresponding neat foam samples. The compression tests have been carried out for both nanocomposite and neat foam samples. These test results show a significant increase in compressive strength and modulus for nanocomposite foam samples as compared to the neat foam samples. These enhancements in compressive properties have been observed repeatedly for multiple batches. The details of synthesis procedure, thermal and mechanical characterization are presented in this paper.
INDIRECT EXCHANGE COUPLING OF NUCLEAR SPINS OF MAGNETIC IMPURITIES IN 2D ELECTRON SYSTEM
Authors: DAHAN P.
Published: October 2008

The indirect exchange interaction between two magnetic impurities in a two-dimensional electron system under a strong magnetic field is studied. The nuclear spin coupling is mediated by Landau electrons bound to these impurities. We consider the contact hyperfine coupling of the bound Landau electrons, which is an s-type wave function and is therefore significant. The d electrons are indirectly involved in the contact interaction through their resonance scattering potential, which is found to be spin selective and therefore binds Landau electrons with proper spin polarization. Thus, the resulting superexchange interaction between two different sites involves the bound Landau states of one site and the impurity d states of the second site, resulting in an antiferromagnetic interaction between the nuclear spins of the impurities. The coupling constant between these nuclear spins, J, is found to depend strongly on the ratio of the impurity separation over the magnetic length. Possible applications of these results may include a long-range mechanism for coupling between two nuclear spins to be used as a qubit interaction with a spacing distance of the order of magnitude of the magnetic length.
GROWTH DYNAMICS OF II–VI COMPOUND SEMICONDUCTOR QUANTUM DOTS EMBEDDED IN BOROSILICATE GLASS MATRIX
Authors: VERMA ABHISHEK , PANDEY P. K. , KUMAR J. , NAGPAL S. , BHATNAGAR P. K. , MATHUR P. C.
Published: October 2008

Wide bandgap II–VI semiconductor quantum dots embedded in glass matrix have shown great potential for opto-electronic device applications. The current problem is to achieve low size dispersion, high volume fraction, and better control over the size of the quantum dots in glass matrix. In this work, a modified growth method has been proposed to achieve a greater control over the size of quantum dots, to reduce their size dispersion and to increase their volume fraction. A theoretical model has been developed to quantitatively estimate the various parameters of the quantum dots. The effects of aging on various parameters of quantum dots in Semiconductor-Doped Glass (SDG) samples have also been discussed in the present work.
TWO-STATE STRUCTURE OF NANOMETER-SIZED Cu PARTICLES
Authors: MANAI GIUSEPPE , DELOGU FRANCESCO
Published: October 2008

Molecular dynamics simulations have been employed to investigate the static and dynamic properties of unsupported spherical Cu particles with size ranging between 1 and 10 nm. The potential energy, the structural arrangement, and the mobility of atomic species were studied for each nanometer-sized particle within the temperature range between 300 K and the melting point. Two distinct regions, namely an internal domain and a surface layer, can be identified within each nanoparticle on the basis of the radial profiles of such quantities. The atomic species belonging to the interior of the particle display a bulk-like behavior. By contrast, the surface layer is characterized by an excess potential energy associated with a disordered structure. At relatively low temperatures, the surface atoms possess structural and energetic features intermediate between the ones of a superheated bulk solid and of an undercooled bulk liquid. Pre-melting processes at the surface are also evident at temperatures close to the melting point. The nanometer-sized particles can be thus regarded as heterogeneous two-state systems consisting of roughly distinguishable bulk-like and surface regions.
Multipartite Circulant States with Positive Partial Transposes
Authors: Chruściński Dariusz , Kossakowski Andrzej
Published: October 2008

We construct a large class of multipartite qudit states which are positive under the family of partial transpositions. The construction is based on certain direct sum decomposition of the total Hilbert space displaying characteristic circular structure and hence generalizes a class of bipartite circulant states proposed recently by the authors. This class contains many well-known examples of multipartite quantum states from the literature and gives rise to a huge family of completely new states.
Algorithm for Quantum-like Representation: Transformation of Probabilistic Data into Vectors on Bloch's Sphere
Authors: Khrennikov Andrei
Published: October 2008

In this paper, we present a simple algorithm for representation of statistical data of any origin by complex probability amplitudes. Numerical simulation with Mathematica-6 is performed, cf. [1] and [2] on recent numerical simulation for quantum correlations. The Bloch's sphere is used for the visualization of results of numerical simulation. On the one hand, creation of such a quantum-like (QL) representation and its numerical approval is an important step in clarification of extremely complicated interrelation between classical and quantum randomness. On the other hand, it opens new possibilities for applying the mathematical formalism of QM in other domains of science.
An efficient, versatile approach to suffix sorting
Authors: Maniscalco Michael A. , Puglisi Simon J.
Published: October 2008

Sorting the suffixes of a string into lexicographical order is a fundamental task in a number of contexts, most notably lossless compression (Burrows--Wheeler transformation) and text indexing (suffix arrays). Most approaches to suffix sorting produce a sorted array of suffixes directly, continually moving suffixes into their final place in the array until the ordering is complete. In this article, we describe a novel and resource-efficient (time and memory) approach to suffix sorting, which works in a complementary way—by assigning each suffix its rank in the final ordering, before converting to a sorted array, if necessary, once all suffixes are ranked. We layer several powerful extensions on this basic idea and show experimentally that our approach is superior to other leading algorithms in a variety of real-world contexts.
Symmetry breaking for pseudo-Boolean formulas
Authors: Aloul Fadi A. , Ramani Arathi , Markov Igor L. , Sakallah Karem A.
Published: October 2008

Many important tasks in design automation and artificial intelligence can be performed in practice via reductions to Boolean satisfiability (SAT). However, such reductions often omit application-specific structure, thus handicapping tools in their competition with creative engineers. Successful attempts to represent and utilize additional structure on Boolean variables include recent work on 0-1 integer linear programming (ILP) and symmetries in SAT. Those extensions gracefully accommodate well-known advances in SAT solving, however, no previous work has attempted to combine both extensions. Our work shows (i) how one can detect and use symmetries in instances of 0-1 ILP, and (ii) what benefits this may bring.
Dynamic spatial approximation trees
Authors: Navarro Gonzalo , Reyes Nora
Published: October 2008

Metric space searching is an emerging technique to address the problem of efficient similarity searching in many applications, including multimedia databases and other repositories handling complex objects. Although promising, the metric space approach is still immature in several aspects that are well established in traditional databases. In particular, most indexing schemes are static, that is, few of them tolerate insertion or deletion of elements at reasonable cost over an existing index. The spatial approximation tree (
sa--tree
) has been experimentally shown to provide a good tradeoff between construction cost, search cost, and space requirement. However, the
sa--tree
is static, which renders it unsuitable for many database applications. In this paper, we study different methods to handle insertions and deletions on the
sa--tree
at low cost. In many cases, the dynamic construction (by successive insertions) is even faster than the previous static construction, and both are similar elsewhere. In addition, the dynamic version significantly improves the search performance of
sa--trees
in virtually all cases. The result is a much more practical data structure that can be useful in a wide range of database applications.
An experimental study of algorithms for fully dynamic transitive closure
Authors: Krommidas Ioannis , Zaroliagis Christos
Published: October 2008

We have conducted an extensive experimental study on algorithms for fully dynamic transitive closure. We have implemented the recent fully dynamic algorithms by King [1999], Roditty [2003], Roditty and Zwick [2002, 2004], and Demetrescu and Italiano [2000, 2005] along with several variants and compared them to pseudo fully dynamic and simple-minded algorithms developed in a previous study [Frigioni et al. 2001]. We tested and compared these implementations on random inputs, synthetic (worst-case) inputs, and on inputs motivated by real-world graphs. Our experiments reveal that some of the dynamic algorithms can really be of practical value in many situations.
Experimental average-case performance evaluation of online algorithms for routing and wavelength assignment and throughput maximization in WDM optical networks
Authors: Li Keqin
Published: October 2008

We investigate the problem of online routing and wavelength assignment and the related throughput maximization problem in wavelength division multiplexing optical networks. It is pointed out that these problems are highly inapproximable, that is, the competitive ratio of any algorithm is at least a polynomial. We evaluate the average-case performance of several online algorithms, which have no knowledge of future arriving connection requests when processing the current connection request. Our experimental results on a wide range of optical networks demonstrate that the average-case performance of these algorithms are very close to optimal.
An experimental study of sorting and branch prediction
Authors: Biggar Paul , Nash Nicholas , Williams Kevin , Gregg David
Published: October 2008

Sorting is one of the most important and well-studied problems in computer science. Many good algorithms are known which offer various trade-offs in efficiency, simplicity, memory use, and other factors. However, these algorithms do not take into account features of modern computer architectures that significantly influence performance. Caches and branch predictors are two such features and, while there has been a significant amount of research into the cache performance of general purpose sorting algorithms, there has been little research on their branch prediction properties. In this paper, we empirically examine the behavior of the branches in all the most common sorting algorithms. We also consider the interaction of cache optimization on the predictability of the branches in these algorithms. We find insertion sort to have the fewest branch mispredictions of any comparison-based sorting algorithm, that bubble and shaker sort operate in a fashion that makes their branches highly unpredictable, that the unpredictability of shellsort's branches improves its caching behavior, and that several cache optimizations have little effect on mergesort's branch mispredictions. We find also that optimizations to quicksort, for example the choice of pivot, have a strong influence on the predictability of its branches. We point out a simple way of removing branch instructions from a classic heapsort implementation and also show that unrolling a loop in a cache-optimized heapsort implementation improves the predicitability of its branches. Finally, we note that when sorting random data two-level adaptive branch predictors are usually no better than simpler bimodal predictors. This is despite the fact that two-level adaptive predictors are almost always superior to bimodal predictors, in general.
Terracost
Authors: Hazel Thomas , Toma Laura , Vahrenhold Jan , Wickremesinghe Rajiv
Published: October 2008

This paper addresses the problem of computing least-cost-path surfaces for massive grid terrains. Consider a grid terrain
T
and let
C
be a cost grid for
T
such that every point in
C
stores a value that represents the cost of traversing the corresponding point in
T
. Given
C
and a set of sources
S
∈
T
, a least-cost-path grid Δ for
T
is a grid such that every point in Δ represents the distance to the source in
S
that can be reached with minimal cost. We present a scalable approach to computing least-cost-path grids. Our algorithm, terracost, is derived from our previous work on I/O-efficient shortest paths on grids and uses
O
(sort(
n
)) I/Os, where sort(
n
) is the complexity of sorting
n
items of data in the I/O-model of Aggarwal and Vitter. We present the design, the analysis, and an experimental study of terracost. An added benefit of the algorithm underlying terracost is that it naturally lends itself to parallelization. We have implemented terracost in a distributed environment using our cluster management tool and report on experiments that show that it obtains speedup near-linear with the size of the cluster. To the best of our knowledge, this is the first experimental evaluation of a multiple-source least-cost-path algorithm in the external memory setting.
A graph approach to the threshold all-against-all substring matching problem
Authors: Barsky Marina , Stege Ulrike , Thomo Alex , Upton Chris
Published: October 2008

We present a novel graph model and an efficient algorithm for solving the “threshold all against all” problem, which involves searching two strings (with length
M
and
N
, respectively) for all maximal approximate substring matches of length at least
S
, with up to
K
differences. Our algorithm solves the problem in time
O
(
MNK
3
), which is a considerable improvement over the previous known bound for this problem. We also provide experimental evidence that, in practice, our algorithm exhibits a better performance than its worst-case running time.
A dictionary implementation based on dynamic perfect hashing
Authors: Dietzfelbinger Martin , Hühne Martin , Weidling Christoph
Published: October 2008

We describe experimental results on an implementation of a dynamic dictionary. The basis of our implementation is “dynamic perfect hashing” as described by Dietzfelbinger et al. (
SIAM J. Computing 23
, 1994, pp. 738--761), an extension of the storage scheme proposed by Fredman et al. (
J. ACM
31, 1984, pp. 538--544). At the top level, a hash function is used to partition the keys to be stored into several sets. On the second level, there is a perfect hash function for each of these sets. This technique guarantees
O
(1) worst-case time for lookup and expected
O
(1) amortized time for insertion and deletion, while only linear space is required. We study the practical performance of dynamic perfect hashing and describe improvements of the basic scheme. The focus is on the choice of the hash function (both for integer and string keys), on the efficiency of rehashing, on the handling of small buckets, and on the space requirements of the implementation.
On the adaptiveness of Quicksort
Authors: Brodal Gerth Stølting , Fagerberg Rolf , Moruz Gabriel
Published: October 2008

Quicksort was first introduced in 1961 by Hoare. Many variants have been developed, the best of which are among the fastest generic-sorting algorithms available, as testified by the choice of Quicksort as the default sorting algorithm in most programming libraries. Some sorting algorithms are adaptive, i.e., they have a complexity analysis that is better for inputs, which are nearly sorted, according to some specified measure of presortedness. Quicksort is not among these, as it uses Ω(
n
log
n
) comparisons even for sorted inputs. However, in this paper, we demonstrate empirically that the actual running time of Quicksort
is
adaptive with respect to the presortedness measure Inv. Differences close to a factor of two are observed between instances with low and high Inv value. We then show that for the randomized version of Quicksort, the number of element
swaps
performed is
provably
adaptive with respect to the measure Inv. More precisely, we prove that randomized Quicksort performs expected
O
(
n
(1 + log(1 + Inv/
n
))) element swaps, where Inv denotes the number of inversions in the input sequence. This result provides a theoretical explanation for the observed behavior and gives new insights on the behavior of Quicksort. We also give some empirical results on the adaptive behavior of Heapsort and Mergesort.
An experimental study of different approaches to solve the market equilibrium problem
Authors: Codenotti Bruno , Mccune Benton , Pemmaraju Sriram , Raman Rajiv , Varadarajan Kasturi
Published: October 2008

Over the last few years, the problem of computing market equilibrium prices for exchange economies has received much attention in the theoretical computer science community. Such activity led to a flurry of polynomial time algorithms for various restricted, yet significant, settings. The most important restrictions arise either when the traders' utility functions satisfy a property known as
gross substitutability
or when the initial endowments are proportional (the Fisher model). In this paper, we experimentally compare the performance of some of these recent algorithms against that of the most used software packages. In particular, we evaluate the following approaches: (1) the solver PATH, available under GAMS/MPSGE, a popular tool for computing market equilibrium prices; (2) a discrete version of a simple iterative price update scheme called tâtonnement; (3) a discrete version of the welfare adjustment process; (4) convex feasibility programs that characterize the equilibrium in some special cases. We analyze the performance of these approaches on models of exchange economies where the consumers are equipped with utility functions, which are widely used in real world applications. The outcomes of our experiments consistently show that many market settings allow for an efficient computation of the equilibrium, well beyond the restrictions under which the theory provides polynomial time guarantees. For some of the approaches, we also identify models where they are are prone to failure.
Drosophila Models of Neurodegenerative Diseases
Authors: Lu Bingwei , Vogel Hannes
Published: October 2008

Neurodegenerative diseases are progressive disorders of the nervous system that affect specific cellular populations in the central and peripheral nervous systems. Although most cases are sporadic, genes associated with familial cases have been identified, thus enabling the development of animal models. Invertebrates such as Drosophila have recently emerged as model systems for studying mechanisms of neurodegeneration in several major neurodegenerative diseases. These models are also excellent in vivo systems for the testing of therapeutic compounds. Genetic studies using these animal models have provided novel insights into the disease process. We anticipate that further exploration of the animal models will further our understanding of mechanisms of neurodegeneration as well as facilitate the development of rational treatments for debilitating degenerative diseases.
Ovarian Cancer
Authors: Cho Kathleen R. , Shih Ie-Ming
Published: October 2008

Ovarian carcinomas are a heterogeneous group of neoplasms and are traditionally subclassified based on type and degree of differentiation. Although current clinical management of ovarian carcinoma largely fails to take this heterogeneity into account, it is becoming evident that each major histological type has characteristic genetic defects that deregulate specific signaling pathways in the tumor cells. Moreover, within the most common histological types, the molecular pathogenesis of low-grade versus high-grade tumors appears to be largely distinct. Mouse models of ovarian carcinoma have been developed that recapitulate many of the morphological features, biological behavior, and gene-expression patterns of selected subtypes of ovarian cancer. Such models will likely prove useful for studying ovarian cancer biology and for preclinical testing of molecularly targeted therapeutics, which may ultimately lead to better clinical outcomes for women with ovarian cancer.
Plant Ion Channels: Gene Families, Physiology, and Functional Genomics Analyses
Authors: Ward John M. , Mäser Pascal , Schroeder Julian I.
Published: October 2008

Distinct potassium, anion, and calcium channels in the plasma membrane and vacuolar membrane of plant cells have been identified and characterized by patch clamping. Primarily owing to advances in Arabidopsis genetics and genomics, and yeast functional complementation, many of the corresponding genes have been identified. Recent advances in our understanding of ion channel genes that mediate signal transduction and ion transport are discussed here. Some plant ion channels, for example, ALMT and SLAC anion channel subunits, are unique. The majority of plant ion channel families exhibit homology to animal genes; such families include both hyperpolarization- and depolarization-activated Shaker-type potassium channels, CLC chloride transporters/channels, cyclic nucleotide–gated channels, and ionotropic glutamate receptor homologs. These plant ion channels offer unique opportunities to analyze the structural mechanisms and functions of ion channels. Here we review gene families of selected plant ion channel classes and discuss unique structure-function aspects and their physiological roles in plant cell signaling and transport.
Bax signaling regulates palmitate-mediated apoptosis in C2C12myotubes
Authors: Peterson Jonathan M. , Wang Yan , Bryner Randall W. , Williamson David L. , Alway Stephen E.
Published: October 2008

Insulin resistance is a primary characteristic of type 2 diabetes. Several lines of evidence suggest that accumulation of free fatty acids in skeletal muscle may at least in part contribute to insulin resistance and may be linked to mitochondrial dysfunction, leading to apoptosis. Palmitate treatment of several cell lines in vitro results in apoptosis and inhibits protein kinase B (Akt) activity in response to insulin. However, the role of Bax and Bcl-2 in regulating palmitate-induced apoptosis has not been well studied. Therefore, the purpose of this study was to determine whether palmitate-induced apoptosis in C2C12myotubes is dependent on Bax to Bcl-2 binding. An additional purpose of this study was to determine whether the changes in Bax to Bcl-2 binding corresponded to decreases in Akt signaling in palmitate-treated myoblasts. Apoptotic signaling proteins were examined in C2C12myotubes treated overnight with palmitate. Bax to Bcl-2 binding was determined through a coimmunoprecipitation assay that was performed in myotubes after 2 h of serum starvation, followed by 10 min of serum reintroduction. This experiment evaluated whether temporal Akt activity coincided with Bax to Bcl-2 binding. Last, the contribution of Bax to palmitate-induced apoptosis was determined by treatment with Bax siRNA. Palmitate treatment increased apoptosis in C2C12myotubes as shown by a twofold increase in DNA fragmentation, an approximately fivefold increase in caspase-3 activity, and a 2.5-fold increase in caspase-9 activity. Palmitate treatment significantly reduced Akt protein expression and Akt activity. In addition, there was a fourfold reduction in Bax to Bcl-2 binding with palmitate treatment, which mirrored the reduction in AktSer473phosphorylation. Furthermore, treatment of the C2C12myotubes with Bax siRNA attenuated the apoptotic effects of palmitate treatment. These data show that palmitate induces Bax-mediated apoptosis in C2C12myotubes and that this effect corresponds to reductions in AktSer473phosphorylation.
Fasting-induced suppression of LH secretion does not require activation of ATP-sensitive potassium channels
Authors: Huang Wenyu , Acosta-Martínez Maricedes , Horton Teresa H. , Levine Jon E.
Published: October 2008

Reproductive hormone secretions are inhibited by fasting and restored by feeding. Metabolic signals mediating these effects include fluctuations in serum glucose, insulin, and leptin. Because ATP-sensitive potassium (KATP) channels mediate glucose sensing and many actions of insulin and leptin in neurons, we assessed their role in suppressing LH secretion during food restriction. Vehicle or a KATP channel blocker, tolbutamide, was infused into the lateral cerebroventricle in ovariectomized mice that were either fed or fasted for 48 h. Tolbutamide infusion resulted in a twofold increase in LH concentrations in both fed and fasted mice compared with both fed and fasted vehicle-treated mice. However, tolbutamide did not reverse the suppression of LH in the majority of fasted animals. In sulfonylurea (SUR)1-null mutant (SUR1−/−) mice, which are deficient in KATP channels, and their wild-type (WT) littermates, a 48-h fast was found to reduce serum LH concentrations in both WT and SUR−/− mice. The present study demonstrates that 1) blockade of KATP channels elevates LH secretion regardless of energy balance and 2) acute fasting suppresses LH secretion in both SUR1−/− and WT mice. These findings support the hypothesis that KATP channels are linked to the regulation of gonadotropin-releasing hormone (GnRH) release but are not obligatory for mediating the effects of fasting on GnRH/LH secretion. Thus it is unlikely that the modulation of KATP channels either as part of the classical glucose-sensing mechanism or as a component of insulin or leptin signaling plays a major role in the suppression of GnRH and LH secretion during food restriction.
Palmitate- and lipopolysaccharide-activated macrophages evoke contrasting insulin responses in muscle cells
Authors: Samokhvalov Victor , Bilan Phillip J. , Schertzer Jonathan D. , Antonescu Costin N. , Klip Amira
Published: October 2008

Factors secreted by macrophages contribute to whole body insulin resistance, acting in part on adipose tissue. Muscle is the major tissue for glucose disposal, but how macrophage-derived factors impact skeletal muscle glucose uptake is unknown, or whether the macrophage environment influences this response. We hypothesized that conditioned medium from macrophages pretreated with palmitate or LPS would directly affect insulin action and glucose uptake in muscle cells. L6-GLUT4 myc myoblasts were exposed to conditioned medium from RAW 264.7 macrophages pretreated with palmitate or LPS. Conditioned medium from palmitate-treated RAW 264.7 macrophages inhibited myoblast insulin-stimulated glucose uptake, GLUT4 translocation, and Akt phosphorylation while activating JNK p38 MAPK, decreasing IκBα, and elevating inflammation markers. Surprisingly, and opposite to its effects on adipose cells, conditioned medium from LPS-treated macrophages stimulated myoblast insulin-stimulated glucose uptake, GLUT4 translocation, and Akt phosphorylation without affecting stress kinases or inflammation indexes. This medium had markedly elevated IL-10 levels, and IL-10, alone, potentiated insulin action in myoblasts and partly reversed the insulin resistance imparted by medium from palmitate-treated macrophages. IL-10 neutralizing antibodies blunted the positive influence of LPS macrophage-conditioned medium. We conclude that myoblasts and adipocytes respond differently to cytokines. Furthermore, depending on their environment, macrophages negatively or positively influence muscle cells. Macrophages exposed to palmitate produce a mixture of proinflammatory cytokines that reduce insulin action in muscle cells; conversely, LPS-activated macrophages increase insulin action, likely via IL-10. Macrophages may be an integral element in glucose homeostasis in vivo, relaying effects of circulating factors to skeletal muscle.
Chewing and taste increase blood velocity in the celiac but not the superior mesenteric arteries
Authors: Someya Nami , Hayashi Naoyuki
Published: October 2008

To investigate the role of chewing and taste in the meal-induced rapid increase in splanchnic blood flow, we compared the blood flow responses in the celiac artery (CA) and superior mesenteric artery (SMA) to chewing solid food with a chocolate taste (FOOD) and paraffin wax without taste (WAX). After 5 min of baseline measurement, 15 healthy subjects repeated chewing and expectorating the FOOD or WAX every 20 s for 4 min followed by 10 min of recovery measurement. We measured the mean blood velocity (MBV) in the CA and SMA. The baseline MBVs in the CA and SMA did not differ between the FOOD and WAX trials. The MBV in the CA was lower than baseline at the 1st min of chewing in both trials. It was higher than baseline at the 3rd min of FOOD chewing, whereas it did not increase during and after WAX chewing. The MBV in the CA was higher in the FOOD trial than in the WAX trial at the 3rd min of chewing and thereafter. In contrast, the MBV in the SMA did not change throughout the protocols. These results suggest that the taste of food plays a role in meal-induced hyperemia in the CA but not the SMA.
An Efficient Estimation Method for Reducing the Axial Intensity Drop in Circular Cone‐Beam CT
Authors: Zhu Lei , Starman Jared , Fahrig Rebecca
Published: October 2008

Reconstruction algorithms for circular cone‐beam (CB) scans have been extensively
studied in the literature. Since insufficient data are measured, an exact reconstruction
is impossible for such a geometry. If the reconstruction algorithm assumes zeros for
the missing data, such as the standard FDK algorithm, a major type of resulting CB
artifacts is the intensity drop along the axial direction. Many algorithms have been
proposed to improve image quality when faced with this problem of data missing; however,
development of an effective and computationally efficient algorithm remains a
major challenge. In this work, we propose a novel method for estimating the unmeasured
data and reducing the intensity drop artifacts. Each CB projection is analyzed in
the Radon space via Grangeat_s first derivative. Assuming the CB projection is taken
from a parallel beam geometry, we extract those data that reside in the unmeasured region of the Radon space. These data are then used as in a parallel beam geometry
to calculate a correction term, which is added together with Hu’s correction term to
the FDK result to form a final reconstruction. More approximations are then made
on the calculation of the additional term, and the final formula is implemented very
efficiently. The algorithm performance is evaluated using computer simulations on analytical
phantoms. The reconstruction comparison with results using other existing
algorithms shows that the proposed algorithm achieves a superior performance on the
reduction of axial intensity drop artifacts with a high computation efficiency.
Vesicoureteral Reflux: Where Have We Been, Where Are We Now, and Where Are We Going?
Authors: McLorie Gordon A.
Published: October 2008

We present a retrospective review of the scientific and clinical advances, extending over four decades, which have linked vesicoureteral reflux, with renal injury, and urinary tract infection. We have traced the original studies, coupled with advances in technology which led to the awareness, and ability to detect and diagnose the problems early in childhood. These advances progressed through clinical studies which defined the epidemiology of both reflux and urinary tract infection. Along with these diagnostic advances, there were numerous surgical developments, which allowed progressive improvements in the outcomes and effectiveness of a variety of treatment modalities. All of this literature leads us to the current era, when several clinical trials are currently underway in an effort to more fully define the most efficacious and safe methods to treat vesicoureteral reflux and associated urinary tract infection.
On the Discrete Harmonic Wavelet Transform
Authors: Cattani Carlo , Kudreyko Aleksey
Published: October 2008

The discrete harmonic wavelet transform has been reviewed
and applied towards given functions. The absolute error of reconstruction
of the functions has been computed.
Intelligent Control of the Complex Technology Process Based on Adaptive Pattern Clustering and Feature Map
Authors: Cheng Wushan
Published: October 2008

A kind of fuzzy neural networks (FNNs) based on adaptive pattern clustering and feature map (APCFM) is proposed to improve the property of the large delay and time varying of the sintering process. By using the density clustering and learning vector quantization (LVQ), the sintering process is divided automatically into subclasses which have similar clustering center and labeled fitting number. Then these labeled subclass samples are taken into fuzzy neural network (FNN) to be trained; this network is used to solve the prediction problem of the burning through point (BTP). Using the 707 groups of actual training process data and the FNN to train APCFM algorithm, experiments prove that the system has stronger robustness and wide generality in clustering analysis and feature extraction.