bluuebunny/crossref_metadata_2025 huggingface dataset:
Relating crustacean zooplankton community structure to residential development and land-cover disturbance near Canadian Shield lakes
Authors: Gélinas Malorie , Pinel-Alloul Bernadette
Published: February 2009

We applied the land-cover cascade (LCC) concept to evaluate whether human disturbance affects crustacean zooplankton community in 13 nutrient-poor lakes of the Laurentian region along a gradient of residential development and land-cover disturbance. Zooplankton biomass responded indirectly to residential disturbances within the watershed based on path analysis. In most LCC models, total phosphorus enrichment was a strong intermediate element linking residential disturbances to increased biomass of small crustaceans ( Bosmina , Ceriodaphnia , and Diaphanosoma ) and Daphnia species ( D. g. mendotae , D. dubia , and D. ambigua ). Zooplanktivory index was also an intermediate element in LCC models of crustacean functional groups and an independent element in daphnid-based LCC models. Low zooplanktivory was associated with higher biomass of large Daphnia ( D. pulicaria and D. catawba ). However, residential disturbance and select environmental factors (phosphate enrichment, zooplanktivory index, lake depth, littoral macrophytes) explained only 42% and 57%, respectively, of among-lake variation in crustacean community and Daphnia assemblages. Variation partitioning analysis suggested that planktivory had a similar or greater influence than human disturbance and phosphate enrichment. Our study improves the knowledge of crustacean zooplankton responses to increasing residential development and land-use disturbances near Canadian Shield lakes.
Pond hydroperiod alters the effect of density-dependent processes on larval anurans
Authors: Rogers Tracy Noel , Chalcraft David R.
Published: February 2009

Many studies examine how changes (disturbances) to the abiotic environment alter the intensity of species interactions by directly changing the numbers of individuals involved in the interaction but few studies examine how the abiotic environment affects how strongly individuals interact with each other. We conducted an experiment to evaluate how pond hydroperiod affected the ability of two larval anuran species ( Hyla squirella and Bufo terrestris ) to interact with intraspecific and interspecific competitors. Pond hydroperiod altered how an increase in the abundance of intraspecific competitors affected fitness components of B. terrestris but not for H. squirella. Specifically, an increase in intraspecific abundance caused a reduction in B. terrestris survivorship in short hydroperiod ponds but had no effect on fitness components of B. terrestris in long hydroperiod ponds. Interspecific competition did not occur between these species in either short or long hydroperiod ponds. Our study highlights the point that the strength of density-dependent processes operating in the aquatic environment can depend on pond hydroperiod. Consequently, the extent to which processes operating in the aquatic environment contribute to the regulation of population and metapopulation size for amphibians will also likely depend on pond hydroperiod.
Acoustic characterization of Mysis relicta at multiple frequencies
Authors: Rudstam Lars G. , Knudsen Frank R. , Balk Helge , Gal Gideon , Boscarino Brent T. , Axenrot Thomas
Published: February 2009

We measured acoustic backscattering from Mysis relicta , a common invertebrate in northern lakes, using five frequencies (38, 120, 200, 430, and 710 kHz). Acoustic backscattering from mysids was highest at 430 kHz and lowest at 38 kHz (19 dB lower). Maximum difference between the four other frequencies was 5.2 dB. Mysid target strength (TS) ranged from –80.1 dB at 430 kHz to –99.4 dB at 38 kHz (12 mm average length, range 5–21 mm). A theoretical scattering model (Stanton’s fluid-like, bent-cylinder model) predicted TS within 0.3–1.9 dB of observed TS for the different frequencies. The detection range was lowest at 38 and 710 kHz and greatest at 120 and 200 kHz. Fish were common above the mysid layer and produced higher acoustic backscattering at 38 kHz than at the other frequencies. A combination of 38 kHz and 120 or 200 kHz provides a strong contrast between mysid and fish acoustic backscattering that would help separate these groups using acoustic data.
Wind-Induced Advection of Larval Decapods into Baie de Plaisance (Îles de la Madeleine, Québec)
Authors: Hudon Christiane , Fradette Pierre
Published: February 2009

Abundance and spatial distribution of the larvae of the American lobster (Homarus americanus), the common rock crab (Cancer irroratus), and the toad crab (Hyas spp.), were monitored weekly during the summer of 1980 at a grid of 12 stations located in Baie de Plaisance. Following a period of winds ≥ 30 km∙h−1 shifting from the north to the southeast, large numbers of late-stage larvae of the three species were advected in the bay, concurrently with an intrusion of low-salinity water. Weekly abundances of consecutive larval stages were highly correlated, indicating that larvae tended to remain in the same water mass. Spatial association tended to be highest among the early stages within each species. The late larval stages of both lobster and rock crab behaved differently from the early stages with respect to light intensity and their horizontal distribution. Although the advection of water masses under the influence of wind events determines the overall abundance of larval decapods in Baie de Plaisance, larval behaviour (vertical migration and swimming ability) also affected distribution of older stage larvae but at a smaller scale. The dependence of advection on sporadic wind events occurring at the time of peak larval abundance reduces the chances of modelling yearly recruitment using average summer climatic conditions.
Detection and Effects on Mortality Estimates of Changes in Tag Loss
Authors: Treble R. J. , Day R. W. , Quinn II T. J.
Published: February 2009

When estimates of mortality are obtained from tagging experiments the rate of tag loss is usually assumed to be constant. Our analysis shows that if the rate of tag loss increases over the time after tagging and is measured over a short period, it will be seriously underestimated when extrapolated to a longer period, with a corresponding overestimate of mortality. We describe a method for testing the assumption of constant tag loss on single-tagged animals, using a multiple release of tagged animals combined with recaptures or "searches" at a number of later times. An experiment of this type using polyethylene shellfish tags attached with cyanoacrylate ("superglue") to the limpet Cellana tramosenca (Sowerby) suggested that the rate of tag loss increased with increasing time after release. We recommend that the assumption of constant tag loss should always be tested using the method described, or all animals should be double tagged so that mortality can be estimated free of bias even if tag loss is not constant.
Factors Influencing Survival and Growth of Stocked Walleye (Stizostedion vitreum) in a Centrarchid-Dominated Impoundment
Authors: Santucci Jr. Victor J. , Wahl David H.
Published: February 2009

We compared survival and growth of fry and small (mean total length = 48–61 mm), medium (132–145 mm), and large (186–216 mm) fingerling walleye (Stizostedion vitreum) stocked for 4 yr in a centrarchid-dominated impoundment. Mean survival based on fall population estimates 1 and 2 yr after stocking indicated highest survival for large fingerlings (mean survival = 31 and 10%, respectively), followed by medium ones (7 and 4%). Few individuals from the fry and small fingerling size groups were recovered in extensive field sampling. Creel census data reinforced these findings. Thermal stress at stocking and predation by largemouth bass (Micropterus salmoides) were more important than either hooking mortality or spillway escapement in influencing survival. Walleye diets were dominated by bluegill (Lepomis macrochirus) in volume (87%) and frequency of occurrence (84%). Growth rates were slower with bluegill as predominant prey compared with walleye growth in waters containing clupeids and cyprinids and may have been influenced by the abundance and size distribution of bluegill. Based on benefit/cost analysis (survival or catch/cost of rearing), stocking walleye > 200 mm provided the highest return on investment.
Seepage through till foundations of dams of the Eastmain – Opinaca – La Grande diversion
Authors: Paré J.-J. , Verma N. S. , Loiselle A. A. , Pinzariu S.
Published: February 2009

The EOL (Eastmain – Opinaca – La Grande) diversion scheme of the La Grande Complex (phase I) for the James Bay Hydroelectric development in northern Québec diverts the waters of the Eastmain, Opinaca, and Petite Opinaca Rivers into the LG 2 reservoir. The EOL diversion consists of four dams and seven dykes about half of which are founded for part of their length on overburden foundations of variable thickness and consisting of heterogeneous deposits of glacial till or sandy and silty alluvia. The till core of these zoned embankments is either placed directly on the till strata or extended through the alluvia to the underlying till by a core trench. The construction of these embankments was completed in 1979 and the maximum reservoir level achieved in November 1980.This paper deals with the seepage and pore pressure behaviour in the overburden foundations, namely, dams OA-10B and OA-11 and the dyke OA-8B, during and subsequent to the reservoir filling. The results of the parametric seepage analyses carried out by finite element methods are compared with the observations. Special attempts are made to resolve the long-existing speculations regarding the anisotropy of natural deposits. Comments are made regarding the effective anisotropy of such deposits in the James Bay region and its effect on exit gradients and uplift forces, which influence the design and safety of dams and dykes. Keywords: seepage, pore pressure, hydraulic conductivity, anisotropy, foundation treatment, cutoff.
Nonuniformities imposed by simple shear apparatus
Authors: Budhu Muniram
Published: February 2009

Two types of simple shear apparatus are in use — one developed at Cambridge, which is elaborately instrumented and accepts a cuboidal sample, and the other developed at the Norwegian Geotechnical Institute (NGI), which is attractively simple and accepts a cylindrical sample, and in which only shear and normal loads applied to the horizontal surface of the sample are measured.Results of drained monotonic and repeated shear straining tests in the Cambridge and an NGI type simple shear apparatus, both elaborately instrumented, show that nonuniformities of stress and strain develop in monotonic loading and grow with the number of cycles of shear straining. The rigid boundaries of the Cambridge type apparatus impose a definite simple shear configuration to the sample. The flexible boundary of the Norwegian Geotechnical Institute type apparatus provides less restraint allowing out-of-plane movements to occur. The characteristic responses of similarly prepared sand samples are different in the two apparatus because the conditions imposed are not exactly the same.The Cambridge apparatus can be expected to give an accurate estimate of the behavior of sand in monotonic loading if stress measurements are taken at the centre of the sample. Keywords: simple shear apparatus, NGI, Cambridge, monotonic and cyclic loading, dense sand, nonuniformities.
General limit equilibrium method for lateral earth force
Authors: Rahardjo Harianto , Fredlund Delwyn G.
Published: February 2009

The calculation of the lateral earth force using the limit equilibrium method of slices is an indeterminate problem. An assumption regarding the direction or the magnitude of certain forces, or the position of the line of thrust can be used to render the problem determinate.A general formulation for the lateral earth force is derived in accordance with the assumptions involved in the general limit equilibrium (GLE) method. An assumption concerning a direction of the interslice forces is utilized to solve the problem of indeterminancy. Horizontal force equilibrium conditions within a sliding mass are used to compute the magnitude of the active and passive forces. The point of application of the lateral earth force is obtained by considering moment equilibrium for each slice.The coefficient of lateral earth force obtained from the GLE method agrees closely with the results obtained from most other theories. Comparisons are made to the Coulomb theory (i.e., using a planar slip surface) and other theories using a curved or a composite slip surface.Data are presented for the case of a horizontal cohesionless backfill against a vertical wall. The lateral earth force can be contoured on the grid of centers of rotation. These contours have a bell-shaped characteristic and can be used to locate the critical center of rotation.The main advantage of this method lies in its capability to analyze arbitrarily stratified soil deposits with complex geometries. Different conditions of pore-water pressure, shear strength, and external loading can be accommodated in the analysis. Factors of safety greater than 1.0 can be applied to the shear strength of the soil for design purposes. Keywords: lateral earth force, active force, passive force, general limit equilibrium, interslice forces, and coefficient of lateral earth force.
Acoustic emission distress monitoring in sensitive clay
Authors: Mitchell Robert J. , Romeril Philip M.
Published: February 2009

A commercial acoustic emission monitoring system (Model MS-1 Geo-monitor) was used to record acoustic emissions in undisturbed block samples of Champlain Sea clays that were deformed to a passive failure state in the laboratory. Laboratory cast samples of Ottawa sand, washed concrete sand, remoulded kaolin clay, and remoulded Champlain Sea clay were also used in order to correlate the acoustic response of various soils. The Geo-monitor system was capable of detecting and quantifying acoustic emissions in all soils tested. Acoustic emissions associated with failure in the coarse-grained soils ranged from 50 to 200 emissions per minute at an amplification of 1000 times. In the fine-grained soils, an amplification of 105 times was required and acoustic emissions of up to 25 emissions per minute were recorded under passive failure conditions. Keywords: acoustic monitoring, slopes, sensitive clay, laboratory study.
Empirical corrections to snow creep pressure equations
Authors: McClung D. M.
Published: February 2009

A one-dimensional analytical model has been proposed for the average quasi-static snow creep pressure parallel to a slope at the centre of a long rigid structure. The model includes forces due to interruption of creep (internal deformation) and glide (slip of the snow cover over the ground). In reality, the problem is two-dimensional. By a series of two-dimensional finite element calculations, an empirical analytical correction has been found to improve the model. This yields a simple analytical model that provides results within 6% or less of the more complex two-dimensional problem. Keywords: snow mechanics, creep, glide, snow pressure, snow-pack, finite element.
Review: Acupuncture Analgesia in Clinical Trials
Authors: Lin Jaung Geng , Chen Wei Liang
Published: February 2009

Acupuncture treatment has been accepted worldwide. Many clinical trials have been conducted especially in analgesia. The present review includes almost all the important trials since 1970. Among all the pain conditions, postoperative pain, lower back pain, osteoarthritis of the knee and chronic headache are the most popular topics. We found that there are diverse conclusions in each condition; however, most trials agree that acupuncture is an effective therapeutic strategy for analgesia. As with regard to the placebo effect, there is no consensus. In chronic headache treatment, the placebo effect of acupuncture seems to be large. However, in osteoarthritis, the placebo effect is minimal. Another issue is the non-specific physiologic response to piercing the skin. We believe that this effect produces analgesia in some heterogeneous syndrome such as lower back pain. However, this effect is not superior to the specific therapeutic effect of acupuncture based on TCM theory in all the pain conditions reviewed here. We also notice that the design of the sham acupuncture or the placebo has great impact on the result. Rigorous design can minimize the non-specific and placebo effects of acupuncture. Therefore, the real effect of acupuncture can be investigated well. We conclude that acupuncture is a proven treatment for relieving pain. This conclusion is based on specific effects of acupuncture rather than placebo.
Supplementation of Emblica Officinalis (Amla) Extract Reduces Oxidative Stress in Uremic Patients
Authors: Chen Tung-Sheng , Liou Show-Yih , Chang Yen-Lin
Published: February 2009

Emblica Officinalis (also known as Amla or Indian Gooseberry), a natural, traditional and functional food in Asia, has physiological benefits such as hepato-, cyto- and radio- protection, as well as hypolipidemic effects. In addition, Amla often functions as a potent antioxidant due to the high level of ascorbic acid (ranging from 1,100 to 1,700 mg/100 g of fruit) in its fruit. The aim of this study was to determine whether supplementation with Amla extract could reduce oxidative stress in patients with uremia. The findings show that supplementation with Amla extract for 4 months reduced the plasma oxidative marker, 8-iso-prostaglandin, (M0 vs. M4 = 1415 ± 1234 pg/ml vs. 750 ± 496 pg/ml, p < 0.05) and increased plasma total antioxidant status (TAS) (M0 vs. M4 = 2.32 ± 0.14 mM vs. 2.55 ± 0.24 mM, p < 0.05) in uremic patients. On the other hand, there were no significant differences observed in liver function (GOP and GPT), renal function (creatinine, blood urea nitrogen and uric acid), diabetic index (plasma glucose and adiponectin) and atherogenic index (LDL/HDL ratio, total cholesterol and homocysteine) in patients treated with Amla for 4 months. Our data suggest that Amla supplementation may increase plasma antioxidant power and decrease oxidative stress in uremic patients. However, Amla extract did not influence hepatic or renal function, or diabetic and atherogenic indices in uremic patients.
Inhibition of LPS-Induced iNOS, COX-2 and Inflammatory Mediator Expression by Paeonol through the MAPKs Inactivation in RAW 264.7 Cells
Authors: Chae Hee-Sung , Kang Ok-Hwa , Lee Young-Seob , Choi Jang-Gi , Oh You-Chang , Jang Hye-Jin , Kim Min-San , Kim Jong-Hak , Jeong Seung-Il , Kwon Dong-Yeul
Published: February 2009

We evaluated the in vivo anti-inflammatory and analgesic activities of orally administered paeonol in mice, and also investigated the anti-inflammatory activity of paeonol in a cell line. Paeonol significantly reduced the edema induced by arachidonic acid in rats. The analgesic effects were assayed using 2 different models, i.e., by acetic acid-induced writhing response and by formalin induced licking and biting time. Moreover, we examined the effects of paeonol on the release of inflammatory mediators such as NO , PGE2 and IL-6. Our results demonstrated that paeonol inhibited LPS induced expression of NO , PGE2 and IL-6. Paeonol prevented LPS induced iNOS, COX-2 and ERK activation. Therefore, paeonol appears to have potential as a treatment for inflammatory disease and analgesic.
EMPLOYEE EQUITY INCENTIVES AND VENTURE CAPITALIST INVOLVEMENT: EXAMINING THE EFFECTS ON IPO PERFORMANCE
Authors: WESTERMAN JAMES W. , GEIGER SCOTT W. , CYR LINDA A.
Published: February 2009

We examine the effects of venture capitalist involvement and equity incentives for all employees on the performance of initial public offering firms. Data was collected from 402 IPO firms, representing 242 non-VC backed and 160 VC backed firms. Results indicate venture capitalists positively influence the likelihood the portfolio firm will offer equity incentives to all employees. Consistent with the agency theory argument that monitoring and incentives can behave as complements to one another, the results suggest venture capitalist backing and incentive stock options for all employees operate in concert to have a positive effect on stock price performance three years after the initial public offering.
THE HIDDEN ENTERPRISE CULTURE OF MOSCOW: ENTREPRENEURSHIP AND OFF-THE-BOOKS WORKING PRACTICES
Authors: WILLIAMS COLIN C. , ROUND JOHN
Published: February 2009

Even though entrepreneurs are commonly depicted as risk takers, little evaluation has occurred on whether they weigh the costs of being caught and the level of punishments, and engage in off-the-books working practices. The aim of this paper is to evaluate the degree to which entrepreneurs engage in such off-the-books work. Reporting a survey conducted in Moscow during late 2005 and early 2006 of 81 entrepreneurs (defined here as individuals starting-up an enterprise in the past three years), just 3.7 percent are found to operate on a wholly legitimate basis. The remaining 96.3 percent have not registered their business, have no license to trade and conduct all of their trade on an off-the-books basis. The outcome is a call to move beyond the wholesome and virtuous ideal-type of legitimate super heroes that pervade textbook depictions of entrepreneurs and toward a fuller understanding of the lived realities of entrepreneurship.
THE ESSENTIAL STRUCTURE OF AFRO-CARIBBEAN IMMIGRANT ENTERPRISE VIABILITY: VIEWS FROM LOCAL ECONOMIC DEVELOPMENT PRACTITIONERS AND IMPLICATIONS
Authors: WAH TATIANA
Published: February 2009

This paper explores the phenomenon of Afro-Caribbean immigrant enterprise viability in two US counties heavily populated by Afro-Caribbean immigrants: Kings (Brooklyn), New York, and Miami-Dade, Florida. It aims to construct an understanding of enterprise viability as it is understood by local economic development agency (LEDA) directors by examining the meanings of their experiences and interactions with this particular group of immigrants. It posits that objectively studying empirical indicators of enterprise viability only from the scholar's or entrepreneur's perspective would not get at the essential structure of enterprise viability as experienced by providers of enterprise development services. Examining the meaning providers ascribe to their experiences lends to better understanding of how potentials and challenges to enterprise viability manifest on the ground. Opportunities, challenges, expectations and unmet needs are exposed. Progress can then be made to provide immigrant entrepreneurs with the quality of programs and policy that can make them viable. Findings suggest that understanding the "American system" and learning and applying basic modern business functions are essential elements in enterprise development and viability. Professionalization, formalization, and systematization effectuate migration from periphery to mainstream.
Opportunities and Limits of Remote Timing Attacks
Authors: Crosby Scott A. , Wallach Dan S. , Riedi Rudolf H.
Published: February 2009

Many algorithms can take a variable amount of time to complete depending on the data being processed. These timing differences can sometimes disclose confidential information. Indeed, researchers have been able to reconstruct an RSA private key purely by querying an SSL Web server and timing the results. Our work analyzes the limits of attacks based on accurately measuring network response times and jitter over a local network and across the Internet. We present the design of filters to significantly reduce the effects of jitter, allowing an attacker to measure events with 15-100
μ
s accuracy across the Internet, and as good as 100ns over a local network. Notably, security-related algorithms on Web servers and other network servers need to be carefully engineered to avoid timing channel leaks at the accuracy demonstrated in this article.
Fault model and test-case generation for the composition of aspects
Authors: Babu Chitra , Krishnan Harshini Ramnath
Published: February 2009

Aspect-Oriented Programming (AOP) is an emerging paradigm that enhances the modularity of Object-Oriented Programming (OOP) by eliminating tangling and scattering in the code. The scattering code is encapsulated within a module called an Aspect. A join point is an execution point in a program. When there is more than one aspect sharing the same join point then it becomes necessary to identify the faults that occur during their composition. A Fault model is instrumental in identifying the faults that can occur in any software system. Research works so far have focused on the composition of Aspects only from the implementation standpoint. It is necessary to identify these faults during the design process, early in the software development lifecycle. This would help in adopting better coding strategies that result in modular, reusable and maintainable code. Towards this objective, this paper proposes a candidate fault model that identifies the faults which occur during Aspect Composition from the design. Use-case scenarios and sequence diagrams are used to reflect the design of the system. The proposed fault model identifies the faults from the sequence diagrams. Test cases are generated from the design using black-box testing strategy. The proposed fault model is also applied to an illustrative case study and has been validated using test case coverage analysis.
Peer review assessment standard for object oriented analysis and design
Authors: Lee Tony
Published: February 2009

In this paper, the author discusses some peer review pitfalls, as well as, the key elements in an effective peer review session. The paper also provides the assessment standard checklist for object-oriented (OO) analysis and design professionals during a peer review inspection.
Causal-based networks supporting process improvement
Authors: Richter Karsten
Published: February 2009

This paper includes a causal-based modelling of software meas-urement processes in order to clarify the real situations in the em-pirical software engineering field. A first overview about existing causal network approaches shows the problems and possible bene-fits using these formal techniques in the software engineering area. The definition and extension of the causal modelling using causal networks helps to understand the relationships between the differ-ent software process artefacts and their causalities. The causal net-work based process model (CNPM) concept is based on the causal network idea of Pearl. The description of first applications of the CNPM approach for CMMI demonstrates the empirical reasoning of the software improvement processes in an explicit manner.
A perceptual approach to trimming and tuning unstructured lumigraphs
Authors: Morvan Yann , O'sullivan Carol
Published: February 2009

We present a novel perceptual method to reduce the visual redundancy of unstructured lumigraphs, an image based representation designed for interactive rendering. We combine features of the unstructured lumigraph algorithm and image fidelity metrics to efficiently rank the perceptual impact of the removal of subregions of input views (
subviews
). We use a greedy approach to estimate the order in which subviews should be pruned to minimize perceptual degradation at each step. Renderings using varying numbers of subviews can then be easily visualized with confidence that the retained subviews are well chosen, thus facilitating the choice of how many to retain. The regions of the input views that are left are repacked into a texture atlas. Our method takes advantage of any scene geometry information available but only requires a very coarse approximation. We perform a user study to validate its behaviour, as well as investigate the impact of the choice of image fidelity metric as well as that of user parameters. The three metrics considered fall in the physical, statistical and perceptual categories. The overall benefit of our method is the semiautomation of the view selection process, resulting in unstructured lumigraphs that are thriftier in texture memory use and faster to render. Using the same framework, we adjust the parameters of the unstructured lumigraph algorithm to optimise it on a scene by scene basis.
A perceptive evaluation of volume rendering techniques
Authors: Boucheny Christian , Bonneau Georges-Pierre , Droulez Jacques , Thibault Guillaume , Ploix Stephane
Published: February 2009

The display of space filling data is still a challenge for the community of visualization. Direct volume rendering (DVR) is one of the most important techniques developed to achieve direct perception of such volumetric data. It is based on semitransparent representations, where the data are accumulated in a depth-dependent order. However, it produces images that may be difficult to understand, and thus several techniques have been proposed so as to improve its effectiveness, using for instance lighting models or simpler representations (e.g., maximum intensity projection). In this article, we present three perceptual studies that examine how DVR meets its goals, in either static or dynamic context. We show that a static representation is highly ambiguous, even in simple cases, but this can be counterbalanced by use of dynamic cues (i.e., motion parallax) provided that the rendering parameters are correctly tuned. In addition, perspective projections are demonstrated to provide relevant information to disambiguate depth perception in dynamic displays.
Recursive Markov chains, stochastic grammars, and monotone systems of nonlinear equations
Authors: Etessami Kousha , Yannakakis Mihalis
Published: February 2009

We define
Recursive Markov Chains
(RMCs), a class of finitely presented denumerable Markov chains, and we study algorithms for their analysis. Informally, an RMC consists of a collection of finite-state Markov chains with the ability to invoke each other in a potentially recursive manner. RMCs offer a natural abstract model for probabilistic programs with procedures. They generalize, in a precise sense, a number of well-studied stochastic models, including Stochastic Context-Free Grammars (SCFG) and Multi-Type Branching Processes (MT-BP).

We focus on algorithms for
reachability
and
termination
analysis for RMCs: what is the probability that an RMC started from a given state reaches another target state, or that it terminates? These probabilities are in general irrational, and they arise as (least) fixed point solutions to certain (monotone) systems of nonlinear equations associated with RMCs. We address both the
qualitative problem
of determining whether the probabilities are 0, 1 or in-between, and the
quantitative problems
of comparing the probabilities with a given bound, or approximating them to desired precision.

We show that all these problems can be solved in PSPACE using a decision procedure for the Existential Theory of Reals. We provide a more practical algorithm, based on a decomposed version of multi-variate Newton's method, and prove that it always converges monotonically to the desired probabilities. We show this method applies more generally to any monotone polynomial system. We obtain polynomial-time algorithms for various special subclasses of RMCs. Among these: for SCFGs and MT-BPs (equivalently, for
1-exit
RMCs) the qualitative problem can be solved in P-time; for
linearly recursive
RMCs the probabilities are rational and can be computed exactly in P-time.

We show that our PSPACE upper bounds cannot be substantially improved without a breakthrough on long standing open problems: the
square-root sum
problem and an arithmetic circuit decision problem that captures P-time on the unit-cost rational arithmetic RAM model. We show that these problems reduce to the qualitative problem and to the approximation problem (to within any nontrivial error) for termination probabilities of general RMCs, and to the quantitative decision problem for termination (extinction) of SCFGs (MT-BPs).
Emerging nanodevice paradigm
Authors: Wang Z. F. , Zheng Huaixiu , Shi Q. W. , Chen Jie
Published: February 2009

The continued miniaturization of silicon-based electronic circuits is fast approaching its physical limitations. It is unlikely that advances in miniaturization, following the so-called Moore's Law, can continue in the foreseeable future. Nanoelectronics has to go beyond silicon technology. New device paradigms based on nanoscale materials, such as molecular electronic devices, spin devices and carbon-based devices, will emerge. In this article, we introduce a nanodevice paradigm: graphene nanoelectronics. Due to its unique quantum effects and electronic properties, researchers predict that graphene-based devices may replace carbon nanotube devices and become major building blocks for future nanoscale computing. To manifest its unique electronic properties, we present some of our recent designs, namely a graphene-based switch, a negative differential resistance (NDR) device and a random access memory array (RAM). Since these basic devices are the building blocks for large-scale circuits, our findings can help researchers construct useful computing systems and study graphene-based circuit performance in the future.
A shift-register-based QCA memory architecture
Authors: Taskin Baris , Chiu Andy , Salkind Jonathan , Venutolo Daniel
Published: February 2009

A quantum-dot cellular automata (QCA) design of an
nxm
-bit, shift-register-based memory architecture is presented. The architecture maintains data at a stable conformation, which is contrary to traditional data in-motion concept for QCA architectures. The memory architecture is based on an existing dual-phase-synchronized, line-based, one-bit QCA memory cell building block that provides size and latency improvements over other known one-bit memory cells through its novel clocking scheme. Read/write latencies up to ∼2X lower than the existing tile-based architecture with three-phase, line-based memory cells are obtained. Simulations with QCADesigner and HDLQ are performed on a sample 4
x
8 bit memory architecture implementation.
A simulator for ballistic nanostructures in a 2-D electron gas
Authors: Huo Dennis , Yu Qiaoyan , Wolpert David , Ampadu Paul
Published: February 2009

A multipurpose simulator for ballistic nanostructures, based on classical mechanics of electrons at the Fermi level, has been successfully implemented. Despite the simplicity of the model, the simulator successfully reproduces a number of experimental results, and is shown to consistently match observed current-voltage characteristics and magnetoresistance phenomena. The simulator results provide design guidelines for devices which operate on ballistic transport principles. Using the simulator, preliminary logic structures have been designed based on the ballistic deflection transistor.
Heme oxygenase system enhances insulin sensitivity and glucose metabolism in streptozotocin-induced diabetes
Authors: Ndisang Joseph Fomusi , Jadhav Ashok
Published: February 2009

Hyperglycemia-induced oxidative stress is a common phenomenon in diabetes. Since oxidative stress depletes adiponectin and insulin levels, we investigated whether an upregulated heme oxygenase (HO) system would attenuate the oxidative destruction of adiponectin/insulin and improve insulin sensitivity and glucose metabolism in streptozotocin (STZ)-induced type 1 diabetes. HO was upregulated with hemin (15 mg/kg ip) or inhibited with chromium mesoporphyrin (CrMP, 4 μmol/kg ip). Administering hemin to STZ-diabetic rats reduced hyperglycemia and improved glucose metabolism, whereas the HO inhibitor CrMP annulled the antidiabetic effects and/or exacerbated fasting/postprandial hyperglycemia. Interestingly, the antidiabetic effects of hemin lasted for 2 mo after termination of therapy and were accompanied by enhanced HO-1 and HO activity of the soleus muscle, along with potentiation of plasma antioxidants like bilirubin, ferritin, and superoxide dismutase, with corresponding elevation of the total antioxidant capacity. Importantly, hemin abated c-Jun NH2-terminal kinase (JNK), a substance known to inhibit insulin biosynthesis, and suppressed markers/mediators of oxidative stress including 8-isoprostane, nuclear-factor (NF)-κB, activating protein (AP)-1, and AP-2 of the soleus muscle. Furthermore, hemin therapy significantly attenuated pancreatic histopathological lesions including acinar cell necrosis, interstitial edema, vacuolization, fibrosis, and mononuclear cell infiltration. Correspondingly, hemin increased plasma insulin and potentiated agents implicated in insulin sensitization and insulin signaling such as adiponectin, adenosine monophosphate-activated protein kinase (AMPK), cAMP, cGMP, and glucose transporter (GLUT)4, a protein required for glucose uptake. These were accompanied by improved glucose tolerance [intraperitoneal glucose tolerance text (IPGTT)], decreased insulin intolerance [intraperitoneal insulin tolerance test (IPITT)], and reduced insulin resistance [homeostasis model assessment of insulin resistance (HOMA-IR) index], whereas CrMP nullified the hemin-dependent antidiabetic and insulin-sensitizing effects. In conclusion, by concomitantly enhancing insulin and paradoxically potentiating insulin sensitivity, this study unveils a novel, unique, and long-lasting antidiabetic characteristic of upregulating HO with hemin that could be exploited against insulin-resistant and insulin-dependent diabetes.
Increased expression of receptors for orexigenic factors in nodose ganglion of diet-induced obese rats
Authors: Paulino Gabriel , Barbier de la Serre Claire , Knotts Trina A. , Oort Pieter J. , Newman John W. , Adams Sean H. , Raybould Helen E.
Published: February 2009

The vagal afferent pathway is important in short-term regulation of food intake, and decreased activation of this neural pathway with long-term ingestion of a high-fat diet may contribute to hyperphagic weight gain. We tested the hypothesis that expression of genes encoding receptors for orexigenic factors in vagal afferent neurons are increased by long-term ingestion of a high-fat diet, thus supporting orexigenic signals from the gut. Obesity-prone (DIO-P) rats fed a high-fat diet showed increased body weight and hyperleptinemia compared with low-fat diet-fed controls and high-fat diet-induced obesity-resistant (DIO-R) rats. Expression of the type I cannabinoid receptor and growth hormone secretagogue receptor 1a in the nodose ganglia was increased in DIO-P compared with low-fat diet-fed controls or DIO-R rats. Shifts in the balance between orexigenic and anorexigenic signals within the vagal afferent pathway may influence food intake and body weight gain induced by high fat diets.
Effects of chronic hypoglycemia and euglycemic correction on lysine metabolism in fetal sheep
Authors: Limesand Sean W. , Rozance Paul J. , Brown Laura D. , Hay William W.
Published: February 2009

In this study, we determined rates of lysine metabolism in fetal sheep during chronic hypoglycemia and following euglycemic recovery and compared results with normal, age-matched euglycemic control fetuses to explain the adaptive response of protein metabolism to low glucose concentrations. Restriction of the maternal glucose supply to the fetus lowered the net rates of fetal (umbilical) glucose (42%) and lactate (36%) uptake, causing compensatory alterations in fetal lysine metabolism. The plasma lysine concentration was 1.9-fold greater in hypoglycemic compared with control fetuses, but the rate of fetal (umbilical) lysine uptake was not different. In the hypoglycemic fetuses, the lysine disposal rate also was higher than in control fetuses due to greater rates of lysine flux back into the placenta and into fetal tissue. The rate of CO2 excretion from lysine decarboxylation was 2.4-fold higher in hypoglycemic than control fetuses, indicating greater rates of lysine oxidative metabolism during chronic hypoglycemia. No differences were detected for rates of fetal protein accretion or synthesis between hypoglycemic and control groups, although there was a significant increase in the rate of protein breakdown ( P < 0.05) in the hypoglycemic fetuses, indicating small changes in each rate. This was supported by elevated muscle specific ubiquitin ligases and greater concentrations of 4E-BP1. Euglycemic recovery after chronic hypoglycemia normalized all fluxes and actually lowered the rate of lysine decarboxylation compared with control fetuses ( P < 0.05). These results indicate that chronic hypoglycemia increases net protein breakdown and lysine oxidative metabolism, both of which contribute to slower rates of fetal growth over time. Furthermore, euglycemic correction for 5 days returns lysine fluxes to normal and causes an overcorrection of lysine oxidation.
The anterolateral projections of the medial basal hypothalamus affect sleep
Authors: Peterfi Zoltan , Makara Gábor B. , Obál Ferenc , Krueger James M.
Published: February 2009

The role of the medial basal hypothalamus (MBH) and the anterior hypothalamus/preoptic area (AH/POA) in sleep regulation was investigated using the Halász knife technique to sever MBH anterior and lateral projections in rats. If both lateral and anterior connections of the MBH were cut, rats spent less time in non-rapid eye movement sleep (NREMS) and rapid eye movement sleep (REMS). In contrast, if the lateral connections remained intact, the duration of NREMS and REMS was normal. The diurnal rhythm of NREMS and REMS was altered in all groups except the sham control group. Changes in NREMS or REMS duration were not detected in a group with pituitary stalk lesions. Water consumption was enhanced in three groups of rats, possibly due to the lesion of vasopressin fibers entering the pituitary. EEG delta power during NREMS and brain temperatures (Tbr) were not affected by the cuts during baseline or after sleep deprivation. In response to 4 h of sleep deprivation, only one group, that with the most anterior-to-posterior cuts, failed to increase its NREMS or REMS time during the recovery sleep. After deprivation, Tbr returned to baseline in most of the treatment groups. Collectively, results indicate that the lateral projections of the MBH are important determinants of duration of NREMS and REMS, while more anterior projections are concerned with the diurnal distribution of sleep. Further, the MBH projections involved in sleep regulation are distinct from those involved in EEG delta activity, water intake, and brain temperature.
Mutations in Phosphoinositide Metabolizing Enzymes and Human Disease
Authors: McCrea Heather J. , De Camilli Pietro
Published: February 2009

Phosphoinositides are implicated in the regulation of a wide variety of cellular functions. Their importance in cellular and organismal physiology is underscored by the growing number of human diseases linked to perturbation of kinases and phosphatases that catalyze interconversion from one phosphoinositide to another. Many such enzymes are attractive targets for therapeutic interventions. Here, we review diseases linked to inheritable or somatic mutations of these enzymes. Phosphatidylinositol (PtdIns), a membrane phospholipid, can be reversibly phosphorylated at the 3, 4, and 5 positions of the inositol ring to generate seven phosphoinositides [PI3P, PI4P, PI5P, PI( 3 , 4 )P2, PI( 4 , 5 )P2, PI( 3 , 5 )P2, and PI( 3 , 4 , 5 )P3] (FIGURE 1A ). The importance of this metabolism in cell regulation was first established in the context of studies on stimulus-secretion coupling. It was found that many stimuli that trigger secretion also trigger enhanced turnover of PtdIns and phosphoinositides ( 42 ). Subsequently, it became clear that phospholipase C-dependent hydrolysis of PI( 4 , 5 )P2 to generate the second messenger molecules diacyl glycerol and Ins( 1 , 4 , 5 )P3 (IP3) is a mechanism through which many cell surface receptors, including many receptors that stimulate secretion, transduce their signals ( 10 ). Diacyl glycerol binds and regulates protein kinase C and a variety of other effectors, whereas IP3 triggers calcium release from the endoplasmic reticulum ( 10 , 42 ). In another signal transduction pathway, PI( 4 , 5 )P2 is cleaved by phospholipase A2 to generate arachidonic acid, a precursor of many signaling molecules.
Intercellular Communication in Atherosclerosis
Authors: Burnier Laurent , Fontana Pierre , Angelillo-Scherrer Anne , Kwak Brenda R.
Published: February 2009

Cell-to-cell communication is a process necessary for physiological tissue homeostasis and appears often altered during disease. Gap junction channels, formed by connexins, allow the direct intercellular communication between adjacent cells. After a brief review of the pathophysiology of atherosclerosis, we will discuss the role of connexins throughout the different stages of the disease.
Probiotics and Gastrointestinal Infections
Authors: Britton Robert A. , Versalovic James
Published: February 2009

Gastrointestinal infections are a major cause of morbidity and mortality worldwide, particularly in developing countries. The use of probiotics to prevent and treat a variety of diarrheal diseases has gained favor in recent years. Examples where probiotics have positively impacted gastroenteritis will be highlighted. However, the overall efficacy of these treatments and the mechanisms by which probiotics ameliorate gastrointestinal infections are mostly unknown. We will discuss possible mechanisms by which probiotics could have a beneficial impact by enhancing the prevention or treatment of diarrheal diseases.
Membrane-Based Separation of Phenol/Water Mixtures Using Ionically and Covalently Cross-Linked Ethylene-Methacrylic Acid Copolymers
Authors: Mixa Alexander , Staudt Claudia
Published: February 2009

Membrane-based separation of phenol/water mixtures with concentrations of phenol between 3 wt% and 8 wt% in the feed has been performed with nonmodified as well as cross-linked ethylene-methacrylic acid (E-MAA) copolymers with different amounts of methacrylic acid. As cross-linking agents, aluminium acetyl acetonate, which leads to ionically cross-linked membranes, and 2,3,5,6-tetramethyl-1,4-phenylene diamine and glycerine digycidether, leading to covalently cross-linked membranes, have been used. Generally, it was found that with increasing phenol content in the feed, the total flux is increasing whereas the enrichment factor is decreasing. Using nonmodified membranes with higher methacrylic acid monomer content in the polymer, lower fluxes and higher enrichment factors were observed. Investigation of different cross-linked membranes showed that with high phenol concentration in the feed, ionic cross-linking seems to be very promising. Furthermore, variation of feed temperature shows that ionically cross-linked membranes reached higher fluxes as well as higher enrichment factors at elevated temperatures. The temperature-dependent data were fitted based on an Arrhenius-type equation, and activation energies for the permeation of phenol and water through the membrane were calculated.
High Speed 3D Tomography on CPU, GPU, and FPGA
Authors: GAC Nicolas , Mancini Stéphane , Desvignes Michel , Houzet Dominique
Published: February 2009

Back-projection (BP) is a costly computational step in tomography image reconstruction such as positron emission tomography (PET). To reduce the computation time, this paper presents a pipelined, prefetch, and parallelized architecture for PET BP (3PA-PET). The key feature of this architecture is its original memory access strategy, masking the high latency of the external memory. Indeed, the pattern of the memory references to the data acquired hinders the processing unit. The memory access bottleneck is overcome by an efficient use of the intrinsic temporal and spatial locality of the BP algorithm. A loop reordering allows an efficient use of general purpose processor's caches, for software implementation, as well as the 3D predictive and adaptive cache (3D-AP cache), when considering hardware implementations. Parallel hardware pipelines are also efficient thanks to a hierarchical 3D-AP cache: each pipeline performs a memory reference in about one clock cycle to reach a computational throughput close to 100%. The 3PA-PET architecture is prototyped on a system on programmable chip (SoPC) to validate the system and to measure its expected performances. Time performances are compared with a desktop PC, a workstation, and a graphic processor unit (GPU).