bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell Signals, Cell Contacts, and the Organization of Yeast Communities
Authors: Honigberg Saul M.
Published: February 2011

Even relatively simple species have evolved mechanisms to organize individual organisms into communities, such that the fitness of the group is greater than the fitness of isolated individuals. Within the fungal kingdom, the ability of many yeast species to organize into communities is crucial for their growth and survival, and this property has important impacts both on the economy and on human health. Over the last few years, studies of
Saccharomyces cerevisiae
have revealed several fundamental properties of yeast communities. First, strain-to-strain variation in the structures of these groups is attributable in part to variability in the expression and functions of adhesin proteins. Second, the extracellular matrix surrounding these communities can protect them from environmental stress and may also be important in cell signaling. Finally, diffusible signals between cells contribute to community organization so that different regions of a community express different genes and adopt different cell fates. These findings provide an arena in which to view fundamental mechanisms by which contacts and signals between individual organisms allow them to assemble into functional communities.
Involvement of Quorum Sensing and Heat-Stable Enterotoxin a in Cell Damage Caused by a Porcine Enterotoxigenic
Escherichia coli
Strain
Authors: Zhu Jing , Yin Xianhua , Yu Hai , Zhao Liping , Sabour Parviz , Gong Joshua
Published: February 2011

Enterotoxigenic
Escherichia coli
(ETEC) strains with K88 fimbriae are often associated with the outbreaks of diarrhea in newborn and weaned piglets worldwide. In the present study, we observed that 10
8
CFU/ml of K88
+
ETEC strain JG280 caused more death of pig intestinal IPEC-J2 cells than did 10
9
CFU/ml, suggesting that ETEC-induced cell death was cell density dependent and that quorum sensing (QS) may play a role in pathogenesis. Subsequent investigations demonstrated a positive correlation between autoinducer 2 (AI-2) activity of JG280 and death of IPEC-J2 cells during the infection for up to 3 h. However, there was a negative correlation between AI-2 activity and expression of the JG280 enterotoxin genes
estA
and
estB
when IPEC-J2 cells were exposed to the pathogen at 10
8
CFU/ml. We therefore cloned the
luxS
gene (responsible for AI-2 production) from JG280 and overexpressed it in
E. coli
DH5α, because deletion of the
luxS
gene was retarded by the lack of suitable antibiotic selection markers and the resistance of this pathogen to a wide range of antibiotics. The addition of culture fluid from
E. coli
DH5α with the overexpressed
luxS
reduced cell death of IPEC-J2 cells by 10
8
CFU/ml JG280. The addition also reduced the
estA
expression by JG280. Nonpathogenic K88
+
strain JFF4, which lacks the enterotoxin genes, caused no death of IPEC-J2 cells, although it produced AI-2 activity comparable to that produced by JG280. These results suggest the involvement of AI-2-mediated quorum sensing in K88
+
ETEC pathogenesis, possibly through a negative regulation of STa production.
Role of the Periplasmic Chaperones Skp, SurA, and DegQ in Outer Membrane Protein Biogenesis in
Neisseria meningitidis
Authors: Volokhina Elena B. , Grijpstra Jan , Stork Michiel , Schilders Ingrid , Tommassen Jan , Bos Martine P.
Published: February 2011

The periplasmic chaperones Skp, SurA, and DegP are implicated in the biogenesis of outer membrane proteins (OMPs) in
Escherichia coli
. Here, we investigated whether these chaperones exert similar functions in
Neisseria meningitidis
. Although
N. meningitidis
does not contain a homolog of the protease/chaperone DegP, it does possess a homolog of another
E. coli
protein, DegQ, which can functionally replace DegP when overproduced. Hence, we examined whether in
N. meningitidis
, DegQ acts as a functional homolog of DegP. Single
skp
,
surA
, and
degQ
mutants were easily obtained, showing that none of these chaperones is essential in
N. meningitidis
. Furthermore, all combinations of double mutants were generated and no synthetic lethality was observed. The absence of SurA or DegQ did not affect OMP biogenesis. In contrast, the absence of Skp resulted in severely lower levels of the porins PorA and PorB but not of other OMPs. These decreased levels were not due to proteolytic activity of DegQ, since porin levels remained low in a
skp degQ
double mutant, indicating that neisserial DegQ is not a functional homolog of
E. coli
DegP. The absence of Skp resulted in lower expression of the
porB
gene, as shown by using a P

porB

-
lacZ
fusion. We found no cross-species complementation when Skp of
E. coli
or
N. meningitidis
was heterologously expressed in
skp
mutants, indicating that Skp functions in a species-specific manner. Our results demonstrate an important role for Skp but not for SurA or DegQ in OMP biogenesis in
N. meningitidis
.
Booster seat legislation: does it work for all children?
Authors: Brixey Suzanne N , Corden Timothy E , Guse Clare E , Layde Peter M
Published: February 2011

Objective

To assess the impact of a booster seat law in Wisconsin on booster seat use in relation to race, ethnicity and socioeconomic status.

Methods

A longitudinal study in Milwaukee County, Wisconsin, involving repeated direct observational assessments of booster seat use rates by child passengers aged 4–7 years over five time periods, before and after legislation mandating booster seat use.

Results

Overall, booster seat use increased from 24% to 43%, whereas proper restraint use increased pre to post-legislation from 21% to 28%. Proper use increased after legislation in white, but not in black or Latino children. White individuals had a proper booster use increase from 48% to 68% over the time period of the study. Black children's proper use dropped from 18% to 7% over the study period and Latino children's proper use rates were stable at 10%. Driver-reported household income had a significant impact on overall use, but not on proper use.

Conclusions

Racial/ethnic minority groups and those of lower socioeconomic status have significantly lower use and proper use of booster seats. Legislation may increase the total use of booster seats but not necessarily the correct use of the restraint, particularly in racial/ethnic minorities.
Pitfalls in obtaining and interpreting bone marrow aspirates: to err is human
Authors: Bain Barbara J , Bailey Katharine
Published: February 2011

Pitfalls relating to bone marrow aspirates and their interpretation start even before the aspirate is obtained. There can be failure to perform an aspiration that is clinically indicated or, conversely, an aspiration may be done that is not actually necessary. Once an aspirate is obtained it may be unhelpful because it is a blood tap or very dilute, or because of the sampling error that is intrinsic to the procedure. Even if an adequate aspirate is obtained, it may be misinterpreted. Megaloblastic marrows and children's marrows with increased haematogones or marked reactive changes are particularly prone to misinterpretation. A constant awareness of potential pitfalls and an assessment of the aspirate in the appropriate clinical context will help to reduce errors.
Loss of cellular polarity/cohesiveness in the invasive front of papillary thyroid carcinoma, a novel predictor for lymph node metastasis; possible morphological indicator of epithelial mesenchymal transition
Authors: Liu Zhiyan , Kakudo Kennichi , Bai Yanhua , Li Yaqiong , Ozaki Takashi , Miyauchi Akira , Taniguchi Emiko , Mori Ichiro
Published: February 2011

Background

Loss of cellular polarity/cohesiveness (LOP/C) in the invasive front of papillary thyroid carcinoma (PTC) results in a high recurrence risk of PTC.

Aims

To investigate the immunohistochemical features of LOP/C in PTC and to show that this feature is linked to a high association of lymph node metastasis (LNM) at surgery and tumour recurrence.

Methods

The degree of LOP/C of the PTCs was evaluated histologically using a cut-off value of 20% and the immunohistochemical features of LOP/C were analysed using immunohistochemical staining for E-cadherin, β-catenin and vimentin. The relationship between the LOP/C and the other clinicopathological parameters was analysed.

Results

43 cases of PTC with LOP/C (≥20%) were selected and 27 cases with LOP/C (<20%) were included as control tumours. 11/44 cases (25%) were observed to develop recurrence, LNM or distant metastasis at an average follow-up of 31 months. Less expression of E-cadherin and aberrant localisation of β-catenin and vimentin were observed in PTC tumour cells with LOP/C. LOP/C (≥20%) was significantly correlated with extrathyroid invasion (r=0.336, p=0.003), advanced tumour stage (r=0.275, p=0.017), LNM (r=0.389, p<0.001) and recurrence after surgery (r=0.302, p=0.036). Both extrathyroid invasion and LOP/C were independent significant predictors of LNM.

Conclusions

LOP/C may be a useful morphological feature of epithelial mesenchymal transition under H&E observation, and it is an important indicator of lymph node metastasis and aggressive clinical behaviour of PTC.
Reversible cerebral vasoconstriction syndromes presenting with subarachnoid hemorrhage: a case series
Authors: Ansari Sameer A , Rath Tanya J , Gandhi Dheeraj
Published: February 2011

Background and purpose

Reversible cerebral vasoconstriction syndromes (RCVS) represent a heterogeneous group of cerebrovascular disease characterized by acute presentations and transient segmental narrowing of the distal intracranial arteries. A series of patients with RCVS were studied to better understand the clinical and imaging characteristics of this rare pathology.

Methods

A retrospective study was performed on patients that met inclusion criteria for a diagnosis of RCVS. Pertinent clinical and laboratory data, initial and follow-up imaging, treatment and outcomes were studied.

Results

11 patients (10 women, mean age 42 years) diagnosed with RCVS presented with acute onset of severe headache, neurological symptoms and subarachnoid hemorrhage (SAH). Cross sectional imaging (CT/MRI) identified presentations of cortical SAH (n=9) and/or acute infarcts (n=3). Initial cerebral angiography (digital subtraction angiography n=10 or MR angiography n=1) confirmed diffuse vasoconstriction involving the intracranial vasculature. Rheumatological panel (n=9) and CSF analysis (n=8) were not supportive of vasculitis in any patient. In nearly all cases, reversal of vasoconstriction was noted on follow-up cerebral angiography with early resolution in less than 3 months.

Conclusions

RCVS classically presents with ‘thunderclap’ headaches and neurological symptoms but cortical SAH is not an uncommon presentation with a unique and focal distribution overlying the cerebral sulci. Although the initial clinical and angiographic appearance of RCVS may be confused for vasospasm related to aneurysmal SAH or primary angiitis of the CNS, its clinical, laboratory and imaging features assist in diagnosis.
A cross-shift study of lung function, exhaled nitric oxide and inflammatory markers in blood in Norwegian cement production workers
Authors: Fell Anne Kristin M , Notø Hilde , Skogstad Marit , Nordby Karl-Christian , Eduard Wijnand , Svendsen Martin Veel , Øvstebø Reidun , Trøseid Anne Marie Siebke , Kongerud Johny
Published: February 2011

Objectives

To study possible effects of aerosol exposure on lung function, fractional exhaled nitric oxide (FeNO) and inflammatory markers in blood from Norwegian cement production workers across one work shift (0 to 8 h) and again 32 h after the non-exposed baseline registration.

Methods

95 workers from two cement plants in Norway were included. Assessment of lung function included spirometry and gas diffusion pre- and post-shift (0 and 8 h). FeNO concentrations were measured and blood samples collected at 0, 8 and 32 h. Blood analysis included cell counts of leucocytes and mediators of inflammation.

Results

The median respirable aerosol level was 0.3 mg/m3(range 0.02–6.2 mg/m3). FEV1, FEF25–75%and DLCOdecreased by 37 ml (p=0.04), 170 ml/s (p<0.001) and 0.17 mmol/min/kPa (p=0.02), respectively, across the shift. A 2 ppm reduction in FeNO between 0 and 32 h was detected (p=0.01). The number of leucocytes increased by 0.6×109 cells/l (p<0.001) across the shift, while fibrinogen levels increased by 0.02 g/l (p<0.001) from 0 to 32 h. TNF-α level increased and IL-10 decreased across the shift. Baseline levels of fibrinogen were associated with the highest level of respirable dust, and increased by 0.39 g/l (95% CI 0.06 to 0.72).

Conclusions

We observed small cross-shift changes in lung function and inflammatory markers among cement production workers, indicating that inflammatory effects may occur at exposure levels well below 1 mg/m3. However, because the associations between these acute changes and personal exposure measurements were weak and as the long-term consequences are unknown, these findings should be tested in a follow-up study.
Respiratory health and lung function in Chinese restaurant kitchen workers
Authors: Wong Tze Wai , Wong Andromeda H S , Lee Frank S C , Qiu Hong
Published: February 2011

Objectives

To measure air pollutant concentrations in Chinese restaurant kitchens using different stove types and assess their influence on workers' respiratory health.

Methods

393 kitchen workers from 53 Chinese restaurants were surveyed over 16 months: 115 workers from 21 restaurants using only electric stoves and 278 workers from 32 restaurants using only gas stoves. Workers were interviewed about their respiratory symptoms and had their lung function tested. Concentrations of nitric oxide (NO), nitrogen dioxide (NO2), carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), non-methane hydrocarbons (NMHC), total volatile organic compounds (TVOC) and fine particulate matter (PM2.5) were measured using portable monitors and air-bag sampling. Temperature and noise levels were assessed.

Results

Median concentrations of NO, NO2and CO were 7.4, 1.5 and 1.6 times higher in gas-fuelled kitchens than in electric ones and average concentrations of PM2.5and TVOC were 81% and 78% higher, respectively. Differences were smaller for CH4and NMHC. Electricity-run kitchens were 4.5°C cooler and 9 dBA less noisy than gas-fuelled ones. Workers using electric cookers had significantly better lung function than their gas-using counterparts and their mean FEV1and FVC values were 5.4% and 3.8% higher, respectively, after adjustment for confounders. Wheeze, phlegm, cough and sore throat were more prevalent in workers using gas. The adjusted OR for having phlegm regularly was significantly higher.

Conclusions

The poorer lung function and higher prevalence of respiratory symptoms among workers in gas-fuelled kitchens compared to those in electricity-powered kitchens may be associated with exposure to higher concentrations of toxic air pollutants generated during gas cooking.
Reduced lung function among sisal processors
Authors: Kayumba Akwilina , Moen Bente Elisabeth , Bråtveit Magne , Eduard Wijnand , Mashalla Yohana
Published: February 2011

Objectives

The objective of this study was to examine lung function and chronic respiratory symptoms among sisal workers in Tanzania and compare the results with a control group.

Methods

A cross-sectional study on chronic respiratory symptoms and lung function was conducted in 2006 among male Tanzanian sisal processing workers from six sisal estates. Participants included 86 workers in decortication departments, 68 workers in brushing departments and 30 low exposed security guards. The response rate was 97%. Chronic respiratory symptoms and background information were obtained by structured interview. Forced ventilatory capacity (FVC) and forced expiratory volume in 1 s (FEV1) were estimated before and after a work shift, and FEV1/FVC ratio calculated.

Results

Workers were aged 19–85, with the oldest in the brushing and security departments. Chronic cough and chest tightness were experienced by 38% and 68% of workers in brushing departments, 20% and 6% of workers in decortication and 7% and 0% of security workers, respectively. A reduced FEV1/FVC ratio related to years of work was found among workers in brushing departments when adjusting for age, smoking, previous respiratory illnesses and body mass index, using regression analyses. Work in decortication departments was not related to reduced lung function parameters. The prevalence of FEV1/FVC<70 was above 50 for all three groups. Lung function parameters were similar before and after work shifts, except that peak expiratory flow increased among workers in brushing departments after work shifts.

Conclusions

The results indicate a relationship between work in sisal brushing departments and the development of obstructive lung disorders.
Republished review: Mitral regurgitation in patients with aortic stenosis undergoing valve replacement
Authors: Unger P , Dedobbeleer C , Van Camp G , Plein D , Cosyns B , Lancellotti P
Published: February 2011

Mitral regurgitation is a frequent finding in patients with aortic stenosis scheduled for aortic valve replacement. Detection of mitral regurgitation in such patients has important implications, as it can independently affect functional status and prognosis. When mitral regurgitation is moderate to severe, a decision to operate on both valves should only be made following a careful clinical and echocardiographic assessment. Indeed, double-valve surgery increases perioperative and postoperative risks, and mitral regurgitation may improve spontaneously after isolated aortic valve replacement. Better understanding of the determinants of these changes appears particularly crucial in the light of recent advances in percutaneous aortic valve replacement.
Response of northeastern North American forests to climate change: Will soil conditions constrain tree species migration?
Authors: Lafleur Benoit , Paré David , Munson Alison D. , Bergeron Yves
Published: February 2011

Plant species distribution and plant community composition vary along environmental gradients. At the continental scale, climate plays a major role in determining plant distribution, while at the local and regional scales vegetation patterns are more strongly related to edaphic and topographic factors. The projected global warming and alteration of the precipitation regime will influence tree physiology and phenology, and is likely to promote northward migration of tree species. However the influence of soil characteristics on tree species migration is not as well understood. Considering the broad tolerance of most tree species to variations in soil factors, soils should not represent a major constraint for the northward shift of tree species. However, locally or regionally, soil properties may constrain species migration. Thus, while climate change has the potential to induce a northward migration of tree species, local or regional soil properties may hinder their migratory response. These antagonistic forces are likely to slow down potential tree migration in response to climate change. Because tree species respond individualistically to climate variables and soil properties, new tree communities are likely to emerge from climate change.
Biotechnology as an alternative for carbon disulfide treatment in air pollution control
Authors: Rojo Naiara , Gallastegi Gorka , Barona Astrid , Gurtubay Luis , Ibarra-Berastegi Gabriel , Elías Ana
Published: February 2011

Biotechnology has emerged as an affordable, effective, and eco-friendly alternative to treat carbon disulfide (CS2) containing waste gases. Carbon disulfide is a chemical of widespread use both in the past and in the present. Its industry demand has dramatically changed over the last two decades and is expected to grow in future in step with those industries involving fibre, mining, rubber products, and the agro-chemical sector. This compound, classified as a hazardous air pollutant about 20 years ago, has been re-appraised, as increasingly restrictive pollution standards are expected to be introduced. An array of physical–chemical technologies for treating CS2 containing air are already in use, but they have a series of drawbacks, such as high energy consumption (incineration, thermal oxidation), the immobilization of the contaminant solely from one phase to another (adsorption), and the generation of secondary by-products that require additional treatment (hydrolysis). Thus, technological research on affordable processing alternatives is of considerable interest for related industries using or producing CS2. The biological technologies whose efficiency is based on the activity of microorganisms to biodegrade air pollutants overcome many of the disadvantages of conventional techniques and are especially useful for the removal of relatively low concentrations of pollutants. In this paper, the main properties, sources, and uses of CS2 are summarized, and alternative biotreatments for CS2 are reviewed. Several applications of the technical and economical feasibility of biofilters and biotrickling filters are shown, although their widespread industrial application still requires further research.
IN-PLANE OPTICAL ANISOTROPY OF STRAINED WURTZITE GaN IN THE A- AND R-PLANES
Authors: HAO GUO-DONG , CHEN Y. H.
Published: February 2011

Using the effective-mass Hamiltonian for an arbitrary direction wurtzite semiconductor on the basis of k⋅p theory, we investigate the strain effects on the optical anisotropy in semi-polar and nonpolar GaN planes. The optical matrix elements are formulated for an arbitrary direction and calculated for the A- and R-planes. It is found that giant optical anisotropy appears in the A- and R-planes and the biaxial strain significantly changes the polarization properties.
BOGOLYUBOV'S THEORY OF SUPERFLUIDITY, REVISITED
Authors: SANKOVICH D. P.
Published: February 2011

The Bogolyubov model of liquid helium is considered. The validity of substituting a c-number for the k = 0 mode operator â0 is established rigorously. The domain of stability of the Bogolyubov's Hamiltonian is found. We derive sufficient conditions which ensure an appearance of the Bose condensate in the model. For some temperatures and some positive values of the chemical potential, there is the gapless Bogolyubov spectrum of elementary excitations, leading to the proper microscopic interpretation of the superfluidity.
THE EVOLUTION OF COMPLEXITY IN SELF-MAINTAINING CELLULAR INFORMATION PROCESSING NETWORKS
Authors: DECRAENE JAMES , MCMULLIN BARRY
Published: February 2011

We examine the role of self-maintenance (collective autocatalysis) in the evolution of computational biochemical networks. In primitive proto-cells (lacking separate genetic machinery) self-maintenance is a necessary condition for the direct reproduction and inheritance of what we here term Cellular Information Processing Networks (CIPNs). Indeed, partially reproduced or defective CIPNs may generally lead to malfunctioning or premature death of affected cells. We explore the interaction of this self-maintenance property with the evolution and adaptation of CIPNs capable of distinct information processing abilities. We present an evolutionary simulation platform capable of evolving artificial CIPNs from a bottom-up perspective. This system is an agent-based multi-level selectional Artificial Chemistry (AC) which employs a term rewriting system called the Molecular Classifier System (MCS.bl). The latter is derived from the Holland broadcast language formalism. Using this system, we successfully evolve an artificial CIPN to improve performance on a simple pre-specified information processing task whilst subject to the constraint of continuous self-maintenance. We also describe the evolution of self-maintaining, cross-talking and multi-tasking, CIPNs exhibiting a higher level of topological and functional complexity. This proof of concept aims at contributing to the understanding of the open-ended evolutionary growth of complexity in artificial systems.
Morphing
Authors: Huang Shan Shan , Smaragdakis Yannis
Published: February 2011

We present MorphJ: a language for specifying general classes whose members are produced by iterating over members of other classes. We call this technique “class morphing” or just “morphing.” Morphing extends the notion of genericity so that not only types of methods and fields, but also the
structure
of a class can vary according to type variables. This adds a disciplined form of metaprogramming to mainstream languages and allows expressing common programming patterns in a highly generic way that is otherwise not supported by conventional techniques. For instance, morphing lets us write generic proxies (i.e., classes that can be parameterized with another class and export the same public methods as that class); default implementations (e.g., a generic do-nothing type, configurable for any interface); semantic extensions (e.g., specialized behavior for methods that declare a certain annotation); and more. MorphJ's hallmark feature is that, despite its emphasis on generality, it allows modular type-checking: a MorphJ class can be checked independently of its uses. Thus, the possibility of supplying a type parameter that will lead to invalid code is detected early, an invaluable feature for highly general components that will be statically instantiated by other programmers. We demonstrate the benefits of morphing with several examples, including a MorphJ reimplementation of DSTM2, a software transactional memory library which reduces 1,484 lines of Java reflection and bytecode engineering library calls to just 586 lines of MorphJ code.
Refinement types for secure implementations
Authors: Bengtson Jesper , Bhargavan Karthikeyan , Fournet Cédric , Gordon Andrew D. , Maffeis Sergio
Published: February 2011

We present the design and implementation of a typechecker for verifying security properties of the source code of cryptographic protocols and access control mechanisms. The underlying type theory is a λ-calculus equipped with refinement types for expressing pre- and post-conditions within first-order logic. We derive formal cryptographic primitives and represent active adversaries within the type theory. Well-typed programs enjoy assertion-based security properties, with respect to a realistic threat model including key compromise. The implementation amounts to an enhanced typechecker for the general-purpose functional language F
#
; typechecking generates verification conditions that are passed to an SMT solver. We describe a series of checked examples. This is the first tool to verify authentication properties of cryptographic protocols by typechecking their source code.
Performance and Energy Impact of Locally Controlled NML Circuits
Authors: Dingler Aaron , Niemier Michael T. , Hu Xiaobo Sharon , Lent Evan
Published: February 2011

This article quantitatively considers the performance of nanomagnetic logic circuits within the context of realistic drive circuitry. We also demonstrate how one of the five fundamental tenets of digital logic---preventing unwanted feedback---can be satisfied by realistic drive circuitry. More specifically, different types of multiphase clocks are investigated and compared. Initial projections suggest that even with drive circuitry overhead, nanomagnet logic can outperform subthreshold CMOS in terms of energy delay product---and paths to lower power exist.
Web services from a service provider perspective
Authors: Haller Klaus
Published: February 2011

While web service discovery and composition are important for web service "consumers", service providers face other challenges. This paper looks on their needs in an important commercial scenario. In this scenario, bundling service providers combine backend services provided by a backend service provider relying on multi-tenant information systems. Multi-tenant systems allow for economies-of-scale -- a prerequisite for the provider's commercial success. The application management of multi-tenant systems demands for tenant management services such as tenant export or upgrade. This paper describes their implementation. Based on experiences in various banking projects, it provides blueprints for sustainable infrastructures having to run for many years.
Engineering web services with attribute grammars
Authors: Sarasa-Cabezuelo Antonio , Temprado-Battad Bryan , Sierra José-Luis
Published: February 2011

Applications based on web services make an extensive use of XML documents. These XML documents are structured according to different markup vocabularies, which represent information such as the inputs and the outputs of the services. This paper proposes a way of implementing web services using a framework called XLOP (XML Language-Oriented Processing). XLOP includes a declarative domain-specific language based on attribute grammars, a well-known declarative specification technique used in the development of language processors. XLOP makes possible the automatic generation of efficient XML-processing components from high-level, declarative specifications, facilitating the development of the aforementioned services and enhancing their maintainability. This technique is illustrated in the context of Chasqui, a system for building repositories of learning objects in specialized domains, which implements a REST web service for checking constraints on the metadata of the stored learning objects.
Measuring complexity of component based architecture
Authors: Sengupta Sabnam , Kanjilal Ananya , Bhattacharya Swapan
Published: February 2011

Component based software development (CBSD) is an evolving paradigm where emphasis is laid on reuse of existing components and effective designing of components. As complexity of software systems increases, the challenge of CBSD lies in designing highly cohesive, testable components. Researcher community is striving hard to identify the attributes characterizing component-based development and proposing metrics that may help in controlling the complexity of the component-based systems. This paper proposes a metric-based approach for the determination of complexity along with a set of architectural aspects of componentbased architectures. The Component Architecture Complexity Measurement Metrics (CACMM) has been proposed based on Component Architecture Graph (CAG), a graphical model used for representing UML component diagram. Analysis of the graph is done to measure complexity at different levels -- individual component level, component-to-component level and the complexity for the overall architecture. This metrics may be used by developers to assess the component based architecture and if required re-design to create highly cohesive components with minimal coupling. A case study is presented for deriving the complexity along with the other aspects of the architecture.
Towards a specific software development process for high integrity systems
Authors: Perseil Isabelle
Published: February 2011

The software development process is the main tool of project management. It serves to plan optimally all activities related to the production of software. It is mainly a scheduling policy of these activities which allows to control and to follow them in time.We moved here toward an adaptation of the RUP for real-time systems. First, our approach is to enrich the current process with other phases, secondly, we consider that the requirements of strategic type must be completely identified, specified, verified since they are those which lead all the development; last, we are redefining the lifecycle which puts the models of highest level of abstraction (analysis, architecture) as the main objectives to reach. The enrichment of the development process relates to additional phases and a parallelization of its sub-processes. The software development process that we propose is subdivided into three sub-processes whose principal is led by the strategic use cases. This allows a seamless development, involving intermediate languages to move gradually from the informal to the formal and provides the opportunity to compose languages of different types.
Complexity and performance results for non FFT-based univariate polynomial multiplication
Authors: Chowdhury Muhammad F.I. , Maza Marc Moreno , Pan Wei , Schost Éric
Published: February 2011

Today's parallel hardware architectures and computer memory hierarchies enforce revisiting fundamental algorithms which were often designed with algebraic complexity as the main complexity measure and with sequential running time as the main performance counter. This study is devoted to two algorithms for univariate polynomial multiplication algorithms that are are independent of the coefficient ring: the plain and the Toom-Cook univariate multiplications. We analyze their cache complexity and report on their parallel implementations in Cilk++.
Invariants and symbolic calculations in the theory of quadratic differential systems
Authors: Schlomiuk Dana , Vulpe Nicolae
Published: February 2011

While quadratic differential systems intervene in many areas of applied mathematics and they also have theoretical importance, the topological classification of this class remains an extremely hard problem. However, in recent years much progress has been achieved due to the use of computer algebra and numerical calculations for obtaining complete classifications of some families of quadratic systems by effectively computing polynomial invariants and by an interplay between computer algebra and numerical computations. We illustrate on a specific family how these techniques yield the complete classification of the family within the 12-dimensional space of the coefficients of the systems.
Controlling the Functionality of Materials for Sustainable Energy
Authors: Crabtree George , Sarrao John
Published: February 2011

Our understanding and control of sustainable energy technologies is in its infancy. Many sustainable energy phenomena depend on the exchange of photons and electrons among quantized energy levels of semiconductors, molecules, and metals at nanoscale spatial scales and at fast or ultrafast time scales. Improving the performance of sustainable energy technologies to make them competitive with fossil technologies requires probing and understanding these quantum phenomena with advanced scientific techniques. This understanding must then be translated into control of the functionality and performance of the materials and chemistry that govern sustainable energy technologies.

The review begins by contrasting the foundations of fossil fuel technology based on combustion, heat, and classical thermodynamics with the foundations of sustainable energy technology based on quantum exchange of energy among photons, chemical bonds, and electrons without conversion to heat. Two sets of tools that are essential to observe, understand, and control the quantum phenomena of sustainable energy are described: in situ and time-resolved experiments and theory, and numerical modeling of the functionality of large assemblies of atoms. Finally, the challenges and opportunities for understanding and ultimately controlling sustainable energy phenomena are presented for catalysis, solar water splitting, and superconductivity.
Equalities and Inequalities: Irreversibility and the Second Law of Thermodynamics at the Nanoscale
Authors: Jarzynski Christopher
Published: February 2011

The reason we never observe violations of the second law of thermodynamics is in part a matter of statistics: When ∼1023 degrees of freedom are involved, the odds are overwhelmingly stacked against the possibility of seeing significant deviations away from the mean behavior. As we turn our attention to smaller systems, however, statistical fluctuations become more prominent. In recent years it has become apparent that the fluctuations of systems far from thermal equilibrium are not mere background noise, but satisfy strong, useful, and unexpected properties. In particular, a proper accounting of fluctuations allows us to rewrite familiar inequalities of macroscopic thermodynamics as equalities. This review describes some of this progress, and argues that it has refined our understanding of irreversibility and the second law.
High-Precision Differential Capacity Analysis of LiMn2O4/graphite Cells
Authors: Smith A. J. , Burns J. C. , Dahn J. R.
Published: February 2011

The differential capacity and charge–discharge end points of a commercial LiMn2O4/graphite cell were examined using high precision constant-current chronopotentiometry and coulometry. The positive and negative electrodes from a fresh commercial cell were recovered and used to generate high precision "reference" potential-capacity data versus Li. The reference data were used to calculate differential capacity versus potential for "theoretical" LiMn2O4/graphite cells which could be perfectly matched to data from experiments on full cells. Matching was achieved primarily by relative "slippage" in capacity of the positive and negative potential-capacity curves. This allowed a detailed understanding of the aging processes and capacity fade of a full cell.
Arginase inhibition restores in vivo coronary microvascular function in type 2 diabetic rats
Authors: Grönros Julia , Jung Christian , Lundberg Jon O. , Cerrato Ruha , Östenson Claes-Göran , Pernow John
Published: February 2011

Nitric oxide (NO) is crucial for maintaining normal endothelial function and vascular integrity. Increased arginase activity in diabetes might compete with NO synthase (NOS) for their common substrate arginine, resulting in diminished production of NO. The aim of this study was to evaluate coronary microvascular function in type 2 diabetic Goto-Kakizaki (GK) rats using in vivo coronary flow velocity reserve (CFVR) and the effect of arginase inhibition to restore vascular function. Different groups of GK and Wistar rats were given vehicle, the arginase inhibitor Nω-hydroxy-nor-l-arginine (nor-NOHA), l-arginine, and the NOS inhibitor NG-monomethyl -l-arginine (l-NMMA). GK rats had impaired CFVR compared with Wistar rats (1.31 ± 0.09 vs. 1.87 ± 0.05, P < 0.001). CFVR was restored by nor-NOHA treatment compared with vehicle in GK rats (1.71 ± 0.13 vs. 1.23 ± 0.12, P < 0.05) but remained unchanged in Wistar rats (1.88 ± 0.10 vs. 1.79 ± 0.16). The beneficial effect of nor-NOHA in GK rats was abolished after NOS inhibition. CFVR was not affected by arginine compared with vehicle. Arginase II expression was increased in the aorta and myocardium from GK rats compared with Wistar rats. Citrulline-to-ornithine and citrulline-to-arginine ratios measured in plasma increased significantly more in GK rats than in Wistar rats after nor-NOHA treatment, suggesting a shift of arginine utilization from arginase to NOS. In conclusion, coronary artery microvascular function is impaired in the type 2 diabetic GK rat. Treatment with nor-NOHA restores the microvascular function by a mechanism related to increased utilization of arginine by NOS and increased NO availability.
Wall stress of the cervical carotid artery in patients with carotid dissection: a case-control study
Authors: Callaghan Fraser M. , Luechinger Roger , Kurtcuoglu Vartan , Sarikaya Hakan , Poulikakos Dimos , Baumgartner Ralf W.
Published: February 2011

Spontaneous internal carotid artery (ICA) dissection (sICAD) results from an intimal tear located around the distal carotid sinus. The mechanisms causing the tear are unknown. This case-control study tested the hypotheses that head movements increase the wall stress in the cervical ICA and that the stress increase is greater in patients with sICAD than in controls. Five patients with unilateral, recanalized, left sICAD and five matched controls were investigated before and after maximal head rotation to the left and neck hyperextension after 45° head rotation to the left. The anatomy of the extracranial carotid arteries was assessed by magnetic resonance imaging and used to create finite element models of the right ICA. Wall stress increased after head movements. Increases above the 80th and 90th percentile were located at the intimal side of the artery wall from 7.4 mm below to 10 mm above the cranial edge of the carotid sinus, i.e., at the same location as histologically confirmed tears in patients with sICAD. Wall stress increase did not differ between patients and controls. The present findings suggest that wall stress increases at the intimal side of the artery wall surrounding the distal edge of the carotid bulb after head movements may be important for the development of carotid dissection. The lack of wall stress difference between the two groups indicates that the carotid arteries of patients with carotid dissection have either distinct functional or anatomical properties or endured unusually heavy wall stresses to initiate dissection.
Molecular regulation of NADPH oxidase 5 via the MAPK pathway
Authors: Pandey D. , Fulton D. J. R.
Published: February 2011

The mechanisms controlling the activity of NADPH oxidase 5 (Nox5) are unique in that they are independent of the protein: protein interactions that coordinate the activation of other Nox isoforms. Instead, the primary driving force for Nox5 activity is calcium. However, in a previous study we reported that the protein kinase C (PKC)-agonist PMA could induce a sustained activation of Nox5 that was independent of calcium changes. This apparent calcium-independent activation was found to be mediated by the PKC-dependent phosphorylation of specific serine and threonine residues on Nox5 which increased the calcium sensitivity of the enzyme and enabled activation at resting levels of calcium. However, the specific kinase(s) mediating the phosphorylation and activation of Nox5 are not known. As PKC can activate the MEK/ERK1/2 signaling pathway, we hypothesized that Nox5 is activated by the coordinated phosphorylation of both MAPK and PKC pathways. The inhibition of MEK1 using PD-98059 and U-0126 significantly reduced the phosphorylation and activity of Nox5 in response to PMA but not to the calcium-mobilizing stimulus ionomycin. Dominant negative MEK1 and knockdown of endogenous MEK1/2 using a specific small interfering RNA also inhibited Nox5 activity in response to PMA. The mutation of S498 to a nonphosphorylatable residue and to a lesser degree T494 blocked the ability of ERK to stimulate Nox5 activity. However, a constitutively active form of MEK1 failed to increase Nox5 activity in the absence of PMA stimulation. These results suggest that the MEK/ERK1/2 pathway is necessary but not sufficient to regulate the PMA-dependent activation of Nox5.
Impaired Ca2+ handling in penile arteries from prediabetic Zucker rats: involvement of Rho kinase
Authors: Villalba Nuria , Contreras Cristina , Hernández Medardo , García-Sacristán Albino , Prieto Dolores
Published: February 2011

Diabetes is associated with an increased vascular tone usually involved in the pathogenesis of diabetic cardiovascular complications such as hypertension, stroke, coronary artery disease, or erectile dysfunction (ED). Enhanced contractility of penile erectile tissue has been associated with augmented activity of the RhoA/Rho kinase (RhoK) pathway in models of diabetes-associated ED. The present study assessed whether abnormal vasoconstriction in penile arteries from prediabetic obese Zucker rats (OZRs) is due to changes in the intracellular Ca2+ concentration ([Ca2+]i) and/or in myofilament Ca2+ sensitivity. Penile arteries from OZRs and lean Zucker rats (LZRs) were mounted on microvascular myographs for simultaneous measurements of [Ca2+]i and tension. The relationships between [Ca2+]i and contraction for the α1-adrenergic vasoconstrictor phenylephrine (PE) were left shifted and steeper in OZRs compared with LZRs, although the magnitude of the contraction was similar in both groups. In contrast, the vasoconstriction induced by the thromboxane A2 receptor agonist U-46619 was augmented in arteries from OZRs, and this increase was associated with an increase in both the sensitivity and maximum responses to Ca2+. The RhoK inhibitor Y-27632 (10 μM) reduced the vasoconstriction induced by PE to a greater extent in OZRs than in LZRs, without altering Ca2+. Y-27632 inhibited with a greater potency the contraction elicited by high KCl in arteries from OZRs compared with LZRs without changing [Ca2+]i. RhoK-II expression was augmented in arteries from OZRs. These results suggest receptor-specific changes in the Ca2+ handling of penile arteries under conditions of metabolic syndrome. Whereas augmented vasoconstriction upon activation of the thromboxane A2 receptor is coupled to enhanced Ca2+ entry, a RhoK-mediated enhancement of myofilament Ca2+ sensitivity is coupled with the α1-adrenergic vasoconstriction in penile arteries from OZRs.
Genetic evidence for NAD(P)H:quinone oxidoreductase 1-catalyzed quinone reduction on passage through the mouse pulmonary circulation
Authors: Lindemer Brian J. , Bongard Robert D. , Hoffmann Raymond , Baumgardt Shelley , Gonzalez Frank J. , Merker Marilyn P.
Published: February 2011

The quinones duroquinone (DQ) and coenzyme Q1(CoQ1) and quinone reductase inhibitors have been used to identify reductases involved in quinone reduction on passage through the pulmonary circulation. In perfused rat lung, NAD(P)H:quinone oxidoreductase 1 (NQO1) was identified as the predominant DQ reductase and NQO1 and mitochondrial complex I as the CoQ1reductases. Since inhibitors have nonspecific effects, the goal was to use Nqo1-null (NQO1−/−) mice to evaluate DQ as an NQO1 probe in the lung. Lung homogenate cytosol NQO1 activities were 97 ± 11, 54 ± 6, and 5 ± 1 (SE) nmol dichlorophenolindophenol reduced·min−1·mg protein−1for NQO1+/+, NQO1+/−, and NQO1−/−lungs, respectively. Intact lung quinone reduction was evaluated by infusion of DQ (50 μM) or CoQ1(60 μM) into the pulmonary arterial inflow of the isolated perfused lung and measurement of pulmonary venous effluent hydroquinone (DQH2or CoQ1H2). DQH2efflux rates for NQO1+/+, NQO1+/−, and NQO1−/−lungs were 0.65 ± 0.08, 0.45 ± 0.04, and 0.13 ± 0.05 (SE) μmol·min−1·g dry lung−1, respectively. DQ reduction in NQO1+/+lungs was inhibited by 90 ± 4% with dicumarol; there was no inhibition in NQO1−/−lungs. There was no significant difference in CoQ1H2efflux rates for NQO1+/+and NQO1−/−lungs. Differences in DQ reduction were not due to differences in lung dry weights, wet-to-dry weight ratios, perfusion pressures, perfused surface areas, or total DQ recoveries. The data provide genetic evidence implicating DQ as a specific NQO1 probe in the perfused rodent lung.
Boundary Value Problems for Systems of Second‐Order Dynamic Equations on Time Scales with Δ‐Carathéodory Functions
Authors: Frigon M. , Gilbert H.
Published: February 2011

We establish the existence of solutions to systems of second‐order
dynamic equations on time scales with the right member f, a Δ‐Carathéodory
function. First, we consider the case where the nonlinearity f does not depend
on the Δ‐derivative, xΔ(t). We obtain existence results for Strum‐Liouville and
for periodic boundary conditions. Finally, we consider more general systems
in which the nonlinearity f depends on the Δ‐derivative and satisfies a linear
growth condition with respect to xΔ(t). Our existence results rely on notions
of solution‐tube that are introduced in this paper.