bluuebunny/crossref_metadata_2025 huggingface dataset:
Chloroplast DNA polymorphism reveals geographic structure and introgression in theQuercus crassifolia ×Quercus crassipeshybrid complex in Mexico
Authors: Tovar-Sánchez E. , Mussali-Galante P. , Esteban-Jiménez R. , Piñero D. , Arias D. M. , Dorado O. , Oyama K.
Published: January 2010

Quercus crassifolia H. & B. and Quercus crassipes H. & B. are two common temperate forest species in Mexico that form hybrids when they occur in mixed (sympatric) areas. In this study, we used chloroplast microsatellite haplotypes to infer phylogeographic patterns onto the genetic structure of populations of both parental species, thus defining probable colonization routes throughout Mexico. Haplotype diversity in seven hybrid zones and four allopatric sites with nonmixed (allopatric) populations of both putative parental species was analyzed. To determine the expansion and colonization routes for the two species, we carried out a nested clade phylogeographic analysis that would allow us to infer the haplotype correspondence to a phylogeographical approach. In spite of sharing many common populations, we determined that there is a different genetic historical colonization for Q. crassipes and for Q. crassifolia. Hybrid populations had the highest levels of genetic variation (Gv), Shannon diversity index (H), and haplotype number (nh) in comparison with nonmixed/allopatric populations of their putative parentals. Furthermore, populations of hybrid zones showed the highest values of genetic differentiation FST, RST. Moreover, both species share four distinctive cpDNA haplotypes, which were most likely acquired by introgression through hybrids located in several populations throughout the Eje Neovolcánico area. This last region was confirmed to be a “hot spot” for oak diversity, a place in which different maternal lineages merged.
5.8S motifs for the identification of pseudogenic ITS regions
Authors: Harpke Doerte , Peterson Angela
Published: January 2010

The internal transcribed spacer (ITS) region (ITS1, 5.8S rDNA, ITS2) represents one of the most popular molecular markers in phylogenetics. The number of investigations revealing high degrees of intra-individual polymorphism connected with the presence of pseudogenic ITS regions is on the increase. Studies including pseudogenic ITS regions can lead to erroneous phylogenetic trees and false taxonomic conclusions. For their recognition, we focus on the 5.8S rDNA as the functional part of this region, which is also affected by degeneration processes. We outline three conserved Viridiplantae 5.8S motifs: GAATTGCAGAAwyC, TTTGAAyGCA, CGATGAAGAACGyAGC, which can be simply checked in sequence alignments. The latter 5.8S motif we also recognised in the large subunit RNA (LSU) of Escherichia coli . The utility of different methods for pseudogene detection based on easily recognisable 5.8S sequence motifs by comparison with 5.8S secondary structure reconstructions and statistical tests are discussed and illustrated with three previously published angiosperm data sets.
Relationships between flowering phenology and female reproductive success in the Japanese tree species Magnolia stellata
Authors: Setsuko Suzuki , Tamaki Ichiro , Ishida Kiyoshi , Tomaru Nobuhiro
Published: January 2010

We have examined the earliness, duration, and amplitude of flowering genets in a Magnolia stellata (Sieb. et Zucc.) Maxim. population in relation to their size, environmental factors (temperature and light), and female reproductive success (ovule survival rate) over three consecutive years. Average flowering durations of individual flowers, genets, and the whole population in these 3 years were 10.2, 15.2, and 29.0 d, respectively. A bisexual phase (with both female and male phase flowers) in genets spanned 62.9% of the total flowering period, suggesting that geitonogamy can occur. The earliness, duration, and amplitude of flowering genets were all significantly correlated, indicating that genets flower early and long periods have high flowering amplitudes. The three parameters were also significantly correlated with the size of the genets (represented by the diameter at breast height of its thickest ramet) and relative photosynthetic photon flux density at the top of their crowns. Therefore, genets that are large and located in well-lit sites tend to have many flowers, and blossom both earlier and longer. Later-flowering genets have higher female reproductive success, probably because M. stellata is protogynous. Significantly positive correlation between flowering amplitude and female reproductive success suggests that large numbers of flowers increase the attractiveness of genets for pollinators, and this outweighs the negative effects of geitonogamy.
Structural and permeability properties of the soybean seed coat
Authors: Qutob Dinah , Ma Fengshan , Peterson Carol A. , Bernards Mark A. , Gijzen Mark
Published: January 2010

The seed coat is a composite structure that serves as a conduit for nutrient acquisition for the developing embryo. Upon seed desiccation and maturation, the seed coat provides cover and protection for the embryo and may impose dormancy or trigger germination by controlling water uptake. For crop plants such as soybean, traits determined by the seed coat impact the overall quality of the seed and the utility of its derived products. There are remarkable examples of unusual genetic mechanisms that control seed coat pigmentation, lustre, and cracking that have been recently described in soybean. Studies on seed permeability to water have resulted in the formulation of new hypotheses to account for variation of this trait. This review summarizes the current advances in our understanding of the structural properties of the soybean seed coat with an emphasis on the control of permeability to water in mature seeds.
A MODIFIED LEAST SQUARES SUPPORT VECTOR MACHINE CLASSIFIER WITH APPLICATION TO CREDIT RISK ANALYSIS
Authors: YU LEAN , WANG SHOUYANG , CAO JIE
Published: January 2010

In this paper, a modified least squares support vector machine classifier, called the C-variable least squares support vector machine (C-VLSSVM) classifier, is proposed for credit risk analysis. The main idea of the proposed classifier is based on the prior knowledge that different classes may have different importance for modeling and more weight should be given to classes having more importance. The C-VLSSVM classifier can be obtained by a simple modification of the regularization parameter, based on the least squares support vector machine (LSSVM) classifier, whereby more weight is given to errors in classification of important classes, than to errors in classification of unimportant classes, while keeping the regularized terms in their original form. For illustration purpose, two real-world credit data sets are used to verify the effectiveness of the C-VLSSVM classifier. Experimental results obtained reveal that the proposed C-VLSSVM classifier can produce promising classification results in credit risk analysis, relative to other classifiers listed in this study.
Connecting women and technology
Authors: Barr Valerie
Published: January 2010

The
Communications
Web site, http://cacm.acm.org, features more than a dozen bloggers in the BLOG@CACM community. In each issue of
Communications
, we'll publish excerpts from selected posts.

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Follow us on Twitter at http://twitter.com/blogCACM

Guest blogger Valerie Barr writes about highlights of the ninth Grace Hopper Celebration of Women in Computing Conference, including keynote speeches by Megan Smith and Francine Berman.
Type theory comes of age
Authors: Wright Alex
Published: January 2010

Type systems are moving beyond the realm of data structure and into more complex domains like security and networking.
Improving disaster management
Authors: Underwood Sarah
Published: January 2010

Social networking, sophisticated imaging, and dual-use technologies promise improved disaster management, but they must be adopted by governments and aid agencies if more lives are to be saved in the wake of crises.
The need for a national cybersecurity research and development agenda
Authors: Maughan Douglas
Published: January 2010

Government-funded initiatives, in cooperation with private-sector partners in key technology areas, are fundamental to cybersecurity technical transformation.
Taking a flexible approach to ASPs
Authors: Altaf Farheen , Schuff David
Published: January 2010

Introduction

In 2001, subscription-based application service providers (ASPs) represented the new paradigm for application deployment. It was anticipated that ASP spending would reach $7.8 billion by 2004, and a 2001 survey conducted by PMP Research revealed that 23% of respondents said they would likely use an ASP in the future. However, this turned out not to be the case. By 2004, spending on ASPs had increased only to $4.2 billion.

Over the past few years, there has been a revival of the ASP model through the notion of cloud computing and "software as a service." The market for cloud-based services was $16 billion in 2008, and projections estimate the market for spending in this area will reach $42 billion by 2012. However, this still only would represent 9% of overall IT spending. These services have traditionally targeted larger companies instead of small or medium-sized businesses (or SMEs). Companies like Oracle, Siebel, and Ariba claim that nearly 60% of their business comes from companies that have annual revenues exceeding $1 billion. However, the ASP model provides the same or greater benefits to SMEs, including lower costs, greater choice, simpler installation (and no related fees), and the ability to access applications from any internet-connected computer. ASP subscribers also often receive "24 by 7" technical support. This access to IT expertise (without maintaining an in-house IT staff) results in further savings for businesses.

Despite the benefits, small businesses have not readily adopted ASPs. The reasons for this lack of adoption include the reluctance of SMEs to replace their existing systems with untried ASPs and the inappropriateness of the "one-size-fits-all" approach that doesn't take in to consideration specific industry or firm requirements. This makes the SME a significant untapped market for companies operating in this space.

The purpose of this article is to more fully understand the SME market for ASPs through an analysis of the factors that are most important to likely adopters. While previous work has broadly investigated adoption by SMEs and the general adoption of ASPs, this study combines both perspectives and proposes the new construct of "flexibility" as influential in the adoption decision. We surveyed 101 SMEs that had not yet adopted ASPs and asked them to rate the importance of several factors that would affect their decision. Correlating likelihood of adoption with the importance of those factors yields several important insights into how ASP vendors should position their product offerings.
Practical intelligence in IT
Authors: Joseph Damien , Ang Soon , Chang Roger H. L. , Slaughter Sandra A.
Published: January 2010

Introduction

What qualities make a successful it professional? Certainty strong technical skills are sine qua non. As a result, the technology geek remains the stereotype of an information technology (IT) professional. Indeed, when companies hire IT professionals, their focus is often on the "hard" skills needed to perform the work, such as years of Java programming experience.

However, there is a growing (and gnawing) awareness that technical skills alone are insufficient for success in IT, particularly in today's dynamic, distributed and complex workplace. Companies are exploring outsourcing and offshoring to become more flexible and contain costs while strategically leveraging IT. Consequently, IT professionals (whether onsite or offshore, in-house or outsourced) must acquire a broader set of skills beyond their traditional technical skills. These broader managerial or interpersonal skills are generically labeled "soft skills."

Despite the increasing importance of soft skills, very little systematic research has conceptualized such skills and even less has measured these skills. Given this gap in the literature, this article introduces "practical intelligence" as the overarching concept that could provide a better understanding of this broader set of skills required of IT professionals. We describe the development of the SoftSkills for IT (SSIT) instrument for assessing an IT professional's level of practical intelligence, and report the results of a study that validates this instrument by comparing the practical intelligence of experienced IT professionals versus novices. We conclude by drawing out implications of our study for IT recruitment, training and development, and suggest future research directions.
A distributed service-oriented architecture for business process execution
Authors: Li Guoli , Muthusamy Vinod , Jacobsen Hans-Arno
Published: January 2010

The Business Process Execution Language (BPEL) standardizes the development of composite enterprise applications that make use of software components exposed as Web services. BPEL processes are currently executed by a centralized orchestration engine, in which issues such as scalability, platform heterogeneity, and division across administrative domains can be difficult to manage. We propose a distributed agent-based orchestration engine in which several lightweight agents execute a portion of the original business process and collaborate in order to execute the complete process. The complete set of standard BPEL activities are supported, and the transformations of several BPEL activities to the agent-based architecture are described. Evaluations of an implementation of this architecture demonstrate that agent-based execution scales better than a non-distributed approach, with at least 70% and 120% improvements in process execution time, and throughput, respectively, even with a large number of concurrent process instances. In addition, the distributed architecture successfully executes large processes that are shown to be infeasible to execute with a nondistributed engine.
Statistical lattice-based spoken document retrieval
Authors: Chia Tee Kiah , Sim Khe Chai , Li Haizhou , Ng Hwee Tou
Published: January 2010

Recent research efforts on spoken document retrieval have tried to overcome the low quality of 1-best automatic speech recognition transcripts, especially in the case of conversational speech, by using statistics derived from speech lattices containing multiple transcription hypotheses as output by a speech recognizer. We present a method for lattice-based spoken document retrieval based on a statistical
n
-gram modeling approach to information retrieval. In this statistical lattice-based retrieval (SLBR) method, a smoothed statistical model is estimated for each document from the expected counts of words given the information in a lattice, and the relevance of each document to a query is measured as a probability under such a model. We investigate the efficacy of our method under various parameter settings of the speech recognition and lattice processing engines, using the Fisher English Corpus of conversational telephone speech. Experimental results show that our method consistently achieves better retrieval performance than using only the 1-best transcripts in statistical retrieval, outperforms a recently proposed lattice-based vector space retrieval method, and also compares favorably with a lattice-based retrieval method based on the Okapi BM25 model.
Teaching compiler code generation
Authors: Mahoney William , Pedersen Jay
Published: January 2010

The code generation portion of a compiler is still typically constructed by hand in an ad-hoc manner. When teaching a compiler construction class, the code generation phase can occupy a large portion of a one semester project. To address this, we have created an extremely small instruction set simulator which is easily learned in a short period of time. We've termed this a RRISC (Really Reduced Instruction Set Computer) and have been using it successfully for several years.
Incremental submission of programming code using object-oriented classes
Authors: Ritter Nicola , McGill Tanya , Thompson Nik
Published: January 2010

Given increasing adoption of agile software development methodologies it is essential that information technology students are exposed to them. This paper describes and evaluates an attempt to introduce agile programming into a core second year programming course. The initiative appeared to be associated with improvements in both drop out and pass rate, and student perceptions of the innovation were largely positive.
On the implementation of self-assessment in an introductory programming course
Authors: Ngai Grace , Lau Winnie W.Y. , Chan Stephen C.F. , Leong Hong-va
Published: January 2010

Much of the work in making the introductory programming course more attractive to students has centered around the course content. However, many student frustrations and anxieties stem from the assessment of the course: students do not have a clear idea of what they need to do to achieve a certain grade, and whether their work meets the expectations. We present the results of a pilot study that aims to reduce student frustrations and anxieties through the use of student self-assessment with clearly-defined criteria. Our study shows that given the proper instruction and guidance, students are able to accurately assess and predict their own grades. The result is an improved and more satisfactory learning experience.
Computing and sustainability
Authors: Mann Samuel , Muller Logan , Davis Janet , Roda Claudia , Young Alison
Published: January 2010

Computing has a significant impact on sustainable outcomes and computing education for sustainability has previously been identified as an important goal. This paper aims to address a barrier to the integration of sustainability into computing teaching -- that of a perceived paucity of resources. The "framework" (Computing Education for Sustainability, CE4S) is developed that could be used by educators to access resources for the integration of sustainability in the computing curriculum.
Perspectives on developing and assessing professional values in computing
Authors: Fuller Ursula , Little Joyce Currie , Keim Bob , Riedesel Charles , Fitch Diana , White Su
Published: January 2010

This paper discusses how to ensure that students attain professional values important to the workplace by integrating them into computing curricula. It describes a survey of the attitudes of students, faculty and professionals in computing towards the teaching and assessment of such values. The results show that these groups share a set of professional values, though students are less convinced of their importance in the work environment. There is broad consensus on the specific behaviors and attitudes reflective of these values to be developed in the curriculum. The groups differed in their opinions of whether these attitudes and behaviors could be workably assessed.
The quest for bandwidth estimation techniques for large-scale distributed systems
Authors: Croce Daniele , Mellia Marco , Leonardi Emilio
Published: January 2010

In recent years the research community has developed many techniques to estimate the end-to-end available bandwidth of an Internet path. This important metric can be potentially exploited to optimize the performance of several distributed systems and, even, to improve the effectiveness of the congestion control mechanism of TCP. Thus, it has been suggested that some existing estimation techniques could be used for this purpose. However, existing tools were not designed for large-scale deployments and were mostly validated in controlled settings, considering only one measurement running at a time. In this paper, we argue that current tools, while offering good estimates when used alone, might not work in large-scale systems where several estimations severely interfere with each other. We analyze the properties of the measurement paradigms employed today and discuss their functioning, study their overhead and analyze their interference. Our testbed results show that current techniques are insufficient as they are. Finally, we will discuss and propose some principles that should be taken into account for including available bandwidth measurements in large-scale distributed systems.
Applying control theory in the real world
Authors: Hellerstein Joseph L. , Morrison Vance , Eilebrecht Eric
Published: January 2010

There has been considerable interest in using control theory to build web servers, database managers, and other systems. We claim that the potential value of using control theory cannot be realized in practice without a methodology that addresses controller design, testing, and tuning. Based on our experience with building a controller for the .NET thread pool, we develop a methodology that: (a) designs for extensibility to integrate diverse control techniques, (b) scales the test infrastructure to enable running a large number of test cases, (c) constructs test cases for which the ideal controller performance is known a priori so that the outcomes of test cases can be readily assessed, and (d) tunes controller parameters to achieve good results for multiple performance metrics. We conclude by discussing how our methodology can be extended, especially to designing controllers for distributed systems.
Energy consumption of multi-hop wireless networks under throughput constraints and range scaling
Authors: Liaskovitis Periklis , Schurgers Curt
Published: January 2010

This paper studies the joint optimization of throughput and energy consumption in multi-hop wireless networks and associated scaling trends. We employ transmission range as the main control knob and forfeit the common, but often unrealistic, premise that communication energy is proportional to the transmission range raised to a path loss exponent. In real systems, idle power, overhearing and power amplifier play a major role and energy efficiency may potentially favor long transmission ranges. On the other hand, throughput maximization favors short transmission ranges. We derive approximate expressions for average per-node energy consumption as a function of the transmission range for various representative system behaviors. Based on these, we build a joint energy-throughput analytical model and validate it through simulations. Then, we address two key problems: Given an upper bound on the average per-node power consumption (or energy budget) find the maximum per-node throughput (or number of transferred bits) and the range that achieves it. And, given a lower bound on average per-node throughput (or minimum bit volume to be transferred), find the transmission range that results in the minimum per-node power consumption (or minimum energy dissipation).
Poster abstract
Authors: Sen Souvik , Ghosh Rahul , Xiong Jie , Choudhury Romit Roy
Published: January 2010

Wireless multicast is an important service primitive for emerging applications such as live video, streaming audio and content telecasts. Transmission rate in such a link layer multicast is bottlenecked by the rate of the weakest client, leading to channel under-utilization. Attempts to increase the data rate results in lower reliability (due to higher bit error rate) and higher unfairness. This poster utilizes smart beamforming antennas to improve multicast performance in wireless LANs. The main idea is to satisfy majority of the (strong) clients with a high-rate omnidirectional transmission, followed by high-rate directional transmission(s) to cover the weaker ones. By selecting an optimal transmission strategy, we show that the multicast throughput can be maximized while achieving a desired delivery ratio at all the clients. We use testbed measurements to verify our main assumptions. We simulate our protocol in Qualnet, and observe consistent performance improvements over a wide range of client topologies and time-varying channel conditions.
Introduction to the SIGACT news online algorithms column
Authors: Chrobak Marek
Published: January 2010

Pros and cons of competitive analysis have been debated since its inception in mid 1980s. Much of this discussion centered around the accuracy of performance evaluation methods for paging, which is probably the most central among online optimization problems studied in the literature, and, at the same time, ironically, the most prominent example of shortcomings of competitive analysis. In this quarter's column, Reza Dorrigiv and Alejandro Lopez-Ortiz review the history of the problem, discuss several performance models from the literature, and propose a new model that avoids shortcomings of previous approaches.

If you are interested in contributing to the column as a guest writer, feel free to contact me by email. All kinds of contributions related to online algorithms and competitive analysis are of interest: technical articles, surveys, conference reports, opinion pieces, and other.
Biliary Atresia: Will Blocking Inflammation Tame the Disease?
Authors: Bessho Kazuhiko , Bezerra Jorge A.
Published: January 2010

Biliary atresia is the most common cholangiopathy of childhood. With complete obstruction of segments or the entire length of extrahepatic bile ducts, the timely pursuit of hepatoportoenterostomy is the best strategy to restore bile drainage. However, even with prompt surgical intervention, ongoing injury of intrahepatic bile ducts and progressive cholangiopathy lead to end-stage cirrhosis. The pace of disease progression is not uniform; it may relate to clinical forms of disease and/or staging of liver pathology at diagnosis. Although the etiology of disease is not yet defined, several biological processes have been linked to pathogenic mechanisms of bile duct injury. Among them, there is increasing evidence that the immune system targets the duct epithelium and disrupts bile flow. We discuss how careful clinical phenotyping, staging of disease, and basic mechanistic research are providing insights into clinical trial designs and directions for development of new therapies to block progression of disease.
Hepcidin and Disorders of Iron Metabolism
Authors: Ganz Tomas , Nemeth Elizabeta
Published: January 2010

The hepatic peptide hormone hepcidin is the principal regulator of iron absorption and its tissue distribution. Pathologically increased hepcidin concentrations cause or contribute to iron-restrictive anemias including anemias associated with inflammation, chronic kidney disease and some cancers. Hepcidin deficiency results in iron overload in hereditary hemochromatosis and ineffective erythropoiesis. The hepcidin-ferroportin axis is the principal regulator of extracellular iron homeostasis in health and disease, and is a promising target for the diagnosis and treatment of iron disorders and anemias.
Stress- and Allostasis-Induced Brain Plasticity
Authors: McEwen Bruce S. , Gianaros Peter J.
Published: January 2010

The brain is the key organ of stress processes. It determines what individuals will experience as stressful, it orchestrates how individuals will cope with stressful experiences, and it changes both functionally and structurally as a result of stressful experiences. Within the brain, a distributed, dynamic, and plastic neural circuitry coordinates, monitors, and calibrates behavioral and physiological stress response systems to meet the demands imposed by particular stressors. These allodynamic processes can be adaptive in the short term (allostasis) and maladaptive in the long term (allostatic load). Critically, these processes involve bidirectional signaling between the brain and body. Consequently, allostasis and allostatic load can jointly affect vulnerability to brain-dependent and stress-related mental and physical health conditions. This review focuses on the role of brain plasticity in adaptation to, and pathophysiology resulting from, stressful experiences. It also considers interventions to prevent and treat chronic and prevalent health conditions via allodynamic brain mechanisms.
Toward Fulfilling the Promise of Molecular Medicine in Fragile X Syndrome
Authors: Krueger Dilja D. , Bear Mark F.
Published: January 2010

Fragile X syndrome (FXS) is the most common inherited form of mental retardation and a leading known cause of autism. It is caused by loss of expression of the fragile X mental retardation protein (FMRP), an RNA-binding protein that negatively regulates protein synthesis. In neurons, multiple lines of evidence suggest that protein synthesis at synapses is triggered by activation of group 1 metabotropic glutamate receptors (Gp1 mGluRs) and that many functional consequences of activating these receptors are altered in the absence of FMRP. These observations have led to the theory that exaggerated protein synthesis downstream of Gp1 mGluRs is a core pathogenic mechanism in FXS. This excess can be corrected by reducing signaling by Gp1 mGluRs, and numerous studies have shown that inhibition of mGluR5, in particular, can ameliorate multiple mutant phenotypes in animal models of FXS. Clinical trials based on this therapeutic strategy are currently under way. FXS is therefore poised to be the first neurobehavioral disorder in which corrective treatments have been developed from the bottom up: from gene identification to pathophysiology in animals to novel therapeutics in humans. The insights gained from FXS and other autism-related single-gene disorders may also assist in identifying molecular mechanisms and potential treatment approaches for idiopathic autism.
New Approaches to the Treatment of Osteoporosis
Authors: Silva Barbara C. , Bilezikian John P.
Published: January 2010

Although safe and effective agents are currently available to treat osteoporosis, fragility fractures remain a significant problem worldwide. Recent improvements in the understanding of the cellular, biochemical, and molecular pathways of bone biology have led to the development of newer agents to treat osteoporosis, which may lead to further improvements in outcomes. In this review, we summarize the most recent advances in the field, including new modes of administration of existing drug classes, various approaches to combination therapy, and drugs with novel mechanisms of action to treat osteoporosis.
Mechanisms of Endocrine Resistance in Breast Cancer
Authors: Osborne C. Kent , Schiff Rachel
Published: January 2010

The estrogen receptor (ER) pathway plays a pivotal role in breast cancer development and progression. Endocrine therapy to block the ER pathway is highly effective, but its usefulness is limited by common intrinsic and acquired resistance. Multiple mechanisms responsible for endocrine resistance have been proposed and include deregulation of various components of the ER pathway itself, alterations in cell cycle and cell survival signaling molecules, and the activation of escape pathways that can provide tumors with alternative proliferative and survival stimuli. Among these, increased expression or signaling of growth factor receptor pathways, especially the EGFR/HER2 pathway, has been associated with both experimental and clinical endocrine therapy resistance. New treatment combinations targeting both ER and growth factor receptor signaling to block the crosstalk between these pathways and eliminate escape routes have been proven highly effective in preclinical models. Results of recent clinical studies, while partly supporting this approach, also highlight the need to better identify a priori the patients whose tumors are most likely to benefit from these specific cotargeting strategies.
Uniform in Time Description for Weak Solutions of the Hopf Equation with Nonconvex Nonlinearity
Authors: Olivas Martinez Antonio , Omel′yanov Georgy A.
Published: January 2010

We consider the Riemann problem for the Hopf equation with concave‐convex flux functions. Applying the weak asymptotics method we construct a uniform in time description for the Cauchy data evolution and show that the use of this method implies automatically the appearance of the Oleinik E‐condition.
Comparing Surface Height Used in NCAR Climate Model with That Observed by ICEsat: Effects on Skin Temperature Simulation
Authors: Jin Menglin
Published: January 2010

This paper tries to identify one of the reasons for the poor land skin temperature simulated by a climate model over Greenland. It first compares ICEsat surface height measurements over Greenland with those used by the model and reveals that the surface height of Greenland prescribed in the National Center for Atmospheric Research (NCAR) Community Climate System Model/Community Land Model version 3 (CCSM/CLM3) differs greatly from the satellite measurements from National Aeronautics and Space Administration (NASA) ICEsat at edges and central glacier regions. This deficiency, in part, leads to underestimated skin temperatures at coastal regions—the areas where significant ice sheet melt is observed. Furthermore, sensitivity studies reveal that surface skin temperature simulations of Greenland would be significantly improved if the more accurate surface height is used. The problem of the height used in current global climate model is mainly due to the fact that the model has to use coarse grid size, and within one grid, land surface height has high heterogeneity. How to assign a proper surface height for each model grid and meanwhile adequately present the high heterogeneity of land surface is a great challenge in current model development.
Harvesting of a Single‐Species System Incorporating Stage Structure and Toxicity
Authors: Wu Huiling , Chen Fengde
Published: January 2010

A single species stage‐structured model incorporating both toxicant and
harvesting is proposed and studied. It is shown that toxicant has no influence on the persistent property of the system. The existence of the bionomic equilibrium is also studied. After that, we consider the system with variable harvest effect; sufficient conditions are obtained for the global stability of bionomic equilibrium by constructing
a suitable Lyapunov function. The optimal policy is also investigated by using Pontryagin′s maximal principle. Some numeric simulations are carried out to illustrate the feasibility of the main results. We end this paper by a brief discussion.
Thermal Radiation Effects on Heat and Mass Transfer over an Unsteady Stretching Surface
Authors: Shateyi Stanford , Motsa Sandile Sydney
Published: January 2010

The unsteady heat, mass, and fluid transfer over a horizontal stretching sheet has been numerically investigated. Using a similarity transformation the governing time‐dependent boundary layer equations for the momentum, heat, and mass transfer were reduced to a sets of ordinary differential equations. These set of ordinary differential equations were then solved using the Chebyshev pseudo‐spectral collocation method, and a parametric analysis was carried out. The study observed, among other observations that the local Sherwood number increases as the values of the stretching parameter A and the Schmidt number Sc increase. Also the fluid temperature was found to be significantly reduced by increases in the values of the Prandtl number Pr, the unsteadiness parameter A, and the radiation parameter R. The velocity and concentration profiles were found to be reduced by increasing values of the unsteadiness parameter A.
BALB/c Mice Vaccinated withLeishmania majorRibosomal Proteins Extracts Combined with CpG Oligodeoxynucleotides Become Resistant to Disease Caused by a Secondary Parasite Challenge
Authors: Ramírez Laura , Iborra Salvador , Cortés Jimena , Bonay Pedro , Alonso Carlos , Barral-Netto Manoel , Soto Manuel
Published: January 2010

Leishmaniasis is an increasing public health problem and effective vaccines are not currently available. We have previously demonstrated that vaccination with ribosomal proteins extracts administered in combination of CpG oligodeoxynucleotides protects susceptible BALB/c mice against primaryLeishmania majorinfection. Here, we evaluate the long-term immunity to secondary infection conferred by this vaccine. We show that vaccinated and infected BALB/c mice were able to control a secondaryLeishmania majorchallenge, since no inflammation and very low number of parasites were observed in the site of reinfection. In addition, although an increment in the parasite burden was observed in the draining lymph nodes of the primary site of infection we did not detected inflammatory lesions at that site. Resistance against reinfection correlated to a predominant Th1 response against parasite antigens. Thus, cell cultures established from spleens and the draining lymph node of the secondary site of infection produced high levels of parasite specific IFN-γin the absence of IL-4 and IL-10 cytokine production. In addition, reinfected mice showed a high IgG2a/IgG1 ratio for anti-Leishmaniaantibodies. Our results suggest that ribosomal vaccine, which prevents pathology in a primary challenge, in combination with parasite persistence might be effective for long-term maintenance of immunity.
Environmental Mechanisms Shaping the Nature of Dwarf Spheroidal Galaxies: The View of Computer Simulations
Authors: Mayer Lucio
Published: January 2010

We review numerical works carried out over the last decade on the role of environmental mechanisms in shaping nature of the faintest galaxies known, dwarf spheroidals (dSphs). The combination of tidally induced morphological transformation, termed tidal stirring, with mass loss due to tidal and ram‐pressure stripping aided by heating due to the cosmic ionizing background can turn late‐type dwarfs resembling present‐day dIrrs into classic dSphs. The time of infall into the primary halo is shown to be a key parameter. Dwarfs accreting atz> 1, when the cosmic ultraviolet ionizing flux was much higher than today, and was thus able to keep the gas in the dwarfs warm and diffuse, were rapidly stripped of their baryons via ram pressure and tidal forces, producing very dark‐matter‐dominated objects with truncated star‐formation histories, such as the Draco dSph. The low star‐formation efficiency expected in such low‐metallicity objects prior to their infall was crucial for keeping their disks gas dominated until stripping took over.Therefore gas stripping along with inefficient star-formation provides a new feedback mechanism, alternative to photoevaporation or supernovae feedback, playing a crucial role in dwarf galaxy formation and evolution. We also discuss how the ultra‐faint dSphs belong to a different population of lower‐mass dwarf satellites that were mostly shaped by reionization rather than by environmental mechanisms (“reionization fossils”). Finally, we scrutinize the various caveats in the current understanding of environmental effects as well as other recent ideas on the origin of Local Group dSphs.
Nocardiosis in a Kidney-Pancreas Transplant
Authors: Fontana I. , Gasloli G. , Rossi A. Magoni , Bornacina C. , Dodi F. , Bertocchi M. , Soro O. , Diviacco P. , De Negri A. , Bocci E. , Ferrari C. , Giannone A. , Valente Umberto
Published: January 2010

34-year-old man with chronic renal and pancreas failure in complicated diabetic disease received a kidney-pancreas transplantation. On the 32nd postoperative day, an acute kidney rejection occurred and resolved with OKT3 therapy. The patient also presented refractory urinary infection byE. FecalisandM. Morganii, and a focal bronchopneumonia in the right-basal lobe resolved with elective chemotherapy. During the 50th post-operative day, an intense soft tissue inflammation localized in the first left metatarsal-phalangeal articulation occurred (Figure 1) followed by an abscess with a cutaneous fistula and extension to the almost totality of foot area. The radiological exam revealed a small osteo-lacunar image localized in the proximal phalanx head of the first finger foot. From the cultural examination of the purulent material,N. Asteroideswas identified. An amoxicillin-based treatment was started and continued for three months, with the complete resolution of infection This case is reported for its rarity in our casuistry, and for its difficult differential diagnosis with other potentially serious infections.
Predicting Happiness among Centenarians
Authors: Bishop Alex J. , Martin Peter , MacDonald Maurice , Poon Leonard
Published: January 2010

Background: Happiness is believed to evolve from the comparison of current circumstances relative to past achievement. However, gerontological literature on happiness in extreme old age has been limited. Objective: The purpose of this study was to determine how perceptions of health, social provisions, and economics link past satisfaction with life to current feelings of happiness among persons living to 100 years of age and beyond. Methods: A total of 158 centenarians from the Georgia Centenarian Study were included to conduct the investigation. Items reflecting congruence and happiness from the Life Satisfaction Index were used to evaluate a model of happiness. Pathways between congruence, perceived economic security, subjective health, perceived social provisions, and happiness were analyzed using structural equation modeling. Results: Congruence emerged as a key predictor of happiness. Furthermore, congruence predicted perceived economic security and subjective health, whereas perceived economic security had a strong influence on subjective health status. Conclusion: It appears that past satisfaction with life influences how centenarians frame subjective evaluations of health status and economic security. Furthermore, past satisfaction with life is directly associated with present happiness. This presents implications relative to understanding how perception of resources may enhance quality of life among persons who live exceptionally long lives.
Wound Stimulation by Growth-Arrested Human Keratinocytes and Fibroblasts: HP802-247, a New-Generation Allogeneic Tissue Engineering Product
Authors: Goedkoop René , Juliet Rodney , You Percy Hou Kang , Daroczy Judit , de Roos Kees-Peter , Lijnen Raf , Rolland Eric , Hunziker Thomas
Published: January 2010

Background: HP802-247 is a new-generation, allogeneic tissue engineering product consisting of growth-arrested, human keratinocytes (K) and fibroblasts (F) delivered in a fibrin matrix by a spray device. Objective: To identify the preferred dose of HP802-247 based on cell concentration and K/F ratio. Methods: A multicenter, randomized, double-blind, placebo-controlled, explorative phase II study of 6 different doses of HP802-247 administered once per week for 12 consecutive weeks in chronic venous leg ulcers. Results: HP802-247 was safe and well tolerated and showed increasing efficacy dependent on cell concentration and K/F ratio, in line with in vitro growth factor release data. The mean complete closure rate at week 12 for all patients treated with HP802-247 was 40%, and for placebo it was 33%. In contrast to placebo, all HP802-247 dose groups improved from week 12 to 24. Conclusion: As an integral part of a rational tissue engineering product development, this explorative trial identified the preferred dose of HP802-247 for further clinical studies.
Parvovirus B19 DNA Is Commonly Harboured in Human Skin
Authors: Bonvicini F. , La Placa M. , Manaresi E. , Gallinella G. , Gentilomi G.A. , Zerbini M. , Musiani M.
Published: January 2010

Background: Parvovirus B19 is the aetiological agent of erythema infectiosum. The presence of B19 DNA in lesional skin of other cutaneous manifestations has frequently been reported although there is disagreement on the role of the B19 virus in tissues. Objectives: To investigate the presence of B19 DNA (1) in skin lesions of patients with a described B19-related disease, (2) in skin lesions of B19-unrelated diseases and (3) in healthy skin. Methods: A total of 121 skin samples were examined for the presence of B19 DNA by PCR assays and peptide-nucleic-acid-based in situ hybridisation techniques. Results: B19 DNA was detected in 11/38 (28.9%) pityriasis lichenoides, 8/30 (26.7%) melanocytic naevi, 5/29 (17.2%) primary melanomas and 6/24 (25.0%) healthy skin biopsies. A difference in B19 DNA prevalence was observed in specimens grouped according to age, irrespective of pathologies. Conclusions: B19 DNA can be found in skin tissues of patients with pityriasis lichenoides as well as in lesions not related to B19 infection and in healthy controls. B19 DNA can be detected in skin of young subjects in a significantly high rate compared to adults, suggesting that viral persistence may be the usual outcome after primary infection.
Angiocentric Glioma-Like Tumor of the Midbrain
Authors: Covington Derek B. , Rosenblum Marc K. , Brathwaite Carole D. , Sandberg David I.
Published: January 2010

Angiocentric glioma, a rare brain neoplasm with features of ependymal differentiation, has only recently been recognized as a distinct clinicopathological entity. To date, all reported cases have involved tumors in the cerebral hemispheres, and the majority have presented with seizures. The authors report the case of a 5-year-old girl who presented with several cranial neuropathies and mild gait disturbance. An exophytic neoplasm arising from the posterior midbrain and causing obstructive hydrocephalus was identified, and surgical resection revealed a neoplasm with features of angiocentric glioma.
The Role of Distraction Osteogenesis in Children with Secondary Craniosynostosis after Shunt Operation in Early Infancy
Authors: Park Dong Ha , Chung Jaiho , Yoon Soo Han
Published: January 2010

Background: Secondary craniosynostosis rarely develops within several months in infants or children after shunt operations in early infancy. However, conventional operations (CO) such as fronto-orbital advancement and total skull reshaping have not been efficient enough to expand the intracranial volume in children with secondary craniosynostosis. Recently, distraction osteogenesis (DO) was reported to be effective in treating most craniosynostosis cases. Methods: We compared 9 children treated with DO and 3 children treated with CO who developed secondary craniosynostosis after shunt operation in early infancy. We measured the preoperative and follow-up head sizes with regard to head circumference, cephalometric intracranial volume, and intracranial volume estimated from the 3-dimensional computed tomogram. Results: The mean intracranial volumes expanded by 10.5% in the DO group 1 month after surgery and by 13.1% in the CO group on the immediate postoperative day. Further expansion was observed 6 months postoperatively, i.e. 10.3 and 4.7% in the DO and CO groups, respectively. Operation time and anesthesia time were significantly shorter in DO compared to CO patients, and the volumes of the blood transfusions were also less for DO patients. Conclusion: We suggest that DO is probably more efficient and safer than CO in expanding the intracranial volume in children with secondary craniosynostosis.
Cephalocele: Report of 55 Cases over 8 Years
Authors: Baradaran Nazanin , Nejat Farideh , Baradaran Nima , El Khashab Mostafa
Published: January 2010

Objective: Cephalocele is a central nervous system (CNS) birth defect. Various CNS and extra-CNS anomalies, as well as prognostic factors have been reported with cephalocele. The aim of this study was to discuss prognostic factors and current possible theories explaining associated anomalies seen in a series of 55 patients with cephalocele. Methods: A retrospective study was performed using the records of 55 children with cephalocele at the Children’s Hospital Medical Center in Tehran, Iran, from October 2000 through October 2008. Patients’ sex, age at the operation time, characteristics of the lesion including location, size, cerebrospinal fluid leakage, radiological assessments and intraoperative findings (sac contents), intracranial and extracranial associated anomalies, and the last situation of the children were reviewed. Conclusion: A genetic role can be proposed while a female predominance is seen in our results as well as in other reports. CNS and extra-CNS anomalies, as well as several genetic syndromes are not explicable as a causal consequence of cephalocele and the probability of a mere coincidence cannot be ruled out; therefore, we propose that the combination of these anomalies is rather a low-frequency association. Ventriculomegaly was the only poor prognostic determinant in our study, which can compel more severe neuroradiologic studies in such patients as a reasonable prognostic evaluation.