bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary study of duplications of the miRNA machinery in aphids associated with striking rate acceleration and changes in expression profiles
Authors: Ortiz-Rivas Benjamín , Jaubert-Possamai Stéphanie , Tanguy Sylvie , Gauthier Jean-Pierre , Tagu Denis , Claude Rispe
Published: November 2012

Background

The sequencing of the genome of the pea aphid Acyrthosiphon pisum revealed an unusual expansion of the miRNA machinery, with two argonaute-1, two dicer-1 and four pasha gene copies. In this report, we have undertaken a deeper evolutionary analysis of the phylogenetic timing of these gene duplications and of the associated selective pressures by sequencing the two copies of ago-1 and dcr-1 in different aphid species of the subfamily Aphidinae. We have also carried out an analysis of the expression of both copies of ago-1 and dcr-1 by semi-quantitative PCR in different morphs of the pea aphid life cycle.

Results

The analysis has shown that the duplication of ago-1 occurred in an ancestor of the subfamily Aphidinae while the duplication of dcr-1 appears to be more recent. Besides, it has confirmed a pattern of one conserved copy and one accelerated copy for both genes, and has revealed the action of positive selection on several regions of the fast-evolving ago-1b. On the other hand, the semi-quantitative PCR experiments have revealed a differential expression of these genes between the morphs of the parthenogenetic and the sexual phases of Acyrthosiphon pisum.

Conclusions

The discovery of these gene duplications in the miRNA machinery of aphids opens new perspectives of research about the regulation of gene expression in these insects. Accelerated evolution, positive selection and differential expression affecting some of the copies of these genes suggests the possibility of a neofunctionalization of these duplicates, which might play a role in the display of the striking phenotypic plasticity of aphids.
An ancient history of gene duplications, fusions and losses in the evolution of APOBEC3 mutators in mammals
Authors: Münk Carsten , Willemsen Anouk , Bravo Ignacio G
Published: November 2012

Background

The APOBEC3 (A3) genes play a key role in innate antiviral defense in mammals by introducing directed mutations in the DNA. The human genome encodes for seven A3 genes, with multiple splice alternatives. Different A3 proteins display different substrate specificity, but the very basic question on how discerning self from non-self still remains unresolved. Further, the expression of A3 activity/ies shapes the way both viral and host genomes evolve.

Results

We present here a detailed temporal analysis of the origin and expansion of the A3 repertoire in mammals. Our data support an evolutionary scenario where the genome of the mammalian ancestor encoded for at least one ancestral A3 gene, and where the genome of the ancestor of placental mammals (and possibly of the ancestor of all mammals) already encoded for an A3Z1-A3Z2-A3Z3 arrangement. Duplication events of the A3 genes have occurred independently in different lineages: humans, cats and horses. In all of them, gene duplication has resulted in changes in enzyme activity and/or substrate specificity, in a paradigmatic example of convergent adaptive evolution at the genomic level. Finally, our results show that evolutionary rates for the three A3Z1, A3Z2 and A3Z3 motifs have significantly decreased in the last 100 Mya. The analysis constitutes a textbook example of the evolution of a gene locus by duplication and sub/neofunctionalization in the context of virus-host arms race.

Conclusions

Our results provide a time framework for identifying ancestral and derived genomic arrangements in the APOBEC loci, and to date the expansion of this gene family for different lineages through time, as a response to changes in viral/retroviral/retrotransposon pressure.
Traffic steering by self-tuning controllers in enterprise LTE femtocells
Authors: Ruiz-Avilés Jose Maria , Luna-Ramírez Salvador , Toril Matias , Ruiz Fernando
Published: November 2012

Femtocells have been suggested as a promising solution for the provision of indoor coverage and capacity. This article investigates the problem of re-distributing traffic demand between long-term evolution (LTE) femtocells with open access in an enterprise scenario. Several traffic sharing algorithms based on automatic tuning of femtocell parameters are considered. The proposed algorithms are implemented by fuzzy logic controllers. Performance assessment is carried out in a dynamic system-level simulator. Results show that localized congestion problems in these scenarios can be solved without impairing connection quality by jointly tuning handover margins and cell transmit power.
A phenyl-thiadiazolylidene-amine derivative ejects zinc from retroviral nucleocapsid zinc fingers and inactivates HIV virions
Authors: Vercruysse Thomas , Basta Beata , Dehaen Wim , Humbert Nicolas , Balzarini Jan , Debaene François , Sanglier-Cianférani Sarah , Pannecouque Christophe , Mély Yves , Daelemans Dirk
Published: November 2012

Background

Sexual acquisition of the human immunodeficiency virus (HIV) through mucosal transmission may be prevented by using topically applied agents that block HIV transmission from one individual to another. Therefore, virucidal agents that inactivate HIV virions may be used as a component in topical microbicides.

Results

Here, we have identified 2-methyl-3-phenyl-2H-[1,2,4]thiadiazol-5-ylideneamine (WDO-217) as a low-molecular-weight molecule that inactivates HIV particles. Both HIV-1 and HIV-2 virions pretreated with this compound were unable to infect permissive cells. Moreover, WDO-217 was able to inhibit infections of a wide spectrum of wild-type and drug-resistant HIV-1, including clinical isolates, HIV-2 and SIV strains. Whereas the capture of virus by DC-SIGN was unaffected by the compound, it efficiently prevented the transmission of DC-SIGN-captured virus to CD4+ T-lymphocytes. Interestingly, exposure of virions to WDO-217 reduced the amount of virion-associated genomic RNA as measured by real-time RT-qPCR. Further mechanism-of-action studies demonstrated that WDO-217 efficiently ejects zinc from the zinc fingers of the retroviral nucleocapsid protein NCp7 and inhibits the cTAR destabilization properties of this protein. Importantly, WDO-217 was able to eject zinc from both zinc fingers, even when NCp7 was bound to oligonucleotides, while no covalent interaction between NCp7 and WDO-217 could be observed.

Conclusion

This compound is a new lead structure that can be used for the development of a new series of NCp7 zinc ejectors as candidate topical microbicide agents.
Mechanical factors play an important role in pectus excavatum with thoracic scoliosis
Authors: Wang Yuncang , Chen Gang , Xie Liang , Tang Jiming , Ben Xiaosong , Zhang Dongkun , Xiao Pu , Zhou Haiyu , Zhou Zihao , Ye Xiong
Published: November 2012

Background

This study investigated the incidence, imaging characteristics and mechanical factors in scoliotic patients with pectus excavatum.

Methods

A total of 142 scoliostic patients with pectus excavatum were evaluated prior to operation. The evaluation included a complete physical exam, phenotype and severity of the pectus excavatum, incidence and severity of scoliosis, and analysis of radiological images, including calculation of the Haller index.

Results

Twenty five out of 142 patients (17.61%) with pectus excavatum had scoliosis with a Cobb angle >10 degrees, and in 80.00% of the cases the spinal column was bent to the right. Seventeen patients had bent-to-the-right spines that involved the 6th to 10 th thoracic vertebrae. We found that 23 out of 25 patients with a Cobb angle more than 10° were teenagers and adults. The incidence of scoliosis was only 6.06% in the children under 11 years whereas it was 21.79% in the teenage group.

Conclusions

Mechanical forces appear to play a role in the coexistence of pectus excavatum and scoliosis. There is a relationship between age, severity (Haller index), asymmetry and scoliosis. The heart and mediastinum play a role in providing an outward force to the left of the sternum which may be an important reason for the coexistence of pectus excavatum and scoliosis, but the correlation needs further proof.
Relaxation Exchange in Nanoporous Silica by Low-Field NMR
Authors: Paciok Eva , Haber Agnes , Van Landeghem Maxime , Blümich Bernhard
Published: November 2012

Investigating the 2D-T
2-T
2-relaxation exchange of inter-stitial water in a packing of sedimented Stöber-silicate spheres, we come the conclusion that contrary to its behaviour in macro-pores, water confined in nano-pores of silica exhibits enhanced diffusivity. The 2D-experiments, performed at different temperatures, reveal a temperature-dependent bimodal relaxation distribution and two-site relaxation exchange. Our recently introduced kinetic multi-site exchange model is applied to derive the according exchange rates. The resulting Arrhenius plot produces an exchange activation energy of 7 kJ/mol, which is well below the hydrogen bond energy or the activation energy for self-diffusion of water in the bulk. A possible hopping-mechanism as the source of enhanced proton-diffusion in nanoporous silica is discussed, as well as its significance to mass transfer in porous media.
Safe water, household income and health challenges in Ugandan homes that harvest rainwater
Authors: Baguma David , Hashim Jamal H. , Aljunid Syed M. , Hauser Michael , Jung Helmut , Loiskandl Willibald
Published: November 2012

Having access to a safe water supply is important to improve a person's quality of life. We examine the relationship between the influence of water availability on monthly household expenditures (the dependent variable) and independent variables such as household characteristics, tank size, usage instructions and post-construction guidance, including the management of water-related health risks. The sample consisted of 301 respondents who harvest rainwater in Uganda. A multiple regression analysis was used to analyse the data. The findings show that post-construction guidance and tank size were significant variables. This study suggests the need for a follow-up to improve health after the installation of water supply equipment, i.e., to provide information about water risks, foster reading norms and facilitate the availability and affordability of information sources, e.g., subsidised newspapers and information support devices (computers). Additionally, this study shows the possibility of increased savings due to reduced expenditures on water from vendors and the management of water-related health risks caused by a water shortage, e.g., dehydration. Overall, the study reveals two possible ways to advance policy and health in developing countries: (1) ensuring sufficient post-construction guidance for all water resources; and (2) ensuring a sustainable supply of adequate safe water in households.
Return of drinking water supply in Paris to public control
Authors: Barraqué Bernard
Published: November 2012

The ‘reclaiming’ by Paris of its water back into public hands is a paradox in the homeland of transnational water companies and at a time when the European Commission rather favours the liberalisation of public services ‘of general economic interest’. Yet what has happened is more complex. A quick historical review of management formulas in Europe reveals both the specific model of delegation to private companies made in France, and also the maintained direct labour management formula (with direct public procurement by municipalities) used in several French cities to be presented. Paris has a long history of public procurement of water, whilst using a private company for metering and billing customers. Mayor Chirac changed to a semi-public company with public production and private distribution contracted out to two private companies (with responsibility for the right and left banks). Mayor Delanoë managed to reclaim the distribution in a commercial but public institution called an Établissement Public à caractère Industriel et Commercial (EPIC); this had unsuspected impacts on water supply issue in the suburbs. While Paris can obviously run its services directly, the emerging issue appears to be multi-level governance at the metropolitan level, rather than just a public–private debate. This paper also discusses in detail the arguments put forward by Anne le Strat, Deputy Mayor for Water, in favour of returning to public control, and presents the difficulties of assessing the performance of a service operator, under both delegation and direct management.
Key issues and trends in the water policy literature
Authors: Chenoweth Jonathan
Published: November 2012

Content analysis of 2 complete years of articles published in the journal Water Policy show that a wide spread of issues dominate the policy analysis discourse, with citations of the articles being spread across the thematic issues published. Few articles in the journal were particularly technical in nature but rather the journal has tended to publish articles which are more directly linked to water policy. Articles related broadly to institutional and regulatory reform were numerically the most significant in terms of the published content of the journal. Examination of the short-term citation rate of articles published did not show a significant bias towards any thematic issue covered by the journal, suggesting broad interest in the wide range of topics relating to water policy issues.
Dynamics of irrigation management and interlinked agrarian relations: empirical findings from a canal irrigation command in Odisha, India
Authors: Mahapatra Sushanta Kumar
Published: November 2012

The literature on the dynamics of irrigation management, in terms of the analysis of interlinked agrarian relations, is very limited. This paper attempts to get a detailed grassroots view of farmers' knowledge of various issues pertaining to the relationship between agrarian structure, land and water. Data from 200 sample cultivators of different farm sizes and 20 landless labour households were collected from eight sample villages situated in head-reach and tail-end distributaries of branch canals in selected Hirakud irrigation commands in Odisha, India. An analysis of the nature of the interlinking of various agrarian markets in the studied distributaries showed that interlinked credit transactions are mostly prevalent among landless labour and small farm households. To some extent, they are higher in head-reach distributaries compared to tail-end distributaries. Research showed that the incidence of tenancy in the head-reach areas is also higher than the tail-end. There is a need for the adequacy, timeliness and reliability of water supply, and for equality in water distribution between head- and tail-reaches.
Free water for all the world's poor? A review of the strategy of South Africa's free basic water policy
Authors: Smith Julie
Published: November 2012

In 2001 South Africa introduced a social policy to provide all citizens, but particularly the poor, with a monthly supply of limited volumes of free water. Although criticised by international agencies at the time, lifeline tariffs to the poor are now promoted as a strategy to meet the Millennium Development Goals. Much of free basic water's contemporary allure lies in its ostensible artifice in offering water security to poor citizens whilst simultaneously strengthening the municipal cost-recovery regime. Past attempts at unravelling what has become something of a social policy allegory were hindered by the absence of a state voice in this intriguing narrative. A legal challenge launched by poor Soweto, Johannesburg citizens has enabled the public to have access to state affidavits. These primary data, together with improved positioning of free water literature within a broader scope of municipal water systems (rights, volumes and tariff structures), socio-political paradigms and a more rigorous interrogation of previously uncontested international standards and ideological ‘neutral’ discourses provide a more comprehensive chronicle of the complex free water narratives. As such, the offering of free water, far from being a benign concession, was used to contain very poor households to limited volumes of water beneath what they required whilst ensuring that the majority of still poor households, who consumed beyond the free volumes, paid the full cost of the water service.
Duloxetine in Affective Disorders: a Naturalistic Study on Psychiatric and Medical Comorbidity, Use in Association and Tolerability Across Different Age Groups
Authors: Dell’Osso Bernardo , Camuri Giulia , Dobrea Cristina , Buoli Massimiliano , Serati Marta , Carlo Altamura A
Published: November 2012

Objective:

Duloxetine, a selective serotonin and norepinephrine reuptake inhibitor (SNRI), is currently approved in many countries for the treatment of Major Depressive Disorder (MDD) and Generalized Anxiety Disorder (GAD). The present naturalistic study was aimed to investigate tolerability of Duloxetine in a sample of patients with affective disorders and psychiatric/medical comorbidity, comparing tolerability in monotherapy versus polytherapy and across different age groups.

Methods:

The sample included 165 patients, affected by anxiety and/or mood disorders with or without comorbidity, who had been taken Duloxetine for at least 1 month. Sample variables were collected through a retrospective chart review.

Results:

Most common primary diagnoses were MDD (49.1 %), Bipolar Disorder (BD) (15.7 %) and GAD (5.5%). The 40 % of the sample had psychiatric comorbidity: in particular, anxiety disorders (15.8 %) (GAD 7.9%, Panic Disorder –PD- 7.3%) and personality disorders (9.1%) as the most frequent ones. With respect to medical comorbidities (68% of the sample), hypertension (12.1%) and diabetes (7.3%) were the most common ones. Mean duration of treatment and dosage of Duloxetine were, respectively, 11 months (± 9.1) and 70 mg/day (± 28.6). The 68 % of the sample received Duloxetine in association with other drugs. Minor side-effects, in particular drowsiness and gastrointestinal problems, were reported by 15 % of the sample. No difference in terms of tolerability across distinct groups, divided on the basis of mono- vs polytherapy as well as of different age, was found.

Conclusion:

Duloxetine, mostly administered in patients with affective disorders with psychiatric/ medical comorbidity and in association with other drugs, appeared to be well tolerated, showing limited rates of side effects of mild intensity. Further naturalistic studies are warranted to confirm present results.
Objective Measures of Behavior Manifestations in Adult ADHD and Differentiation from Participants with Bipolar II Disorder, Borderline Personality Disorder, Participants with Disconfirmed ADHD as Well as Normative Participants
Authors: Edebol Hanna , Helldin Lars , Norlander Torsten
Published: November 2012

Background:

The present study evaluated two psychometric instruments derived from the objective measurement of adult ADHD using the Quantified Behavior Test Plus. The instruments were examined in ADHD versus a clinical group with overlapping symptoms including borderline personality disorder and bipolar II disorder, and another clinical group with participants assessed for but disconfirmed a diagnosis of ADHD as well as adult normative participants.

Methods:

The Quantified Behavior Test Plus includes Continuous Performance Testing and a Motion Tracking System with parameters related to attention and activity operationalized as the cardinal symptoms of ADHD and then summarized into a Weighed Core Symptoms scale with ten cut-points ranging from 0 to 100. A categorical predictor variable called Prediction of ADHD was used to examine the levels of sensitivity and specificity for the Quantified Behavior Test Plus with regard to ADHD.

Results:

The Weighed Core Symptoms scale separated ADHD and normative participants from each other as well as from the two clinical reference groups. The scale reported highest levels of core symptoms in the ADHD group and the lowest level of core symptoms in the normative group. Analyses with Prediction of ADHD yielded 85 % specificity for the normative group, 87 % sensitivity for the ADHD group, 36 % sensitivity for the bipolar II and borderline group and 41 % sensitivity for the group with a disconfirmed diagnosis of ADHD.

Conclusions:

The Weighed Core Symptoms scale facilitated objective assessment of adult ADHD insofar that the ADHD group presented more core symptoms than the other two clinical groups and the normative group. Sensitivity for the Quantified Behavior Test Plus was lower in complex clinical groups with Bipolar II disorder, Borderline disorder and in patients with a disconfirmed diagnosis of ADHD. The psychometric instruments may be further evaluated with regard to well-documented and effective treatment programs for ADHD core symptoms.
Determining Bone Bruises of the Knee with Magnetic Resonance Imaging
Authors: Uçar Bekir Yavuz , Necmioğlu Serdar , Bulut Mehmet , Azboy İbrahim , Demirtaş Abdullah , Gümüş Hatice
Published: November 2012

Introduction

Injuries that develop secondary to minor traumas and cannot be detected via direct examination methods, but are detected via advanced imaging methods, such as magnetic resonance (MR) imaging, are called occult bone injuries or bone bruises. In such injuries, diagnostic arthroscopy usually does not reveal any pathology. MR imaging methods are quite beneficial for the diagnosis of such clinical conditions, which cause acute pain and restriction of motion. The present study aimed to assess occult bone injuries via MR imaging in patients who presented with minor knee trauma.

Patients and Methods

Twelve patients who presented with minor knee trauma were included in the study. Etiological factors in these patients included walking a long distance, falls, and minor trauma. All patients underwent physical examinations, direct radiological imaging, MR imaging, and diagnostic arthroscopy.

Results

Direct radiographs of the patients showed no pathological fracture. Bone marrow changes detected on the MR images were classified according to Lynch’s classification as Type I lesions in nine patients and Type II lesions in three patients.

Conclusion

We suggest that MR imaging methods should be the gold standard for the diagnosis of minor traumatic bruise injuries of the knee.
Unilateral Lumbosacral Dislocation: Case Report and a Comprehensive Review
Authors: Grivas Theodoros B , Papadakis Stamatios A , Katsiva Vassiliki , Koufopoulos George , Mouzakis Vassilios
Published: November 2012

Lumbosacral fracture-dislocation is a rare occurrence. There are more than 73 cases reported in the English literature. We report on the imaging findings and surgical treatment in a patient suffered of unilateral traumatic L5-S1 dislocation associated with severe disruption of the posterior ligamentous complex. The patient underwent open reduction and stabilization of L4-S1 vertebrae with posterior instrumentation system. Open reduction and internal fixation was mandatory as post-traumatic ligamentous insufficiency would lead to abnormal motion. Operative treatment managed to produce a solid arthrodesis and restore stability of the lumbosacral junction. Follow-up revealed excellent results. This study reports a rare injury of the lumbosacral junction, and the literature concerning this unusual condition is extensively reviewed.
Two-point boundary value problems for the generalized Bagley-Torvik fractional differential equation
Authors: Staněk Svatoslav
Published: November 2012

We investigate the fractional differential equation u″ + A c D α u = f(t, u, c D μ u, u′) subject to the boundary conditions u′(0) = 0, u(T)+au′(T) = 0. Here α ∈ (1, 2), µ ∈ (0, 1), f is a Carathéodory function and c D is the Caputo fractional derivative. Existence and uniqueness results for the problem are given. The existence results are proved by the nonlinear Leray-Schauder alternative. We discuss the existence of positive and negative solutions to the problem and properties of their derivatives.
"A Denial of Our Boasted Civilisation
Authors: Cox Peter
Published: November 2012

In the interwar period, cyclists, the most numerous road users, came into increasing conflict with motorists. The debate around road safety and casualties reveals significant differences between the social and political capital available to different classes of road users, despite their legal equality. Drawing on the coverage of the conflict by the Cyclists' Touring Club (CTC) through their monthly Gazette and on the parliamentary record, this article examines how cyclists understood the problem of increasing accident rates and the solutions proffered in press and parliament to address them. The paper considers cyclists in terms of class, representation, power, and status. It further examines how these factors shaped perceptions of the issues at stake in the safety debate in relation to the governance of road space and the appropriate behaviors and responsibilities of road users.
In Defence of Ballet: Women, Agency and the Philosophy of Pleasure
Authors: Kolb Alexandra , Kalogeropoulou Sophia
Published: November 2012

This article offers a novel approach to conceptualising ballet practice as a leisurely activity that exudes pleasure. It argues that the notion of pleasure in ballet has been neglected in scholarly research which criticises ballet for its negative impact on the physical and mental health of dancers, its authoritarian teaching methods and its trivial aesthetic that objectifies the female body and perpetuates the construction of stereotypical gender roles within a patriarchal society. This study focuses on the lived experiences of female amateur ballet participants, emphasising their agency. It provides first-hand accounts to illuminate the significance of ballet in women dancers’ personal growth, development and psychological wellbeing, drawing on sociologist Roger Caillois's categorisation of pleasures involved in games and play. Overall, the article highlights the multiple types of pleasure associated with ballet dancing as a key motivational factor and rationale for participation.
Functional Aspects of PARP1 in DNA Repair and Transcription
Authors: Ko Hui Ling , Ren Ee Chee
Published: November 2012

Poly (ADP-ribose) polymerase 1 (PARP1) is an ADP-ribosylating enzyme essential for initiating various forms of DNA repair. Inhibiting its enzyme activity with small molecules thus achieves synthetic lethality by preventing unwanted DNA repair in the treatment of cancers. Through enzyme-dependent chromatin remodeling and enzyme-independent motif recognition, PARP1 also plays important roles in regulating gene expression. Besides presenting current findings on how each process is individually controlled by PARP1, we shall discuss how transcription and DNA repair are so intricately linked that disturbance by PARP1 enzymatic inhibition, enzyme hyperactivation in diseases, and viral replication can favor one function while suppressing the other.
Nucleus Accumbens Volume Is Associated with Frequency of Alcohol Use among Juvenile Justice-Involved Adolescents
Authors: Thayer Rachel E. , Crotwell Shirley M. , Callahan Tiffany J. , Hutchison Kent E. , Bryan Angela D.
Published: November 2012

Differential neural development of structures associated with reward and control systems may underlie risky behavior in adolescence. The nucleus accumbens and orbitofrontal cortex (OFC) have been implicated in substance use behavior, although structural studies have yet to explore specific relationships between nucleus accumbens and OFC volumes and alcohol use in adolescence. High resolution structural MRI scans and assessments of recent alcohol use and lifetime substance use were collected in a sample of 168 juvenile justice-involved adolescents to explore whether gray matter volumes were associated with past 3-month quantity and frequency of alcohol use. Gray matter volumes were not associated with average quantity of alcohol use. Accumbens volume was positively associated with past 3-month frequency of drinking, and OFC volume was negatively associated with drinking frequency. Results may suggest that structural differences in regions related to reward and control processing may contribute to risk behavior in adolescence.
Mesenchymal Stem or Stromal Cells from Amnion and Umbilical Cord Tissue and Their Potential for Clinical Applications
Authors: Lindenmair Andrea , Hatlapatka Tim , Kollwig Gregor , Hennerbichler Simone , Gabriel Christian , Wolbank Susanne , Redl Heinz , Kasper Cornelia
Published: November 2012

Mesenchymal stem or stromal cells (MSC) have proven to offer great promise for cell-based therapies and tissue engineering applications, as these cells are capable of extensive self-renewal and display a multilineage differentiation potential. Furthermore, MSC were shown to exhibit immunomodulatory properties and display supportive functions through parakrine effects. Besides bone marrow (BM), still today the most common source of MSC, these cells were found to be present in a variety of postnatal and extraembryonic tissues and organs as well as in a large variety of fetal tissues. Over the last decade, the human umbilical cord and human amnion have been found to be a rich and valuable source of MSC that is bio-equivalent to BM-MSC. Since these tissues are discarded after birth, the cells are easily accessible without ethical concerns.
Violation of the Third Law of Black Hole Thermodynamics inHigher Curvature Gravity
Authors: Torii Takashi
Published: November 2012

We examine the weak version of the third law of black hole thermodynamics inthe n-dimensional Einstein–Gauss–Bonnet system with a negative cosmological constant.To see whether the extreme black hole solution with zero temperature is formed, weinvestigate the motion of the thin shell that has the equal mass to the extreme black holein the background described by the non-GR branch solutions. The interior of the shell isempty. Our analysis using the generalized Israel's junction condition shows that the shellcan contract beyond a certain radius and the degenerate horizon is formed for same range ofparameters. Hence, this model can be a counterexample of the third law.
Viscosity in Modified Gravity
Authors: Brevik Iver
Published: November 2012

A bulk viscosity is introduced in the formalism of modified gravity. It is shownthat, based on a natural scaling law for the viscosity, a simple solution can be found forquantities such as the Hubble parameter and the energy density. These solutions mayincorporate a viscosity-induced Big Rip singularity. By introducing a phase transition inthe cosmic fluid, the future singularity can nevertheless in principle be avoided.
A Site-Specific Index Based on Weathering Forms Visible in Central Oxford, UK
Authors: Thornbush Mary J.
Published: November 2012

The authenticity of much of the stone-work along Queen’s Lane in central Oxford, UK presented an opportunity to produce a photographic survey from which a weathering index could be established. This represents a site-specific approach to devising a weathering form. Because it is photo-based, weathering forms are visible for comparison and classification purposes across disciplines. Limestone pertaining to building ashlar and plinths along this roadway, which mainly belong to Queen’s College, St Edmund Hall, New College, and Hertford College, was classified according to this newly introduced weathering index, the size-extent (S-E) index, through consideration of type, size, extent, impact, and trigger. This size- (range) and extent-based classification system enables for the assessment of weathering forms of various types, including soiling and decay features as well as those potentially expected in the presence of vegetation and animals. Weathering forms of a range of sizes were present, with a slightly greater abundance of small types (mm-cm in the micro- to mesoscale) and more discrete types with a low extent. For this location in central Oxford, chemical weathering was found to be the predominant type of soiling and decay.
Role of Btg2 in the Progression of a PDGF-Induced Oligodendroglioma Model
Authors: Appolloni Irene , Curreli Sebastiano , Caviglia Sara , Barilari Manuela , Gambini Eleonora , Pagano Aldo , Malatesta Paolo
Published: November 2012

Tumor progression is a key aspect in oncology. Not even the overexpression of a powerful oncogenic stimulus such as platelet derived growth factor-B (PDGF-B) is sufficient per se to confer full malignancy to cells. In previous studies we showed that neural progenitors overexpressing PDGF-B need to undergo progression to acquire the capability to give rise to secondary tumor following transplant. By comparing the expression profile of PDGF-expressing cells before and after progression, we found that progressed tumors consistently downregulate the expression of the antiproliferative gene Btg2. We therefore tested whether the downregulation of Btg2 is sufficient and necessary for glioma progression with loss and gain of function experiments. Our results show that downregulation of Btg2 is not sufficient but is necessary for tumor progression since the re-introduction of Btg2 in fully progressed tumors dramatically impairs their gliomagenic potential. These results suggest an important role of Btg2 in glioma progression. Accordingly with this view, the analysis of public datasets of human gliomas showed that reduced level of Btg2 expression correlates with a significantly worse prognosis.
Dual Bioactivities of Essential Oil Extracted from the Leaves of Artemisia argyi as an Antimelanogenic versus Antioxidant Agent and Chemical Composition Analysis by GC/MS
Authors: Huang Huey-Chun , Wang Hsiao-Fen , Yih Kuang-Hway , Chang Long-Zen , Chang Tsong-Min
Published: November 2012

The study was aimed at investigating the antimelanogenic and antioxidant properties of essential oil when extracted from the leaves of Artemisia argyi, then analyzing the chemical composition of the essential oil. The inhibitory effect of the essential oil on melanogenesis was evaluated by a mushroom tyrosinase activity assay and B16F10 melanoma cell model. The antioxidant capacity of the essential oil was assayed by spectrophotometric analysis, and the volatile chemical composition of the essential oil was analyzed with gas chromatography-mass spectrometry (GC/MS). The results revealed that the essential oil significantly inhibits mushroom tyrosinase activity (IC50 = 19.16 mg/mL), down-regulates B16F10 intracellular tyrosinase activity and decreases the amount of melanin content in a dose-dependent pattern. Furthermore, the essential oil significantly scavenged 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid) ABTS radicals, showed an apparent reduction power as compared with metal-ion chelating activities. The chemicals constituents in the essential oil are ether (23.66%), alcohols (16.72%), sesquiterpenes (15.21%), esters (11.78%), monoterpenes (11.63%), ketones (6.09%), aromatic compounds (5.01%), and account for a 90.10% analysis of its chemical composition. It is predicted that eucalyptol and the other constituents, except for alcohols, in the essential oil may contribute to its antioxidant activities. The results indicated that essential oil extracted from A. argyi leaves decreased melanin production in B16F10 cells and showed potent antioxidant activity. The essential oil can thereby be applied as an inhibitor of melanogenesis and could also act as a natural antioxidant in skin care products.
New Triterpenes from Maytenus robusta: Structural Elucidation Based on NMR Experimental Data and Theoretical Calculations
Authors: Sousa Grasiely , Duarte Lucienir , Alcântara Antônio , Silva Grácia , Vieira-Filho Sidney , Silva Roqueline , Oliveira Djalma , Takahashi Jacqueline
Published: November 2012

Leaves of Maytenus robusta (Celastraceae) were subjected to phytochemical investigation mainly directed at the isolation of pentacyclic triterpenes. The compounds friedelin (1), β-friedelinol (2), 3-oxo-21β-H-hop-22(29)-ene (7), 3,4-seco-friedelan-3,11β-olide (8), 3β-hydroxy-21β-H-hop-22(29)-ene (9), 3,4-seco-21β-H-hop-22(29)-en-3-oic acid (10), 3,4-seco-friedelan-3-oic acid (11), and sitosterol were identified in the hexane extract of M. robusta leaves. Compounds 8 and 9 are described herein for the first time. The structure and stereochemistry of both compounds were experimentally established by IR, HRLC-MS, and 1D (1H, 13C, and DEPT 135) and 2D (HSQC, HMBC and COSY) NMR data and supported by correlations with carbon chemical shifts calculated using the DFT method (BLYP/6-31G* level). Compounds 7 and 10 are also described for the first time, and their chemical structures were established by comparison with NMR data of similar structures described in the literature and correlations with BLYP/6-31G* calculated carbon chemical shifts. Compound 9, a mixture of 11 and sitosterol, and 3β,11β-dihydroxyfriedelane (4) were evaluated by the Ellman’s method and all these compounds showed acethylcholinesterase inhibitory properties.
N-Heterocyclic carbene–palladium(II)-1-methylimidazole complex catalyzed Mizoroki–Heck reaction of aryl chlorides with styrenes
Authors: Gao Ting-Ting , Jin Ai-Ping , Shao Li-Xiong
Published: November 2012

A well-defined N-heterocyclic carbene–palladium(II)-1-methylimidazole [NHC-Pd(II)-Im] complex 1 was found to be an effective catalyst for the Mizoroki–Heck reaction of a variety of aryl chlorides with styrenes. Both activated and deactivated aryl chlorides work well to give the corresponding coupling products in good to excellent yields by using tetrabutylammonium bromide (TBAB) as the ionic liquid.
Agency and Identity in Social Media
Authors: Code Jillianne
Published: November 2012

Social and group interactions in online and virtual communities develop and evolve from expressions of human agency. The exploration of the emergence of agency in social situations is of critical importance to understanding the psychology of agency and group interactions in social media. The purpose of this chapter is to explore the prevalence of agency in existing research in educational psychology relative to its potential impact on the bourgeoning field of identity in social media. Published articles from leading theorists in identity theory, agency, life course studies, and educational psychology provide a framework in which agentic behavior and digital identity formation in social media can be studied. Through an examination of Bandura’s Social Cognitive Theory of Agency (Bandura, 1989, 2000, 2006), this chapter identifies and discusses agentic behavior evident in social media and its potential impacts for research and practice.
A Sociocultural Perspective on Negotiating Digital Identities in a Community of Learners
Authors: Peachey Anna , Withnail Greg
Published: November 2012

Three dimensional virtual world environments are becoming an increasingly regular feature of the education landscape, providing the opportunity for richly graphical augmented and immersive learning activities. Those who participate in these experiences must mediate through an avatar, negotiating and managing the complexities of this new variation of digital identity alongside their more familiar identity as learner and/or teacher/facilitator. This chapter describes some key moments in the construction of digital identities as a lecturer and a student in the Open University’s community in Second LifeTM. The authors explore experiences in relation to the impact of trust and consistency from a sociocultural perspective, privileging the role of social interaction and context where meaning is socially produced and situationally interpreted, concluding that social interaction is pivotal to any meaningful identity development that takes place. The chapter ends with thoughts for future issues surrounding digital identity in relation to lifelong learning.
Multi-Dimensional Factors Impacting on E-Government Adoption in Botswana, Mozambique, and Malawi
Authors: Bwalya Kelvin Joseph , Du Plessis Tanya , Rensleigh Chris
Published: November 2012

With widespread adoption of ICT usage in public service delivery platforms (e-Government) throughout the world, African countries have vowed not to be left behind in this marathon. Robust e-Government adoption depends on the strategy employed to implement it. This paper presents the different initiatives that have been employed to promote e-Government development and development in Botswana, Mozambique and Malawi thereby showing the impact of such initiatives on overall e-Government agenda. Using extensive document and literature reviews, this paper further intends to investigate the status of e-Government implementation in these three countries and understand the multi-dimensional factors that dictate adoption and use of e-Government services. The paper has found that deliberate fiscal ICT policies, trust of e-applications, availability of ICT infrastructures such as appropriate mobile phone and base stations technology, usability of ICT platforms, and relevant ICT skills of ordinary citizens have a lasting positive impact on people’s intention to engage in e-Government.
Determinants of E-Banking Among Bruneian Corporate Customers
Authors: Seyal Afzaal H.
Published: November 2012

E-banking has become a new way of doing business and an important alternative for many banks and their customers. The acceptance of e-banking is affected by several factors, including the personal attitude of the users that influences normality and the context in which it is used. This study examines 150 customers of four major banks in Brunei Darussalam to explore the behavioral intent of the corporate customers toward e-banking through their attitudes. The Theory of Planned Behavior (TPB) is used as a reference framework to understand the intention toward using e-banking. The data is analyzed using PLS smart graph; analysis suggests that customers’ attitudes toward e-banking are a significant predictor of behavioral intention, whereas subjective norms and perceived behavioral control are insignificant. The causal link between perceived behavioral control and behavior (use of e-banking) is also insignificant. However, use of e-banking is further supported by the behavioral intention. The implications of these findings are discussed and conclusions are drawn.
Preventing Social Engineering and Espionage in Collaborative Knowledge Management Systems (KMSs)
Authors: Ogunseye Oluwafemi S. , Folorunso Olusegun , Zhang Jeff
Published: November 2012

Insider attack and espionage on computer-based information is a major problem for business organizations and governments. Knowledge Management Systems (KMSs) are not exempt from this threat. Prior research presented the Congenial Access Control Model (CAC), a relationship-based access control model, as a better access control method for KMS because it reduces the adverse effect of stringent security measures on the usability of KMSs. However, the CAC model, like other models, e.g., Role Based Access Control (RBAC), Time-Based Access Control (TBAC), and History Based Access Control (HBAC), does not provide adequate protection against privilege abuse by authorized users that can lead to industrial espionage. In this paper, the authors provide an Espionage Prevention Model (EP) that uses Semantic web-based annotations on knowledge assets to store relevant information and compares it to the Friend-Of-A-Friend (FOAF) data of the potential recipient of the resource. It can serve as an additional layer to previous access control models, preferably the Congenial Access Control (CAC) model.
Use of Virtual Classrooms in Online Learning Environments
Authors: Gümüs Salih , Okur M. Recep
Published: November 2012

With the help of enhancements in communication technologies, especially within the framework of opportunities provided by the internet, learning can be done both in traditional environments and online environments. Besides numerical content, online learning content has the ability to offer multiple learning tools together. The one which steps forward among these tools for providing communication and interaction is virtual classroom applications. In this study, virtual classroom structure in online learning environments is examined. Within the framework of the study, academic personnel who have experience with distance education and who have given courses in virtual classroom application are defined. In order to gain detailed information, research is designed qualitatively. After the data is analyzed, suggestions are provided by reporting the research. Action research design of qualitative methods is used in this study.
Understanding the Continued Usage Intention of Educators toward an e-Learning System
Authors: Islam A.K.M. Najmul
Published: November 2012

The tremendous development of technologies over recent decades has offered many e-learning systems to faculty educators to support teaching. The advantage of using such systems in connection with on-site courses is that it increases flexibility in teaching/learning by making resources available online. However, there is little empirical evidence to suggest which factors shape educators’ continuance intention to use such systems. This study builds a model, based on the Unified Theory of Acceptance and Use of Technology to identify the factors. The model was tested among university educators who use the popular e-learning system, Moodle. The results suggest that the continuance intention is driven by perceived usefulness and access. Perceived ease of use, perceived behavioral control, compatibility, and social influence do not have a significant direct impact on continuance intention, although perceived ease of use and compatibility significantly affect perceived usefulness. Taken together, the core determinants of the continuance intention explained around 70% of the total variance in intention in this study.
Interactive Self-Assessment Questions within a Virtual Environment
Authors: Evans Chris , Palacios Luis
Published: November 2012

This study considers the impact that different levels of interactivity have on the memory and understanding. In particular, it focuses in the use of interactive self-assessment questions (ISAQs) as a mechanism to help students learn better. An ISAQ is a computer-based multiple-choice or text-entry question that requires input from the learner, and provides feedback based on that input. This study extends some of Mayer’s (1990) multimedia design principles and considers their applicability in this context. The study also takes into account whether the incorporation of ISAQs has a measurable impact on learning as indicated by their performance in tests. The study considers three different types of ISAQs, designed to engage either memory or understanding, in an effort to determine which one is the most effective. It considers the effect of adding interactivity in the form of memory (retention) and understanding (transfer) self-assessment questions in a learning-object content management system used by undergraduate students at Brunel University in West London, UK. It was predicted that both types of ISAQ would increase the performance of learners in tests but with different degrees. The results indicate that transfer tests have a significant impact on retention.
Supporting Online Collaborative Mathematical Exploration
Authors: Roulet Geoffrey
Published: November 2012

Math-Towers is a collaborative mathematics environment for pupils in grades 7 to 9. Using a fantasy adventure game context, students are presented with a mathematical challenge, given online tools for working on the problem, and provided with a messaging system by which they may exchange ideas and partial solutions. This paper presents the philosophy behind the design of Math-Towers and, using a complexity science framework, explores the extent to which it has been successful in meeting goals. The technical and social problems encountered and revisions made to address these are also described.