bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing without concepts
Authors: Yermolayeva Yevdokiya , Rakison David H.
Published: June 2010

We evaluate the heterogeneity hypothesis by considering the developmental time course and the mechanism of acquisition of exemplars, prototypes, and theories. We argue that behavioral and modeling data point to a sequential emergence of these three types of concepts within a single system. This suggests that similar or identical underlying cognitive processes – rather than separate ones – underpin representation acquisition.
Network models of psychopathology and comorbidity: Philosophical and pragmatic considerations
Authors: Hood S. Brian , Lovett Benjamin J.
Published: June 2010

Cramer et al.'s account of comorbidity comes with a substantive philosophical view concerning the nature of psychological disorders. Although the network account is responsive to problems with extant approaches, it faces several practical and conceptual challenges of its own, especially in cases where the individual differences in network structures require the analysis of intra-individual time-series data.
Network origins of anxiety and depression
Authors: Hyland Michael E.
Published: June 2010

Cramer et al. contrast two possible explanations for psychological symptoms: latent variables (i.e., specific cause) versus a network of causality between symptoms. There is a third explanation: The reason for comorbidity and the reported network structure of psychological symptoms is that the underlying biological cause is a psychoneuroimmunoendocrine information network which, when dysregulated, leads to several maladaptive psychological and somatic symptoms.
The network perspective will help, but is comorbidity the question?
Authors: Johnson Wendy , Penke Lars
Published: June 2010

Latent variable modeling has revealed important conundrums in the DSM classification system. We agree that the network perspective has potential to inspire new insights and resolve some of these conundrums. We note, however, that alone it cannot really help us understand etiology. Etiology, not comorbidity, is the fundamental question.
Some mental disorders are based on networks, others on latent variables
Authors: Ross Don
Published: June 2010

Cramer et al. persuasively conceptualize major depressive disorder (MDD) and generalized anxiety disorder (GAD) as network disorders, rejecting latent variable accounts. But how does their radical picture generalize across the suite of mental and personality disorders? Addictions are Axis I disorders that may be better characterized by latent variables. Their comorbidity relationships could be captured by inserting them as nodes in a super-network of Axis I conditions.
Aligning psychological assessment with psychological science
Authors: Cervone Daniel
Published: June 2010

Network analysis is a promising step forward in efforts to align psychological assessment with explanatory theory in psychological science. The implications of Cramer et al.'s analysis are quite general. Networks analysis may illuminate functional relations not only among observable behaviors that comprise psychological disorders, but among cognitive and affective processes that causally contribute to everyday experience and action.
Extending the network perspective on comorbidity
Authors: Haig Brian D. , Vertue Frances M.
Published: June 2010

Cramer et al. make a good case for reconceptualizing comorbid psychopathologies in terms of complex network theory. We suggest the need for an extension of their network model to include reference to latent causes. We also draw attention to a neglected approach to theory appraisal that might usefully be incorporated into the methodology of network theory.
The abandonment of latent variables: Philosophical considerations
Authors: Zachar Peter
Published: June 2010

Cramer et al.'s critique of latent variables implicitly advocates a type of scientific anti-realism which can be extended to many dispositional constructs in scientific psychology. However, generalizing Cramer et al.'s network model in this way raises concerns about its applicability to psychopathology. The model could be improved by articulating why a given cluster of symptoms should be considered disordered.
Complex realities require complex theories: Refining and extending the network approach to mental disorders
Authors: Cramer Angélique O. J. , Waldorp Lourens J. , van der Maas Han L. J. , Borsboom Denny
Published: June 2010

The majority of commentators agree on one thing: Our network approach might be the prime candidate for offering a new perspective on the origins of mental disorders. In our response, we elaborate on refinements (e.g., cognitive and genetic levels) and extensions (e.g., to Axis II disorders) of the network model, as well as discuss ways to test its validity.
Extending influenza vaccination to individuals aged 50–64: A budget impact analysis
Authors: Cicchetti Americo , Ruggeri Matteo , Gitto Lara , Mennini Francesco Saverio
Published: June 2010

Objectives: Influenza (vernacular name, flu) is a viral infection that causes a high consumption of resources. Several studies have been carried out to provide an economic evaluation of the vaccination programs against influenza. Nevertheless, there is still a lack of evidence about the dynamic effects resulting from the reduction of the transmission power. This study considers the impact on contagiousness of alternative strategies against influenza in people aged 50–64 in Italy, France, Germany, and Spain.

Methods: By using the Influsim 2.0 dynamic model, we have determined the social benefits of different coverage levels in every country compared with the ones currently recommended. We have subsequently performed a Budget Impact Analysis to determine whether the currently recommended coverage results from an optimal budget allocation. A probabilistic sensitivity analysis was also conducted.

Results: We found that in Germany, the optimal coverage level is 38.5 percent, in France 32.4 percent, in Italy 32.75 percent, and 28.3 percent in Spain. By extending the coverage level, social saving tends to increase up to 100 percent for France and Italy and up to 80 percent for Germany and Spain.

Conclusions: Decision makers should allocate the budget for vaccination against influenza consistently with the estimation of the optimal coverage level and with the dynamic effects resulting from the reduction of the transmission power.
Economic evaluation, human immunodeficiency virus infection and screening: A review and critical appraisal of economic studies
Authors: Dibosa-Osadolor Onome , Roberts Tracy
Published: June 2010

Objectives:The aim of this study was to review, systematically and critically, evidence used to derive estimates of cost-effectiveness of human immunodeficiency virus (HIV) screening.

Methods:A systematic review was conducted.Searched werethree mainelectronic bibliographic databases from 1993 to 2008 using key words including HIV, mass screening, HAART, economic evaluation, cost-effectiveness analysis, modeling. We included studies of sexually transmitted HIV infection in both sexes, including studies comparing diagnostic testing protocols and partner notification. Outcomes included were cases of HIV infection detected, deterioration to the AIDS state, secondary transmission of HIV, the quality-adjusted life-years/survival, costs, and cost-effectiveness of HIV screening.

Results:Eighty-four papers were identified; ten of which were formal economic evaluations, one cost study, three effectiveness studies, and three systematic reviews of HIV prevention programs. The predominant assertion was that HIV screening is cost-effective; methodological problems, such as the preponderance of static models which are inappropriate for infectious diseases, varying perspectives from which the studies were analyzed, and arbitrary threshold incremental cost-effectiveness ratio levels, limited the validity of these findings, and their usefulness in informing health policy decisions.

Conclusions:The majority of published economic evaluations are based on inappropriate static models. This flaw renders the results of these studies as inconclusive and the purported cost-effectiveness of HIV screening debatable. The results of this review could form a basis for consideration of further research and analysis by health economists into the cost-effectiveness of HIV screening.
Integrating local data into hospital-based healthcare technology assessment: Two case studies
Authors: Mitchell Matthew D. , Williams Kendal , Brennan Patrick J. , Umscheid Craig A.
Published: June 2010

Objectives: Health technology assessment (HTA) programs influence practice on a broad scale through reimbursement decisions or national guidelines. Hospital-based HTA programs inform clinical decisions at the local level. Typically, they do this by adapting general HTA to their local setting, or by creating new HTA. However, unlike payer-based HTA organizations, hospital-based HTA organizations can also integrate local data into their reports.

Methods: We describe two examples of local data integrated into hospital-based HTA. In the first, qualitative data were used to select a new cardiac catheterization lab. In the second, quantitative data was used to inform a decision on whether to continue telemedicine services to critical care units. Local evidence sources included equipment service records, and interviews with physicians, technicians, and administrative staff in the first example, and the hospital's administrative and claims databases in the second example.

Results: In each case, there was little evidence from the peer-reviewed literature that could be applied to the decision. In the first example, staffing patterns and local preferences had considerable bearing on technology choices. In the second example, local outcomes data from administrative records were decisive.

Conclusions: Hospital-based HTA using local data can fill gaps in the published evidence, and also improve the generalizability of evidence to the local setting. To take advantage of local evidence, health systems should encourage the development of hospital-based HTA centers, seek out local preference data, and maintain databases of patient outcomes and utilization of services.
Evaluation criteria to assess the value of identification sources for horizon scanning
Authors: Smith Joanna , Cook Alison , Packer Claire
Published: June 2010

Objectives: The English National Horizon Scanning Centre routinely scans thirty-five sources to identify new and emerging health technologies. The aim of the study was to develop and apply evaluation criteria and scores to assess the value of sources, and to identify a cutoff score below which sources would be recommended for removal from routine horizon scanning. Criteria to evaluate each source scanned could result in a more efficient approach in the selection process.

Methods: Evaluation criteria were developed following a review of the literature and discussions with horizon analysts. Proposed criteria were piloted on a random selection of six sources, and then applied to all thirty-five sources. The criteria were assessed using the Analytic Hierarchy Process.

Results: Eight criteria were identified as being most relevant for assessing the value of scanning sources. The three most important (primary) criteria were coverage (approximate percentage of relevant information), quality (reliable, accurate, objective), and efficiency (estimated time to identify one potentially significant health technology or other relevant information). Seven sources fell beneath the cutoff score and were recommended for removal from routine scanning.

Conclusions: The criteria were considered useful in the assessment of current sources, and have the potential to be used to assess new ones. These criteria may be useful for other horizon scanning centers to pilot and validate.
Are adverse effects incorporated in economic models? A survey of current practice
Authors: Craig Dawn , McDaid Catriona , Fonseca Tiago , Stock Christian , Duffy Steven , Woolacott Nerys
Published: June 2010

Background: Clearly the benefits of a treatment must not be outweighed by the adverse effects. If researchers fail to incorporate adverse effects adequately in models, this could limit the validity of the results obtained. In the worst case, interventions that are cost-effective may be shown not to be. The aim of this research was to review current practice when incorporating adverse effects in economic models.

Methods: A survey of HTA reports commissioned by the National Institute for Health Research (NIHR) Health Technology Assessment programme, published between 2004 and 2007 was conducted. All reports which investigated the clinical and cost-effectiveness of a health technology using a systematic review and an economic model framework were included.

Results: A total of eighty reports met the inclusion criteria. Of the models including adverse effects (43/80), 67 percent used a clinical adverse effects parameter, 79 percent a cost of adverse effects parameter, 86 percent used one of these, and 60 percent used both. Of the thirty-seven models that did not include adverse effects, eighteen justified this omission, most commonly lack of data; nineteen appeared to make no explicit consideration of adverse effects in the model.

Conclusions: In many cases, poor reporting made it difficult to ascertain if there had been any consideration of adverse effects. We suggest that the findings of this survey support a call for much clearer and explicit reporting of adverse effects, or their exclusion, in decision models and for explicit recognition in future guidelines that “all relevant outcomes” should include some consideration of adverse events.
An outbreak of hepatitis A affecting a nursery school and a primary school
Authors: McFARLAND N. , DRYDEN M. , RAMSAY M. , TEDDER R. S. , NGUI S. L.
Published: June 2010

Between March and June 2008, 12 cases of hepatitis A were notified in Winchester. Cases were from a primary school and a nursery school with no direct linkage. Hepatitis A virus (HAV) RNA sequenced from nine cases confirmed the strain in both schools to be identical. The outbreak could have affected three other schools and a maternity unit and was controlled by immunization and screening of neonates in the maternity unit by dried blood spots. No neonates were infected and no further cases were reported until 5 months later when the index case's mother became infected with same strain of virus associated with the outbreak despite vaccination. Neither the source of the outbreak or the subsequent infection of the index case's mother was identified; however, with the timing of the cases continued transmission in the community by children with asymptomatic infection or a recurrent source cannot be ruled out.
The Genesis of Russian Warlordism: Violence and Governance during the First World War and the Civil War
Authors: SANBORN JOSHUA
Published: June 2010

The article looks at how the collapse of the tsarist regime in Russia and the civil war which followed created the conditions wherein a class of violent paramilitary entrepreneurs, usually veterans of the Great War, were able to operate almost entirely without restraint. The author terms this phenomenon ‘warlordism’, and shows how the rise and eventual fall of warlords was connected to the absence and restoration of state control during 1917–23. The article calls for an interpretation of violence during this period which eschews the reductive dualism of ‘red’ and ‘white’ terror in favour of an analysis which emphasises the role played by individual and largely autonomous warlords.
The duration of obesity and the risk of type 2 diabetes
Authors: Abdullah Asnawi , Stoelwinder Johannes , Shortreed Susan , Wolfe Rory , Stevenson Christopher , Walls Helen , de Courten Maximilian , Peeters Anna
Published: June 2010

Objective

The evidence for the association between obesity and the risk of type 2 diabetes has been derived mainly from the analysis of the degree of obesity. The role of the duration of obesity as an independent risk has not been fully explored. The objective of the present study was to investigate the association between the duration of obesity and the risk of type 2 diabetes.

Design

Prospective cohort study.

Setting

The Framingham Heart Study (FHS), follow-up from 1948 to 1998.

Subjects

A total of 1256 FHS participants who were free from type 2 diabetes at baseline, but were obese on at least two consecutive of the study’s twenty-four biennial examinations, were included. Type 2 diabetes status was collected throughout the 48 years of follow-up of the study. The relationship between duration of obesity and type 2 diabetes was analysed using time-dependent Cox models, adjusting for a number of covariates.

Results

The unadjusted hazard ratio (HR) for the risk of type 2 diabetes for men was 1·13 (95 % CI 1·09, 1·17) and for women was 1·12 (95 % CI 1·08, 1·16) per additional 2-year increase in the duration of obesity. Adjustment for sociodemographic variables, family history of diabetes, health behaviour and physical activity made little difference to these HR. For women the evidence of a dose–response relationship was less clear than for men, particularly for women with an older age at obesity onset.

Conclusions

The duration of obesity is a relevant risk factor for type 2 diabetes, independent of the degree of BMI.
Lifetime health outcomes of breast-feeding: a comparison of the policy documents of five European countries
Authors: Martin-Bautista Elena , Gage Heather , von Rosen-von Hoewel Julia , Jakobik Viktoria , Laitinen Kirsi , Schmid Martina , Morgan Jane , Williams Peter , Decsi Tamas , Campoy Cristina , Koletzko Berthold , Raats Monique
Published: June 2010

Objective

To (i) identify and describe prevailing infant feeding policy documents in five diverse European countries; (ii) analyse types of health outcomes for the infant that are associated with feeding breast milk rather than formula milk in the documents of different countries; and (iii) assess the extent to which documents reflect the WHO global recommendation of exclusive breast-feeding for 6 months.

Design

Documentary review and analysis.

Setting

Five geographically dispersed countries of Europe (England, Finland, Germany, Hungary and Spain).

Subjects

Policy documents on infant feeding were identified; statements that linked choice between breast- and formula-feeding to a health outcome for the infant were extracted.

Results

Twenty-six documents (varied authorships, dates, length and character) were identified: four from England; two from Finland; nine from Germany; six from Hungary; and five from Spain. There was no consistency in the way in which health outcomes were cited as factors in the recommendations for breast- rather than formula-feeding. Seven documents contained no reference to the health implications of infant feeding choice. Of 203 statements in remaining documents citing health outcomes, 24·1 % mentioned general health effects, 32·5 % protection against infections, 31·5 % long-term conditions (e.g. diabetes, CVD) and 11·8 % mentioned allergy. Health outcomes were linked to exclusive breast-feeding in only 25 % of statements.

Conclusions

Policy documents in the study countries varied in the extent to which they reflect the health outcomes for the baby of breast-feeding, and this may limit effective promotion by health professionals. There is scope to improve the process of bringing evidence and recommendations into policy documents.
The portfolio effect of pension reforms: evidence from Italy
Authors: BOTTAZZI RENATA , JAPPELLI TULLIO , PADULA MARIO
Published: June 2010

We estimate the portfolio effect of changes in social security wealth exploiting a decade of Italian pension reforms. The Italian Survey of Household Income and Wealth records detailed portfolio data and elicits expectations of retirement outcomes, thus allowing us to measure expected social security wealth and assess to what extent Italian households perceive the innovations brought about by the reforms. We find that households have responded to cuts in pension benefits mostly by increasing real estate wealth, and that this response is stronger among households able more accurately to estimate future social security benefits. We also compute that for the average household consumable wealth increases by 40 percent of the reduction in social security wealth.
Occupational pensions, tenure, and taxes
Authors: HERNÆS ERIK , PIGGOTT JOHN , ZHANG TAO , STRØM STEINAR
Published: June 2010

The occurrence in firms of occupational pensions is investigated with a linked employer–employee dataset, supplemented with actuarial calculations of tax savings when labour compensation is in the form of pensions compared to wages. Tax gains, which can be shared between employers and employees, and expected increases in average tenure are both clearly associated with the occurrence of an occupational pension. Occupational pensions are typically found in large firms, with decentralized wage negotiations, a high degree of unionization, and the requirement of long training. The results and the approach provide a basis for analyzing also the trend towards DB pensions.
Celebrity Worship Among University Students in Malaysia
Authors: Swami Viren , Chamorro-Premuzic Tomas , Mastor Khairul , Hazwani Siran Fatin , Said Mohammad Mohsein Mohammad , Jaafar Jas , Sinniah Dhachayani , Pillai Subash K.
Published: June 2010

The present study examined conceptual issues surrounding celebrity worship in a Malay-speaking population. In total, 512 Malay and 269 Chinese participants from Malaysia indicated who their favorite celebrity was and completed the Celebrity Attitude Scale (CAS) as well as a range of demographic items. Results showed that the majority of Malay and Chinese participants selected pop stars and movie stars as their favourite celebrities, mirroring findings in Western settings. In addition, exploratory factor analysis revealed a three-factor solution of the CAS that was consistent with previous studies conducted in the West. Structural equation modeling further revealed that participant’s age was negatively associated with celebrity worship and that self-rated attractiveness was positively associated with celebrity worship. Overall, the present results suggest that celebrity worship in Malaysia may be driven by market and media forces, and future research may well be guided by use of the CAS.
Observations on the circulation of the Saronikos Gulf: A Mediterranean embayment sea border of Athens, Greece
Authors: Kontoyiannis Harilaos
Published: June 2010

The Saronikos Gulf three‐dimensional flow structure is mapped by objective analysis in 12 acoustic Doppler current profiler surveys (4 seasonal surveys per period for the periods May 1998–May 1999, May 2000–May 2001, May 2003–May 2004) under various winds. Robust seasonal flows throughout the Gulf are basically induced by thermohaline effects (winter water subduction, different responses to atmospheric heating of shallow and deeper areas of the Gulf) and density contrasts with inflowing Aegean waters. Inner Gulf observations show that the seasonal flows are modified by the wind, while recurrent structures (cyclonic and anticyclonic) appear between the seasonal flows and the coast of Attica. In summer an anticyclonic and a cyclonic flow exists throughout the Gulf above and below the pycnocline, respectively, with a jet observed to meander within the Inner Gulf. In winter and early spring an anticyclonic flow prevails in the upper ∼100 m. In late spring‐early summer cyclonic and anticyclonic flow occurs in the upper (∼0–40 m) and deeper (∼60–100 m) layers, respectively. The predominant northerly winds in summer and winter push the Inner Gulf eastward seasonal jet to the south and favor the formation of a recurrent cyclonic upwelling structure between this jet and Attica. Northwesterly, westerly, and southerly winds favor the northward meandering of the seasonal jet in the Inner Gulf and no recurrent structures appear in the limited space between this jet and Attica. In the southeast area of the Inner Gulf, the wind‐driven flow fluctuations at 30 m have time scales of 3.5–4 days. Observed meandering period is ∼13 days; meandering characteristics are close to instability predictions. Time scales of flows due to recurrent structures are ∼8 days.
Atmospheric events disrupting coastal upwelling in the southwestern Caribbean
Authors: Lonin Serguei A. , Hernández José L. , Palacios Daniel M.
Published: June 2010

Year‐round coastal upwelling is a prevalent phenomenon in the southwestern Caribbean region, driven by northeast trade winds. This pattern can be disrupted during the boreal winter‐to‐spring transition by event‐scale departures in the pressure systems, characterized by a change in wind direction to northward, with the accompanying relaxation of coastal upwelling. To study these poorly understood events, regional atmospheric and data‐assimilative ocean modeling experiments were carried out for the period 4 March to 9 April 2003 and compared to shipboard observations This combined ocean‐atmosphere approach allowed us to study the evolution of a 3‐day atmospheric disturbance affecting ocean currents and collapsing the upwelling pattern against the Colombian coast along the Guajira Peninsula near 12°N. The southward extension of the coastal upwelling, which normally reaches 10.5°N, was blocked by the warmer and slightly lower salinity waters of the cyclonic Panama‐Colombia gyre. Under typical conditions, the ocean model and shipboard observations of temperature and salinity profiles were in good agreement with each other, both at coastal and oceanic stations. The presence of a low‐level westward wind jet was manifested in the atmospheric model simulation, confirming that it promotes the Guajira upwelling system; however, the jet vanishes under disturbed atmospheric conditions.
Tsunami damage reduction performance of a mangrove forest in Banda Aceh, Indonesia inferred from field data and a numerical model
Authors: Yanagisawa H. , Koshimura S. , Miyagi T. , Imamura F.
Published: June 2010

Since the 26 December 2004 Indian Ocean tsunami, the role of mangrove forests as natural defenses protecting coastal communities from tsunami disaster has been highlighted. However, some mangrove forests were destroyed by that tsunami. They are expected to have lost their protective functions. In this study, we develop a fragility function to assess the mangrove trees' vulnerability, expressed as the damage probability of mangrove trees, based on field surveys and numerical modeling of the 2004 Indian Ocean tsunami in Banda Aceh, Indonesia. Based on the fragility function, we reconstruct a numerical model of tsunami inundation including the performance of mangrove forests in terms of reducing tsunami damage. The model reveals that a 10 year old mangrove forest in a 500 m wide area can reduce a tsunami's hydrodynamic force by approximately 70% for an incident wave of 3.0 m inundation depth and a wave period of 40 min at the shoreline. The model also shows, for a tsunami inundation depth of greater than 4 m, that a 10 year old mangrove forest would be mostly destroyed and that it would lose its force reduction capacity. Moreover, approximately 80% of a 30 year old mangrove forest would survive a 5 m tsunami and absorb 50% of the tsunami's hydrodynamic force.
Analysis and modeling of hydrothermal plume data acquired from the 85°E segment of the Gakkel Ridge
Authors: Stranne Christian , Sohn Robert A. , Liljebladh Bengt , Nakamura Ko‐ichi
Published: June 2010

We use data from a CTD plume‐mapping campaign conducted during the Arctic Gakkel Vents (AGAVE) expedition in 2007 to constrain the nature of hydrothermal processes on the Gakkel Ridge at 85°E. Thermal and redox potential (Eh) anomalies were detected in two discrete depth intervals: 2400–2800 m (Interval 1) and 3000–3800 m (Interval 2). The spatial and temporal patterns of the signals indicate that the Interval 1 anomalies were most likely generated by a single large, high‐temperature (T > 100°C) vent field located on the fault terraces that form the NE axial valley wall. In contrast, the Interval 2 anomalies appear to have been generated by up to 7 spatially distinct vent fields associated with constructional volcanic features on the floor of the axial valley, many of which may be sites of diffuse, low‐temperature (T < 10°C) discharge. Numerical simulations of turbulent plumes rising in a weakly stratified Arctic Ocean water column indicate that the high‐temperature field on the axial valley wall has a thermal power of ∼1.8 GW, similar to the Trans‐Atlantic Geotraverse and Rainbow fields in the Atlantic Ocean, whereas the sites on the axial valley floor have values ranging from 5 to 110 MW.
Quantification of large uncertainties in fossil leaf paleoaltimetry
Authors: Peppe Daniel J. , Royer Dana L. , Wilf Peter , Kowalski Elizabeth A.
Published: June 2010

Estimates of paleoelevation potentially constrain geodynamic models of continental deformation and inform interpretations of landscape and climate evolution. One widely used, paleobotanical approach reconstructs paleoelevation from the difference in estimated atmospheric enthalpy between a known sea level and a targeted, coeval, elevated fossil floral site. Enthalpy is estimated using Climate‐Leaf Analysis Multivariate Program (CLAMP) on 31 leaf size and shape variables that have been calibrated in living forests. Errors related to CLAMP are significantly greater than often reported, and there are many sources of large potential error related to this method that are either difficult to quantify or unquantifiable and are thus not documented. Here, we quantify one significant bias, toward underestimation of leaf area in the CLAMP data set (∼50%), that affects all CLAMP climate estimates, including enthalpy. Crucially, errors in paleoelevation when the leaf size bias is included are in the range of ±2 km or more, at least 2 times the previous estimates, and exceeding the plausible paleoelevations of many fossil sites. Previously published paleoelevations derived from this technique are unlikely to be accurate either in magnitude or in estimated error.
Polyclonal Treg cells enhance the activity of a mucosal adjuvant
Authors: Vendetti Silvia , Davidson Todd S , Veglia Filippo , Riccomi Antonella , Negri Donatella RM , Lindstedt Ragnar , Pasquali Paolo , Shevach Ethan M , De Magistris Maria Teresa
Published: June 2010

The efficacy of vaccines can be greatly improved by adjuvants that enhance and modify the magnitude and the duration of the immune response. Several approaches to design rational adjuvants are based on the suppression of regulatory T‐cell (Treg) function. Here, we evaluated whether removal or addition of Treg at the time of vaccination with tetanus toxoid and the mucosal adjuvant cholera toxin (CT), would affect immune responses. We found that depletion/inactivation of CD4+CD25+ Treg, either by treatment of BALB/c mice with anti‐CD25 monoclonal antibodies or by adoptive transfer of CD4+CD25− T lymphocytes depleted of CD4+CD25+ Treg into nu/nu mice, impaired antibody production after mucosal immunization in the presence of CT. Conversely, transfer of polyclonal, but not Ag‐specific, CD4+CD25+Foxp3+ Treg to normal BALB/c mice enhanced CT‐induced antibody responses. An increased titer of both immunoglobulin IgG1 and IgG2a antibody subclasses was found, however, the ratio between IgG1/IgG2a with or without polyclonal Treg was comparable, suggesting that polyclonal Treg influence the magnitude, but not the quality of the immune response. Recipients of polyclonal Treg that had been immunized with CT had an increased number of Ag‐specific CD4+ T cells with an activated phenotype (CD44hi) in the draining lymph nodes. This accumulation of Ag‐specific CD4+ T lymphocytes could favour the germinal centre formation and may promote T‐dependent B‐cell responses. Overall, our study indicates that Foxp3+ Treg can not only function as suppressor cells but also as helper T cells, depending on the type of immune response being evaluated and the microenvironment in which the response is generated.
Defect in efferocytosis leads to alternative activation of macrophages in Francisella infections
Authors: Mares Chris A , Sharma Jyotika , Li Qun , Rangel Edward L , Morris Elizabeth G , Enriquez Melissa I , Teale Judy M
Published: June 2010

The macrophage is a versatile cell type that can sense and respond to a particular need based on the conditions of the microenvironment. Some studies have recently suggested that pathogens can directly influence the polarization of macrophages. As Francisella infections are characterized by intense necrotic infiltrates in the lung as well as in distal sites of infection, we sought to investigate whether pulmonary Francisella infections could cause the polarization of alternatively activated macrophages (M2/aaMs). Our results indicate that Francisella infections can cause the polarization of M2/aaM in vivo and that macrophages can be polarized toward an M2/aaM phenotype more potently if dead cell debris is used for stimulation in the presence and absence of Francisella infections. Finally, we also demonstrate that efferocytosis is inhibited in macrophages infected with Francisella, thus providing a potential explanation for the lack of clearance and eventual accumulation of dead cell debris associated with this disease.
Bifurcation of binary systems with the Onsager mobility
Authors: Hsia Chun-Hsiung
Published: June 2010

The main objective of this article is to study the effect of the (nonlinear) Onsager mobility to the phase separation of the binary system, using rigorous bifurcation analysis. In particular, a nondimensional parameter K, depending on the molar density u0 of the homogeneous state, and the critical temperature is derived; the sign of this parameter dictates the type of transition. Also, the analysis indicates that the type of the transition, the critical temperature Tc, and the strength of the deviation of the transition solutions from the homogeneous state are all independent of the choices of the Onsager mobility.
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-deformed quantum algebras: Coherent states and special functions
Authors: Hounkonnou Mahouton Norbert , Kyemba Joseph Désiré Bukweli
Published: June 2010

We provide with a generalization of well known (p,q)-deformed Heisenberg algebras, called (R,p,q)-deformed quantum algebras, and study the corresponding (R,p,q)-series. A general formulation of the binomial theorem is given. Special functions are obtained as limit cases. This work well prolongs a previous work by Odzijewicz [Commun. Math. Phys. 192, 183 (1998)]. Known results in the literature are recovered.
A miniaturized continuous dielectrophoretic cell sorter and its applications
Authors: Valero Ana , Braschler Thomas , Demierre Nicolas , Renaud Philippe
Published: June 2010

There is great interest in highly sensitive separation methods capable of quickly isolating a particular cell type within a single manipulation step prior to their analysis. We present a cell sorting device based on the opposition of dielectrophoretic forces that discriminates between cell types according to their dielectric properties, such as the membrane permittivity and the cytoplasm conductivity. The forces are generated by an array of electrodes located in both sidewalls of a main flow channel. Cells with different dielectric responses perceive different force magnitudes and are, therefore, continuously focused to different equilibrium positions in the flow channel, thus avoiding the need of a specific cell labeling as discriminating factor. We relate the cells’ dielectric response to their output position in the downstream channel. Using this microfluidic platform that integrates a method of continuous-flow cell separation based on multiple frequency dielectrophoresis, we succeeded in sorting viable from nonviable yeast with nearly 100% purity. The method also allowed to increase the infection rate of a cell culture up to 50% of parasitemia percentage, which facilitates the study of the parasite cycle. Finally, we prove the versatility of our device by synchronizing a yeast cell culture at a particular phase of the cell cycle avoiding the use of metabolic agents interfering with the cells’ physiology.
New representations of π and Dirac delta using the nonextensive-statistical-mechanics q-exponential function
Authors: Jauregui M. , Tsallis C.
Published: June 2010

We present a generalization of the representation in plane waves of Dirac delta, δ(x)=(1/2π)∫−∞∞e−ikxdk, namely, δ(x)=[(2−q)/2π]∫−∞∞eq−ikxdk, using the non-extensive-statistical-mechanics q-exponential function, eqix≡[1+(1−q)ix]1/(1−q) with e1ix≡eix, x being any real number, for real values of q within the interval [1,2[. Concomitantly, with the development of these new representations of Dirac delta, we also present two new families of representations of the transcendental number π. Incidentally, we remark that the q-plane wave form which emerges, namely, eqikx, is normalizable for 1<q<3, in contrast to the standard one, eikx, which is not.
Cranking approach for a complex quantum system
Authors: Kolomietz V. M. , Radionov S. V.
Published: June 2010

Within random matrix model, the response of a complex quantum system Ĥ(q[t]) on time variations in an external parameter q. In the limit of weak coupling of the external parameter to the quantum system, the different dynamical regimes of the diffusion in a space of the occupancies of eigenstates of Ĥ(q) are considered. The main focus is made on measuring the role of memory effects in the quantum diffusive dynamics. Possible macroscopic manifestations of the quantum mechanical diffusion are discussed in the context of the cranking approach, where the time variations in the classical parameter q provides the constancy of energy of the total system.
Biphase sinusoidal oscillator based on negative resistor
Authors: Bayard Jean
Published: June 2010

This paper describes a biphase sinusoidal generator which provides two signals: vref=VM sin(ωt) and vout=VM sin(ωt+ΔΦ), where ΔΦ is in the range 0, π/2 or −π/2, 0 and is not dependent on the frequency value. It is based on a negative resistor and it requires very few components. SPICE simulations and measurements on an experimental setup confirm the theoretical analysis.
Nonadiabatic dynamics with the help of multiconfigurational Ehrenfest method: Improved theory and fully quantum 24D simulation of pyrazine
Authors: Shalashilin Dmitrii V.
Published: June 2010

This article proposes an improved version of recently developed multiconfigurational Ehrenfest approach to quantum dynamics. The idea of the approach is to use frozen Gaussians (FG) guided by Ehrenfest trajectories as a basis set for fully quantum propagation. The method is applied to simulation of nonadiabatic dynamics of pyrazine and shows that nonadiabatic dynamics on two coupled electronic states S2 and S1, which determines pyrazine absorption spectrum, can be simulated with the help of a basis comprised of very small number of trajectory guided basis functions. For the 24 dimensional (24D) model, good results were obtained with the basis of only 250 trajectories guided FG per electronic state. The efficiency of the method makes it particularly suitable for future application together with direct dynamics, calculating potentials on the fly.
Fractal model for estimating fracture toughness of carbon nanotube reinforced aluminum oxide
Authors: Rishabh Abhishek , Joshi Milind R. , Balani Kantesh
Published: June 2010

The current work focuses on predicting the fracture toughness of Al2O3 ceramic matrix composites using a modified Mandelbrot’s fractal approach. The first step confirms that the experimental fracture toughness values fluctuate within the fracture toughness range predicted as per the modified fractal approach. Additionally, the secondary reinforcements [such as carbon nanotubes (CNTs)] have shown to enhance the fracture toughness of Al2O3. Conventional fractural toughness evaluation via fractal approach underestimates the fracture toughness by considering the shortest crack path. Hence, the modified Mandelbrot’s fractal approach considers the crack propagation along the CNT semicircumferential surface (three-dimensional crack path propagation) for achieving an improved fracture toughness estimation of Al2O3-CNT composite. The estimations obtained in the current approach range within 4% error regime of the experimentally measured fracture toughness values of the Al2O3-CNT composite.
Transport study of intense-laser-produced fast electrons in solid targets with a preplasma created by a long pulse laser
Authors: Yabuuchi T. , Paradkar B. S. , Wei M. S. , King J. A. , Beg F. N. , Stephens R. B. , Nakanii N. , Hatakeyama M. , Habara H. , Mima K. , Tanaka K. A. , Larsen J. T.
Published: June 2010

The effect of preplasma on fast electron generation and transport has been studied using an intense-laser pulse (I=2×1018 W/cm2) at the Osaka University. An external long pulse laser beam (E<1.5 J) was used to create various levels of preplasmas in front of a planar target for a systematic study. Kα x-ray emission from a fluorescence layer (copper) was absolutely counted and its spatial distribution was monitored. Experimental data show Kα x-ray signal reduction (up to 60%) with an increase in the preplasma level. In addition, a ring structure of Kα x rays was observed with a large preplasma. The underlying physics of the ring structure production was studied by integrating the modeling using a radiation hydrodynamics code and a hybrid particle-in-cell code. Modeling shows that the ring structure is due to the thermoelectric magnetic field excited by the long pulse laser irradiation and an electrostatic field due to the fast electrons in the preplasma.
Ingrain and grain boundary scattering effects on electron mobility of transparent conducting polycrystalline Ga-doped ZnO films
Authors: Yamada Takahiro , Makino Hisao , Yamamoto Naoki , Yamamoto Tetsuya
Published: June 2010

Transparent conducting polycrystalline Ga-doped ZnO (GZO) films with different thicknesses were deposited on glass substrates at a substrate temperature of 200 °C by ion-plating deposition with direct current arc-discharge. The dependences of crystal structure, electrical, and optical properties of the GZO films on thickness have been systematically studied. Optical response due to free electrons of the GZO films was characterized in the photon energy range from 0.73 to 3.8 eV by spectroscopic ellipsometry (SE). The free electron response was expressed by the simple Drude model combined with the Tauc–Lorentz model. From the SE analysis and the results of Hall measurements, electron effective mass, m∗, and optical mobility, μopt, of the GZO films were determined, based on the assumptions that the films are homogeneous and optically isotropic. By comparing the μopt and Hall mobility, μHall, an indication on the effect of ingrain and grain boundary scattering limiting the electron mobility has been obtained. Moreover, the variation in scattering mechanism causing thickness dependence of μHall was correlated with the development of polycrystalline grain structure.
High performance conductivity monitoring instrument with pulsating sensor
Authors: Sahoo P. , Malathi N. , Praveen K. , Ananthanarayanan R. , Arun A. D. , Murali N. , Swaminathan P.
Published: June 2010

We present an unconventional but high performance pulsating conductivity monitoring instrument constructed by using a new class of sensor, viz., pulsating sensor developed in house. The design consists of a special type of logic gate oscillator (LGO) powered by 5 V direct current (dc). The conductivity cell constitutes a part of LGO. In this conductivity meter the primary signal generated from the sensor is directly in digital domain which is easily transmitted either to a personal computer or to a stand-alone embedded system. Hence it reduces the hardware components making the instrumentation highly simplified. The output of the instrument is pulse frequency which is directly related to the conductivity of solution used for measurement. The relation between pulse frequency and conductivity is determined following a multipoint calibration technique developed in our laboratory using a series of KCl standards. The performance of the instrument is demonstrated with a few examples which reveal the diverse application of this new approach of measurement technique.
Thermostating highly confined fluids
Authors: Bernardi Stefano , Todd B. D. , Searles Debra J.
Published: June 2010

In this work we show how different use of thermostating devices and modeling of walls influence the mechanical and dynamical properties of confined nanofluids. We consider a two dimensional fluid undergoing Couette flow using nonequilibrium molecular dynamics simulations. Because the system is highly inhomogeneous, the density shows strong fluctuations across the channel. We compare the dynamics produced by applying a thermostating device directly to the fluid with that obtained when the wall is thermostated, considering also the effects of using rigid walls. This comparison involves an analysis of the chaoticity of the fluid and evaluation of mechanical properties across the channel. We look at two thermostating devices with either rigid or vibrating atomic walls and compare them with a system only thermostated by conduction through vibrating atomic walls. Sensitive changes are observed in the xy component of the pressure tensor, streaming velocity, and density across the pore and the Lyapunov localization of the fluid. We also find that the fluid slip can be significantly reduced by rigid walls. Our results suggest caution in interpreting the results of systems in which fluid atoms are thermostated and/or wall atoms are constrained to be rigid, such as, for example, water inside carbon nanotubes.
Spherical single-roll dynamos at large magnetic Reynolds numbers
Authors: Latter Henrik , Ivers David
Published: June 2010

This paper concerns kinematic helical dynamos in a spherical fluid body surrounded by an insulator. In particular, we examine their behavior in the regime of large magnetic Reynolds number Rm, for which dynamo action is usually concentrated on a simple resonant stream surface. The dynamo eigensolutions are computed numerically for two representative single-roll flows using a compact spherical harmonic decomposition and fourth-order finite differences in radius. These solutions are then compared with the growth rates and eigenfunctions of the Gilbert and Ponty large Rm asymptotic theory [Geophys. Astrophys. Fluid Dyn. 93, 55 (2000)]. We find good agreement between the growth rates when Rm>104 and between the eigenfunctions when Rm>105.
Light-emitting dendrimer film morphology: A neutron reflectivity study
Authors: Vickers S. V. , Barcena H. , Knights K. A. , Thomas R. K. , Ribierre J.-C. , Gambino S. , Samuel I. D. W. , Burn P. L. , Fragneto Giovanna
Published: June 2010

We have used neutron reflectivity (NR) measurements to probe the physical structure of phosphorescent dendrimer films. The dendrimers consisted of fac-tris(2-phenylpyridyl)iridium(III) cores, biphenyl-based dendrons (first or second generation), and perdeuterated 2-ethylhexyloxy surface groups. We found that the shape and hydrodynamic radius of the dendrimer were both important factors in determining the packing density of the dendrimers. “Cone” shaped dendrimers were found to pack more effectively than “spherical” dendrimers even when the latter had a smaller radius. The morphology of the films determined by NR was consistent with the measured photoluminescence and charge transporting properties of the materials.
Evidence for surface states in a single 3 nm diameter Co3O4 nanowire
Authors: Sun Yi , Yang Ji-Yong , Xu Rui , He Lin , Dou Rui-Fen , Nie Jia-Cai
Published: June 2010

The electronic local density of states of a single Co3O4 semiconductor nanowire with the diameter of 3 nm is explored using low-temperature scanning tunneling microscopy and spectroscopy. The energy gap between the conduction band and valence band of the nanowire is about 1.7 eV, which is slightly enhanced compared to the bulk value, ∼1.5 eV, due to the quantum confinement effect. Two surface states are observed locating near the Fermi level in the band gap.