bluuebunny/crossref_metadata_2025 huggingface dataset:
Improving Intrusion Prevention Models: Dual-Threshold and Dual-Filter Approaches
Authors: Ryu Young U. , Rhee Hyeun-Suk
Published: January 2008

Intrusion detection, once considered as the last line of defense in the layered architecture for technical security, is observed not to deliver the promised protection. It suffers from high false-alarm rates and puts too much of a burden on the information security officers. Intrusion prevention has evolved from intrusion detection technologies to overcome difficulties faced in intrusion detection and more actively encounter ever-increasing attacks. While intrusion prevention provides immediate/real-time protection, it suffers from two deficiencies, which are the sensitivity and specificity trade-off and the accuracy and efficiency trade-off. To address these issues, we introduce two models of intrusion prevention. The first model is for a hybrid system playing both detection and protection roles. The second model suggests the use of dual filters in the evaluation of activities. Mathematical programming formulations for both models are developed and optional configuration solutions are proposed.
Physicians' Persistence and Its Implications for Their Response to Promotion of Prescription Drugs
Authors: Janakiraman Ramkumar , Dutta Shantanu , Sismeiro Catarina , Stern Philip
Published: January 2008

Motivated by the medical literature findings that physicians are inertial, we seek to understand (1) whether physicians exhibit structural persistence in drug choice (structural persistence occurs when the drug chosen for a patient depends structurally on the drug previously prescribed by the physician to other patients) and (2) whether persistence, if present, is a physician-specific characteristic or a physician state that can change over time. We further explore the role of promotional tools on persistence and drug choice, and we investigate whether physicians who exhibit persistence respond differently to three forms of sales promotion: one-to-one meetings (detailing), out-of-office meetings, and symposium meetings.

Our results show significant levels of physician persistence in drug choice. We find that persistence is mostly a cross-sectional physician feature. Nonpersistent physicians appear to be responsive to detailing and symposium meetings, whereas persistent physicians seem to be responsive only to symposium meetings. Out-of-office meetings, such as golf or lunch, have no effect on physicians' drug choice. We also find that (1) older physicians and those who work in smaller practices are more likely to be persistent and (2) physicians who are more willing to receive sales force representatives have a lower likelihood of being persistent. Finally, we discuss implications for public policy from our rich set of results.
Scheduling Arrivals to Queues: A Single-Server Model with No-Shows
Authors: Hassin Refael , Mendel Sharon
Published: January 2008

Queueing systems with scheduled arrivals, i.e., appointment systems, are typical for frontal service systems, e.g., health clinics. An aspect of customer behavior that influences the overall efficiency of such systems is the phenomenon of no-shows. The consequences of no-shows cannot be underestimated; e.g., British surveys reveal that in the United Kingdom alone more than 12 million general practitioner (GP) appointments are missed every year, costing the British health service an estimated £250 million annually. In this study we answer the following key questions: How should the schedule be computed when there are no-shows? Is it sufficiently accurate to use a schedule designed for the same expected number of customers without no-shows? How important is it to invest in efforts that reduce no-shows—i.e., given that we apply a schedule that takes no-shows into consideration, is the existence of no-shows still costly to the server and customers?
Learning by Doing in the Newsvendor Problem: A Laboratory Investigation of the Role of Experience and Feedback
Authors: Bolton Gary E. , Katok Elena
Published: January 2008

We investigate learning by doing in the newsvendor inventory problem. An earlier study observed that decision makers tend to anchor their orders around average demand and fail to adjust sufficiently toward the expected profit-maximizing order. Principles of behavioral theory suggest some relatively simple interventions into the decision maker's experience and feedback that might improve performance, and these guide our investigation. The results imply that the institutional organization of experience and feedback may have a significant influence on whether inventory is stocked optimally.
Long-Term Contracts Under the Threat of Supplier Default
Authors: Swinney Robert , Netessine Serguei
Published: January 2008

Contracting with suppliers prone to default is an increasingly common problem in some industries, particularly automotive manufacturing. We model this phenomenon as a two-period contracting game with two identical suppliers, a single buyer, deterministic demand, and uncertain production costs. The suppliers are distressed at the start of the game and do not have access to external sources of capital; hence, revenues from the buyer are crucial in determining whether default occurs. The production cost of each supplier is the sum of two stochastic components: a common term that is identical for both suppliers (representing raw materials costs, design specifications, etc.) and an idiosyncratic term that is unique to a given supplier (representing inherent firm capability). The buyer chooses a supplier and then decides on a single- or two-period contract. Comparing models with and without the possibility of default, we find that, without the possibility of supplier failure, the buyer always prefers short-term contracts over long-term contracts, whereas this preference is typically reversed in the presence of failure. Neither of these contracts coordinates the supply chain. We also consider dynamic contracts, in which the contract price is partially tied to some index representing the common component of production costs (e.g., commodity prices of raw materials such as steel or oil), allowing the buyer to shoulder some of the risk from cost uncertainty. We find that dynamic long-term contracts allow the buyer to coordinate the supply chain in the presence of default risk. We also demonstrate that our results continue to hold under a variety of alternative assumptions, including stochastic demand, allowing the buyer the option of subsidizing a bankrupt supplier via a contingent transfer payment or loan and allowing the buyer to unilaterally renegotiate contracts. We conclude that the possibility of supplier default offers a new reason to prefer long-term contracts over short-term contracts.
Revisiting the Strategy, Structure, and Performance Paradigm: The Case of Venture Capital
Authors: Wasserman Noam
Published: January 2008

The strategy-structure-performance (SSP) paradigm has developed a central role within strategy research. However, recent critiques of the paradigm have called for research that uses more appropriate measures of strategy and structure, inductive methods that enable richer exploration of the paradigm, and extension of the paradigm to the expert-focused organizations that have grown in importance since the paradigm was first developed. This paper answers this call by integrating inductive methods with quantitative analysis of a unique panel data set of 317 professional services firms (PSFs) to find new measures of strategy and to understand their linkages to organizational structure within such firms. It shows how the core knowledge required for decision making and the coordination challenges in these firms drive their internal structures and that the degree of strategy-structure fit has important performance implications for those firms.
Knowledge Collaboration Among Professionals Protecting National Security: Role of Transactive Memories in Ego-Centered Knowledge Networks
Authors: Jarvenpaa Sirkka L. , Majchrzak Ann
Published: January 2008

Current social cognition models of knowledge coordination based on transactive memory systems (TMS) theory have not generally considered conditions in which goals among partners are incongruent, and that those with specialized knowledge will not necessarily act to share their knowledge. As expected from previous literature, when facing a problem requiring inputs from others, an individual will draw on her personal or ego-centered network using the knowledge of her network's TMS; however, we theorize that the mixed motives within her network will cause the individual to also take into account her perception of the level of distrust within the network when combining the received knowledge from others in the network. Moreover, an individual's view of her network's TMS will be shaped not by specific policies or enforcement mechanisms, but by semistructures for how knowledge is disseminated, owned, and discussed. Our theory is supported based on a survey of security professionals responding to national security threats. The findings encourage a reexamination of certain assumptions of TMS theory, as well as extending theories of ego-centered networks and social-cognitive information processing to include how individuals manage the knowledge-sharing/protection tension in interorganizational collaborations.
Changes in working patterns hit emergency general surgical training
Authors: Kara N , Patil PV , Shimi SM
Published: January 2008

The last decade has seen major changes in the working pattern of surgical trainees. This commenced with the introduction of the maximum 72-hour working week in 1991. The European Working Time Directive reduced the working hours to a maximum of 56 hours, with the intention to reduce it further to 48 hours by 2009. This is additionally affected by compliance with the SiMAP and Jaeger Rulings. The results of the Calman report coupled with those of the Confidential Enquiry into Perioperative Deaths (CEPOD) report have also had a significant effect on the amount and level of experience obtained during surgical training.
Prosthodontic paradigms
Authors: Prieskel Harold
Published: January 2008

Until recently it was taken for granted in the UK that an educated and cultivated person was well versed in classical literature and philosophy. Fussing with unpleasant potions and fiddly equipment did not a scholar make. A first class degree in Classics was an entry ticket into the upper echelons of the British power structure. Clinicians returning home after a day of prodding abdomens, peering down throats, poking in ears or examining mouths could restore the mind by dipping into their well-worn copies of the world's best literature.
Innovative new vascular programme combines surgery and radiology
Authors: King Mary
Published: January 2008

2008 looks set to be a year of major challenges for vascular surgery. Vascular surgeons could soon be training alongside other medical professionals including radiologists if a new curriculum and training programme, devised by the Vascular Society of Great Britain and Ireland, is accepted by the royal colleges and the Postgraduate Medical Education and Training Board. The programme will combine surgical experience with the interventional radiology needed to carry out endovascular procedures and aims to meet the increased demands of aneurysm screening.
Agronomic Implications of Converter Basic Slag as a Magnesium Source on Acid Soils
Authors: Peregrina F. , Mariscal I. , Ordóñez R. , González P. , Terefe T. , Espejo R.
Published: January 2008

The feasibility of using converter basic slag (CBS) as a source of Mg for gypsum‐amended acidic soils was studied in a Plinthic Palexerult from western Spain. An experimental farm was established and the Ap horizon of the soil was amended with limestone (L), phosphogypsum (PG), or red gypsum (RG) to alleviate Al toxicity. The PG and RG were supplied at 8.0 and 8.8 Mg ha−1, respectively. In addition, the gypsum‐amended plots received either CBS at 0.9 Mg ha−1or limestone at 1.1 Mg ha−1We studied the effects of the treatments on the exchange complex, soil solution, and the biomass production of ‘Jabato’ wheat (Triticum aestivumL.) under field and greenhouse conditions. The CBS proved highly effective in replenishing Mg lost from the soil through application of gypsum amendments. In the field experiment, only the RG + CBS treatment resulted in a statistically significant increase of biomass production relative to the control. In the greenhouse experiment, all treatments resulted in significantly increased production relative to the control, the largest (26 times) by RG + CBS. The PG + CBS and RG + CBS treatments resulted in significantly increased production relative to PG + L and RG + L, which testifies to the favorable effect of the Mg supplied by CBS. Also, the treatments including RG resulted in significantly increased production with respect to those including PG; the increased productivity is tentatively ascribed to a potential toxic effect of Al–F ion pairs, which were more abundant in the soil solution of PG‐treated soil.
Elevated Carbon Dioxide and Irrigation Effects on Soil Nitrogen Gas Exchange in Irrigated Sorghum
Authors: Welzmiller Jaydene T. , Matthias Allan D. , White Scott , Thompson Thomas L.
Published: January 2008

The impacts of increasing atmospheric CO2, an important greenhouse gas, on soil microbial production and consumption of other greenhouse gases such as N2O are uncertain. This study was conducted during the 1998 and 1999 summer growing seasons at the Free‐Air CO2Enrichment (FACE) site in Maricopa, AZ. The objective was to measure N2O and denitrification emission rates in a C4sorghum [Sorghum bicolor(L.) Moench] production system with ample and limited flood irrigation rates under FACE (seasonal mean = 579 μmol mol−1) and control (seasonal mean = 396 μmol mol−1) CO2Plots were sampled for N2O flux using both chamber and intact incubated soil core techniques. Nitrogen gas (N2O plus N2) emissions were measured using intact incubated soil cores with C2H2inhibition. Nitrous oxide emissions measured with chambers increased markedly after irrigation and fertilization following prolonged periods without water under both elevated and control CO2conditions. Within 5 d of fertilization and irrigation, N2O emissions measured with chambers were <250 g N2O‐N ha−1d−1until subsequent irrigations. Emissions measured from cores ranged from −0.11 to >250 g N2O‐N ha−1d−1Seasonal cumulative N2O‐N emissions measured using chambers were <1.5 kg N ha−1Seasonal N‐gas losses measured during 1999 were as high as 3.7 kg N ha−1, and were highest with elevated CO2and the high irrigation treatment. During periods when significant emissions were recorded, the primary end product of denitrification was N2rather than N2O. Water‐filled pore space (WFPS) was the most important single factor controlling N‐gas emissions, with the largest emissions (>500 g N2O‐N ha−1d−1) coming with >55% WFPS. Neither soil NO3−nor soil organic C alone limited N gas emissions. Elevated CO2did not result in increased N2O or N‐gas emissions with either ample or limited irrigation.
Determination and Characterization of Preferential Water Flow in Unsaturated Subsoil of Andisol
Authors: Eguchi Sadao , Hasegawa Shuichi
Published: January 2008

Experimental approaches for directly determining preferential water flow in field soils usually require artificial interruption of the soil matrix's water flow. This interruption may change the quantitative as well as the qualitative nature of the preferential water flow, particularly in soils such as Andisols where matrix water flow is the dominant process of drainage. To overcome this problem, we applied both the one‐dimensional form of Darcy's equation and the soil water balance method, during and shortly after each rain event, for characterizing as well as determining the preferential water flow across a depth of 1 m in an Andisol. The volumetric water contents and pressure potentials at different soil depths were monitored by time domain reflectometry and tensiometry during a 7‐yr period. Preferential water flow was detected only two to seven times per year; nevertheless, it accounted for 16 to 27% of the annual total drainage. These flows occurred under macroscopically homogeneous soil water conditions, with pressure potentials mostly below the air‐entry pressure in the subsoil. The in situ unsaturated hydraulic conductivity at the depth of 1 m, determined to apparently explain the total drainage during a preferential water flow event, varied over more than one order of magnitude, with little change in water content, and the maximum value reached the saturated hydraulic conductivity. This indicates that preferential water flow occurred mainly through the largest macropores at this depth due to pore‐scale physical nonequilibrium. Macropore‐mediated preferential water flow and solute transport should be considered in unsaturated subsoil of Andisols.
Influence of Soil Moisture Content on Soil Solution Composition
Authors: Dyer Carmen L. , Kopittke Peter M. , Sheldon Anna R. , Menzies Neal W.
Published: January 2008

Despite the importance of the soil solution to plant growth, few studies have considered the influence of moisture content on the composition of the soil solution. Indeed, soil solution has seldom been extracted from soils below field capacity, despite the relevance of such conditions to plants grown in the field. Soil solution was extracted from a variable‐charge soil (Oxisol) and from several permanent‐charge soils (Vertisols) at various moisture contents (potentials ranging from −5 to −230 kPa) using polyacrylonitrile hollow‐fiber filter elements and pressure chamber apparatus. For the Vertisols, a decrease in moisture content resulted in a proportionate increase in the soil solution ionic strength, a behavior similar to that expected from a solution without any solid‐phase interaction. In contrast, for the Oxisol, the ionic strength remained constant as the soil moisture content decreased due to “salt adsorption.” For soils containing excess gypsum (CaSO4·2H2O) or lime (CaCO3), the dissolution (with increasing moisture) and precipitation (with decreasing moisture) of these minerals controlled the solution concentrations of their constituent elements. The soil solution composition appeared to conform to that expected from the ratio law (valency effect). The results of this study provide evidence that the method used can extract representative soil solution from soils at moisture contents lower than field capacity. They also demonstrate that changes in soil solution ionic strength and composition, while obeying simple control mechanisms, could not be readily predicted without a detailed understanding of the soil's surface charge and exchange behavior.
Double-Stranded RNA Induces Pancreatic β-Cell Apoptosis by Activation of the Toll-Like Receptor 3 and Interferon Regulatory Factor 3 Pathways
Authors: Dogusan Zeynep , García Mónica , Flamez Daisy , Alexopoulou Lena , Goldman Michel , Gysemans Conny , Mathieu Chantal , Libert Claude , Eizirik Decio L. , Rasschaert Joanne
Published: January 2008

OBJECTIVE— Viral infections contribute to the pathogenesis of type 1 diabetes. Viruses, or viral products such as double-stranded RNA (dsRNA), affect pancreatic β-cell survival and trigger autoimmunity by unknown mechanisms. We presently investigated the mediators and downstream effectors of dsRNA-induced β-cell death.

RESEARCH DESIGN AND METHODS— Primary rat β-cells and islet cells from wild-type, toll-like receptor (TLR) 3, type I interferon receptor (IFNAR1), or interferon regulatory factor (IRF)-3 knockout mice were exposed to external dsRNA (external polyinosinic-polycytidylic acid [PICex]) or were transfected with dsRNA ([PICin]).

RESULTS— TLR3 signaling mediated PICex-induced nuclear factor-κB (NF-κB) and IRF-3 activation and β-cell apoptosis. PICin activated NF-κB and IRF-3 in a TLR3-independent manner, induced eukaryotic initiation factor 2α phosphorylation, and triggered a massive production of interferon (IFN)-β. This contributed to β-cell death, as islet cells from IFNAR1−/− or IRF-3−/− mice were protected against PICin-induced apoptosis.

CONCLUSIONS— PICex and PICin trigger β-cell apoptosis via the TLR3 pathway or IRF-3 signaling, respectively. Execution of PICin-mediated apoptosis depends on autocrine effects of type I IFNs.
Direct Administration of Insulin Into Skeletal Muscle Reveals That the Transport of Insulin Across the Capillary Endothelium Limits the Time Course of Insulin to Activate Glucose Disposal
Authors: Chiu Jenny D. , Richey Joyce M. , Harrison L. Nicole , Zuniga Edward , Kolka Cathryn M. , Kirkman Erlinda , Ellmerer Martin , Bergman Richard N.
Published: January 2008

OBJECTIVE—Intravenous insulin infusion rapidly increases plasma insulin, yet glucose disposal occurs at a much slower rate. This delay in insulin's action may be related to the protracted time for insulin to traverse the capillary endothelium. An increased delay may be associated with the development of insulin resistance. The purpose of the present study was to investigate whether bypassing the transendothelial insulin transport step and injecting insulin directly into the interstitial space would moderate the delay in glucose uptake observed with intravenous administration of the hormone.

RESEARCH DESIGN AND METHODS—Intramuscular injections of saline (n = 3) or insulin (n = 10) were administered directly into the vastus medialis of anesthetized dogs. Injections of 0.3, 0.5, 0.7, 1.0, and 3.0 units insulin were administered hourly during a basal insulin euglycemic glucose clamp (0.2mU · min−1 · kg−1).

RESULTS—Unlike the saline group, each incremental insulin injection caused interstitial (lymph) insulin to rise within 10 min, indicating rapid diffusion of the hormone within the interstitial matrix. Delay in insulin action was virtually eliminated, indicated by immediate dose-dependent increments in hindlimb glucose uptake. Additionally, bypassing insulin transport by direct injection into muscle revealed a fourfold greater sensitivity to insulin of in vivo muscle tissue than previously reported from intravenous insulin administration.

CONCLUSIONS—Our results indicate that the transport of insulin to skeletal muscle is a rate-limiting step for insulin to activate glucose disposal. Based on these results, we speculate that defects in insulin transport across the endothelial layer of skeletal muscle will contribute to insulin resistance.
Expansion and de novo generation of potentially therapeutic regulatory T cells in patients with autoimmune hepatitis
Authors: Longhi Maria Serena , Meda Francesca , Wang Pengyun , Samyn Marianne , Mieli-Vergani Giorgina , Vergani Diego , Ma Yun
Published: January 2008

CD4+CD25+ regulatory T cells (T-regs) are central to the maintenance of immune tolerance and represent an immune intervention candidate in autoimmune hepatitis (AIH), a condition characterized by impaired T-reg number and function. We investigated whether T-regs can be expanded from the existing CD4+CD25+ T cell pool and generated

de novo

from CD4+CD25− T cells in AIH patients and healthy controls. Purified CD4+CD25+ and CD4+CD25− T cells from 24 patients with type 1 AIH and 22 healthy controls were cultured for up to 5 weeks with anti-CD3/anti-CD28 T cell expander and high-dose interleukin-2 (IL-2). Cell phenotypes, suppressor ability, forkhead winged/helix transcription factor box P3 (FOXP3) gene, and protein expression were assessed weekly by cytofluorimetry, proliferation assay, real-time polymerase chain reaction (PCR), and immunoblot. During culture, the number of CD4+CD25+ T cells derived from the existing T-reg pool (expanded T-regs) and generated

de novo

from CD4+CD25− T cells (newly generated T-regs) increased constantly up to week 4 in both healthy controls and, to a lesser extent, in AIH patients. Expanded T-regs retained conventional T-reg phenotype and, compared with baseline, demonstrated more vigorous suppressive function and increased FOXP3 gene and protein expression. Newly generated T-regs not only acquired T-reg phenotype but underwent greater growth and were more resistant to apoptosis than expanded T-regs. Their suppressive function augmented throughout culture, reaching a peak at week 4, preceded by a peak FOXP3 gene and protein expression at week 2. Suppressor function and FOXP3 expression of both expanded and newly generated T-regs were higher in normal controls than in AIH patients.

Conclusion:

Functionally enhanced T-regs can be expanded and generated

de novo

in patients with AIH. This finding may assist in reconstituting impaired immune regulation and restoring peripheral tolerance through T-reg infusion in this condition. (Hepatology 2008;47:581–591.)
Secondary social anxiety in hyperkinesias
Authors: Ozel‐Kizil Erguvan Tugba , Akbostanci M. Cenk , Ozguven Halise D. , Atbasoglu Esref Cem
Published: January 2008

This is a comparison study that is aimed to investigate and compare the frequency and severity of secondary social anxiety disorder (SAD) in patients with hyperkinesias, which is associated with a significant sense of disfigurement and compromised social interaction. Patients with hemifacial spasm (n = 20), cervical dystonia (n = 20), and essential tremor (n = 20) were evaluated by SCID‐I, Liebowitz Social Anxiety Scale, Hamilton Anxiety and Depression Rating Scales, and Sheehan Disability Scale. The DSM‐IV H criterion excluding social anxiety related to a medical condition was disregarded for the diagnosis of secondary SAD. The control group (n = 60) consisted of matched healthy subjects. The frequency of the diagnosis and severity of symptoms were compared and associations with sociodemographic and clinical factors were explored. There was no difference between three patient groups in terms of the frequency or the severity of secondary SAD. Younger age and depressive symptoms were associated with the severity of secondary SAD, while severity or duration of the movement disorder or social disability was not. This study revealed a high frequency of secondary SAD in hyperkinesias, emphasizing the need for psychiatric assessment, especially for younger and depressed patients, who seem to be at greater risk. © 2007 Movement Disorder Society
Tumor Size Predicts Malignant Potential in Hürthle Cell Neoplasms of the Thyroid
Authors: Sippel Rebecca S. , Elaraj Dina M. , Khanafshar Elham , Zarnegar Rasa , Kebebew Electron , Duh Quan‐Yang , Clark Orlo H.
Published: January 2008

Background

A fine needle aspiration (FNA) diagnosis of a Hürthle cell neoplasm is associated with a 20% risk of malignancy. We sought to determine if the primary tumor size correlated with the risk of malignancy in patients with a preoperative FNA diagnosis of a Hürthle cell neoplasm.

Methods

Between January 2000 and November 2006, 57 patients underwent a thyroidectomy with a preoperative FNA diagnosis of a Hürthle cell neoplasm. Patient histories, FNA reports, operative notes, and pathology reports were retrospectively reviewed. Statistical analysis was performed.

Results

The overall rate of malignancy in patients with Hürthle cell neoplasms was 21%. The average tumor size was 3.2 cm, with malignant tumors being significantly larger than benign tumors (5.0 vs. 2.7 cm, p < 0.01). The risk of malignancy directly correlated with tumor size. No malignancies were seen in tumors 2 cm or smaller (0/15). The risk of malignancy was only 13% (6/46) in tumors 4 cm or smaller and increased to 55% (6/11) in tumors larger than 4 cm. All tumors larger than 6 cm were malignant (4/4).

Conclusions

Tumor size correlates directly with malignant potential in patients with Hürthle cell neoplasms of the thyroid. Among our patients, malignancy was not present in any tumors 2 cm or smaller and was present in all tumors larger than 6 cm. Because the risk of malignancy is greater than 50% in patients with a tumor larger than 4 cm, consideration should be given for an initial total thyroidectomy in these patients.
The so-called dry laser cleaning governed by humidity at the nanometer scale
Authors: Grojo D. , Delaporte Ph. , Sentis M. , Pakarinen O. H. , Foster A. S.
Published: January 2008

Illumination with single nanosecond pulses leads to the detachment of silica particles with 250nm radii from silicon surfaces. We identify two laser-energy dependent cleaning regimes by time-of-flight particle-scattering diagnostics. For the higher energies, the ejection of particles is produced by nanoscale ablation due to the laser field enhancement at the particle-surface interface. The damage-free regime at lower energy is shown to be governed by the residual water molecules, which are inevitably trapped on the materials. We discuss the great importance that the humidity plays on the cleaning force and on the adhesion in the experiments.
Polymer based organic solar cells using ink-jet printed active layers
Authors: Aernouts T. , Aleksandrov T. , Girotto C. , Genoe J. , Poortmans J.
Published: January 2008

Ink-jet printing is used to deposit polymer:fullerene blends suitable as active layer for organic solar cells. We show that merging of separately deposited ink droplets into a continuous, pinhole-free organic thin film results from a balance between ink viscosity and surface wetting, whereas for certain of the studied solutions clear coffee drop effect occurs for single droplets; this can be minimized for larger printed areas, yielding smooth layers with minimal surface roughness. Resulting organic films are used as active layer for solar cells with power conversion efficiency of 1.4% under simulated AM1.5 solar illumination.
Photoluminescence thermal quenching in three-dimensional multilayer Si∕SiGe nanostructures
Authors: Lee E.-K. , Tsybeskov L. , Kamins T. I.
Published: January 2008

We find that in Si∕SiGe three-dimensional multilayer nanostructures, photoluminescence intensity as a function of temperature depends on the excitation intensity. The experimental results are explained using a model where electron-hole separation and nonradiative recombination is controlled by a competition between hole tunneling and thermally activated hole diffusion over the valence band energy barriers at Si∕SiGe heterointerfaces.
Strain and vacancy cluster behavior of vanadium and tungsten-doped Ba[Zr0.10Ti0.90]O3 ceramics
Authors: Moura F. , Simões A. Z. , Cavalcante L. S. , Zampieri M. , Varela J. A. , Longo E. , Zaghete M. A. , Simões M. L.
Published: January 2008

Strain and vacancy clusters behavior of polycrystalline vanadium (V) and tungsten (W)-doped Ba[Zr0.10Ti0.90]O3, (BZT:2%V) and (BZT:2%W) ceramics obtained by the mixed oxide method was evaluated. Substitution of V and W reduces the distortion of octahedral clusters, decreasing the Raman modes. Electron paramagnetic resonance data indicate that the addition of dopants leads to defects and symmetry changes in the BZT lattice. Remnant polarization and coercive field are affected by V and W substitution due the electron-relaxation mode. The unipolar strain E curves as a function of electric field reach its maximum value for BZT:2%V and BZT:2%W ceramics.
Shape transition between symmetric and asymmetric structures in epitaxial three-dimensional strained islands
Authors: Chu Y. C. , Tsai C. J.
Published: January 2008

The total energies for the shape transition processes between symmetric and asymmetric structures in epitaxial three-dimensional strained islands are discussed here. For structures that allow height to increase simultaneously with width and length during growth, the shapes formed should be symmetric or transform from asymmetric to symmetric; for truncated-hut structures with fixed heights smaller than a critical value, the shapes formed should be asymmetric or transform from symmetric to asymmetric. The relation between the shape transition processes and the systematic conditions obtained here can be used to anticipate whether the elongated epitaxial structures are driven energetically or kinetically.
Switchable and tunable strontium titanate electrostrictive bulk acoustic wave resonator integrated with a Bragg mirror
Authors: Volatier Alexandre , Defaÿ Emmanuel , Aïd Marc , N’hari Amy , Ancey Pascal , Dubus Bertrand
Published: January 2008

The realization and the radio-frequency characterization of a tunable strontium titanate (STO) electrostrictive solidly mounted acoustic resonator (SMR) bulk acoustic wave are reported. For a 430nm thick strontium titanate layer, the resonance frequency at 2.2GHz can be switched on with a bias voltage of 6V and tuned ±0.85% with a bias voltage between 6 and 30V. No hysteresis is observed. The SMR tunability is found to be affected by (i) the variation of coupling factor versus bias which is the dominant effect and (ii) the variation of SrTiO3 stiffness at constant electric displacement.
Generation and detection of tunable phonon polaritons using a single transmission grating
Authors: Katayama Kenji , Inoue Hayato , Sugiya Hisashi , Shen Qing , Toyoda Taro , Nelson Keith A.
Published: January 2008

Frequency tunable phonon polariton waves were generated and detected using an original optical configuration of the transient grating method. In this technique, the excitation beam was shone onto a transmission grating after being transmitted through a lens, and a lithium niobate wafer located at a defocus position of the lens was irradiated by an expanded or reduced image of the transmission grating, causing excitation of phonon polaritons. Because the magnification of the light intensity pattern can be controlled by the sample-grating distance, the wavelength of the phonon polaritons, which is equal to the optical fringe spacing, can be continuously varied.
Effect of surface charge trapping on dielectric barrier discharge
Authors: Li Ming , Li Chengrong , Zhan Huamao , Xu Jinbao , Wang Xinxin
Published: January 2008

The experiment of dielectric barrier discharge in a 2mm air gap shows that the pressure range of a uniform discharge using polytetrafluoroethylene as barrier is much wider than that using quartz or alumina. The parameters of the charge trapped on the surface of these three dielectric barriers were obtained by surface charge measurement and thermally stimulated current measurement. It was found that surface charge trapping has much influence on the uniform discharge, i.e., the seed electrons necessary for uniform discharge may be produced by the desorption of the absorbed electrons in the shallow trap with energy level lower than 1eV.
Magnetic-field-induced martensitic transformation in MnNiGa:Co alloys
Authors: Ma L. , Zhang H. W. , Yu S. Y. , Zhu Z. Y. , Chen J. L. , Wu G. H. , Liu H. Y. , Qu J. P. , Li Y. X.
Published: January 2008

With a high Curie temperature and low entropy change, the magnetic-field-induced martensitic transformation has been obtained in ferromagnetic shape memory alloys MnNiGa by doping a small amount of Co. Due to the ferromagnetic activation effect of Co, a large amount of antiferromagnetically aligned Mn moments are turned into ferromagnetic ordering, which is verified by our electronic structural calculation and experimental observation. Consequently, the magnetization rises up to 70emu∕g and the magnetization difference between two phases increases about ten times, resulting in a considerable dT∕dH of 4K∕T and a well-defined reversed transformation induced by a magnetic field.
HSP72 protects against obesity-induced insulin resistance
Authors: Chung Jason , Nguyen Anh-Khoi , Henstridge Darren C. , Holmes Anna G. , Chan M. H. Stanley , Mesa Jose L. , Lancaster Graeme I. , Southgate Robert J. , Bruce Clinton R. , Duffy Stephen J. , Horvath Ibolya , Mestril Ruben , Watt Matthew J. , Hooper Philip L. , Kingwell Bronwyn A. , Vigh Laszlo , Hevener Andrea , Febbraio Mark A.
Published: January 2008

Patients with type 2 diabetes have reduced gene expression of heat shock protein (HSP) 72, which correlates with reduced insulin sensitivity. Heat therapy, which activates HSP72, improves clinical parameters in these patients. Activation of several inflammatory signaling proteins such as c-jun amino terminal kinase (JNK), inhibitor of κB kinase, and tumor necrosis factor-α, can induce insulin resistance, but HSP 72 can block the induction of these molecules
in vitro
. Accordingly, we examined whether activation of HSP72 can protect against the development of insulin resistance. First, we show that obese, insulin resistant humans have reduced HSP72 protein expression and increased JNK phosphorylation in skeletal muscle. We next used heat shock therapy, transgenic overexpression, and pharmacologic means to overexpress HSP72 either specifically in skeletal muscle or globally in mice. Herein, we show that regardless of the means used to achieve an elevation in HSP72 protein, protection against diet- or obesity-induced hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance was observed. This protection was tightly associated with the prevention of JNK phosphorylation. These findings identify an essential role for HSP72 in blocking inflammation and preventing insulin resistance in the context of genetic obesity or high-fat feeding.
Evolutionary tradeoffs can select against nitrogen fixation and thereby maintain nitrogen limitation
Authors: Menge Duncan N. L. , Levin Simon A. , Hedin Lars O.
Published: January 2008

Symbiotic nitrogen (N) fixing trees are absent from old-growth temperate and boreal ecosystems, even though many of these are N-limited. To explore mechanisms that could select against N fixation in N-limited, old-growth ecosystems, we developed a simple resource-based evolutionary model of N fixation. When there are no costs of N fixation, increasing amounts of N fixation will be selected for until N no longer limits production. However, tradeoffs between N fixation and plant mortality or turnover, plant uptake of available soil N, or N use efficiency (NUE) can select against N fixation in N-limited ecosystems and can thereby maintain N limitation indefinitely (provided that there are losses of plant-unavailable N). Three key traits influence the threshold that determines how large these tradeoffs must be to select against N fixation. A low NUE, high mortality (or turnover) rate and low losses of plant-unavailable N all increase the likelihood that N fixation will be selected against, and a preliminary examination of published data on these parameters shows that these mechanisms, particularly the tradeoff with NUE, are quite feasible in some systems. Although these results are promising, a better characterization of these parameters in multiple ecosystems is necessary to determine whether these mechanisms explain the lack of symbiotic N fixers—and thus the maintenance of N limitation—in old-growth forests.
Subjects great and small: Maxwell on Saturn's rings and kinetic theory
Authors: Garber Elizabeth
Published: January 2008

Since 1890, James Clerk Maxwell's reputation has rested upon his theory of electromagnetism. However, during his lifetime he was recognized ‘as the leading molecular scientist’ of his generation. We will explore the foundation of his significance before 1890 using his work on the stability of Saturn's rings and the development of his kinetic theory of gases, and then briefly discuss the grounds for the change of his reputation.
Localization of intense electromagnetic waves in plasmas
Authors: Shukla Padma Kant , Eliasson Bengt
Published: January 2008

We present theoretical and numerical studies of the interaction between relativistically intense laser light and a two-temperature plasma consisting of one relativistically hot and one cold component of electrons. Such plasmas are frequently encountered in intense laser–plasma experiments where collisionless heating via Raman instabilities leads to a high-energetic tail in the electron distribution function. The electromagnetic waves (EMWs) are governed by the Maxwell equations, and the plasma is governed by the relativistic Vlasov and hydrodynamic equations. Owing to the interaction between the laser light and the plasma, we can have trapping of electrons in the intense wakefield of the laser pulse and the formation of relativistic electron holes (REHs) in which laser light is trapped. Such electron holes are characterized by a non-Maxwellian distribution of electrons where we have trapped and free electron populations. We present a model for the interaction between laser light and REHs, and computer simulations that show the stability and dynamics of the coupled electron hole and EMW envelopes.
On Maxwell's equations in non-stationary media
Authors: Vorgul I
Published: January 2008

Maxwell's equations formulated for media with gradually changing conductivity are reduced to Volterra integral equations. Analytical and numerical investigations of the equations are presented for the case of gradual splash-like change in conductivity. Splash-like change in medium parameters can model any discharge phenomena, growing plasma, charge injection, etc. Exact analytical solution for the resolvent is presented and different field behaviours are analysed for the incident field as a plane wave and as an impulse.
Boundary integral equations in elastodynamics of interface cracks
Authors: Menshykov O.V , Guz I.A , Menshykov V.A
Published: January 2008

The paper concerns the validation of a method for solving elastodynamics problems for cracked solids. The proposed method is based on the application of boundary integral equations. The problem of an interface penny-shaped crack between two dissimilar elastic half-spaces under harmonic loading is considered as an example.
The effect of the interaction of cracks in orthotropic layered materials under compressive loading
Authors: Winiarski B , Guz I.A
Published: January 2008

The non-classical problem of fracture mechanics of composites compressed along the layers with interfacial cracks is analysed. The statement of the problem is based on the model of piecewise homogeneous medium, the most accurate within the framework of the mechanics of deformable bodies as applied to composites. The condition of plane strain state is examined. The layers are modelled by a transversally isotropic material (a matrix reinforced by continuous parallel fibres). The frictionless Hertzian contact of the crack faces is considered. The complex fracture mechanics problem is solved using the finite-element analysis. The shear mode of stability loss is studied. The results are obtained for the typical dispositions of cracks. It was found that the interacting crack faces, the crack length and the mutual position of cracks influence the critical strain in the composite.
Three-dimensional analysis of a functionally graded coating/substrate system of finite thickness
Authors: Kashtalyan M , Menshykova M
Published: January 2008

The concept of functionally graded material (FGM) is currently actively explored in coating design for the purpose of eliminating the mismatch of thermomechanical properties at the interfaces and thus increasing the resistance of coatings to functional failure. In the present paper, three-dimensional elastic deformation of a functionally graded coating/substrate system of finite thickness subjected to mechanical loading is investigated. A comparative study of FGM versus homogeneous coating is conducted to examine the effect of the coating type on stress and displacement fields in the system.
Derivation of special relativity from Maxwell and Newton
Authors: Dunstan D.J
Published: January 2008

Special relativity derives directly from the principle of relativity and from Newton's laws of motion with a single undetermined parameter, which is found from Faraday's and Ampère's experimental work and from Maxwell's own introduction of the displacement current to be the −
c
−2
term in the Lorentz transformations. The axiom of the constancy of the speed of light is quite unnecessary. The behaviour and the mechanism of the propagation of light are not at the foundations of special relativity.
Arabidopsis NAD-Malic Enzyme Functions As a Homodimer and Heterodimer and Has a Major Impact on Nocturnal Metabolism
Authors: Tronconi Marcos A. , Fahnenstich Holger , Gerrard Weehler Mariel C. , Andreo Carlos S. , Flügge Ulf-Ingo , Drincovich María F. , Maurino Verónica G.
Published: January 2008

Although the nonphotosynthetic NAD-malic enzyme (NAD-ME) was assumed to play a central role in the metabolite flux through the tricarboxylic acid cycle, the knowledge on this enzyme is still limited. Here, we report on the identification and characterization of two genes encoding mitochondrial NAD-MEs from Arabidopsis (Arabidopsis thaliana), AtNAD-ME1 and AtNAD-ME2. The encoded proteins can be grouped into the two clades found in the plant NAD-ME phylogenetic tree. AtNAD-ME1 belongs to the clade that includes known α-subunits with molecular masses of approximately 65 kD, while AtNAD-ME2 clusters with the known β-subunits with molecular masses of approximately 58 kD. The separated recombinant proteins showed NAD-ME activity, presented comparable kinetic properties, and are dimers in their active conformation. Native electrophoresis coupled to denaturing electrophoresis revealed that in vivo AtNAD-ME forms a dimer of nonidentical subunits in Arabidopsis. Further support for this conclusion was obtained by reconstitution of the active heterodimer in vitro. The characterization of loss-of-function mutants for both AtNAD-MEs indicated that both proteins also exhibit enzymatic activity in vivo. Neither the single nor the double mutants showed a growth or developmental phenotype, suggesting that NAD-ME activity is not essential for normal autotrophic development. Nevertheless, metabolic profiling of plants completely lacking NAD-ME activity revealed differential patterns of modifications in light and dark periods and indicates a major role for NAD-MEs during nocturnal metabolism.
A bibliometric analysis of the literature of chemoinformatics
Authors: Willett Peter
Published: January 2008

Purpose

The purpose of this article is to analyse the literature of chemoinformatics, a subject that has arisen over the last few years and that draws on techniques from a range of disciplines, most notably chemistry (particularly computational and medicinal chemistry), computer science and information science.

Design/methodology/approach

Discusses subject, author and citation searches of (principally) the web of knowledge database.

Findings

The Journal of Chemical Information and Modeling (previously the Journal of Chemical Information and Computer Sciences) is the core journal for the subject, but with many significant papers being published in journals whose principal focus is molecular modelling, quantitative structure‐activity relationships or more general aspects of chemistry. The discipline is international in scope, and many of the most cited papers describe software packages that play a key role in modern chemoinformatics research.

Originality/value

This is the first bibliometric study of chemoinformatics, and one of only a very few that consider the bibliometrics of computational chemistry more generally.