bluuebunny/crossref_metadata_2025 huggingface dataset:
Compounds from an unbiased chemical screen reverse both ER-to-Golgi trafficking defects and mitochondrial dysfunction in Parkinson’s disease models
Authors: Su Linhui Julie , Auluck Pavan K. , Outeiro Tiago Fleming , Yeger-Lotem Esti , Kritzer Joshua A. , Tardiff Daniel F. , Strathearn Katherine E. , Liu Fang , Cao Songsong , Hamamichi Shusei , Hill Kathryn J. , Caldwell Kim A. , Bell George W. , Fraenkel Ernest , Cooper Antony A. , Caldwell Guy A. , McCaffery J. Michael , Rochet Jean-Christophe , Lindquist Susan
Published: December 2009

α-Synuclein (α-syn) is a small lipid-binding protein involved in vesicle trafficking whose function is poorly characterized. It is of great interest to human biology and medicine because α-syn dysfunction is associated with several neurodegenerative disorders, including Parkinson’s disease (PD). We previously created a yeast model of α-syn pathobiology, which established vesicle trafficking as a process that is particularly sensitive to α-syn expression. We also uncovered a core group of proteins with diverse activities related to α-syn toxicity that is conserved from yeast to mammalian neurons. Here, we report that a yeast strain expressing a somewhat higher level of α-syn also exhibits strong defects in mitochondrial function. Unlike our previous strain, genetic suppression of endoplasmic reticulum (ER)-to-Golgi trafficking alone does not suppress α-syn toxicity in this strain. In an effort to identify individual compounds that could simultaneously rescue these apparently disparate pathological effects of α-syn, we screened a library of 115,000 compounds. We identified a class of small molecules that reduced α-syn toxicity at micromolar concentrations in this higher toxicity strain. These compounds reduced the formation of α-syn foci, re-established ER-to-Golgi trafficking and ameliorated α-syn-mediated damage to mitochondria. They also corrected the toxicity of α-syn in nematode neurons and in primary rat neuronal midbrain cultures. Remarkably, the compounds also protected neurons against rotenone-induced toxicity, which has been used to model the mitochondrial defects associated with PD in humans. That single compounds are capable of rescuing the diverse toxicities of α-syn in yeast and neurons suggests that they are acting on deeply rooted biological processes that connect these toxicities and have been conserved for a billion years of eukaryotic evolution. Thus, it seems possible to develop novel therapeutic strategies to simultaneously target the multiple pathological features of PD.
Experimental and crystal plasticity studies of deformation and crack nucleation in a titanium alloy
Authors: Bache M R , Dunne F P E , Madrigal C
Published: December 2009

This paper presents recent developments in crystal plasticity modelling to incorporate a non-local crack nucleation criterion and the comparison of experimental observations and model predictions for deformation and crack nucleation in a near-alpha titanium (Ti) alloy polycrystal. The model polycrystal was established so as to have grain morphology and crystallography nominally identical to that in the experiment, enabling direct interpretation and comparison of the results. The experimental measurements of strain fields were obtained using electronic speckle pattern interferometry on a large-grained polycrystalline sample.

The crystal plasticity model predictions and experiments show strong agreement in a number of important features relating to crack nucleation: the location of crack nucleation, the direction changes in crack growth when the crack crosses two grain boundaries, and the important role of crystallographic orientation in nucleation site and in growth directions. There was also good agreement in the establishment of strain heterogeneity and in localization; both experiment and crystal plasticity predictions demonstrate that the heterogeneity is established early in the loading history and that the localization correlates closely with the crack nucleation site.
Laser pulse heating and phase change process: A comparison of volumetric heat source models
Authors: Shuja S Z , Yilbas B S , Ayar Z
Published: December 2009

In the laser heating process, irradiated energy is absorbed on the surface skin of the substrate material. This results in excess computational efforts due to grid arrangement in the irradiated region and the remaining region in the solution domain due to the fine grid spacing in the irradiated region. However, consideration of the surface heat source minimizes this problem, since it does not require fine grid spacing in the skin of the surface. In the present study, laser heating and phase change in the irradiated region are modelled. The laser heating situation is modelled after considering the volumetric heat source incorporating an absorption process (Beer—Lambert's Law) and the surface heat source model. The temperature distribution, melt layer, and solid—liquid zone (mushy zone) formed in the heated region are predicted for the volumetric and surface heat source heating models. This study is extended to include the influence of spatial distribution of the laser pulse on temperature rise and phase change processes. It is found that the surface heat source model predicts higher values of temperature than those corresponding to the volumetric heat source in the surface vicinity. As the depth increases, temperature distributions predicted from both models become almost identical. In addition, the melt layer thickness and mushy zone predicted from both models are almost identical.
Analysis of micro-stresses in the SiC/Ti metal matrix composite using a truly local meshless method
Authors: Ahmadi I , Aghdam M M
Published: December 2009

A generalized plane strain micromechanical model is developed for the analysis of unidirectional fibre-reinforced composites subjected to various combined normal loading conditions. Based on the integral form of the equilibrium equations, a truly meshless method is presented to obtain the solution for the governing equations of the problem. By employing the integral form of equilibrium equations for each sub-domain, the domain integration is eliminated from the formulation and the computational time is considerably reduced. The solution domain includes a quarter of the fibre surrounded by the corresponding matrix known as the representative volume element (RVE). The appropriate boundary conditions are imposed on the RVE using a direct interpolation method. The continuity of displacements and reciprocity of traction are imposed on the fibre—matrix interface based on the fully bonded interface condition. The presented model is used to predict the micro-stresses in the SiC/Ti metal matrix composites. Comparison of the CPU time between the presented model and the conventional meshless local Petrov—Galerkin model shows significant reduction of computational time. The results also revealed that the presented model can provide highly accurate predictions with a relatively small number of nodes. Comparison of the predicted results shows excellent agreement with available experimental and finite-element studies.
The fixed-points theory revisited with new applications
Authors: Dayou J
Published: December 2009

The fixed-points theory has its root dating back to 1932. Hahnkamm suggested that there are two fixed points in the undamped primary structure's frequency response function (FRF) for the two-degree-of-freedom system when a harmonic force is applied to the primary mass. These points are independent of the damping value in the auxiliary system, which is the control system, and their heights are mainly determined by the mass ratio of the device. The desired optimum value of the tuning ratio is obtained when the heights of the fixed points are equal. Fourteen years later, Brock suggested that the optimum value of the damping ratio in the control device can be determined by making the height of the fixed points the maximum. Since then, the fixed-points theory has been used in many applications as one of the design laws in fabricating a vibration neutralizer. In this article, the theory is reformulated by using the conventional definition of the damping ratio. It is proved that the same result can be obtained as in the original derivation. The application of the theory is then extended to the control of global vibration of an undamped continuous structure and is demonstrated on a simply supported beam.
An active mount using an electromagnetic actuator for vibration control: Experimental investigation
Authors: Sohn J W , Paeng Y-S , Choi S-B
Published: December 2009

In this work, the vibration control performance of an active mount using an electromagnetic actuator is experimentally evaluated. After manufacturing an electromagnetic actuator, dynamic characteristics such as the actuating force and response time of the electromagnetic actuator are experimentally investigated. The material properties of the rubber element are also experimentally identified. An active mount system using an electromagnetic actuator and a rubber element is designed and the governing equation is derived. A sliding mode controller that has inherent robustness to external disturbance is designed and implemented in the system. Vibration control performances of the active mount system, such as acceleration and transmitted force, are experimentally evaluated and they are presented in both time and frequency domains. It is observed that the structural vibration is effectively attenuated by applying proper control input to the electromagnetic actuator.
A mathematical model of a worm mechanism generated by a conical cutter
Authors: Yang S-C
Published: December 2009

In this article, an imaginary conical cutter was used to determine the geometric models of the worm—gear mechanism including a worm and a gear. Mathematical models of the worm and the gear were derived using an imaginary conical cutter and gear theory. Based on the geometric relations between the worm and conical cutter surfaces and between the gear and conical cutter surfaces, the worm and the gear were regarded as an envelope to the family of conical cutter surfaces when they rotated for one cycle. Using the developed mathematical model, the stress analysis of the proposed mechanism was examined. The results show that the von Mises stress and volume of the proposed worm and gear were smaller than those of the conventional worm—gear mechanism. Lastly, a numerical example was used to illustrate the geometric model of a gear and a worm with a gear ratio of 30:1.
Analysis and simulation of a new Cartesian cable-suspended robot
Authors: Castelli G , Ottaviano E , González A
Published: December 2009

In this article, a manipulator is presented belonging to the class of cable-suspended robots, for which the cable length variations are related by suitable functions in order to achieve specific kinematic characteristics. In particular, in this article, a Cartesian cable-suspended robot is proposed that has eight cables to have three degrees of freedom (DOF) in Cartesian space. The eight cables of the robot are arranged in parallel by pairs with identical length, with the aim of constraining the moving platform to keep a constant orientation with respect to the fixed frame. The robot can be used for selective compliant assembly robot arm (SCARA) motions (when an additional revolute actuated joint is placed on the moving platform) for a variety of applications in which a large workspace is required. In this article, a geometry analysis of the robot is presented together with a numerical simulation of the kinetostatics and dynamics to investigate the robot's performances in several operative conditions. Furthermore, a characterization of the position workspace regions is reported for this cable-suspended robot.
A Galerkin-type finite element solution for simulation of mass diffusion in the application of tissue engineering: Heterogeneous and non-porous media
Authors: Mohammadi H , Mequanint K , Bahramian F
Published: December 2009

This study is an effort to produce a generic and comprehensive solution to the simulation of mass diffusion through a multiphasic and heterogeneous material model. A Galerkin-type finite element formulation is developed to solve Fick's equation for steady-state and time-dependent analysis. The effect of the interface in modelling of a liquid—solid medium is presented in this work. To show the robustness of the proposed approach, the gas exchange (oxygen and carbon dioxide) process through the capillary network between the alveolar membrane and red blood cells has been analysed and then validated with experimental data. The current work is a significant asset to modelling the diffusion of oxygen between cells and scaffolds in tissue engineering or tissue regeneration/repair studies. It is one step towards the development of high-order elements for application of the simulation of mass transfer through a multiphasic and porous model with varying degrees of interconnectivity and pore size for tissue engineering applications.
Discriminating contact in lumen with a moving flexible digit using fibre Bragg grating sensing elements
Authors: Tam B , Ma X , Webb D J , Holding D J , Brett P N
Published: December 2009

Minimal access procedures in surgery offer benefits of reduced patient recovery time and less pain, yet for the surgeon the task is more complex, as both tactile and visual perception of the working site is reduced. In this paper, experimental evidence of the performance of a novel sensing system embedded in an actuated flexible digit element is presented. The digit represents a steerable tip element of devices such as endoscopes and laparoscopes. This solution is able to discriminate types of contact and tissue interaction, and to feed back this information with the shape of the flexible digit. As an alternative to this information, force level, force distribution, and other quantifiable descriptors can also be evaluated. These can be used to aid perception in processes such as navigation and investigation of tissues through palpation. The solution is pragmatic, and by virtue of its efficient mechanical construction and a polymer construction, it offers opportunities for a disposable element with suitability for magnetic resonance imaging (MRI) and other scanning environments. By using only four photonics sensing elements, full perception of tissue contact and the shape of the actuated digit can be described in the feedback of this information. The distributive sensory method applied to the sensory signals relies on the coupled values of the sensory data transients of the four deployed sensing elements to discriminate tissue interaction directly in near real time.
Polyethylene insert damage in unicondylar knee replacement: A comparison of in vivo function and in vitro simulation
Authors: Harman M , Affatato S , Spinelli M , Zavalloni M , Stea S , Toni A
Published: December 2009

Modification of knee joint wear simulation methods has included ‘anatomic attachment’ of unicondylar knee replacements (UKR) onto synthetic femurs with material properties and morphology similar to human femurs. The present study assesses the effect of such modification by comparing the damage patterns on UKR polyethylene inserts after in vitro simulation using standard and modified simulation methods with those on inserts retrieved after in vivo function. Three groups of UKR inserts were evaluated after retrieval (Explant Group, n = 17) or after knee joint wear simulation with the components attached to standard metal blocks (Standard Group, n = 6) or synthetic femurs (Anatomic Group, n = 6). All UKR had similar non-conforming articular surfaces. Articular damage patterns (mode, frequency, and area) were quantified using digital image photogrammetry. Although some common damage modes were noted, knee joint wear simulation with standard or ‘anatomic’ attachment did not generate damage pattern sizes similar to the explanted UKR. A focal damage pattern consistent with contact between the metal femoral articular surface and the polyethylene inserts was evident on all inserts, but only the Explant Group had evidence of dispersed damage dominated by abrasive modes. Synthetic femurs added complexity to the wear simulation without generating wear patterns substantially more similar to those observed on retrieved inserts.
Bi-unicondylar knee prosthesis functional assessment utilizing force-control wear testing
Authors: Spinelli M , Affatato S , Harman M K , DesJardins J D
Published: December 2009

Recent in vivo studies have identified variations in knee prosthesis function depending on prosthesis geometry, kinematic conditions, and the absence/presence of soft-tissue constraints after knee replacement surgery. In particular, unicondylar knee replacements (UKR) are highly sensitive to such variations. However, rigorous descriptions of UKR function through experimental simulation studies, performed under physiological force-controlled conditions, are lacking. The current study evaluated the long-term functional performance of a widely used fixed-bearing unicompartmental knee replacement, mounted in a bi-unicondylar configuration (Bi-UKR), utilizing a force-controlled knee simulator during a simulated (ISO 14243) walking cycle. The wear behaviour, the femoral—tibial kinematics, and the incurred damage scars were analysed. The wear rates for the medial and the lateral compartments were 10.27 ± 1.83 mg/million cycles and 4.49 ± 0.53 mg/million cycles, respectively. Although constant-input force-controlled loading conditions were maintained throughout the simulation, femoral—tibial contact point kinematics decreased by 65 to 68 per cent for average anterior/posterior travel and by 58 to 74 per cent for average medial/lateral travel with increasing cycling time up to 2 million cycles. There were no significant differences in damage area or damage extent between the medial and the lateral compartments. Focal damage scars representing the working region of the femoral component on the articular surface extended over a range of 16—21 mm in the anterior—posterior direction. Kinematics on the shear plane showed slight variations with increasing cycling time, and the platform exhibited medial pivoting over the entire test. These measures provide valuable experimental insight into the effect of the prosthesis design on wear, kinematics, and working area. These functional assessments of Bi-UKR under force-controlled knee joint wear simulation show that accumulated changes in the UKR articular conformity manifested as altered kinematics both for anterior/posterior translations and internal/external rotations.
Stall inception and its control in an axial flow fan under dynamic inflow distortion
Authors: Salunkhe P B , Pradeep A M
Published: December 2009

The present experimental study demonstrates the effects of clean and distorted inflow conditions on the performance and nature of stall inception in a single stage axial flow fan. A 90° distortion screen located upstream of the rotor leading edge was rotated up to 40 per cent of the rotor speed in the clockwise (co-rotation) and counterclockwise (counter-rotation) directions to generate dynamic inflow distortion. It was observed that the stall margin deteriorated substantially under co-rotating inflow distortion as compared to counter-rotating inflow distortion. The degradation in stall margin was about 15 per cent and 1.98 per cent under co- and counter-rotating inflow distortions, respectively. Tip injection was used as a means of enhancing the fan performance under distorted inflow. With tip injection under co-rotating inflow distortion, about 2.8 per cent improvement in stall margin was observed. The improvement in stall margin under counter-rotating inflow distortion with tip injection was 2.98 per cent. The unsteady static pressure traces show clear differences in the nature of stall inception under co- and counter-rotating inflow distortions. The stall inception occurs through long-length-scale disturbances under co-rotating inflow distortion, while the mode of stall inception under clean flow and counter-rotating inflow distortions was through short-length-scale disturbances. The nature of stall inception under dynamic inflow distortion with tip injection remains the same as without tip injection.
Performance and emission investigation of a four-stroke liquefied petroleum gas spark-ignition engine generator used in a Malaysian night market
Authors: Yusaf T F , Said M A , Hussein I
Published: December 2009

The objective of this study is to investigate and compare the performance and emission characteristics of the liquefied petroleum gas (LPG)-fuelled engine generator and the conventional gasoline-fuelled engine generator. The approach involves converting a gasoline engine generator, commonly used in Malaysian night markets to generate electricity, to the LPG engine generator. A four-stroke SI single-cylinder engine is equipped with an LPG injection system with minor modifications and then tested with both LPG and gasoline fuels. A venturi mixer (carburettor) was designed and in house constructed and then installed to deliver a proper A/ F ratio to the combustion chamber. The commercial computational fluid dynamics software FLUENT was used for simulation of air flow inside the mixer.

The converted engine was tested at constant speed for its brake-specific fuel consumption (BSFC), efficiency, exhaust temperature, and exhaust gas emissions. The results show that the performance and emission characteristics of the LPG-fuelled engine are well suited for use in night markets. Average BSFC and average efficiency for the LPG engine over a range of loads were quite similar to those for the gasoline engine: the average BSFC was 0.95 kg/kWh for the LPG engine and 1 kg/kWh for the gasoline engine.

The use of LPG as fuel in a gasoline engine causes only a slight reduction in efficiency as a 17 per cent reduction in average efficiency was recorded over the entire load range; however, the LPG engine fared better at higher loads than the gasoline engine for which only as low as a 4 per cent reduction was recorded at high loads. Emission tests seem to verify the minimal pollution products; there are significant reductions in the emission concentration results when LPG is used. Average decreases of 32 per cent for nitrogen oxide, 10 per cent for carbon dioxide, and 40 per cent for carbon monoxide were recorded. Although higher values of hydrocarbon (HC) were recorded, a 50 per cent reduction in HC was found for loads higher than 700 W. The study verified the more favourable features of LPG compared to gasoline as it is one of the best alternative fuels to gasoline for spark-ignition engine generators to solve the air pollution problem in night markets.
The adenosine wedge: A new structural motif in ribosomal RNA
Authors: Gagnon Matthieu G. , Steinberg Sergey V.
Published: December 2009

Here, we present a new recurrent RNA arrangement, the so-called adenosine wedge (A-wedge), which is found in three places of the ribosomal RNA in both ribosomal subunits. The arrangement has a hierarchical structure, consisting of elements previously described as recurrent motifs, namely, the along-groove packing motif, the A-minor and the hook-turn. Within the A-wedge, these elements are involved in different types of cause–effect relationships, providing together for the particular tertiary structure of the motif.
Computational prediction of Caenorhabditis box H/ACA snoRNAs using genomic properties of their host genes
Authors: Wang Paul Po-Shen , Ruvinsky Ilya
Published: December 2009

Identification of small nucleolar RNAs (snoRNAs) in genomic sequences has been challenging due to the relative paucity of sequence features. Many current prediction algorithms rely on detection of snoRNA motifs complementary to target sites in snRNAs and rRNAs. However, recent discovery of snoRNAs without apparent targets requires development of alternative prediction methods. We present an approach that combines rule-based filters and a Bayesian Classifier to identify a class of snoRNAs (H/ACA) without requiring target sequence information. It takes advantage of unique attributes of their genomic organization and improved species-specific motif characterization to predict snoRNAs that may otherwise be difficult to discover. Searches in the genomes of Caenorhabditis elegans and the closely related Caenorhabditis briggsae suggest that our method performs well compared to recent benchmark algorithms. Our results illustrate the benefits of training gene discovery engines on features restricted to particular phylogenetic groups and the utility of incorporating diverse data types in gene prediction.
High-throughput quantification of splicing isoforms
Authors: Brosseau Jean-Philippe , Lucier Jean-François , Lapointe Elvy , Durand Mathieu , Gendron Daniel , Gervais-Bird Julien , Tremblay Karine , Perreault Jean-Pierre , Elela Sherif Abou
Published: December 2009

Most human messenger RNAs (mRNAs) are alternatively spliced and many exhibit disease-specific splicing patterns. However, the contribution of most splicing events to the development and maintenance of human diseases remains unclear. As the contribution of alternative splicing events to diagnosis and prognosis is becoming increasingly recognized, it becomes important to develop precise methods to quantify the abundance of these isoforms in clinical samples. Here we present a pipeline for real-time PCR annotation of splicing events (RASE) that allows accurate identification of a large number of splicing isoforms in human tissues. The RASE automatically designed specific primer pairs for 81% of all alternative splicing events in the NCBI build 36 database. Experimentally, the majority of the RASE designed primers resulted in isoform-specific amplification suitable for quantification in human cell lines or in formalin-fixed, paraffin-embedded (FFPE) RNA extract. Using this pipeline it is now possible to rapidly identify splicing isoform signatures in different types of human tissues or to validate complete sets of data generated by microarray expression profiling and deep sequencing techniques.
Proteomics Research to Discover Markers: What Can We Learn from Netflix®?
Authors: Ransohoff David F
Published: December 2009

Background: Research in the field of proteomics to discover markers for detection of cancer has produced disappointing results, with few markers gaining US Food and Drug Administration approval, and few claims borne out when subsequently tested in rigorous studies. What is the role of better mathematical or statistical analysis in improving the situation?

Content: This article examines whether a recent successful Netflix-sponsored competition using mathematical analysis to develop a prediction model for movie ratings of individual subscribers can serve to improve studies of markers in the field of proteomics. Netflix developed a database of movie preferences of individual subscribers using a longitudinal cohort research design. Groups of researchers then competed to develop better ways to analyze the data. Against this background, the strengths and weaknesses of research design are reviewed, contrasting the Netflix design with that of studies of biomarkers to detect cancer. Such biomarker studies generally have less-strong design, lower numbers of outcomes, and greater difficulty in even just measuring predictors and outcomes, so the fundamental data that will be used in mathematical analysis tend to be much weaker than in other kinds of research.

Conclusions: If the fundamental data that will be analyzed are not strong, then better analytic methods have limited use in improving the situation. Recognition of this situation is an important first step toward improving the quality of clinical research about markers to detect cancer.
Ssz1 Restores Endoplasmic Reticulum-Associated Protein Degradation in Cells Expressing Defective Cdc48–Ufd1–Npl4 Complex by Upregulating Cdc48
Authors: Bosis Eran , Salomon Dor , Ohayon Orit , Sivan Gilad , Bar-Nun Shoshana , Rabinovich Efrat
Published: December 2009

The endoplasmic reticulum (ER)-associated protein degradation (ERAD) pathway eliminates aberrant proteins from the ER. The key role of Cdc48p–Ufd1p–Npl4p is indicated by impaired ERAD in Saccharomyces cerevisiae with mutations in any of this complex's genes. We identified SSZ1 in genetic screens for cdc48-10 suppressors and show that it upregulates Cdc48p via the pleiotropic drug resistance (PDR) network. A pSSZ1 plasmid restored impaired ERAD-M of 6myc-Hmg2 in cdc48-10, ufd1-2, and npl4-1, while SSZ1 deletion had no effect. Ssz1p activates Pdr1p, the PDR master regulator. Indeed, plasmids of PDR1 or its target gene RPN4 increased cdc48-10p levels and restored ERAD-M in cdc48-10. Rpn4p regulates transcription of proteasome subunits and CDC48, thus RPN4 deletion abolished ERAD. However, the diminished proteasome level in Δrpn4 was sufficient for degrading a cytosolic substrate, whereas the impaired ERAD-M was the result of diminished Cdc48p and was restored by expression of pCDC48. The corrected ERAD-M in the hypomorphic strains of the Cdc48 partners ufd1-2 and npl4-1 by the pCDC48 plasmid, and in cdc48-10 cells by the pcdc48-10 plasmid, combined with the finding that neither pSSZ1 nor pcdc48-10 restored ERAD-L of CPY*-HA, support our conclusion that Ssz1p suppressing effects is brought about by upregulating Cdc48p.
The Rim101p/PacC Pathway and Alkaline pH Regulate Pattern Formation in Yeast Colonies
Authors: Piccirillo Sarah , White Melissa G , Murphy Jeffrey C , Law Douglas J , Honigberg Saul M
Published: December 2009

Multicellular organisms utilize cell-to-cell signals to build patterns of cell types within embryos, but the ability of fungi to form organized communities has been largely unexplored. Here we report that colonies of the yeast Saccharomyces cerevisiae formed sharply divided layers of sporulating and nonsporulating cells. Sporulation initiated in the colony's interior, and this region expanded upward as the colony matured. Two key activators of sporulation, IME1 and IME2, were initially transcribed in overlapping regions of the colony, and this overlap corresponded to the initial sporulation region. The development of colony sporulation patterns depended on cell-to-cell signals, as demonstrated by chimeric colonies, which contain a mixture of two strains. One such signal is alkaline pH, mediated through the Rim101p/PacC pathway. Meiotic-arrest mutants that increased alkali production stimulated expression of an early meiotic gene in neighboring cells, whereas a mutant that decreased alkali production (cit1Δ) decreased this expression. Addition of alkali to colonies accelerated the expansion of the interior region of sporulation, whereas inactivation of the Rim101p pathway inhibited this expansion. Thus, the Rim101 pathway mediates colony patterning by responding to cell-to-cell pH signals. Cell-to-cell signals coupled with nutrient gradients may allow efficient spore formation and spore dispersal in natural environments.
Tatra Tiger growth miracle or belated recovery?
Authors: Pogátsa Z.
Published: December 2009

The article agues that the much heralded Tatra Tiger phenomenon in Slovakia is much less of a miraculous growth and catch up story akin to the Asian Tigers or Ireland, and much more of a late economic recovery based on a radical opening to FDI and the reduction of the Slovak welfare state. It attempts to demonstrate how the low rate flat tax system had much less influence on this success story, and how the average Slovak citizen benefited less from it than it is usually assumed. It also aims to raise concerns about the sustainability of this model, as well as its applicability in other economies of the region.
Return calculation methodology: Evidence from the Hungarian mutual fund industry
Authors: Erdős P. , Ormos M.
Published: December 2009

In the empirical finance literature most frequently monthly returns are applied for measuring fund performance or testing market efficiency. We propose a new return calculation method, the daily recalculated monthly returns which has not been used in academic studies for asset pricing purposes. We argue that our method outperforms daily and monthly return calculations in the case of Hungarian mutual funds when only short time series are available. Daily recalculated monthly returns induce the best fitting property of the market model while the time series remain sufficiently long to derive asymptotic tests even when we work on a one-year-long time series. Using our method the estimated parameters and theR2s are very close to the results obtained when using monthly returns which are considered a good working approximation.
A simultaneous equation model for estimating corruption in higher education
Authors: Andrei T. , Teodorescu D. , Bourbonnais R. , Oancea B.
Published: December 2009

The aim of this study is to highlight the characteristics of corruption and non-academic behaviour in higher education. Using data series recorded at a representative student sample we emphasise causal relationships between certain components of corruption and aspects of academic behaviour in universities, and the usefulness and quality of university education. The novelty of this study is the usage of a simultaneous equation model in analysing the causal relationship between corruption, academic behaviour, the quality of education and the utility of studies. By applying the simultaneous equation model we outline a number of factors that can directly contribute to the reduction of corruption. These factors include the stimulation of the academic behaviour of students and teachers, the improvement of the quality of education, and the increase of the usefulness of studies in personality development.
On the relationship between education and country-risk: A new fact
Authors: Sequeira T.
Published: December 2009

The relationship between education and country-risk is an almost neglected question in economic literature, despite the several reasons for which these two issues could be related. In a recent article by Sequeira — Ferraz (2009) a linear relationship is documented. The present article provides evidence that the strength of the relationship between country-risk and education decreases for higher levels of GDP. It also proves that this decrease consistently applies for secondary and tertiary education levels and for the three types of risk considered: economic, financial and political. The relationship obtained here is quite robust across the different subcomponents of country-risk.
Real-time Imaging of the Electric field Distribution in CdZnTe at low temperature
Authors: Sellin Paul , Prekas Georgios , Lohstroh Annika , Ozsan Ersin , Veeramani Perumal , Veale Matt , Seller Paul
Published: December 2009

Real time imaging of the electric field distribution in CZT at low temperature has been carried out using the Pockels electro-optical effect. CZT detectors have been observed to show degraded spectroscopic resolution at low temperature due to so-called ‘polarization’ phenomena. By mounting a CZT device in a custom optical cryostat, we have used Pockels imaging to observe the distortion of the electric field distribution in the temperature range 240K - 300K. At 240K the electric field has a severely non-uniform depth distribution, with a high field region occupying ∼10% of the depth of the device under the cathode electrode and a low field in the remainder of the device. Using an alpha particle source positioned inside the vacuum chamber we have performed simultaneous alpha particle transient current (TCT) measurements. At low temperatures the alpha particle current pulses become significantly shorter, consistent with the reduced electron drift time due to a non-uniform electric field. These data provide useful insights into the mechanisms which limit the spectroscopic performance of CZT devices at reduced temperature.
Scintillating Metal Organic Frameworks: A New Class of Radiation Detection Materials
Authors: Allendorf Mark , Houk Ronald , Bhakta Raghu , Nielsen Ida Beck , Doty Patrick
Published: December 2009

The detection and identification of subatomic particles is an important scientific problem with implications for medical devices, radiography, biochemical analysis, particle physics, and astrophysics. In addition, the development of efficient detectors of neutrons generated by fissile material is a pressing need for nuclear nonproliferation and counterterrorism efforts. A critical objective in the field of radiation detection is to develop the physical insight necessary to rationally design new scintillation materials for specific applications. However, none of the material types currently used in has sufficient synthetic versatility to exert systematic control over the factors controlling the light output and its dynamics. Here we describe a spectroscopic investigation of two stilbene-based metal-organic frameworks (MOFs) we synthesized, demonstrating that they emit light in response to ionizing radiation, creating the first completely new class of scintillation materials since the advent of plastic scintillators in 1950. This highly novel and unexpected property of MOFs opens a new route to rational design of radiation detection materials, since the spectroscopy shows that both the luminescence spectrum and its timing can be varied by altering the local environment of the chromophore within the MOF. Therefore, the inherent synthetic flexibility of MOFs, which enables both the chromophore structure and its local environment to be systematically varied, suggests that this class of materials can serve as a controlled “nanolaboratory” for probing a broad range of photophysical and radiation detection phenomena. In this presentation we report on the time-dependent fluorescence and radioluminescence of these MOFs and related structures. Multiple decay characteristics have been observed for some materials under study, including fast (ns) exponential and slow (microsecond) non-exponential components. We interpret the results in terms of the electronic states, crystal structures, intermolecular interactions, and transport effects mediating the luminescence. The potential for particle discrimination schemes and large scale production of MOFs and will be discussed.
A Study of Bismuth Induced Levels in CZT Using TEES/TSC
Authors: Soundararajan Raji , Jones Kelly A. , Swain Santosh , Lynn Kelvin
Published: December 2009

Considering the desirable effects of doping CdTe with heavy elements like Bi, we have grown a Cadmium Zinc Telluride (Zn=10%) ingot with Bi (doping levels ∼1014 to 1015 at/cm3) as the heavy element dopant for use as a room temperature radiation detector, using the Bridgman method. In-spite of a high bulk resitivity (∼1010?cm), and the ability to hold high electric field (>2000 V/cm), these lightly doped crystals had a poor spectral resolution for the Co-57 photo peaks and ??e measurements were so low that these measurement were not reliable. Thermo electric effect spectroscopy (TEES) and thermally stimulated current (TSC) experiments on samples C and F (single crystals close to the tip and the heel of the ingot respectively) have revealed various defect levels in the band gap. Among these defect levels, we have identified and characterized two Bi-related deep levels namely a deep donor level L5 (thermal ionization energy: 0.33[5] to 0.39[5] eV and trap cross-section: 7.1[5] × 10-17 to 2.54 [5] × 10-16 cm2), and a deep acceptor level L8 (thermal ionization energy of 0.82 [5] eV and trap cross-section of 2.59 [5] × 10-12 cm2). These levels were responsible for the observed high electrical resistivity (∼1010 ?*cm) in the CdZnTe samples. From a comparison to studies on Bi doped CdTe samples, level L8 was tentatively associated with the (0/-) transition of (BiCd- - OTe) complex, however is still under study. Since these defect levels also act as trapping centers for charge carriers, in spite of the semi-insulating behavior the samples are poor radiation detectors.
Quantifying the Flow of Exergy and Carbon through the Natural and Human Systems
Authors: Sassoon Richard E , Hermann Weston A , Hsiao I-Chun , Milkovic Ljuba , Simon Aaron J , Benson Sally M
Published: December 2009

Exergy is the useful portion of energy that allows us to do work and perform energy services. While energy is conserved, exergy is not; some exergy is destroyed whenever energy undergoes a conversion. We gather exergy from distinct, energy-carrying resources that are found in the natural world. These resources are converted into energy carriers that are convenient to use in our factories, vehicles, and buildings for heating, lighting and mechanical services. While there is no shortage of exergy resources, there are considerable environmental, economic, and other constraints associated with the manner and magnitude of their use. This article describes an approach to examining and presenting data on energy use at a global scale. It provides insights into the efficiencies and carbon emissions of many energy pathways, and can provide a basis for an examination of future energy options. In this study, we trace the flow of exergy and carbon through the natural and human systems, revealing the major destructions of exergy, the exergy efficiency of engineered energy processes, and the processes with the highest associated atmospheric carbon emissions. These data have been collected in a relational database available online at http://gcep.stanford.edu/research/exergy/data.html and are presented here in a set of exergy and carbon flow charts.
High-temperature Oxidation of Metallic Alloys for SOFC Interconnects: Stress and Morphological Developments during Oxide Scale Growth
Authors: Saillard Audric , Cherkaoui Mohammed , Capolungo Laurent , Busso Esteban P.
Published: December 2009

This work investigates the critical stress and morphological evolutions which occur during the high-temperature oxidation of metallic alloys for SOFC interconnects. Two mechanisms of stress generation are considered related to (1) the local volume change associated with the direct oxidation of the metal and to (2) a secondary oxidation process within grain boundaries. A specific formulation is developed to include the influence of the stress state at the metal-oxide interface on the local oxidation kinetics. The oxidation of a chromia-forming SOFC interconnect metallic alloy is simulated and stress and morphological evolutions are investigated.
Localized56Fe+ion implantation of TiO2using anodic porous alumina
Authors: Jensen Jens , Sanz Ruy , Jaafar Mirian , Hernández-Vélez Manuel , Asenjo Agustina , Hallen Anders , Vázquez Manuel
Published: December 2009

We present result following localized ion implantation of rutile titanium dioxide (TiO2) using anodic porous alumina as a mask. The implantation were performed with 100 keV56Fe+ions using a fluence of 1.3·1016ions/cm2. The surface modifications where studied by means of SEM, AFM/MFM and XRD. A well-defined hexagonal pattern of modified material in the near surface structure is observed. Local examination of the implanted areas revealed no clear magnetic signal. However, a variation in mechanical and electrostatic behavior between implanted and non-implanted zones is inferred from the variation in AFM signals.
Thermoelectric Generators of Sequentially Deposited Si/Si+Ge Nano-layered Superlattices
Authors: Smith Cydale , Pugh Marcus , Martin Hervie , Hill Rufus Durel , James Brittany , Budak Satilmis , Heidary K , Muntele Claudiu , Ila Daryush
Published: December 2009

Effective thermoelectric materials have a low thermal conductivity and a high electrical conductivity. The performance of the thermoelectric materials and devices is shown by a dimensionless figure of merit, ZT = S2sσ/ KTC, σ is the electrical conductivity T/KTC, where S is the Seebeck coefficient, T is the absolute temperature and KTC is the thermal conductivity. In this study we have prepared the thermoelectric generator device of Si/Si+Ge multi-layer superlattice films using the ion beam assisted deposition (IBAD). To determine the stoichiometry of the elements of Si and Ge in the grown multilayer films and the thickness of the grown multi-layer films Rutherford Backscattering Spectrometry (RBS) and RUMP simulation software package were used. The 5 MeV Si ion bombardments were performed to make quantum clusters in the multi-layer superlattice thin films to decrease the cross plane thermal conductivity, increase the cross plane Seebeck coefficient and cross plane electrical conductivity.

Keywords: Ion bombardment, thermoelectric properties, multi-nanolayers, Figure of merit.
Fabrication of Micro-Fluid-Channel Structures by Focused Ion Beam Techniques
Authors: Yanagisawa Junichi , Kobayashi Hiroaki , Koreyama Kakunen , Akasaka Yoichi
Published: December 2009

One of the new applications of focused Ga ion beam (Ga FIB) techniques to fabricate micro fluid channels on plate glass was demonstrated. After discussing features of the FIB etched patterns, narrow channel or Y-shaped channels were fabricated by FIB etching on a patterned plate glass which was prepared by photo-lithography and wet etching processes. Micro fluid devices were then constructed using polydimethylsiloxane (PDMS) sheet and silicone rubber tubes and the water (or ink) flow in the devices was observed under a microscope using a syringe pump. Although no discussion based on fluid mechanics has done at present, the present results indicate a possibility of applying FIB techniques to fabricate micro fluid devices which can be used in bio- and/or chemical-related fields.
Swift Heavy Ion Irradiation Induced Effects in Si/SiOx Multi-Layered Films and Nanostructures
Authors: Gerlach Jurgen W , Patzig C. , Assmann W. , Bergmaier A. , Höche Th. , Zajadacz J. , Fechner R. , Rauschenbach Bernd
Published: December 2009

Amorphous Si/SiOx multi-layered films and nanostructures were deposited on Si substrates by the glancing angle deposition technique using Ar ion beam sputtering of a Si sputter target in an intermittent oxygen atmosphere at room temperature. The chemical composition of the samples was characterized by time-of-flight secondary ion mass spectrometry, as well as - for quantifying these first results - by elastic recoil detection analysis using a 200 MeV Au ion beam. The latter method was found to lead to a significant alteration of the sample morphology, resulting in the formation of complex nanometric structures within the layer stacks. In order to investigate these swift heavy ion irradiation induced effects in more detail, a series of experiments was conducted to determine the dominating influences. For this purpose, specific glancing angle deposited multilayered films and nanostructures were irradiated to constant ion fluence with the same 200 MeV Au ion beam at different incidence angles. Scanning electron microscopy of the stacks before and after swift Au ion irradiation revealed considerable changes in film morphology and density as a function of the ion incidence angle, such as an increased porosity of the silicon layers, accompanied by a layer swelling. In contrast, the SiOx layers did not show such effects, but exhibited clearly visible swift heavy ion tracks. The observed effects became stronger with decreasing ion incidence angle.
Localized Gallium Doping and Cryogenic Deep Reactive Ion etching in Fabrication of Silicon Nanostructures
Authors: Chekurov Nikolai , Grigoras Kestutis , Peltonen Antti , Franssila Sami , Tittonen Ilkka
Published: December 2009

We present a novel fabrication method to create controlled 3-dimensional silicon nanostructures with the lateral dimensions that are less than 50 nm as a result of a rapid clean room compatible process. We also demonstrate periodic and nonperiodic lattices of nanopillars in predetermined positions with the minimum pitch of 100 nm. One of the uses of this process is to fabricate suspended silicon nanowhiskers.