bluuebunny/crossref_metadata_2025 huggingface dataset:
Perfect class hashing and numbering for object‐oriented implementation
Authors: Ducournau Roland , Morandat Floréal
Published: December 2010

Late binding and subtyping create run‐time overhead for object‐oriented languages, especially in the context of both multiple inheritance and dynamic loading, for instance for JAVA interfaces. In a previous article, we proposed a novel approach based on perfect hashing and truly constant‐time hashtables for implementing subtype testing and method invocation in a dynamic loading setting. In this first study, we based our efficiency assessment on Driesen's abstract computational model for the time aspect, and on large‐scale benchmarks for the space aspect. The conclusions were that the technique was promising but required further research in order to assess its scalability. This article presents some new results on perfect class hashing that enhance its interest. We propose and test both new hashing functions and an inverse problem that amounts to selecting the best class identifiers in order to minimize the overall hashtable size. This optimizing approach is proven to be optimal for single‐inheritance hierarchies. Experiments within an extended testbed with random class loading and under cautious assumptions about what should be a sensible class‐loading order show that perfect class hashing scales up gracefully, especially on JAVA‐like multiple‐subtyping hierarchies. Furthermore, perfect class hashing is implemented in the PRM compiler testbed, and compared here with the coloring technique, which amounts to maintaining the single‐inheritance implementation in multiple inheritance. The overall conclusion is that the approach is efficient from both time and space standpoints with the bit‐wise and hashing function. In contrast, the poor time efficiency of modulus hashing function on most processors is confirmed. Copyright © 2010 John Wiley & Sons, Ltd.
Automated scheduling for clone‐based refactoring using a competent GA
Authors: Lee Sukhee , Bae Gigon , Chae Heung Seok , Bae Doo‐Hwan , Kwon Yong Rae
Published: December 2010

Refactoring is a widely accepted technique to improve the software quality by restructuring its design without changing its behavior. In general, a sequence of refactorings needs to be applied until the quality of the code is improved satisfactorily. In this case, the final design after refactoring can vary with the application order of refactorings, thereby producing different quality improvements. Therefore, it is necessary to determine a proper refactoring schedule to obtain as many benefits as possible. However, there is little research on the problem of generating appropriate schedules to maximize quality improvement. In this paper, we propose an approach to automatically determine an appropriate schedule to maximize quality improvement through refactoring. We first detect code clones that are suitable for refactoring and generate the most beneficial refactoring schedule to remove them. It is straightforward to select the best from the exhaustively enumerated schedules. However, such a technique becomes NP‐hard, as the number of available refactorings increases. We apply a genetic algorithm (GA) to generate the best refactoring schedule within a reasonable time to cope with this problem. We compare the GA‐based approach with manual scheduling, greedy heuristic‐based, and exhaustive approaches for four open systems. The results show that the proposed GA‐based approach generates more beneficial schedules than the others. Copyright © 2010 John Wiley & Sons, Ltd.
Effect of primary filter using theoretical intensity of fluorescent X‐rays and scattered X‐rays
Authors: Ogawa R. , Ochi H. , Nishino M. , Ichimaru N. , Yamato R.
Published: December 2010

A primary filter is often used for low‐concentration analysis by energy‐dispersive X‐ray fluorescence spectrometer. We determined the material and thickness of the primary filter and calculated the theoretical intensities of the fluorescent X‐rays and scattered X‐rays using lead in brass, for which the concentration is known. The filter materials were zirconium, nickel, titanium, aluminum, and molybdenum with a thickness between 20 and 125 µm.

For verification, we calculated the lower limits of detection using theoretical intensities for several filters and compared them with values calculated using the measured intensities. For example, both values were similar for a 125 µm zirconium filter: 128.0 ppm using theoretical intensities and 147.7 ppm using measured intensities.

The theoretical intensity values are obtained by measurements and calculations, but require no primary filters for the measurements. This method is extremely effective for selecting the optimal filter for multiple samples and elements. Copyright © 2010 John Wiley & Sons, Ltd.
Hydrogen‐Bond‐Based Magnetic Exchange Between μ‐Diethylnicotinamide(aqua)bis(X‐salicylato)copper(II) Polymeric Chains
Authors: Korabik Maria , Repická Zuzana , Martiška Ladislav , Moncol Jan , Švorec Jozef , Padělková Zdeňka , Lis Tadeusz , Mazúr Milan , Valigura Dušan
Published: December 2010

Polymeric salicylatocopper(II) complexes of unusual composition [Cu(X‐sal)2(μ‐denia)(H2O)]n [denia = diethylnicotinamide, and X‐sal = 5‐methylsalicylate (1), 3‐methylsalicylate (2), 4‐methoxysalicylate (3), 3,5‐dichlorosalicylate (4) and 3,5‐dibromosalicylate (5)] were synthesized and characterized. Magnetic measurements were performed in the temperature range 1.8–300 K. The structural unit of all complexes consists of a CuII atom, which is monodentately coordinated by the pair of X‐salicylate anions in trans positions. Water and the diethylnicotinamide ligand occupy the other two basal plane positions of the tetragonal pyramid. The axial positions are occupied by a diethylnicotinamide oxygen atom of neighboring structural units, thus forming a spiral polymeric structure parallel to b axis. Magnetic measurements showed that all complexes 1–5 exhibit a susceptibility maximum at about 6–8 K. The obtained data fit to Bleaney–Bowers equation gave singlet‐triplet energy gaps 2J = –8.60 cm–1 for 1, 2J = –6.57 cm–1 for 2, 2J = –8.57 cm–1 for 3, 2J = –6.82 cm–1 for 4, and 2J = –6.45 cm–1 for 5. The supramolecular structure based on hydrogen bonds [described by supramolecular synthons R22(10) and R22(12)] is the pathway for antiferromagnetic interactions of the magnetically coupled pairs of copper atoms of neighboring chains within the 2D supramolecular layers. The results of the magnetic measurements suggest involvement of the COO groups in the magnetic interaction pathway for all five complexes.
Heteroleptic Organostannylenes and an Organoplumbylene Bearing Phosphorus‐Containing Pincer‐Type Ligands – Structural Variations and Insights into the Configurational Stability
Authors: Henn Markus , Deáky Vajk , Krabbe Stefan , Schürmann Markus , Prosenc Marc H. , Herres‐Pawlis Sonja , Mahieu Bernard , Jurkschat Klaus
Published: December 2010

The syntheses of the arylphosphonic esters 3‐Br‐5‐tBu‐1‐{P(O)(OiPr)2}C6H3 (1), 5‐tBu‐1,3‐{P(O)(OiPr)2}2C6H3 (2), of the heteroleptic intramolecularly coordinated organostannylenes [4‐tBu‐2,6‐{P(O)(OiPr)2}2C6H2]SnX (3, X = Cl; 4, X = Br; 5, X = I; 6, X = SPh), the organoplumbylene [4‐tBu‐2,6‐{P(O)(OiPr)2}2C6H2]PbCl (7), and the transition metal complex [4‐tBu‐2,6‐{P(O)(OiPr)2}2C6H2]Sn(Cl)Cr(CO)5 (8) are reported. The compounds were characterized by 1H, 13C, 31P, 31P MAS (3), 119Sn, and 119Sn MAS (3) NMR spectroscopy, electrospray ionization mass spectrometry (3), Mössbauer spectroscopy (3–5, 8) and single‐crystal X‐ray diffraction analyses (2, 3–5, 6–8). In contrast to its ethoxy‐substituted analogue [4‐tBu‐2,6‐{P(O)(OEt)2}2C6H2]SnCl, compound 3, like the thiophenolate derivative 6, is monomeric in solution as well as in the solid state. This difference is also manifested by the Mössbauer as well as solid state NMR spectroscopic data. On the other hand, the corresponding organoplumbylene 7 shows a similar chlorido‐bridged polymeric structure as its ethoxy‐substituted analogue. Variable‐temperature and concentration‐dependent 1H and 31P NMR spectra reveal, on the respective time scales, the tin atom in compound 3 to be configurationally unstable and those in compounds 6 and 8 to be configurationally stable. DFT calculations support a chlorido‐bridged dimer to account for the configurational instability in compound 3. Surprisingly and in contrast to compounds 3 and 6, the organobromido‐ and organoiodidostannylenes 4 and 5, respectively, show intermolecular Sn···Sn distances of 3.6809(4) and 3.5953(4) Å being shorter than twice the van der Waals radius of tin (2.20 Å). Quantum chemical calculations were performed on monomeric and dimeric model compounds, which revealed a weak Sn···Sn bonding interaction for dimer 3 (16 kJ·mol–1) as well as for dimer 5 (20 kJ·mol–1) whereas the hypothetical model compound p‐tBuC6H4SnI showed an iodido‐bridged dimer rather than a Sn···Sn bonding interaction.
Rhabdomyolysis after Prolonged Suspension in a Cave
Authors: Wharton David R. , Mortimer Roger B.
Published: December 2010

A 29-year-old man was caving and could not ascend his rope. He was rescued after 4+ hours of hanging after which he could not feel his legs and could not move one of them. He was shivering but still alert. In the field, he received calcium chloride, normal saline, and bicarbonate. At the hospital, he was found to have elevated creatine phosphokinase levels that resolved after continued intravenous fluid. Suspension trauma can include early syncope and late rhabdomyolysis. Persons suspended passively must be rescued immediately and given intravenous fluid to prevent rhabdomyolysis and renal failure.
Where Do We Stand in the Control of Rabies? Knowledge and Practices Among Physicians in a Health District in Turkey
Authors: Koruk Suda Tekın , Koruk Ibrahim , Kutlu Seher
Published: December 2010

Objective

The aim of this study was to determine the level of knowledge of rabies transmission and control among physicians practicing in healthcare centers in Sanliurfa, Turkey where 2 cases of human rabies were reported in the past 12 months. Implementation issues regarding the current guidelines will also be discussed.

Methods

A cross-sectional study was conducted among 84 physicians practicing in healthcare centers in Sanliurfa, located in the Southeastern Anatolian region of Turkey.

Results

Among physicians, average duration of medical practice was 8.5 ± 6.7 years. The correct incubation period of rabies cases was known by 57.1% of the physicians. While 88.1% of physicians were aware of possible exposure routes, only 44.0% of them had the information that mucosal contact may also lead to transmission. While 96.4% of the physicians correctly indicated that cats and dogs can transmit the disease, the fact that foxes also have a role in transmission was known by only 48.8%. Post-exposure prophylaxis was correctly indicated by 65.5% of participants, but only 17.9% had correct information about pre-exposure prophylaxis.

Conclusion

An important approach in rabies control is to increase community awareness, particularly among healthcare providers. It was found that basic management issues and insufficient awareness still exist despite the presence of legal regulations. To control rabies, the issue must be dealt with locally, through both economic and social means, by supporting rabies control efforts of local health and agricultural directorate managers and by encouraging collaboration with academics.
Do Ski Helmets Affect Reaction Time to Peripheral Stimuli?
Authors: Ruedl Gerhard , Herzog Simone , Schöpf Stephanie , Anewanter Pia , Geiger Astrid , Burtscher Martin , Kopp Martin
Published: December 2010

Background

Ski helmet use has steadily increased worldwide over the last 10 years in part as a result of preventive helmet campaigns but also in part as a result of increased media coverage after fatal injuries involving celebrities. However, a commonly reported reason for nonuse is impaired vision.

Objective

The aim of this pilot study was to investigate whether ski helmet use affects reaction time to peripheral stimuli.

Methods

A randomized controlled trial using the Compensatory-Tracking-Test (CTT) was conducted in a laboratory situation. This test measures reaction time to peripheral stimuli during a tracking task and was carried out by 10 males and 10 females (age: 22.1 ± 2.5 years) during 4 conditions in a randomized order: (A) with a ski cap; (B) with a ski helmet; (C) with a ski cap and ski goggles; and (D) with a ski helmet and ski goggles.

Results

Friedman-tests revealed significant differences in reaction times (ms) between the 4 conditions ( p = .031). The lowest mean reaction time (± standard error) was measured for cap only use (477.3 ± 16.6), which was not different than helmet-only use (478.5 ± 19.1, p = 0.911). However, reaction time was significantly longer for cap + goggles use (514.1 ± 20.8, p = 0.005) and for helmet + goggles use (497.6 ± 17.3, p = 0.017) when compared to cap-only use.

Conclusion

Our results showed that ski helmet use did not increase reaction time to peripheral stimuli. This information should be implemented in future preventive campaigns to increase helmet use in skiers and snowboarders.
Ambulante Soziotherapie
Authors: Schlagloth-Kley Claudia , Jox Rolf
Published: December 2010

Fragestellung: Im Rahmen der Neufassung des SGB V – Gesetzliche Krankenversicherung – durch die Gesundheitsreform 2000 wurde mit § 37a SGB V die Behandlungsform «ambulante Soziotherapie» für schwer psychisch Kranke eingeführt. In der Praxis sind Suchtkranke jedoch von der Inanspruchnahme ausgeschlossen, da sie die Indikationsvoraussetzungen der Durchführungsrichtlinien des Gemeinsamen Bundesausschusses scheinbar nicht erfüllen. Dies stellt eine erhebliche Benachteiligung dieser Patientengruppe dar. Methodik, Ergebnisse und Schlussfolgerungen: Unter Berücksichtigung der in der Literatur vertretenen Auffassungen stellt der Beitrag dar, inwieweit die Indikationsvoraussetzungen von Suchtkranken doch erfüllt werden können. Ambulante Soziotherapie kann Suchtkranken die Möglichkeit eröffnen, mit professioneller zeitlich begrenzter Hilfe ihre gesundheitliche und soziale Situation nachhaltig zu verbessern. Weiterhin wird überlegt, wie Ambulante Soziotherapie besonders unter Berücksichtigung der derzeitigen Rechtslage für Suchtkranke therapeutisch anwendbar gemacht werden kann.
Optimization of water level monitoring network in polder systems using information theory
Authors: Alfonso Leonardo , Lobbrecht Arnold , Price Roland
Published: December 2010

A method for siting water level monitors based on information theory measurements is presented. The first measurement is joint entropy, which evaluates the amount of information content that a monitoring set is able to collect, and the second measurement is total correlation, which evaluates the level of dependency or redundancy among monitors in the set. In order to find the most convenient set of places to put monitors from a large number of potential sites, a multiobjective optimization problem is posed under two different considerations: (1) taking into account the costs of placing new monitors and (2) considering the cost of placing monitors too close to hydraulic structures. In both cases, the joint entropy of the set is maximized and its total correlation is minimized. The costs are considered in terms of information theory units, for which additional terms affecting the objective functions are introduced. The proposed method is applied in a case study of the Delfland region, Netherlands. Results show that total correlation is an effective way to measure multivariate independency and that it must be combined with joint entropy to get results that cover a significant proportion of the total information content of the system. The maximization of joint entropy gives results that cover between 82% and 85% of the total information content.
Nonconservative behavior of dissolved organic carbon across the Laptev and East Siberian seas
Authors: Alling Vanja , Sanchez‐Garcia Laura , Porcelli Don , Pugach Sveta , Vonk Jorien E. , van Dongen Bart , Mörth Carl‐Magnus , Anderson Leif G. , Sokolov Alexander , Andersson Per , Humborg Christoph , Semiletov Igor , Gustafsson Örjan
Published: December 2010

Climate change is expected to have a strong effect on the Eastern Siberian Arctic Shelf (ESAS) region, which includes 40% of the Arctic shelves and comprises the Laptev and East Siberian seas. The largest organic carbon pool, the dissolved organic carbon (DOC), may change significantly due to changes in both riverine inputs and transformation rates; however, the present DOC inventories and transformation patterns are poorly understood. Using samples from the International Siberian Shelf Study 2008, this study examines for the first time DOC removal in Arctic shelf waters with residence times that range from months to years. Removals of up to 10%–20% were found in the Lena River estuary, consistent with earlier studies in this area, where surface waters were shown to have a residence time of approximately 2 months. In contrast, the DOC concentrations showed a strong nonconservative pattern in areas with freshwater residence times of several years. The average losses of DOC were estimated to be 30%–50% during mixing along the shelf, corresponding to a first‐order removal rate constant of 0.3 yr−1. These data provide the first observational evidence for losses of DOC in the Arctic shelf seas, and the calculated DOC deficit reflects DOC losses that are higher than recent model estimates for the region. Overall, a large proportion of riverine DOC is removed from the surface waters across the Arctic shelves. Such significant losses must be included in models of the carbon cycle for the Arctic Ocean, especially since the breakdown of terrestrial DOC to CO2 in Arctic shelf seas may constitute a positive feedback mechanism for Arctic climate warming. These data also provide a baseline for considering the effects of future changes in carbon fluxes, as the vast northern carbon‐rich permafrost areas draining into the Arctic are affected by global warming.
A note on the fluxes of abiogenic methane and hydrogen from mid‐ocean ridges
Authors: Keir R. S.
Published: December 2010

The concentrations of methane and hydrogen in hydrothermal vent fluids issuing from mid‐ocean ridges tend to fall into two groups, one with high concentrations of these gases in ultramafic‐hosted vent fields and a second group with relatively lower concentrations in basalt‐hosted vent fluids. Ultramafic‐hosted systems, however, appear to be restricted to slow‐spreading ridges and constitute only a fraction of the hydrothermal systems found there. In this note, the hydrothermal fluxes of methane and hydrogen have been calculated by estimating the percentages of the total subsurface hydrothermal circulation that circulate through each type of host rock. Even though the percentage of the total subsurface flow that is affected by serpentinization appears to be rather small (8%), it still appears that this process produces about 70% of the total mid‐ocean flux of these gases. The total production of methane and hydrogen is calculated to be about 20 × 109 mol yr−1 and 190 × 109 mol yr−1, respectively. The hydrogen flux is comparable to that most recently calculated on the basis of the rate of hydration of mantle rock in newly formed crust and the stoichiometry of the serpentinization reaction. This suggests that, except for the production of methane, a major portion of the hydrogen produced in the subsurface is not consumed before venting.
InSAR data as a field guide for mapping minor earthquake surface ruptures: Ground displacements along the Paganica Fault during the 6 April 2009 L'Aquila earthquake
Authors: Guerrieri L. , Baer G. , Hamiel Y. , Amit R. , Blumetti A. M. , Comerci V. , Di Manna P. , Michetti A. M. , Salamon A. , Mushkin A. , Sileo G. , Vittori E.
Published: December 2010

On 6 April 2009, a moderate earthquake (Mw = 6.3; Ml = 5.8) struck the Abruzzo region in central Italy, causing more than 300 fatalities and heavy damage to L'Aquila and surrounding villages. Coseismic surface effects have been thoroughly documented by timely field surveys as well as by remote sensing analyses of satellite images. The outstanding quality of geological, seismological, geodetic, and interferometric synthetic aperture radar (InSAR) information arguably represents the best ever data set made available immediately after a moderate seismic event. Based on this data set, we aim at testing the capability of coupled geological and InSAR data to map surface faulting patterns associated with moderate earthquakes. Coseismic ground ruptures have been mapped at a scale of 1:500 in the whole epicentral area. Traces of surface ruptures have been inferred from linear phase discontinuities identified in the interferogram. A very good agreement between the two methods resulted in the characterization of the main surface rupture along the Paganica fault. The same approach applied to ground ruptures hypothesized along other capable fault segments provided more questionable results. Thus, the combined field and InSAR approach appeared useful for detecting continuous surface ruptures exceeding 1 km in length and showing displacements greater than a few centimeters. These are the typical faulting parameters for moderate earthquakes (6.0 < Mw < 6.5) in central Apennines. For continuous ground cracks shorter than a few hundred meters and/or that show displacements smaller than 1–2 cm, the described approach may be less helpful, most probably due to the limited resolution of the data.
The effect of temperature, soil nitrogen and gastropods on Thuja plicata growth and reproduction
Authors: O'Brien Anna , HilleRisLambers Jannke , Ettinger Ailene
Published: December 2010

Humans are changing the environment. For example, nitrogen deposition, rising temperatures, and non-native species are influencing plant communities. These changes have and will continue to affect trees, thus, understanding the response of species to global change will help conservationists plan for the future. Urban areas already experience higher temperatures, elevated CO~2~, greater nitrogen levels, and more non-native species compared to rural areas. The response of trees to urban parks and park edges can therefore be used as a proxy for the net effects of global change on trees. We investigate the growth and reproduction of Thuja plicata, a native Pacific Northwest conifer, in both urban and rural forest fragments to understand global change impacts. Data collected from sites include hourly temperature, soil NO~3~^-^, seedling counts, and an increment core. After observing extremely low conifer germination rates across sites, we concluded that factors such as herbivory might be important. Gastropods have been shown to impact communities through consumption of plants at the seedling stage, and to limit seedling survival of a European conifer. The effects of soil moisture, soil nitrogen, and gastropod herbivory on Thuja plicata seedlings was analyzed experimentally to determine the relative effect each might be having on the observed germination rate. Our results suggest that urban forest edges resemble future global change conditions of higher temperature and nitrogen. These global change factors appear to be positively influencing tree growth, suggesting that Thuja plicata will benefit from future conditions. However, low seedling recruitment may be a concern, because it appears that urban and rural forests are currently failing to regenerate on their own. Introduced gastropods could play a role, as they have the ability to reduce seedling biomass significantly. The relative impacts of invasive slug herbivory and other global change factors on native conifer recruitment should be prioritized in future study.
Data citation in the wild
Authors: Enriquez Valerie , Walker Judson Sarah , Walker Nicholas , Allard Suzie , Cook Robert , Piwowar Heather , Sandusky Robert , Vision Todd , Wilson Bruce
Published: December 2010

Consistent attribution of research data upon reuse is necessary to reward the original data-producing investigators, reconstruct provenance, and inform data sharing policies, tool requirements, and funding decisions. Unfortunately, norms for data attribution are varied and often weak. As part of the DataONE 2010 summer internship program, three interns studied the policies, practice, and implications of current data attribution behavior in the environmental sciences. We found that few policies recommend robust data citation practices: in our preliminary evaluation, only one-third of repositories (n=26), 6% of journals (n=307), and 1 of 53 funders suggested a best practice for data citation. We manually reviewed 500 papers published between 2000 and 2010 across six journals; of the 198 papers that reused datasets, only 14% reported a unique dataset identifier in their dataset attribution, and a partially-overlapping 12% mentioned the author name and repository name. Few citations to datasets themselves were made in the article references section. In multivariate analysis, citation patterns were more correlated with repository (with citations to Genbank being most complete) than journal or datatype. Attribution patterns were found to be steady over time. Consistent with these findings, dataset reuse was difficult to track through standard retrieval resources. Searching by repository name retrieved many instances of data submission rather than data reuse, combing the citation history of data creation articles was time consuming, and searching citation databases for the few early-adopter dataset DOIs and HDLs in reference lists failed due to apparent limitations in database query capabilities and structured extraction of DOIs. We hope these descriptions of the current data attribution environment will highlight outstanding issues and motivate change in policy, tools, and practice. This research was done as open science (http://openwetware.org/wiki/DataONE:Notebook/Summer_2010): ask us about it!
Hematopoietic Stem Cell Transcription Factor PU.1 with Mutated β3/β4 Domain Selectively Elicits Myeloid Differentiation
Authors: Gupta Pallavi , Gangenahalli Gurudutta , Saluja Daman , Verma Yogesh , Zack Jyoti , Singh Vimal , Satija Neeraj , Tripathi Rajendra
Published: December 2010

In many hematopoietic malignancies such as lymphomas & leukemias, aberrant differentiation is the major feature of malignant phenotype that often results from a single genetic alteration and provides a site-specific target for therapy. Therefore, targeting of protein-protein interactions that have been identified as mediators of transcriptional repression that blocks normal hematopoietic differentiation holds great promise for therapeutic applications. An example is GATA-1, a critical erythroid transcription factor that is capable of suppressing the myeloid phenotype by down-regulating PU.1 in a dose-dependent manner. PU.1 is the most crucial transcription factor known to be required for myeloid differentiation of hematopoietic stem cells or progenitor cells. Its reduced expression correlates with a bad prognosis and immature phenotype in acute myeloid leukemia (AML). GATA-1 downregulates PU.1 by interacting though its C-terminal zinc finger region with the β3/β4 region of PU.1 and displacing its coactivator c-Jun. We hypothesize that disruption of PU.1-GATA-1 interaction by mutating the β3/β4 region of PU.1 may prevent its GATA-1-mediated repression, which in turn will upregulate PU.1 expression and hence myelopoiesis. Our analysis of the PU.1 mutants, Lys240Arg and Tyr244Ala, revealed that they exhibit an increase in myelopoiesis in vitro. Thus our data have implications for the prospect of targeting PU.1-GATA-1 interaction for therapeutic intervention.
Effects of the attractive interactions in the thermodynamic, dynamic, and structural anomalies of a two length scale potential
Authors: da Silva Jonathas Nunes , Salcedo Evy , de Oliveira Alan Barros , Barbosa Marcia C.
Published: December 2010

Using molecular dynamic simulations, we study a system of particles interacting through a continuous core-softened potentials consisting of a hard core, a shoulder at closest distances, and an attractive well at further distance. We obtain the pressure–temperature phase diagram of this system for various depths of the tunable attractive well. Since this is a two length scale potential, density, diffusion, and structural anomalies are expected. We show that the effect of increasing the attractive interaction between the molecules is to shrink the region in pressure in which the density and the diffusion anomalies are present. If the attractive forces are too strong, particle will be predominantly in one of the two length scales and no density of diffusion anomaly is observed. The structural anomalous region is present for all the cases.
Gas adsorption and high-emission current induced degradation of field emission characteristics in solution-processed ZnO nanoneedles
Authors: Dardona Sameh , Peles Amra , Wrobel Gregory , Piech Martin , Gao Pu-Xian
Published: December 2010

The effects of gas adsorption and high current on the field emission characteristics of ZnO nanoneedles grown directly from metal electrodes have been systematically investigated. Exposure of nanoneedles to H2, N2, or O2 gas degraded the field emission characteristics, with O2 having the strongest impact. Complete recovery of emission current following H2 and N2 treatment was accomplished by vacuum annealing at 450 °C. Meanwhile, changes induced by O2 adsorption were irreversible. First-principle calculations revealed electronic structure modifications through change of work function and charge density distribution upon gas exposure. It is suggested that the emission current degradation originates from shifts in the Fermi level caused by charge transfer from nanoneedle surface to gas adsorbates. Moreover, field emission degradation has been observed at high currents as a result of surface melting at the nanoneedles apex caused by resistive heating.
Strain-driven noncollinear magnetic ordering in orthorhombic epitaxial YMnO3 thin films
Authors: Marti X. , Skumryev V. , Laukhin V. , Bachelet R. , Ferrater C. , García-Cuenca M. V. , Varela M. , Sánchez F. , Fontcuberta J.
Published: December 2010

We show that using epitaxial strain and chemical pressure in orthorhombic YMnO3 and Co-substituted (YMn0.95Co0.05O3) thin films, a ferromagnetic response can be gradually introduced and tuned. These results, together with the measured anisotropy of the magnetic response, indicate that the unexpected observation of ferromagnetism in orthorhombic o-RMnO3 (R=Y,Ho,Tb, etc.) films originates from strain-driven breaking of the fully compensated magnetic ordering by pushing magnetic moments away from the antiferromagnetic [010] axis. We show that the resulting canting angle and the subsequent ferromagnetic response, gradually increase (up to ∼1.2°) by compression of the unit cell. We will discuss the relevance of these findings, in connection to the magnetoelectric response of orthorhombic manganites.
Invited Review Article: A 10 mK scanning probe microscopy facility
Authors: Song Young Jae , Otte Alexander F. , Shvarts Vladimir , Zhao Zuyu , Kuk Young , Blankenship Steven R. , Band Alan , Hess Frank M. , Stroscio Joseph A.
Published: December 2010

We describe the design, development and performance of a scanning probe microscopy (SPM) facility operating at a base temperature of 10 mK in magnetic fields up to 15 T. The microscope is cooled by a custom designed, fully ultra-high vacuum (UHV) compatible dilution refrigerator (DR) and is capable of in situ tip and sample exchange. Subpicometer stability at the tip-sample junction is achieved through three independent vibration isolation stages and careful design of the dilution refrigerator. The system can be connected to, or disconnected from, a network of interconnected auxiliary UHV chambers, which include growth chambers for metal and semiconductor samples, a field-ion microscope for tip characterization, and a fully independent additional quick access low temperature scanning tunneling microscope (STM) and atomic force microscope (AFM) system. To characterize the system, we present the cooling performance of the DR, vibrational, tunneling current, and tip-sample displacement noise measurements. In addition, we show the spectral resolution capabilities with tunneling spectroscopy results obtained on an epitaxial graphene sample resolving the quantum Landau levels in a magnetic field, including the sublevels corresponding to the lifting of the electron spin and valley degeneracies.
Polyelectrolyte multilayer surface functionalization of poly(dimethylsiloxane) (PDMS) for reduction of yeast cell adhesion in microfluidic devices
Authors: Schmolke Hannah , Demming Stefanie , Edlich Astrid , Magdanz Veronika , Büttgenbach Stephanus , Franco-Lara Ezequiel , Krull Rainer , Klages Claus-Peter
Published: December 2010

Polyelectrolyte multilayers (PEMs) based on the combinations poly(diallyldimethylammonium chloride)/poly(acrylic acid) (PDADMAC/PAA) and poly(allylamine hydrochloride)/PAA (PAH/PAA) were adsorbed on poly(dimethylsiloxane) (PDMS) and tested for nonspecific surface attachment of hydrophobic yeast cells using a parallel plate flow chamber. A custom-made graft copolymer containing poly(ethylene glycol) (PEG) side chains (PAA-g-PEG) was additionally adsorbed on the PEMs as a terminal layer. A suitable PEM modification effectively decreased the adhesion strength of Saccharomyces cerevisiae DSM 2155 to the channel walls. However, a further decrease in initial cell attachment and adhesion strength was observed after adsorption of PAA-g-PEG copolymer onto PEMs from aqueous solution. The results demonstrate that a facile layer-by-layer surface functionalization from aqueous solutions can be successfully applied to reduce cell adhesion strength of S. cerevisiae by at least two orders of magnitude compared to bare PDMS. Therefore, this method is potentially suitable to promote planktonic growth inside capped PDMS-based microfluidic devices if the PEM deposition is completed by a dynamic flow-through process.
X-ray photoelectron spectroscopy analysis of TlInGaAsN semiconductor system and their annealing-induced structural changes
Authors: Kim Kang Min , Kim Woo-Byoung , Krishnamurthy Daivasigamani , Ishimaru Manabu , Kobayashi Hikaru , Hasegawa Shigehiko , Asahi Hajime
Published: December 2010

TlInGaAsN thin films grown by gas-source molecular-beam epitaxy were investigated by x-ray photoelectron spectroscopy (XPS) to analyze the Tl incorporation and to study the annealing-induced transformation of the atomic configurations. XPS analysis revealed that the Tl composition in the grown TlInGaAsN is around 1.5% and that the dominant atomic configuration of the TlInGaAsN changes from the In–As and Ga–N bonds to the In–N and Ga–As bonds by 700 °C rapid thermal annealing. High-resolution x-ray diffraction and reciprocal space mapping measurements showed that no significant out-diffusion of the elements occurs in the TlInGaAsN/TlGaAsN quantum wells (QWs) even after the same annealing. It is concluded that the blueshift in the photoluminescence peak for the TlInGaAsN/TlGaAsN QWs after annealing is attributed to the transformation of the atomic configuration in TlInGaAsN.
Array of Josephson junctions with a nonsinusoidal current-phase relation as a model of the resistive transition of unconventional superconductors
Authors: Carbone Anna , Gilli Marco , Mazzetti Piero , Ponta Linda
Published: December 2010

An array of resistively and capacitively shunted Josephson junctions with nonsinusoidal current-phase relation is considered for modeling the transition in high-Tc superconductors. The emergence of higher harmonics, besides the simple sinusoid Ic sin ϕ, is expected for dominant d-wave symmetry of the Cooper pairs, random distribution of potential drops, dirty grains, or nonstationary conditions. We show that additional cosine and sine terms act, respectively, by modulating the global resistance and by changing the Josephson coupling of the mixed superconductive-normal states. First, the approach is applied to simulate the transition in disordered granular superconductors with the weak-links characterized by nonsinusoidal current-phase relation. In granular superconductors, the emergence of higher-order harmonics affects the slope of the transition. Then, arrays of intrinsic Josephson junctions, naturally formed by the CuO2 planes in cuprates, are considered. The critical temperature suppression, observed at values of hole doping close to p=1/8, is investigated. Such suppression, related to the sign change and modulation of the Josephson coupling across the array, is quantified in terms of the intensities of the first and second sinusoids of the current-phase relation. Applications are envisaged for the design and control of quantum devices based on stacks of intrinsic Josephson junctions.
Exact solution to the general Riemann problem in nonuniform and nonstationary media: A simplified analysis of a shock wave accelerated at a constant rate
Authors: Mori Koichi
Published: December 2010

Exact solutions to special cases of the general Riemann problem, in which two nonuniform and nonstationary flows are initially separated by a discontinuity at the origin, are proposed. By describing the evolution of flows using a family of the group-invariant solutions derived by Ovsiannikov [Dokl. Akad. Nauk S.S.S.R. 111, 439 (1958)] the flows ahead of and behind a shock wave accelerated at a constant rate are formulated analytically. Transition relations across a contact discontinuity and a characteristic wave in a nonuniform and nonstationary flow are formulated as well. The entire flow field is solved by combining these waves.
Leakage current behavior in lead-free ferroelectric (K,Na)NbO3-LiTaO3-LiSbO3 thin films
Authors: Abazari M. , Safari A.
Published: December 2010

Conduction mechanisms in epitaxial (001)-oriented pure and 1 mol % Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.1,Sb0.06)O3 (KNN-LT-LS) thin films on SrTiO3 substrate were investigated. Temperature dependence of leakage current density was measured as a function of applied electric field in the range of 200–380 K. It was shown that the different transport mechanisms dominate in pure and Mn-doped thin films. In pure (KNN-LT-LS) thin films, Poole-Frenkel emission was found to be responsible for the leakage, while Schottky emission was the dominant mechanism in Mn-doped thin films at higher electric fields. This is a remarkable yet clear indication of effect of 1 mol % Mn on the resistive behavior of such thin films.
Fine tuning epitaxial strain in ferroelectrics: PbxSr1−xTiO3 on DyScO3
Authors: Rispens G. , Heuver J. A. , Noheda B.
Published: December 2010

Epitaxial strain can be efficiently used to modify the properties of ferroelectric thin films. From the experimental viewpoint, the challenge is to fine-tune the magnitude of the strain. We illustrate here how, by using a suitable combination of composition and substrate, the magnitude of the epitaxial strain can be controlled in a continuous manner. The phase diagram of PbxSr1−xTiO3 films grown epitaxially on (110)-DyScO3 is calculated using a Devonshire–Landau approach. A boundary between in-plane and out-of-plane oriented ferroelectric phases is predicted to take place at x≈0.8. A series of PbxSr1−xTiO3 epitaxial films grown by molecular beam epitaxy shows good agreement with the proposed phase diagram.
Transmission properties of surface plasmon polaritons and localized resonance in semiconductor hole arrays
Authors: Okada T. , Tsuji S. , Tanaka K. , Hirao K. , Tanaka K.
Published: December 2010

We study optical modulated transmission in semiconductor hole arrays using terahertz time-domain measurements in combination with the optical pump-terahertz probe technique. When the density of photoexcited carriers is varied, we observe an evanescent decay profile for the propagation of surface plasmon polaritons, whereas steady behavior is exhibited for transmission attributed to the localized resonance in the holes. We also demonstrate an optically controlled transition of the transmission mechanism, attributed to the change from a dielectric structure to a plasmonic material.
Scattering focusing and localized surface plasmons in a single Ag nanoring
Authors: Zhang Qing , Shan Xin-Yan , Zhou Li , Zhan Tian-Rong , Wang Chun-Xiao , Li Min , Jia Jin-Feng , Zi Jian , Wang Qu-Quan , Xue Qi-Kun
Published: December 2010

We investigate the far-field scattering property of a single Ag nanoring. Under oblique excitation, two-focus scatterings with distinct intensities were observed. We show that the two-focus scatterings result from the interference of far-field scattering light from the ring circumference, and the local field enhancement effect of surface plasmons plays the key role in the focus intensity. By finite difference time domain and numerical integer methods, we calculated far-field scattering and surface plasmons’ distributions, and the results are in good agreement with the experiment.
Plasma oscillations and terahertz instability in field-effect transistors with Corbino geometry
Authors: Sydoruk O. , Syms R. R. A. , Solymar L.
Published: December 2010

Propagating between the contacts of a field-effect transistor (FET), plasma waves in its channel can become unstable and lead to generation of terahertz radiation. While previous studies of this instability concentrated on rectangular FETs, alternative geometries present fresh opportunities. We studied theoretically plasma oscillations in a gated FET with Corbino geometry where, in contrast with the rectangular FET, the oscillations become unstable at symmetric boundary conditions. Moreover, their lowest eigenfrequency is almost twice as high as that in the rectangular FET at comparable instability increments. These advantages make the Corbino FET promising for practical realizations of terahertz oscillators.
Electron-phonon coupling in single-walled carbon nanotubes determined by shot noise
Authors: Wu F. , Virtanen P. , Andresen S. , Plaçais B. , Hakonen P. J.
Published: December 2010

We have measured shot noise in metallic single-walled carbon nanotubes of length L=1 μm and have found strong suppression of noise with increasing voltage. We conclude that the coupling of electron and phonon baths at temperatures Te and Tph is described at intermediate bias (20 mV<Vds≲200 mV) by heat flow equation P=ΣL(Te3−Tph3), where Σ∼3×10−9 W/m K3 due to electron interaction with acoustic phonons, while at higher voltages optical phonon-electron interaction leads to P=κopL[N(Te)−N(Tph)], where N(T)=1/[exp(ℏΩ/kBT)−1] with optical phonon energy ℏΩ and κop=2×102 W/m.
Effects of Sb/As intermixing on optical properties of GaSb type-II quantum dots in GaAs grown by droplet epitaxy
Authors: Kawazu Takuya , Sakaki Hiroyuki
Published: December 2010

Optical properties of GaSb type-II quantum dots (QDs) in GaAs were studied and compared with a theoretical model to clarify how the spatial overlap of holes in the dot and electrons outside is affected by the interdiffusion of Sb and As. GaSb QDs were grown in a GaAs substrate by droplet epitaxy and annealed at the temperature Ta=650–850 °C to induce the Sb/As intermixing. Photoluminescence (PL) studies showed that the integrated PL intensity I decreases to less than 1/10 as Ta is raised from 650 to 750 °C, while I increases by three orders of magnitude with the increase of Ta from 750 to 850 °C. This behavior is explained by the overlap Θ between electron and hole wave functions; in an initial stage of the interdiffusion, the mixing occurs only near the dot/matrix boundary, leading to the decrease in the overlap Θ, since electrons are more repelled by the dot. In later stages, however, the hole confinement and the electron repulsion in the dot both weaken, leading to the increase in the overlap Θ.
Molecular conductivity switching of two benzene rings under electric field
Authors: Vergniory M. G. , Granadino-Roldan J. M. , Garcia-Lekue A. , Wang Lin-Wang
Published: December 2010

A molecular transistor based on torsion-angle conformation change driven by gate electric field is designed and studied using ab initio calculations. This transistor consists of a SH–C6H2F(CH3)C6H2(CH3)F–SH molecule sandwiched between two Au(111) electrodes, where the interaction between the molecular dipole and a gate voltage induced electric field will cause the molecule to twist along its c-axis, changing the quantum conductivity of the molecule. The effect of thermal fluctuation on the molecular conformation is studied, so is the ability of the transistor to shut off its current. The advantages and challenges of using such molecular conformation change as a mechanism for transistor gating are discussed.
Disruption of small RNA signaling caused by competition for Hfq
Authors: Hussein Razika , Lim Han N.
Published: December 2010

Small RNAs (sRNAs) regulate diverse pathways, including stress responses, virulence, and metabolism in
Escherichia coli
. At the center of this large sRNA regulatory network is the Hfq protein. Hfq mediates the binding of sRNAs to their target mRNAs; without Hfq, most sRNAs cannot efficiently regulate target mRNA expression. Here, we show in vivo that Hfq can be a limiting factor for sRNA activity and that it can be easily depleted, causing disruption of the sRNA network. Depletion of the available Hfq can occur when sRNAs and target mRNAs are transcribed at high levels without their partners, resulting in the sequestration of Hfq into sRNA–Hfq and target mRNA–Hfq complexes. This can be avoided by coordinating the transcription of sRNAs with their target mRNAs so that they are turned on and off together to maximize duplex formation and minimize Hfq sequestration. Therefore, the limited availability of Hfq results in a highly interdependent sRNA network, wherein the activity of each sRNA depends on the activity of the other sRNAs and target mRNAs in the network.
Microenvironmental control of malignancy exerted by RNASET2, a widely conserved extracellular RNase
Authors: Acquati Francesco , Bertilaccio Sabrina , Grimaldi Annalisa , Monti Laura , Cinquetti Raffaella , Bonetti Paolo , Lualdi Marta , Vidalino Laura , Fabbri Marco , Sacco Maria Grazia , Rooijen Nico van , Campomenosi Paola , Vigetti Davide , Passi Alberto , Riva Cristina , Capella Carlo , Sanvito Francesca , Doglioni Claudio , Gribaldo Laura , Macchi Paolo , Sica Antonio , Noonan Douglas M. , Ghia Paolo , Taramelli Roberto
Published: December 2010

A recent body of evidence indicates an active role for stromal (mis)-regulation in the progression of neoplasias. Within this conceptual framework, genes belonging to the growing but still poorly characterized class of tumor antagonizing/malignancy suppressor genes (TAG/MSG) seem to play a crucial role in the regulation of the cross-talk between stromal and epithelial cells by controlling malignant growth in vivo without affecting any cancer-related phenotype in vitro. Here, we have functionally characterized the human RNASET2 gene, which encodes the first human member of the widespread Rh/T2/S family of extracellular RNases and was recently found to be down-regulated at the transcript level in several primary ovarian tumors or cell lines and in melanoma cell lines. Although we could not detect any activity for RNASET2 in several functional in vitro assays, a remarkable control of ovarian tumorigenesis could be detected in vivo. Moreover, the control of ovarian tumorigenesis mediated by this unique tumor suppressor gene occurs through modification of the cellular microenvironment and the induction of immunocompetent cells of the monocyte/macrophage lineage. Taken together, the data presented in this work strongly indicate RNASET2 as a previously unexplored member of the growing family of tumor-antagonizing genes.