bluuebunny/crossref_metadata_2025 huggingface dataset:
Including copy number variation in association studies to predict genotypic values
Authors: CALUS M. P. L. , DE KONING D. J. , HALEY C. S.
Published: June 2010

The objective of this study was to investigate, both empirically and deterministically, the ability to explain genetic variation resulting from a copy number polymorphism (CNP) by including the CNP, either by its genotype or by a continuous derivation thereof, alone or together with a nearby single nucleotide polymorphism (SNP) in the model. This continuous measure of a CNP genotype could be a raw hybridization measurement, or a predicted CNP genotype. Results from simulations showed that the linkage disequilibrium (LD) between an SNP and CNP was lower than LD between two SNPs, due to the higher mutation rate at the CNP loci. The modelR2values from analysing the simulated data were very similar to theR2values predicted with the deterministic formulae. Under the assumption thatxcopies at a CNP locus lead to the effect ofxtimes the effect of 1 copy, including a continuous measure of a CNP locus in the model together with the genotype of a nearby SNP increased power to explain variation at the CNP locus, even when the continuous measure explained only 15% of the variation at the CNP locus.
Continuous approximations for optimizing allele trajectories
Authors: LIU A. Y. H. , WOOLLIAMS J. A.
Published: June 2010

The incorporation of genetic information such as quantitative trait loci (QTL) data into breeding schemes has become feasible as DNA technologies have advanced. Such strategies allow the frequency of desirable QTL to be controlled over a predefined time frame, allowing the allele trajectory for QTL to be manipulated. A continuous approximation to changes in allele frequency was developed to approximate the selection procedure as a continuous rather than a discrete process, and analytical solutions were obtained, which shed light on how allele trajectories behave under different objective functions. Three different objectives were considered: (1) minimizing the total selection intensity, (2) minimizing the sum of squared selection intensities and (3) equalizing the selection intensity applied over time. Simulations and genetic algorithms were performed to test the accuracy and robustness of the continuous approximation. Theory shows firstly that the total selection intensity required for moving an allele from a starting frequency to another frequency point can be predicted independent of its trajectory, and secondly that objectives (2) and (3) are equivalent as the number of selection opportunities (T) becomes large. The prediction of total selection intensity provides a good fit for these two objectives, with the accuracy of prediction improving asTincreases. However, for (1) the continuous approximation does not fit due to the existence of a discontinuous solution in which the continuous approximation is applied before the frequency of the selected allele reaches 0·5 followed by rapid fixation.
Correlations between bed occupancy rates andClostridium difficileinfections: a time-series analysis
Authors: KAIER K. , LUFT D. , DETTENKOFER M. , KIST M. , FRANK U.
Published: June 2010

A time-series analysis was performed to identify the impact of bed occupancy rates and length of hospital stay on the incidence ofClostridium difficileinfections (CDI). Between January 2003 and July 2008, a mean incidence of 0·5 CDI cases/1000 patient days was recorded. Application of a multivariate model (R2=0·50) showed that bed occupancy rates on general wards (P<0·01) and length of stay in intensive care units (ICUs) (P<0·01) influenced the incidence of CDI. Overcrowding on general wards and long periods in ICUs were identified as being positively associated with the incidence of CDI.
Explaining the 25-year decline of serum cholesterol by dietary changes and use of lipid-lowering medication in Finland
Authors: Valsta Liisa M , Tapanainen Heli , Sundvall Jouko , Laatikainen Tiina , Männistö Satu , Pietinen Pirjo , Vartiainen Erkki
Published: June 2010

Objective

To assess to what extent the observed dietary changes and increased use of lipid-lowering medication can explain the almost 20 % decline in serum cholesterol (referring to serum total cholesterol) level observed from 1982 to 2007 in Finland.

Design

Predicted changes of serum cholesterol were calculated by the Keys’ equation assuming the effect of trans fatty acids to be similar to SFA and using the dietary intake data of the national dietary surveys between 1982 and 2007. The effect of medication was estimated based on the information on use of lipid-lowering medication among survey participants. The predicted serum cholesterol levels were compared with observed changes in analysed serum cholesterol levels.

Setting

Four cross-sectional population surveys, in 1982, 1992, 2002 and 2007, in the provinces of North Karelia, Northern Savo and Southwestern Finland.

Subjects

A total of 2325 men and 2638 women aged 26–64 years selected randomly from the national population register for the four surveys.

Results

Changes in dietary fat quality and cholesterol intake explain 0·70 mmol/l (65 %) of the decrease in men and 0·65 mmol/l (60 %) of the decrease in women in all subjects. Decline in dietary SFA intake is the main explanatory factor (47 % in men and 41 % in women) for the changes. The impact of lipid-lowering medication on observed cholesterol levels was found to be 16 % among men and 7 % among women.

Conclusions

The decrease in serum cholesterol levels in Finland can be explained mainly by dietary changes, especially changes in fat quality. The effect of lipid-lowering medication is less significant.
Diet composition of pregnant Finnish women: changes over time and across seasons
Authors: Prasad Marianne , Lumia Mirka , Erkkola Maijaliisa , Tapanainen Heli , Kronberg-Kippilä Carina , Tuokkola Jetta , Uusitalo Ulla , Simell Olli , Veijola Riitta , Knip Mikael , Ovaskainen Marja-Leena , Virtanen Suvi M
Published: June 2010

Objective

To describe the diet of a population of pregnant Finnish women over a period of 7 years, with special attention paid to seasonal fluctuations in food consumption and nutrient intake.

Design

A validated 181-item FFQ was applied retrospectively, after delivery, to assess the maternal diet during the 8th month of pregnancy.

Setting

Type 1 Diabetes Prediction and Prevention Nutrition Study Cohort.

Subjects

The cohort comprised a total of 4880 women who had newly delivered during the years 1997–2004, with the offspring carrying increased genetic risk for type 1 diabetes mellitus.

Results

Over the study period, the proportion of energy derived from fat decreased while the intake from protein and carbohydrate increased. The intake of vitamin D increased from food sources. Seasonal variation was observed in the mean daily consumption of vegetables, fruits and berries and cereals. Intake of dietary fibre, total fat, MUFA, vitamins A, D, E and C, folate and iron also showed seasonal fluctuation.

Conclusions

These results show an overall positive trend in the diet of pregnant Finnish women through the study years. However, there is still room for improvement, particularly in the types of dietary fats. Although food fortification with vitamin D since 2003 was reflected in the increased intake of vitamin D from foods, the mean intake levels still fell below the recommendations. Seasonal changes in food consumption were observed and related to corresponding fluctuations in nutrient intakes. The mean folate intake fell below the recommendation throughout the year.
Dietary habits and nutrient intake of Finnish adolescents
Authors: Hoppu Ulla , Lehtisalo Jenni , Tapanainen Heli , Pietinen Pirjo
Published: June 2010

Objective

To evaluate food and nutrient intake and especially eating during the school day among Finnish secondary-school pupils.

Design

Cross-sectional study. Data were collected using a structured questionnaire mailed to home and by 48 h dietary recall interviews performed at schools in 2007.

Setting

Twelve schools in three cities in Finland.

Subjects

The seventh grade pupils (a total of 1469 at the mean age of 13·8 years). Questionnaire data were available from 726 pupils and dietary data from a subgroup of 40 % (n 306).

Results

According to the questionnaire data, 40 % of the girls and 28 % of the boys reported eating fresh vegetables daily and the respective figures for fruit were 32 % and 23 %. Altogether, 71 % of the adolescents reported having school lunch every day. The average intake of sucrose was higher and the average intakes of fibre, iron, folate and vitamin D were lower than recommended. School lunch provided around 20 % of daily energy intake, while the recommended daily energy intake level is one-third. However, the school lunch as consumed was nutritionally superior to the other daily meals. Snacks provided 41 % of the daily energy. The most common sources of sucrose were sugary drinks.

Conclusions

Low consumption of fruit and vegetables and abundant consumption of sucrose-rich drinks and snacks are the main problems in the diet of Finnish adolescents. The nutritional quality of the school lunch is good, but the supply of healthy snacks must be improved in schools. Schools can promote healthy eating habits by making healthy choices easy during the school day.
Domestic-Sector Work in the UK: Locating Men in the Configuration of Gendered Care and Migration Regimes
Authors: Kilkey Majella
Published: June 2010

Research on the processes underpinning the contemporary growth in the commoditisation of domestic labour focuses on feminised areas of work, such as cleaning and care. Yet research examining trends in domestic outsourcing highlights how men's, as well as women's, household work is subject to increased commoditisation. Through a qualitative enquiry of households which outsource stereotypically male domestic chores – essentially, household and garden repair and maintenance – and men who do such work for pay, we seek to understand the processes underpinning its outsourcing. In doing so, we adopt a framework which treats the paid domestic-work sector as a critical nexus at which gendered care and migration regimes intersect. The focus on male domestic chores, however, requires that we broaden that framework in ways which can more fully illuminate men's positions within it.
Concurrent variations of water vapor and temperature corresponding to the interannual variation of precipitation in the North American Regional Reanalysis
Authors: Lu Er , Takle Eugene S.
Published: June 2010

The concurrent variation patterns of water vapor and temperature corresponding to the interannual variation of winter precipitation and the roles of change in atmospheric circulation are studied with the North American Regional Reanalysis. A very tight positive relationship between precipitation and relative humidity at interannual time scale is found from the large spatially sampled data set. On the basis of this relationship, the concurrent variations of water vapor and temperature between the wettest and the driest years are categorized into three patterns. The distribution of the patterns shows that more winter precipitation of wetter years corresponds to more water vapor but not lower temperature (moistening pattern) in high latitudes, lower temperature but not more water vapor (cooling pattern) in midlatitudes, and both more water vapor and lower temperature (moistening‐cooling pattern) in low latitudes. The characteristics and roles of change in atmospheric circulation from the driest years to the wettest years are analyzed for two selected areas. It is found that, around the selected cooling pattern (moistening pattern) area, the field of wind difference between the wettest years and the driest years is divergent (convergent). Dominated by this, the fields of differences in both heat flux and water vapor flux are divergent (convergent). This leads to the decreases (increases) of the heating and moistening rates and, thus, the characteristics of the cooling pattern (moistening pattern) area with cooling and drying (warming and moistening) from the driest years to the wettest years. This study suggests that, for interannual prediction of precipitation, temperature, in addition to water vapor, should also be considered.
Enhanced riverine carbon flux from carbonate catchment to the ocean: A comparative hydrogeochemical study on Ishigaki and Iriomote islands, southwestern Japan
Authors: Ushie Hiroyuki , Kawahata Hodaka , Suzuki Atsushi , Murayama Shohei , Inoue Mayuri
Published: June 2010

Riverine carbon transportation is an important carbon flux connecting reservoirs of the atmosphere, continents, and oceans. The flux is strongly related to the important roles of rivers such as regulation of climate change and buffering of ocean acidification. Here, to evaluate the linkage of such functions of rivers and geological characteristics of the watersheds, we present the results of a comparative hydrogeochemical study conducted on small subtropical watersheds of aluminosilicate‐dominated Iriomote Island and carbonate‐based Ishigaki Island, southwestern Japan. Rivers on Ishigaki Island exhibited much higher alkalinity than rivers on Iriomote Island, which was even higher than the mean value of major rivers in the world, such as the Saint Lawrence and the Mississippi. This high alkalinity was the result of carbonate dissolution enhanced by soil‐originated CO2. As a result of this high inorganic carbon input, the ratio of inorganic carbon and nutrients of the river water was higher than that of marine organic matter such as the Redfield ratio, making the coastal seas a potential source of CO2 for the atmosphere.
Anything you touch may be used against you
Authors: Hunter Philip
Published: June 2010

Philip Hunter explores current progress in forensic biology and its application beyond serious crimes. Yet, while these technological tools are a great help for criminal investigators, they do not replace thorough detective work.
A ‘metaphising’ dung beetle
Authors: Kováč Ladislav
Published: June 2010

Humans and beetles both have a species‐specificUmweltcircumscribed by their sensory equipment. However, Ladislav Kováč argues that humans, unlike beetles, have invented scientific instruments that are able to reach beyond the conceptual borders of ourUmwelt.
Phenotypic and functional switch of macrophages induced by regulatory CD4+CD25+ T cells in mice
Authors: Liu Guangwei , Ma Haixia , Qiu Lin , Li Long , Cao Yuhong , Ma Jun , Zhao Yong
Published: June 2010

CD4+CD25+ regulatory T cells (Treg cells) are important in maintenance of peripheral tolerance. The direct effect of CD4+CD25+ Treg cells on macrophages was studied using a mouse model in which syngeneic CD4+CD25+ Treg cells were adoptively transferred into the peritoneal cavity of SCID mice. Peritoneal macrophages in mice transferred with CD4+CD25+ Treg cells expressed significantly higher levels of CD23, CD47 and CD206 and less CD80 and major histocompatibility complex class II molecules as compared with those mice that received either CD4+CD25− T cells or no cells. Macrophages of mice injected with CD4+CD25+ Treg cells displayed a remarkably enhanced phagocytosis of chicken red blood cells, and arginase activity together with an increased interleukin‐10 (IL‐10) production, whereas they showed a decreased antigen‐presenting ability and nitric oxide production. Furthermore, CD4+CD25+ Treg cells and CD4+CD25− T cells showed strong antagonistic effects on macrophage polarizations in vivo. Blocking arginase, IL‐10 and/or transforming growth factor‐β (TGF‐β) partially but significantly reversed the effects of CD4+CD25+ Treg cells to induce M2 macrophages in vivo suggesting that CD4+CD25+ Treg cells have the ability to induce M2 macrophages at least in part through arginase, IL‐10 and TGF‐β pathways. Thus, we have provided the in vivo evidence to support the unknown pathways for CD4+CD25+ Treg cells to regulate innate immunity by promoting the differentiation of M2 macrophages as well as by inhibiting M1 macrophage induction by CD4+CD25− T cells in mice. CD4+CD25+ Treg cells efficiently induced M2 macrophage differentiation in mice, offering the in vivo evidence to support the role of CD4+CD25+ Treg cells in regulating innate immunity.
Traumatic Brain Injury: An Overview of Pathobiology with Emphasis on Military Populations
Authors: Cernak Ibolja , Noble-Haeusslein Linda J
Published: June 2010

Correction to: Journal of Cerebral Blood Flow & Metabolism (2010) 30, 255–266; doi:10.1038/jcbfm.2009.203

Following the publication of this article, the authors noted that the definition for TBI in the footnote to Table 2, ‘TBI, total body irradiation’, was incorrect. It should have read ‘TBI, traumatic brain injury’. The typesetters would like to apologize for this error.
Deficiency of PAR4 Attenuates Cerebral Ischemia–Reperfusion Injury in Mice
Authors: Mao Yingying , Zhang Ming , Tuma Ronald F , Kunapuli Satya P
Published: June 2010

Correction to: Journal of Cerebral Blood Flow & Metabolism (2010) 30, 1044–1052; doi: 10.1038/jcbfm.2009.283

Following the online publication of this article, the authors noticed that one of the names in the Acknowledgements section was misspelled. The correct spelling is Ms Varshana Gurusamy.
(Corrected) Speed effects in gliding motility assays due to surface passivation, water isotope, and osmotic stress.
Authors: Maloney Andy , Herskowitz Lawrence , Koch Steven
Published: June 2010

The molecular motor kinesin-1, an ATPase, and the substrate it walks along, microtubules, are vital components of eukaryotic cells. Kinesin converts chemical energy to linear motion as its two motor domains step along microtubules in a process similar to how we walk. Cells create systems of microtubules that direct the motion of kinesin. This directed motion allows kinesin to transport various cargos inside cells.During the stepping process, the kinesin motor domains bind and unbind from their binding sites on the microtubules. Binding and unbinding rates of biomolecules are highly dependent on hydration and exclusion of water from the binding interface. Osmotic stress will likely strongly affect the binding and unbinding rates for kinesin and thus offers a tool to specifically probe those steps. We will report the effects of different osmolytes on microtubule speed and other observables in the gliding motility assay.Kinesin’s kinetic core cycle hydrolyzes ATP with the help of a water molecule. Any modification to the water molecules the kinesin is in will change how ATP hydrolyzes and will ultimately affect how kinesin moves along microtubules. We will report preliminary results showing how kinesin is affected when the solvent it is in is changed from light water to heavy water.When used in a surface assay or in devices, the kinesin and microtubule system is also dependent on substrate passivation. Kinesin motor domains do not transport microtubules in the gliding motility assay if kinesin is added to a glass microscope slide that has not been functionalized. Functionalization of the glass slides and slips is typically performed with bovine milk proteins called caseins. Bovine casein is a globular protein that can be broken up into four constituents: αs1, αs2, β, and κ. Each casein constituent affects how kinesin adheres to the glass and ultimately the speed at which microtubules are observed to glide at. Building on the work of Verma et.al., we have found that each constituent individually produces different outcomes in gliding assays. We will present these findings and discuss implications they have for use of gliding assays to study kinesin and use of kinesin-microtubule system in microdevices.[1] Chaen, S, N Yamamoto, I Shirakawa, and H Sugi. 2001. Effect of deuterium oxide on actomyosin motility in vitro. Biochimica et biophysica acta 1506, no. 3: 218-23.[2] Vivek Verma, William O Hancock, Jeffrey M Catchmark, "The role of casein in supporting the operation of surface bound kinesin," J. Biol. Eng. 2008; 2: 14.

Acknowledgements:

This work was supported by the DTRA CB Basic Research Program under Grant No. HDTRA1-09-1-008.CORRECTIONS: At the workshop, Erik Schaffer pointed out to us that some of our speed differences (casein data) were surely due to microscope increasing in temperature. I've edited the poster to correct for this. Thanks, Erik!
Grape seed extract enhances eNOS expression and NO production through regulating calcium‐mediated AKT phosphorylation in H2O2‐treated endothelium
Authors: Feng Zhe , Wei Ri‐Bao , Hong Quan , Cui Shao‐Yuan , Chen Xiang‐Mei
Published: June 2010

GSE (grape seed extract) has been shown to exhibit protective effects against cardiovascular events and atherosclerosis, although the underlying molecular mechanisms of action are unknown. Herein, we assessed the ability of GSE to enhance eNOS (endothelial nitric oxide synthase) expression and NO (nitric oxide) production in H2O2(hydrogen peroxide)‐treated HUVECs (human umbilical vein endothelial cells). GSE enhanced eNOS expression and NO release in H2O2‐treated cells in a dose‐dependent manner. GSE inhibited intracellular ROS (reactive oxygen species) and reduced intracellular calcium in a dose‐dependent manner in H2O2‐treated cells, as shown by confocal microscopy. ROS was inhibited in cells pretreated with 5.0 μM GSE, 2.0 μM TG (thapsigargin) and 20.0 μM 2‐APB (2‐aminoethoxydiphenyl borate) instead of 0.25 μM extracellular calcium. In addition, GSE enhanced eNOS expression and reduced ROS production via increasing p‐AKT (AKT phosphorylation) with high extracellular calcium (13 mM). In conclusion, GSE protected against endothelial injury by up‐regulation of eNOS and NO expression via inhibiting InsP3Rs (inositol 1,4,5‐trisphosphate receptors)‐mediated intracellular excessive calcium release and by activating p‐AKT in endothelial cells.
Flow cytometric sorting and analysis of human epidermal stem cell candidates
Authors: Pikuła Michał , Kondej Karolina , Jaśkiewicz Janusz , Skokowski Jarosław , Trzonkowski Piotr
Published: June 2010

ESC (epidermal stem cells) play a central role in the regeneration of human epidermis. These cells are also responsible for wound healing and neoplasm formation. Efficient isolation of ESC allows their use in medicine and pharmacy as well as in basic science. Cultured keratinocytes and ESC may be used as biological dressing in burn injuries, chronic wounds and hereditary disorders. Therefore, the isolation and characterization of ESC have been goals in biomedical science. Here, we present a flow cytometric method for the isolation and analysis of human ESC candidates. The strategy presented for the isolation of ESC combines previously proposed enzymatic digestion and FACS‐sorting of the obtained cell suspension that utilizes morphological features, integrin‐β1 expression and Rh123 (Rhodamine 123) accumulation of the cells. We also performed a flow cytometric analysis of sorted cells using a cell tracer.
Device physics of inverted all-polymer solar cells
Authors: Brenner Thomas J. K. , Hwang Inchan , Greenham Neil C. , McNeill Christopher R.
Published: June 2010

The device physics of inverted all-polymer solar cells based on a blend of the polymers poly(3-hexylthiophene) and poly(9,9-dioctylfluorene)-2,7-diyl-alt-[4,7-bis(3-hexylthiophen-5-yl)2,1,3-benzothiadiazole]-2′,2″-diyl) is investigated. In particular, the influence of active layer thickness on device parameters is investigated and compared to that of devices with a standard geometry. Increasing the active layer thickness from 70 to 480 nm is found to increase the open circuit voltage from 0.1 to 0.71 V and the external quantum efficiency (EQE) from 7% to 24%. In contrast, an optimum EQE of about 25% for the standard geometry is found for a film thickness of 70 nm, which decreases sharply with increasing active layer thickness. The shape of the EQE spectra of standard geometry devices also become severely distorted with increasing active layer thickness, with a minimum in EQE coinciding with the wavelength corresponding to maximum light absorption. In contrast, the shape of the EQE spectra of inverted devices remains essentially unchanged with increasing active layer thickness. Optical simulations of light absorption in the active layer have also been performed and demonstrate that the distortion in the EQE spectra of thicker standard geometry devices is consistent with photoexcitations created in the back half of these devices being more efficiently harvested than those in the first 100 nm of the inverted device. Furthermore, the fact that the EQE spectrum of inverted devices does not significantly broaden with increasing thickness suggests that harvesting of photoexcitations remains efficient in the front half of the device where most of the light is absorbed. Device modeling is employed to demonstrate that the lower mobility of electrons (and electron trapping) causes a favorable redistribution of the internal electric field in the inverted device with electric field increasing near the transparent electrode coinciding with the region of maximum light absorption. In contrast, in the standard device the internal electric significantly decreases near the transparent electrode causing a reduction in field-dependent charge separation and increased bimolecular recombination. Our results demonstrate that inverted devices may be an effective way to overcome losses in organic solar cells where electron mobility is typically lower than hole mobility.
On the bandstructure velocity and ballistic current of ultra-narrow silicon nanowire transistors as a function of cross section size, orientation, and bias
Authors: Neophytou Neophytos , Kim Sung Geun , Klimeck Gerhard , Kosina Hans
Published: June 2010

A 20 band sp3d5s∗ spin-orbit-coupled, semiempirical, atomistic tight-binding model is used with a semiclassical, ballistic field-effect-transistor model, to theoretically examine the bandstructure carrier velocity and ballistic current in silicon nanowire (NW) transistors. Infinitely long, uniform, cylindrical, and rectangular NWs, of cross sectional diameters/sides ranging from 3–12 nm are considered. For a comprehensive analysis, n-type and p-type metal-oxide semiconductor (NMOS and PMOS) NWs in [100], [110], and [111] transport orientations are examined. In general, physical cross section reduction increases velocities, either by lifting the heavy mass valleys or significantly changing the curvature of the bands. The carrier velocities of PMOS [110] and [111] NWs are a strong function of diameter, with the narrower D=3 nm wires having twice the velocities of the D=12 nm NWs. The velocity in the rest of the NW categories shows only minor diameter dependence. This behavior is explained through features in the electronic structure of the silicon host material. The ballistic current, on the other hand, shows the least sensitivity with cross section in the cases where the velocity has large variations. Since the carrier velocity is a measure of the effective mass and reflects on the channel mobility, these results can provide insight into the design of NW devices with enhanced performance and performance tolerant to structure geometry variations. In the case of ballistic transport in high performance devices, the [110] NWs are the ones with both high NMOS and PMOS performance as well as low on-current variations with cross section geometry variations.
Localized eigenfunctions in Šeba billiards
Authors: Keating J. P. , Marklof J. , Winn B.
Published: June 2010

We describe some new families of quasimodes for the Laplacian perturbed by the addition of a potential formally described by a Dirac delta function. As an application, we find, under some additional hypotheses on the spectrum, subsequences of eigenfunctions of Šeba billiards that localize around a pair of unperturbed eigenfunctions.
Connection between the two branches of the quantum two-stream instability across the k space
Authors: Bret A. , Haas F.
Published: June 2010

The stability of two quantum counterstreaming electron beams is investigated within the quantum plasma fluid equations for arbitrarily oriented wave vectors k. The analysis reveals that the two quantum two-stream unstable branches are indeed connected by a continuum of unstable modes with oblique wave vectors. Using the longitudinal approximation, the stability domain for any k is analytically explained, together with the growth rate.
Optical sensing and determination of complex reflection coefficients of plasmonic structures using transmission interferometric plasmonic sensor
Authors: Sannomiya Takumi , Balmer Tobias E. , Hafner Christian , Heuberger Manfred , Vörös Janos
Published: June 2010

The combination of interferometry and plasmonic structure, which consists of gold nanoparticle layer, sputter coated silicon oxide spacer layer, and aluminum mirror layer, was studied in transmission mode for biosensing and refractive index sensing applications. Because of the interferometric nature of the system, the information of the reflection amplitude and phase of the plasmonic layer can be deduced from one spectrum. The modulation amplitude in the transmission spectrum, caused by the interference between the plasmonic particle layer and the mirror layer, increases upon the refractive index increase around the plasmonic particles due to their coherent backscattering property. Our proposed evaluation method requires only two light sources with different wavelengths for a stable self-referenced signal, which can be easily and precisely tuned by a transparent spacer layer thickness. Unlike the standard localized surface plasmon sensors, where a sharp resonance peak is essential, a broad band plasmon resonance is accepted in this method. This leads to large fabrication tolerance of the plasmonic structures. We investigated bulk and adsorption layer sensitivities both experimentally and by simulation. The highest sensitivity wavelength corresponded to the resonance of the plasmonic particles, but useful signals are produced in a much broader spectral range. Analysis of a single transmission spectrum allowed us to access the wavelength-dependent complex reflection coefficient of the plasmonic particle layer, which confirmed the reflection amplitude increase in the plasmonic particle layer upon molecular adsorption.
Experimental studies of edge turbulence and confinement in Alcator C-Mod
Authors: Cziegler I. , Terry J. L. , Hughes J. W. , LaBombard B.
Published: June 2010

The steep gradient edge region and scrape-off-layer (SOL) on the low-field-side of Alcator C-Mod [I. H. Hutchinson, R. Boivin, F. Bombarda et al., Phys. Plasmas 1, 1511 (1994)] tokamak plasmas are studied using gas-puff-imaging diagnostics. In L-mode plasmas, the region extending ∼2 cm inside the magnetic separatrix has fluctuations showing a broad, turbulent spectrum, propagating in the electron diamagnetic drift direction, whereas features in the open field line region propagate in the ion diamagnetic drift direction. This structure is robust against toroidal field strength, poloidal null-point geometry, plasma current, and plasma density. Global parameter dependence of spectral and spatial structure of the turbulence inside the separatrix is explored and characterized, and both the intensity and spectral distributions are found to depend strongly on the plasma density normalized to the tokamak density limit. In H-mode discharges the fluctuations at and inside the magnetic separatrix show fundamentally different trends compared to L-mode, with the electron diamagnetic direction propagating turbulence greatly reduced in ELM-free [F. Wagner et al., Proceedings of the Thirteenth Conference on Plasma Physics and Controlled Nuclear Fusion Research (IAEA, Vienna, 1982), Vol. I, p. 277], and completely dominated by the modelike structure of the quasicoherent mode in enhanced D-alpha regimes [A. E. Hubbard, R. L. Boivin, R. S. Granetz et al., Phys. Plasmas 8, 2033 (2001)], while the normalized SOL turbulence is largely unaffected.
A multipurpose modular system for high-resolution microscopy at high hydrostatic pressure
Authors: Vass Hugh , Black S. Lucas , Herzig Eva M. , Ward F. Bruce , Clegg Paul S. , Allen Rosalind J.
Published: June 2010

We have developed a modular system for high-resolution microscopy at high hydrostatic pressure. The system consists of a pressurized cell of volume ∼100 μl, a temperature controlled holder, a ram, and a piston. We have made each of these components in several versions which can be interchanged to allow a wide range of applications. Here, we report two pressure cells with pressure ranges 0.1–700 MPa and 0.1–100 MPa, which can be combined with hollow or solid rams and pistons. Our system is designed to work with fluorescent samples (using a confocal or epifluorescence microscope), but also allows for transmitted light microscopy via the hollow ram and piston. The system allows precise control of pressure and temperature (−20 to 70 °C), as well as rapid pressure quenching. We demonstrate its performance and versatility with two applications: time-resolved imaging of colloidal phase transitions caused by pressure changes between 0.1 and 100 MPa, and imaging the growth of Escherichia coli bacteria at 50 MPa. We also show that the isotropic-nematic phase transition of pentyl-cyanobiphenyl (5CB) liquid crystal provides a simple, convenient, and accurate method for calibrating pressure in the range 0.1–200 MPa.
Multitemperature synchrotron powder diffraction and thermoelectric properties of the skutterudite La0.1Co4Sb12
Authors: Mi Jian-Li , Christensen Mogens , Nishibori Eiji , Kuznetsov Vladimir , Rowe David Micheal , Iversen Bo Brummerstedt
Published: June 2010

Compounds with the skutterudite structure have potential use in thermoelectric power generation and the role of the filler atoms in filled skutterudites is still an open question regarding their effects on thermal conductivity. Partially filled skutterudite La0.1Co4Sb12 has been investigated by synchrotron powder x-ray diffraction between 90 and 700 K, as well as heat capacity, electrical and thermal transport property measurements, and Hall effect measurements. Anomalously large atomic displacement parameters (ADPs) are found for the La filler atoms, indicating that the La atoms are weakly bound in the structure. Analysis of the multitemperature ADPs of La using the Einstein model and the ADPs of the framework atoms using the Debye model gives an Einstein temperature of 79 K and a Debye temperature of 268 K. The heat capacity estimated from the Debye and Einstein temperatures is in good agreement with the measured experimental data. The ADP analysis also indicates that the La atoms are slightly displaced (0.06 Å) from the cage center possible due to covalent bonding with the host structure. Compared with unfilled CoSb3, the low energy La vibration modes significantly increase the heat capacity of La0.1Co4Sb12 at lower temperature despite the low La occupancy (refined occupancy of 4.9%). The small content of filling atoms results in a large reduction in the thermal conductivity.
Direct observation of electronic inhomogeneities induced by point defect disorder in manganite films
Authors: Sirena M. , Zimmers A. , Haberkorn N. , Kaul E. , Steren L. B. , Lesueur J. , Wolf T. , Le Gall Y. , Grob J.-J. , Faini G.
Published: June 2010

We have investigated the influence of point defect disorder in the electronic properties of manganite films. Real-time mapping of ion irradiated samples conductivity was performed through conductive atomic force microscopy (CAFM). CAFM images show electronic inhomogeneities in the samples with different physical properties due to spatial fluctuations in the point defect distribution. As disorder increases, the distance between conducting regions increases and the metal-insulator transition shifts to lower temperatures. Transport properties in these systems can be interpreted in terms of a percolative model. The samples saturation magnetization decreases as the irradiation dose increases whereas the Curie temperature remains unchanged.
The radiation from a planar metamaterial waveguide
Authors: Basharin A. A. , Balabukha N. P. , Semenenko V. N.
Published: June 2010

Propagation of electromagnetic waves in planar waveguides made of metamaterials with negative values of the relative permittivity and relative permeability is analyzed. The specific features of radiation from antennas manufactured on the basis of planar metamaterial waveguides are studied. It is shown that radiation of such antennas is characterized by the backward radiation effect, i.e., the maximum of the radiation pattern is formed at 180°. The causes of this effect and the conditions for its appearance are revealed. It is proved that this effect appears only in the antennas manufactured on the basis of metamaterial waveguides with negative values of the relative permittivity and relative permeability. A design version of a scanning two-mode antenna operating on the basis of this effect is proposed.
Multistate electron transfer dynamics in the condensed phase: Exact calculations from the reduced hierarchy equations of motion approach
Authors: Tanaka Midori , Tanimura Yoshitaka
Published: June 2010

Multiple displaced oscillators coupled to an Ohmic heat bath are used to describe electron transfer (ET) in a dissipative environment. By performing a canonical transformation, the model is reduced to a multilevel system coupled to a heat bath with the Brownian spectral distribution. A reduced hierarchy equations of motion approach is introduced for numerically rigorous simulation of the dynamics of the three-level system with various oscillator configurations, for different nonadiabatic coupling strengths and damping rates, and at different temperatures. The time evolution of the reduced density matrix elements illustrates the interplay of coherences between the electronic and vibrational states. The ET reaction rates, defined as a flux-flux correlation function, are calculated using the linear response of the system to an external perturbation as a function of activation energy. The results exhibit an asymmetric inverted parabolic profile in a small activation regime due to the presence of the intermediate state between the reactant and product states and a slowly decaying profile in a large activation energy regime, which arises from the quantum coherent transitions.
Transformation twinning of Ni–Mn–Ga characterized with temperature-controlled atomic force microscopy
Authors: Reinhold Matthew , Watson Chad , Knowlton William B. , Müllner Peter
Published: June 2010

The magnetomechanical properties of ferromagnetic shape memory alloy Ni–Mn–Ga single crystals depend strongly on the twin microstructure, which can be modified through thermomagnetomechanical training. Atomic force microscopy (AFM) and magnetic force microscopy (MFM) were used to characterize the evolution of twin microstructures during thermomechanical training of a Ni–Mn–Ga single crystal. Experiments were performed in the martensite phase at 25 °C and in the austenite phase at 55 °C. Two distinct twinning surface reliefs were observed at room temperature. At elevated temperature (55 °C), the surface relief of one twinning mode disappeared while the other relief remained unchanged. When cooled back to 25 °C, the twin surface relief recovered. The relief persisting at elevated temperature specifies the positions of twin boundaries that were present when the sample was polished prior to surface characterization. AFM and MFM following thermomechanical treatment provide a nondestructive method to identify the crystallographic orientation of each twin and of each twin boundary plane. Temperature dependent AFM and MFM experiments reveal the twinning history thereby establishing the technique as a unique predictive tool for revealing the path of the martensitic and reverse transformations of magnetic shape memory alloys.
Permanent optical doping of amorphous metal oxide semiconductors by deep ultraviolet irradiation at room temperature
Authors: Seo Hyungtak , Cho Young-Je , Kim Jinwoo , M.bobade Santosh , Park Kyoung-Youn , Lee Jaegab , Choi Duck-Kyun
Published: June 2010

We report an investigation of two photon ultraviolet (UV) irradiation induced permanent n-type doping of amorphous InGaZnO (a-IGZO) at room temperature. The photoinduced excess electrons were donated to change the Fermi-level to a conduction band edge under the UV irradiation, owing to the hole scavenging process at the oxide interface. The use of optically n-doped a-IGZO channel increased the carrier density to ∼1018 cm−3 from the background level of 1016 cm−3, as well as the comprehensive enhancement upon UV irradiation of a-IGZO thin film transistor parameters, such as an on-off current ratio at ∼108 and field-effect mobility at 22.7 cm2/V s.
The influence of buoyant convection on the nucleation of n-propanol in thermal diffusion cloud chambers
Authors: Ferguson Frank T. , Heist Richard H. , Nuth Joseph A.
Published: June 2010

A two-dimensional numerical model has been applied to three thermal diffusion cloud chamber (TDCC) investigations of n-propanol in helium taken by two different research groups to provide a quantitative example of how the results in these chambers can be affected by buoyant convection. In the first set of TDCC data, corrections for buoyancy resolve an apparent discontinuity in critical supersaturation data and also yield nucleation rate data that tend to agree better with higher rate, expansion-based studies at the same temperature. In the second TDCC study, the nucleation of propanol was studied over an extended pressure range. When the model was applied to these data, the possible variation in supersaturation values due to convection induced by conditions at the chamber sidewall was found to be comparable in magnitude to the experimentally observed range and may be responsible for some of this observed pressure dependence. In the third TDCC study, the combination of an error in a transport property and buoyant convection appear responsible for a perceived pressure effect in the experimental data. After correcting for this transport property and for buoyancy, the results at higher temperatures agree quite closely with the predictions of classical nucleation theory.
Spontaneous long and short-range ferroelectric ordering in Pb0.55La0.30TiO3 ceramics
Authors: Mastelaro V. R. , Mascarenhas Y. P. , Neves P. P. , Mir M. , Doriguetto A. C. , Michalowicz A. , Moscovici J. , Lente M. H. , Eiras J. A.
Published: June 2010

In this work, we investigated the temperature dependence of short and long-range ferroelectric ordering in Pb0.55La0.30TiO3 relaxor composition. High-resolution x-ray powder diffraction measurements revealed a clear spontaneous macroscopic cubic-to-tetragonal phase transition in the PLT relaxor sample at ∼60 K below the maximum of the dielectric constant peak (Tm). Indeed, the x-ray diffraction (XRD) data showed that at 300 K (above Tm but below the Burns temperature, TB) the long-range order structure corresponds to a macroscopic cubic symmetry, space group number 221 (Pm-3m), whereas the data collected at 20 K revealed a macroscopic tetragonal symmetry, space group number 99 (P4mm) with c/a=1.0078, that is comparable to that of a normal ferroelectric. These results show that for samples with tetragonal composition, the long-range ferroelectric order may be recovered spontaneously at cryogenics temperatures, in contrast to ferroelectric samples with rhombohedral symmetry. On the other hand, x-ray absorption spectroscopy investigations intriguingly revealed the existence of local tetragonal disorder around Ti atoms for temperatures far below Tm and above TB, for which the sample presents macroscopic tetragonal and cubic symmetries, respectively.
Surface-passivation effects on the photoluminescence enhancement in ZnS:Mn nanoparticles by ultraviolet irradiation with oxygen bubbling
Authors: Jung Dae-Ryong , Kim Jongmin , Park Byungwoo
Published: June 2010

This study examined the effects of surface-passivation on the photoluminescence (PL) properties of ZnS:Mn nanoparticles treated by ultraviolet (UV) irradiation with oxygen bubbling. Compared to the pristine Mn-doped zinc-sulfide nanocrystals (quantum efficiency: ∼16%), the UV-irradiated ZnS:Mn showed significantly enhanced luminescence properties (quantum efficiency: ∼35%). The photoinduced surface passivation was characterized by x-ray diffraction, x-ray photoelectron spectroscopy, and time-resolved PL. The optimum thickness of the passivation layer for the quantum efficiency was examined considering the nanocrystal size, local strain, and radiative/nonradiative recombination rates.
Tuning electronic and magnetic properties of endohedral Co@B80 and exohedral Co-B80 metallofullerenes by positioning Co atom
Authors: Li J. L. , Yang G. W.
Published: June 2010

We have performed a systematical study of the structural configurations, electronic and magnetic properties of the single Co-doped endohedral Co@B80 and exohedral Co–B80 metallofullerene complexes using spin-polarized density functional calculations. Our calculations revealed that there are four stable configurations of the Co-doped metallofullerenes depending on different positions of the doping Co atoms as follows. In the case of the exohedral Co–B80 metallofullerene complexes, Co atom energetically prefers standing near the centers of pentagon (pentagon-out) and hexagon (hexagon-out) on the surface of B80. In the case of the endohedral Co@B80 metallofullerene complexes, the encapsulated Co atom energetically prefers standing near the centers of pentagon (pentagon-in) and hexagon (hexagon-in) on the inner surface of the hollow cage of B80. Electronically, the energy gaps of the hexagon-near adsorbed metallofullerenes have been greatly modified compared with that of B80. At the same time, the magnetic moments of both of the exohedral Co–B80 metallofullerenes are one third of that of the isolated Co atom. The tunable electronic and magnetic properties of the Co-doped B80 metallofullerenes clearly showed that this new type of metallofullerenes may be a promising candidate for molecular devices, especially single molecular spin electronic devices.
High frequency, high time resolution time-to-digital converter employing passive resonating circuits
Authors: Ripamonti Giancarlo , Abba Andrea , Geraci Angelo
Published: June 2010

A method for measuring time intervals accurate to the picosecond range is based on phase measurements of oscillating waveforms synchronous with their beginning and/or end. The oscillation is generated by triggering an LC resonant circuit, whose capacitance is precharged. By using high Q resonators and a final active quenching of the oscillation, it is possible to conjugate high time resolution and a small measurement time, which allows a high measurement rate. Methods for fast analysis of the data are considered and discussed with reference to computing resource requirements, speed, and accuracy. Experimental tests show the feasibility of the method and a time accuracy better than 4 ps rms. Methods aimed at further reducing hardware resources are finally discussed.
Enhanced low field magnetoresistance in nanocrystalline La0.7Sr0.3MnO3 synthesized on MgO nanowires
Authors: Zhang Z. , Ranjith R. , Xie B. T. , You L. , Wong L. M. , Wang S. J. , Wang J. L. , Prellier W. , Zhao Y. G. , Wu T.
Published: June 2010

We report on the structure and transport properties of nanocrystalline manganite La0.7Sr0.3MnO3 (LSMO) synthesized on nanowires-engineered MgO substrates by pulsed laser deposition, which is compared with reference samples deposited directly on flat MgO substrates. Such LSMO/MgO nanocomposites show enhanced low field magnetoresistance, especially at low temperature, due to the dominant spin-polarized intergrain tunneling. This work suggests that growing on nanoengineered substrates is a viable route to achieve nanostructured materials with desired crystalline structure and physical properties.