bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoluminescence enhancement and high gain amplification of ErxY2−xSiO5 waveguide
Authors: Wang X. J. , Yuan G. , Isshiki H. , Kimura T. , Zhou Z.
Published: July 2010

Er x Y 2 − x SiO 5  (x=0–2) films have been fabricated on Si(100) substrates by the sol-gel method. Enhanced Er3+ photoluminescence of around 30 times for the ErxY2−xSiO5 (x=0.1) film was observed compared with pure Er2SiO5 film at the wavelength pump of 654 nm. Reduced upconversion effect and decreased nonradiative transient rate are two main reasons for the enhanced Er3+ luminescence in the new film of ErxY2−xSiO5. Above 10 dB optical gain can be achieved at the 1 mm length ErxY2−xSiO5 (x=0.1) waveguide under 30 mW pumping power, indicating it is sought candidate material for compact waveguide amplifiers and emitters in silicon photonics integration.
Electric probe investigations of microwave generated, atmospheric pressure, plasma jets
Authors: Porteanu H. E. , Kühn S. , Gesche R.
Published: July 2010

We examine the applicability of the Langmuir-type of characterization for atmospheric pressure plasma jets generated in a millimeter-size cavity microwave resonator at 2.45 GHz. Wide range I-V characteristics of helium, argon, nitrogen, air and oxygen are presented for different gas fluxes, distances probe-resonator, and microwave powers. A detailed analysis is performed for the fine variation in the current around the floating potential. A simplified theory specially developed for this case is presented, considering the ionic and electronic saturation currents and the floating potential. Based on this theory, we conclude that, while the charge carrier density depends on gas flow, distance to plasma source, and microwave absorbed power, the electron temperature is quite independent of these parameters. The resulting plasma parameters for helium, argon, and nitrogen are presented.
Analytic model for minority carrier effects in nanoscale Schottky contacts
Authors: Hao Lifeng , Bennett P. A.
Published: July 2010

We present an analytic model for the current-voltage (I-V) behavior for a nanoscale Schottky contact, emphasizing the role of minority carriers. The minority carriers give rise to a surface recombination current that can strongly dominate the majority current flow throughout the bias range. The I-V curve for the surface recombination current shows a weak rectifying behavior, which could be misinterpreted as large variations of ideality factor and effective barrier height. The model calculations show a good match with experimental I-V curves for nanoscale CoSi2 epitaxial islands on Si(111) and for direct scanning tunnel microscope tip point contacts, for a range of island size, doping type, and surface Fermi level.
Inductive conductivity tensor measurement for flowline or material samples
Authors: Kickhofel John L. , Mohamide Amine , Jalfin Jonatan , Gibson Joshua , Thomas Philip , Minerbo Gerald , Wang Hanming , Homan Dean M.
Published: July 2010

Present-day galvanic-based electrical conductivity measurements are hampered by limitations and necessary corrections, especially in the domain of geological core analysis. Low-accuracy techniques such as crucible, two-electrode, and four-electrode are constricted by current-path requirements, while high-accuracy techniques are time consuming and have limited domains of applicability. We present a novel apparatus capable of electrical conductivity tensor measurements in a noninvasive, noncontact, inductive manner with resolution from 5 mS/m. Inspired by the triaxial induction logging technology appearing in the oil patch today, our apparatus is naturally applicable in a novel way not only to anisotropic geological core analysis but also to arbitrary material samples and flowline systems.
Inertia dominated thin-film flows over microdecorated surfaces
Authors: Dressaire Emilie , Courbin Laurent , Crest Jérome , Stone Howard A.
Published: July 2010

We analyze the inertia dominated flow of thin liquid films on microtextured substrates, which here are assemblies of micron-size posts arranged on regular lattices. We focus on situations for which the thin-film thickness and the roughness characteristic length scale are of the same order of magnitude, i.e., a few hundred microns. We assume that the liquid flows isotropically through the roughness at a flow rate that depends on the geometrical features of the porous layer; above the texture, the flow is characterized by a larger Reynolds number and modeled using a boundary layer approach. The influence of the microtexture on the thin-film flow above the microposts is captured by a reduction of the flow rate due to the leakage flow through the texture and a slip boundary condition, which depends on the flow direction as well as on the lattice properties. In this way, the velocity field in the free surface flow adopts the symmetry of the microtexture underneath. The results of this model are in good agreement with experimental observations obtained for thin-film flows formed upon jet impact on microtextures. The characteristics of the polygonal hydraulic jumps that we obtain depend on both the jet parameters and the topographical features of the surface roughness. We use the measurements and the numerical predictions to estimate the flow rate through the shallow porous layer and the effective slip length for this inertia dominated flow regime. We also discuss the limitations of the model.
Oxygen deficiency defects in amorphous Al2O3
Authors: Perevalov T. V. , Tereshenko O. E. , Gritsenko V. A. , Pustovarov V. A. , Yelisseyev A. P. , Park Chanjin , Han Jeong Hee , Lee Choongman
Published: July 2010

In the electron energy loss spectra for amorphous, atomic layer deposited (ALD) Al2O3 film, a peak at 6.4 eV was observed. First principle quantum chemical simulation shows that it relates to excitation of neutral oxygen vacancy in Al2O3. The 2.91 eV luminescence excited in a band near 6.0 eV in amorphous Al2O3 is similar to that in bulk crystals which is associated with neutral oxygen vacancy. Thus, the amorphous ALD Al2O3 film is oxygen deficient and the oxygen vacancy parameters are similar in crystalline and amorphous Al2O3.
Direct observation of low frequency confined acoustic phonons in silver nanoparticles: Terahertz time domain spectroscopy
Authors: Kumar Sunil , Kamaraju N. , Karthikeyan B. , Tondusson M. , Freysz E. , Sood A. K.
Published: July 2010

Terahertz time domain spectroscopy has been used to study low frequency confined acoustic phonons of silver nanoparticles embedded in poly(vinyl alcohol) matrix in the spectral range of 0.1–2.5 THz. The real and imaginary parts of the dielectric function show two bands at 0.60 and 2.12 THz attributed to the spheroidal and toroidal modes of silver nanoparticles, thus demonstrating the usefulness of terahertz time domain spectroscopy as a complementary technique to Raman spectroscopy in characterizing the nanoparticles.
High extraction efficiency GaN-based light-emitting diodes on embedded SiO2 nanorod array and nanoscale patterned sapphire substrate
Authors: Huang Hung-Wen , Huang Jhi-Kai , Kuo Shou-Yi , Lee Kang-Yuan , Kuo Hao-Chung
Published: July 2010

In this paper, GaN-based LEDs with a nanoscale patterned sapphire substrate (NPSS) and a SiO2 photonic quasicrystal (PQC) structure on an n-GaN layer using nanoimprint lithography are fabricated and investigated. The light output power of LED with a NPSS and a SiO2 PQC structure on an n-GaN layer was 48% greater than that of conventional LED. Strong enhancement in output power is attributed to better epitaxial quality and higher reflectance resulted from NPSS and PQC structures. Transmission electron microscopy images reveal that threading dislocations are blocked or bended in the vicinities of NPSS layer. These results provide promising potential to increase output power for commercial light emitting devices.
Predicting the flying performance of thermal flying-height control sliders in hard disk drives
Authors: Liu Nan , Zheng Jinglin , Bogy David B.
Published: July 2010

Thermal flying-height control (TFC) sliders have been recently used in commercial hard disk drives (HDDs) to increase the HDDs’ capacity. The design of this new class of sliders depends on the numerical prediction of their flying performance, which requires a model for heat flux on the surface of the slider facing the disk. The currently widely used heat flux model is based on a first order slip theory and is believed to lack sufficient accuracy due to its limitation of applicability. This paper implements an improved heat flux model and compares numerical predictions of a TFC slider’s flying performance based on these two models with experiments. It is found that the numerical prediction based on the currently used model has a relative error less than 10% for a state-of-the-art TFC slider. It is suggested that the currently used model might cause large errors for the sliders which do not have a pressure peak near the transducer.
Effects of electrical stress on the leakage current characteristics of multilayer capacitor structures
Authors: Kim Soon-Wook , Lee Sung Kyun , Do Kim Young , Kim Sibum
Published: July 2010

The degradation of a high-k dielectric multilayer was investigated by measuring the time dependent leakage current under a constant voltage stress in metal-insulator-metal capacitor structures. When comparing the two multilayer structures of Al2O3/HfO2/Al2O3 and HfO2/Al2O3/HfO2, the former was characterized by a large fluctuation of the leakage current and the latter had an increased leakage current at the initial stage. These results are related to the different voltage drops of each individual layer as well as the thickness impact on the behavior of the current density versus electric field.
Enhancement of electroluminescence in GaN-based light-emitting diodes by metallic nanoparticles
Authors: Sung Jun-Ho , Yang Jeong Su , Kim Bo-Soon , Choi Chul-Hyun , Lee Min-Woo , Lee Seung-Gol , Park Se-Geun , Lee El-Hang , O Beom-Hoan
Published: July 2010

The enhanced electroluminescence of GaN-based light-emitting diodes (LEDs) with noble metallic nanoparticles (MNPs) is demonstrated. The sample with well-designed Ag MNPs has shown the best performance enhancement of 126% in electroluminescent intensity compared with a conventional LED sample, even though the MNPs are placed at least 200 nm away from the quantum-well active layer. The MNPs provide enhanced photon scattering and coupling between localized surface plasmon resonance (LSPR) modes and photon modes internally trapped in a device. To investigate this effect, the peculiarities of the LSPR and the corresponding structural properties of the MNPs are discussed through the effective medium approach.
Direct-search deep level photothermal spectroscopy: An enhanced reliability method for overlapped semiconductor defect state characterization
Authors: Xia Jun , Mandelis Andreas
Published: July 2010

A method for resolving highly overlapped defects in rate-window analysis is proposed. This method offers high defect-state characterization reliability because it is based on direct multiparameter fitting of deep level photothermal spectra using combined temperature and frequency scans. Two direct search optimization algorithms are utilized as follows: the genetic algorithm for a search of possible solution areas and the pattern search algorithm for a refined search of global minimum. Four defect levels are identified using this technique.
Ambipolar graphene field effect transistors by local metal side gates
Authors: Tian J. F. , Jauregui L. A. , Lopez G. , Cao H. , Chen Y. P.
Published: July 2010

We demonstrate ambipolar graphene field effect transistors individually controlled by local metal side gates. The side gated field effect can have on/off ratio comparable with that of the global back gate, and can be tuned in a large range by the back gate and/or a second side gate. We also find that the side gated field effect is significantly stronger by electrically floating the back gate compared to grounding the back gate, consistent with the finding from electrostatic simulation.
High-speed phonon imaging using frequency-multiplexed kinetic inductance detectors
Authors: Swenson L. J. , Cruciani A. , Benoit A. , Roesch M. , Yung C. S. , Bideaud A. , Monfardini A.
Published: July 2010

We present a measurement of phonon propagation in a silicon wafer utilizing an array of frequency-multiplexed superconducting resonators coupled to a single transmission line. The electronic readout permits fully synchronous array sampling with a per-resonator bandwidth of 1.2 MHz, allowing submicrosecond array imaging. This technological achievement is potentially vital in a variety of low-temperature applications, including single-photon counting, quantum-computing, and dark-matter searches.
High power single-lateral-mode operation of InAs quantum dot based ridge type laser diodes by utilizing a double bend waveguide structure
Authors: Kim Kyoung Chan , Han Il Ki , Lee Jung Il , Kim Tae Geun
Published: July 2010

We report on the high-power, single-lateral-mode operation of InAs quantum dot (QD) based ridge type laser diodes (LDs) by utilizing a double bend (DB) waveguide structure. The LDs were designed so that only fundamental modes propagate and higher optical modes are suppressed through the bent regions. DB waveguide LDs allow the use of wide ridge widths for fundamental mode operations, which helps to increase their output power via the increase in their net gain. We measured continuous wave single-lateral-mode output power of up to 310 mW from InAs QD DB waveguide LDs manufactured with 10-μm-wide stripes without facet coating.
Correlation between kink and cathodoluminescence spectra in AlGaN/GaN high electron mobility transistors
Authors: Meneghesso G. , Rossi F. , Salviati G. , Uren M. J. , Muñoz E. , Zanoni E.
Published: July 2010

The “kink” effect in AlGaN/GaN high electron mobility transistor current-voltage characteristics is shown to be associated with the epitaxial growth and is unaffected by fabrication process or growth substrate in device wafers from two epitaxy sources and three foundries. We demonstrate that there is a direct correlation between the presence of the “kink” and the presence of a broad yellow cathodoluminescence band. On the basis of generally accepted models for yellow luminescence, we propose that the kink is due to the presence of deep levels in the GaN buffer layer which decrease the drain current when negatively charged.
Cl - uptake, transport and accumulation in grapevine rootstocks of differing capacity for Cl - -exclusion
Authors: Tregeagle Joanna M. , Tisdall Judy M. , Tester Mark , Walker Rob R.
Published: July 2010

Mechanisms of chloride (Cl–) exclusion in rootstocks of grapevine (Vitis spp.) were studied using a strong Cl–-excluding rootstock (140 Ruggeri) and a poor Cl–-excluding rootstock (K51–40). Xylem Cl– concentration in potted whole grapevines of 140 Ruggeri treated with 50 mM Cl– was 6.8-fold lower than that in K51–40. Five-fold lower total shoot Cl– in salt-treated 140 Ruggeri grapevines relative to that in K51–40 after 50 days, when shoots were of similar biomass, was unrelated to water use. Unidirectional influx of 36Cl– into excised roots (up to 30 min), and uptake of 36Cl– in roots of intact rooted-leaves (up to 180 min) in 10 mM Cl– was similar between the genotypes. However, net accumulation of Cl– by excised roots of K51–40 up to 180 min in 10 mM Cl– was significantly higher than that of 140 Ruggeri. Intact rooted-leaves of 140 Ruggeri in 10 mM Cl– accumulated higher Cl– concentrations in roots, and had a lower percentage of total plant 36Cl– accumulation in the shoot (petiole plus lamina) than those of K51–40. The greater Cl– exclusion capacity of 140 Ruggeri appears to be associated with restricted entry of Cl– to xylem and lower root to shoot Cl– transport.
Sensitivity to high salinity in tetraploid citrus seedlings increases with water availability and correlates with expression of candidate genes
Authors: Mouhaya Wafa , Allario Thierry , Brumos Javier , Andrés Fernando , Froelicher Yann , Luro François , Talon Manuel , Ollitrault Patrick , Morillon Raphaël
Published: July 2010

We investigated tolerance to high salinity in well-irrigated diploid and tetraploid citrus. Comparisons were made between two diploids (2×) of trifoliate orange (Poncirus trifoliata (L.) Raf.) and willow leaf mandarin (Citrus deliciosa Ten), their respective doubled diploids (4×) and the allotetraploid (FLHORAG1) obtained from the protoplast fusion of trifoliate orange and Willow leaf mandarin. Salinity stress was applied by progressively increasing the concentration of NaCl from 50 mM to 400 mM for 8 weeks. Two-year-old plants were watered daily. Maximum quantum yield of PSII, and leaf and root chloride and sodium content were monitored. We previously reported that under moderate saline stress, citrus 4× genotypes were more tolerant that the 2×, but under these experimental conditions, 4× seedlings were certainly more sensitive to salt stress than 2×, as they accumulated more toxic ions and were more affected than 2×. Chloride accumulation in 4× leaves was greater and the maximum quantum yield of PSII was more reduced in 4× than in 2×. The expression of several candidate genes involved in signal transduction, sodium and chloride transport, osmotic adjustment, regulation of the stomata opening and detoxification processes were also investigated by quantitative real-time reverse transcription-PCR. A high correlation was observed between phenotype of sensitivity to stress and gene expression changes.
Promoter melting triggered by bacterial RNA polymerase occurs in three steps
Authors: Chen Jie , Darst Seth A. , Thirumalai D.
Published: July 2010

RNA synthesis, carried out by DNA-dependent RNA polymerase (RNAP) in a process called transcription, involves several stages. In bacteria, transcription initiation starts with promoter recognition and binding of RNAP holoenzyme, resulting in the formation of the closed (
R
·
P

c

) RNAP-promoter DNA complex. Subsequently, a transition to the open
R
·
P

o

complex occurs, characterized by separation of the promoter DNA strands in an approximately 12 base-pair region to form the transcription bubble. Using coarse-grained self-organized polymer models of
Thermus aquatics
RNAP holoenzyme and promoter DNA complexes, we performed Brownian dynamics simulations of the
R
·
P

c

 → 
R
·
P

o

transition. In the fast trajectories, unwinding of the promoter DNA begins by local melting around the -10 element, which is followed by sequential unzipping of DNA till the +2 site. The
R
·
P

c

 → 
R
·
P

o

transition occurs in three steps. In step I, dsDNA melts and the nontemplate strand makes stable interactions with RNAP. In step II, DNA scrunches into RNA polymerase and the downstream base pairs sequentially open to form the transcription bubble, which results in strain build up. Subsequently, downstream dsDNA bending relieves the strain as
R
·
P

o

forms. Entry of the dsDNA into the active-site channel of RNAP requires widening of the channel, which occurs by a swing mechanism involving transient movements of a subdomain of the β subunit caused by steric repulsion with the DNA template strand. If premature local melting away from the -10 element occurs first then the transcription bubble formation is slow involving reformation of the opened base pairs and subsequent sequential unzipping as in the fast trajectories.
A table of the first factor for prime cyclotomic fields
Authors: Newman Morris
Published: July 2010

The first factor of the prime cyclotomic fields for all primes

>
200

> 200

is computed by means of a determinantal formula, correcting some errors in tables of Kummer.
Table for third-degree spline interpolation with equally spaced arguments
Authors: Greville T. N. E.
Published: July 2010

A table is given to facilitate the calculation of the parameters of the interpolating third-degree natural spline function for

n
n

given data points

(
n
>
2
)

(n > 2)

with equally spaced abscissas. The use of the table is described and the correctness of the algorithm is demonstrated.
Symmetric elliptic integrals of the third kind
Authors: Zill D. G. , Carlson B. C.
Published: July 2010

Legendre’s incomplete elliptic integral of the third kind can be replaced by an integral which possesses permutation symmetry instead of a set of linear transformations. Two such symmetric integrals are discussed, and direct proofs are given of properties corresponding to the following parts of the Legendre theory: change of parameter, Landen and Gauss transformations, interchange of argument and parameter, relation of the complete integral to integrals of the first and second kinds, and addition theorem. The theory of the symmetric integrals offers gains in simplicity and unity, as well as some new generalizations and some inequalities.
Linear multistep methods with mildly varying coefficients
Authors: Lambert J. D.
Published: July 2010

Consideration of a common assumption in the theory of weak stability of linear multistep methods for ordinary differential equations leads to the study of a class of linear multistep methods with mildly varying coefficients. It is well known that, in the case of constant-coefficient methods, optimal stable methods suffer from weak instability. Corresponding methods of the new class, of step-number

2
2

and

4
4

, which do not suffer from weak instability are derived.
Intraoperative Systolic Blood Pressure Variability Predicts 30-day Mortality in Aortocoronary Bypass Surgery Patients
Authors: Aronson Solomon , Stafford-Smith Mark , Phillips-Bute Barbara , Shaw Andrew , Gaca Jeffrey , Newman Mark
Published: July 2010

Background

Few data support an association between blood pressure variability and clinical outcomes during cardiac surgery. We tested the hypothesis that intraoperative systolic blood pressure variability outside a targeted blood pressure range predicts 30-day mortality in patients undergoing cardiac surgery.

Methods

Electronically captured blood pressure data from 7,504 consecutive coronary bypass surgery procedures between September 1, 1996, and December 31, 2005, were divided into development and validation cohorts. Systolic blood pressure variability episodes outside a blood pressure range (e.g., higher than 135 or lower than 95 mmHg) were characterized by number of episodes, magnitude of episode, duration of episode, and magnitude x duration of excursion (i.e., area under the curve). Multiple logistic regression analysis was used to assess 30-day mortality association. The most predictive mortality risk characteristic and blood pressure range was tested in the validation cohort.

Results

A total of 3.1 million intraoperative blood pressure evaluations were analyzed. Systolic blood pressure variability was derived in 5,038 patients and validated in 2,466 patients (8% without cardiopulmonary bypass and 6% with valve procedure). Among all tested indices of blood pressure variability, mean duration of systolic excursion (outside a range of 105-130 mmHg) was most predictive of 30-day mortality (odds ratio = 1.03 per minute, 95% CI 1.02-1.39, P < 0.0001).

Conclusions

Intraoperative blood pressure variability is associated with 30-day postoperative mortality in patients undergoing aortocoronary bypass surgery.
Feasibility and Efficacy of Preoperative Epidural Catheter Placement for Anterior Scoliosis Surgery
Authors: Wenk Manuel , Ertmer Christian , Weber Thomas P. , Liljenqvist Ulf R. , Pöpping Daniel M. , Möllmann Michael , Bullmann Viola
Published: July 2010

Background

Postoperative pain control via thoracic epidural catheters (TECs) is an important aspect of postoperative care, and ample evidence highlights its positive physiologic effects and superiority to intravenous analgesia. If epidural catheters for postoperative pain relief are used in scoliosis surgery, current practice is the intraoperative placement of the TEC by the surgeon because preoperative placement is considered challenging and dangerous. On the basis of magnetic resonance imaging of scoliotic spines, the authors developed a technique for preoperative placement of TEC and investigated its safety and feasibility.

Methods

Patients undergoing anterior scoliosis surgery were included, who received preoperative placement of TEC. Postoperative pain, problems associated with the TEC placement, possible side effects, radiographic data, and insertion levels of the TEC were noted.

Results

The apex vertebra was identified as a possible site for TEC placement due to dural sac shift leaving a wider epidural space on the convex side. Scoliosis-induced rotation of the vertebrae required realignment of the needle toward the convex side. Sixty patients were included. The success rate for TEC placement was 96.6%: one failed attempt, one catheter placed intrapleurally, and one patient with Horner syndrome. Seven percent of patients required additional rescue analgesia. All other patients had pain scores within acceptable limits (Visual Analogue Scale <5).

Conclusions

The authors have demonstrated that it is possible to insert a TEC in patients with scoliotic spines with a high degree of success using a redesigned approach and thus provide adequate postoperative analgesia with a single epidural catheter. However, precautions have to be taken.
Meticillin-resistant Staphylococcus aureus isolated from foot ulcers in diabetic patients in a Chinese care hospital: risk factors for infection and prevalence
Authors: Wang Shao-Hua , Sun Zi-Lin , Guo Yi-Jing , Yang Bing-Quan , Yuan Yang , Wei Qiong , Ye Kuan-Ping
Published: July 2010

A retrospective case–control study of 118 (male : female, 68 : 50) Chinese type 2 diabetic patients with foot ulcers (Wagner's grade 3–5) was conducted to determine the prevalence and risk factors for meticillin-resistant Staphylococcus aureus (MRSA) infection in relation to the original community or hospital parameters. Ulcer specimens were processed for Gram staining, aerobic culture and antimicrobial susceptibility testing. Staphylococcus species were tested for meticillin resistance using oxacillin. S. aureus was the most frequent pathogen (25.6 %) in diabetic patient specimens (160 isolates), and a high proportion of S. aureus isolates were MRSA (63.4 %). A high percentage of S. aureus isolates (65.4 %) satisfied the definition for hospital-associated MRSA (HA-MRSA) infection. The size of ulcers [adjusted odds ratio (OR) 1.61; 95 % confidence interval (CI) 1.22–2.12] and osteomyelitis (adjusted OR 18.51, 95 % CI 2.50–137.21) were independent predictors of MRSA infection. The HA-MRSA group had a significantly different distribution from the community-associated MRSA group with respect to age, history of diabetes and length of hospital stay (all P<0.001). Neuropathy, vascular disease (all P=0.049) and osteomyelitis (P=0.026) were the most common underlying conditions observed in the HA-MRSA group. This study contributes to the establishment of precautions against the emergence of MRSA including MRSA acquired from different sources among the Chinese population with diabetic foot ulcers based on their original or clinical parameters.
regT can modulate gingipain activity and response to oxidative stress in Porphyromonas gingivalis
Authors: Vanterpool E. , Aruni A. Wilson , Roy F. , Fletcher H. M.
Published: July 2010

Recombinant VimA protein can interact with the gingipains and several other proteins that may play a role in its biogenesis in Porphyromonas gingivalis. In silico analysis of PG2096, a hypothetical protein that was shown to interact with VimA, suggests that it may have environmental stress resistance properties. To further evaluate the role(s) of PG2096, the predicted open reading frame was PCR amplified from P. gingivalis W83 and insertionally inactivated using the ermF-ermAM antibiotic-resistance cassette. One randomly chosen PG2096-defective mutant created by allelic exchange and designated FLL205 was further characterized. Under normal growth conditions at 37 °C, Arg-X and Lys-X gingipain activities in FLL205 were reduced by approximately 35 % and 21 %, respectively, compared to the wild-type strain. However, during prolonged growth at an elevated temperature of 42 °C, Arg-X activity was increased by more than 40 % in FLL205 in comparison to the wild-type strain. In addition, the PG2096-defective mutant was more resistant to oxidative stress when treated with 0.25 mM hydrogen peroxide. Taken together these results suggest that the PG2096 gene, designated regT (regulator of gingipain activity at elevated temperatures), may be involved in regulating gingipain activity at elevated temperatures and be important in oxidative stress resistance in P. gingivalis.
Mechanisms of oxygen inhibition of nirK expression in Rhodobacter sphaeroides
Authors: Hartsock Angela , Shapleigh James P.
Published: July 2010

R. sphaeroidesstrain 2.4.3, when lacking thecbb3oxidase, is unable to transition from aerobic respiration to denitrification using cellular respiration as a means of reducing oxygen levels. This is due to an inability to expressnirK, the gene encoding nitrite reductase. Under certain photosynthetic conditions this strain can transition from aerobic to nitrate respiration, demonstrating thatnirKexpression can occur in the absence of a functionalcbb3oxidase. If oxygen levels are reduced under non-photosynthetic conditions using low-oxygen gas mixes, nitrite reductase activity is detected at wild-type levels in the strain lacking the oxidase. In addition, co-culture experiments show that incubation of thecbb3deficient strain 2.4.3 withR. sphaeroides2.4.1, which isnirKdeficient but has the high-affinitycbb3oxidase, restores denitrification in sealed-vessel experiments. Taken together these results indicate that high end-point O2levels are the reason why the strain lacking thecbb3oxidase cannot transition from aerobic respiration to denitrification under certain conditions. The protein probably being affected by these O2levels is the transcriptional regulator NnrR.
Epidemiology and aetiology of diarrhoeal diseases in adults engaged in wastewater‐fed agriculture and aquaculture in Hanoi, Vietnam
Authors: Trang Do Thuy , Hien Bui Thi Thu , Mølbak Kåre , Cam Phung Dac , Dalsgaard Anders
Published: July 2010

Objectives  To determine the occurrence of and risk factors for diarrhoea in an adult population exposed to wastewater used for agricultural and aquacultural productions.

Methods  An open cohort of 636 adults aged 15–70 years living in a wastewater‐irrigated area in Hanoi was followed by weekly visit for 18 months. The aetiology and risk factors for diarrhoeal diseases were determined in a nested case‐control study. Stool specimens and exposure information related to wastewater, hygiene, water and food consumption were collected from 163 unmatched pairs of cases and controls.

Results  The incidence rate of diarrhoeal diseases was 28.1 episodes per 100 person‐years at risk. Of the 326 stool specimens, 47 cases and 24 controls were identified with enteric pathogens, of which diarrhoeagenic Escherichia coli and Entamoeba histolytica were the most common. Risk factors for diarrhoeal diseases included contact with wastewater [odds ratio (OR) = 1.98, attributable fraction of the population (AF) 35%], not washing hands after defecation (OR = 3.34, AF 3%), drinking water from a well (OR = 6.21, AF 6%), consumption of raw or undercooked foods (OR = 2.45, AF 6%), and contact with persons with diarrhoea (OR = 4.22, AF 5%).

Conclusion  Wastewater contact was the principal risk factor for diarrhoea in this population. As the local economy depends on the use of wastewater for agriculture and aquaculture, it is important to find ways to mitigate the public health risks associated with this use, in addition to promotions of personal, domestic and food hygiene.
Genomic selection
Authors: Goddard M.E. , Hayes B.J.
Published: July 2010

Genomic selection is a form of marker‐assisted selection in which genetic markers covering the whole genome are used so that all quantitative trait loci (QTL) are in linkage disequilibrium with at least one marker. This approach has become feasible thanks to the large number of single nucleotide polymorphisms (SNP) discovered by genome sequencing and new methods to efficiently genotype large number of SNP. Simulation results and limited experimental results suggest that breeding values can be predicted with high accuracy using genetic markers alone but more validation is required especially in samples of the population different from that in which the effect of the markers was estimated. The ideal method to estimate the breeding value from genomic data is to calculate the conditional mean of the breeding value given the genotype of the animal at each QTL. This conditional mean can only be calculated by using a prior distribution of QTL effects so this should be part of the research carried out to implement genomic selection. In practice, this method of estimating breeding values is approximated by using the marker genotypes instead of the QTL genotypes but the ideal method is likely to be approached more closely as more sequence and SNP data is obtained. Implementation of genomic selection is likely to have major implications for genetic evaluation systems and for genetic improvement programmes generally and these are discussed.
Initiation of limb regeneration: The critical steps for regenerative capacity
Authors: Yokoyama Hitoshi
Published: July 2010

While urodele amphibians (newts and salamanders) can regenerate limbs as adults, other tetrapods (reptiles, birds and mammals) cannot and just undergo wound healing. In adult mammals such as mice and humans, the wound heals and a scar is formed after injury, while wound healing is completed without scarring in an embryonic mouse. Completion of regeneration and wound healing takes a long time in regenerative and non‐regenerative limbs, respectively. However, it is the early steps that are critical for determining the extent of regenerative response after limb amputation, ranging from wound healing with scar formation, scar‐free wound healing, hypomorphic limb regeneration to complete limb regeneration. In addition to the accumulation of information on gene expression during limb regeneration, functional analysis of signaling molecules has recently shown important roles of fibroblast growth factor (FGF), Wnt/β‐catenin and bone morphogenic protein (BMP)/Msx signaling. Here, the routine steps of wound healing/limb regeneration and signaling molecules specifically involved in limb regeneration are summarized. Regeneration of embryonic mouse digit tips and anuran amphibian (Xenopus) limbs shows intermediate regenerative responses between the two extremes, those of adult mammals (least regenerative) and urodele amphibians (more regenerative), providing a range of models to study the various abilities of limbs to regenerate.
Novel functions of ribosomal protein S6 in growth and differentiation of Dictyostelium cells
Authors: Ishii Kazutaka , Nakao Yusaku , Amagai Aiko , Maeda Yasuo
Published: July 2010

We have previously shown that in Dictyostelium cells a 32 kDa protein is rapidly and completely dephosphorylated in response to starvation that is essential for the initiation of differentiation (Akiyama & Maeda 1992). In the present work, this phosphoprotein was identified as a homologue (Dd‐RPS6) of ribosomal protein S6 (RPS6) that is an essential member for protein synthesis. As expected, Dd‐RPS6 seems to be absolutely required for cell survival, because we failed to obtain antisense‐RNA mediated cells as well as Dd‐rps6‐null cells by homologous recombination in spite of many trials. In many kinds of cell lines, RPS6 is known to be located in the nucleus and cytosol, but Dd‐RPS6 is predominantly located in the cell cortex with cytoskeletons, and in the contractile ring of just‐dividing cells. In this connection, the overexpression of Dd‐RPS6 greatly impairs cytokinesis during axenic shake‐cultures in growth medium, resulting in the formation of multinucleate cells. Much severe impairment of cytokinesis was observed when Dd‐RPS6‐overexpressing cells (Dd‐RPS6OE cells) were incubated on a living Escherichia coli lawn. The initiation of differentiation triggered by starvation was also delayed in Dd‐RPS6OE cells. In addition, Dd‐RPS6OE cells exhibit defective differentiation into prespore cells and spores during late development. Thus, it is likely that the proper expression of Dd‐RPS6 may be of importance for the normal progression of late differentiation as well as for the initiation of differentiation.
Structural insights into ligand‐induced activation of the insulin receptor
Authors: Ward C. , Lawrence M. , Streltsov V. , Garrett T. , McKern N. , Lou M.‐Z. , Lovrecz G. , Adams T.
Published: July 2010

The current model for insulin binding to the insulin receptor proposes that there are two binding sites, referred to as sites 1 and 2, on each monomer in the receptor homodimer and two binding surfaces on insulin, one involving residues predominantly from the dimerization face of insulin (the classical binding surface) and the other residues from the hexamerization face. High‐affinity binding involves one insulin molecule using its two surfaces to make bridging contacts with site 1 from one receptor monomer and site 2 from the other. Whilst the receptor dimer has two identical site 1‐site 2 pairs, insulin molecules cannot bridge both pairs simultaneously. Our structures of the insulin receptor (IR) ectodomain dimer and the L1‐CR‐L2 fragments of IR and insulin‐like growth factor receptor (IGF‐1R) explain many of the features of ligand‐receptor binding and allow the two binding sites on the receptor to be described. The IR dimer has an unexpected folded‐over conformation which places the C‐terminal surface of the first fibronectin‐III domain in close juxtaposition to the known L1 domain ligand‐binding surface suggesting that the C‐terminal surface of FnIII‐1 is the second binding site involved in high‐affinity binding. This is very different from previous models based on three‐dimensional reconstruction from scanning transmission electron micrographs. Our single‐molecule images indicate that IGF‐1R has a morphology similar to that of IR. In addition, the structures of the first three domains (L1‐CR‐L2) of the IR and IGF‐1R show that there are major differences in the two regions governing ligand specificity. The implications of these findings for ligand‐induced receptor activation will be discussed.

This review summarizes the key findings regarding the discovery and characterization of the insulin receptor, the identification and arrangement of its structural domains in the sequence and the key features associated with ligand binding. The remainder of the review deals with a description of the receptor structure and how it explains much of the large body of biochemical data in the literature on insulin binding and receptor activation.
The questionable value of some science‐based ‘welfare’ assessments in intensive animal farming: sow stalls as an illustrative example
Authors: Caulfield MP , Cambridge H
Published: July 2010

A recent review of the code of practice for pigs brought attention to the question of how to assess the impact of housing conditions on pig welfare. The stance adopted by the law‐makers, which mirrors that of industry, is that the status quo should be maintained until there is irrefutable scientific evidence in favour of change. Sows in intensive pig farms are often confined in cages (sow stalls) that are little bigger than their body. Many people find this repellent and the question of whether keeping sows in stalls is detrimental to their welfare has become a major focus of debate. All animal welfare groups in Australia, including the RSPCA, oppose the use of sow stalls. This brief essay critically examines the rationale for refusing to sanction change unless supported by scientific evidence. We conclude that the criteria for assessing welfare should not be restricted to consideration of scientific evidence alone, but should be widened to encompass moral and ethical considerations.
Dynamics and Control of Global Instabilities in Open-Flows: A Linearized Approach
Authors: Sipp Denis , Marquet Olivier , Meliga Philippe , Barbagallo Alexandre
Published: July 2010

This review article addresses the dynamics and control of low-frequency unsteadiness, as observed in some aerodynamic applications. It presents a coherent and rigorous linearized approach, which enables both to describe the dynamics of commonly encountered open-flows and to design open-loop and closed-loop control strategies, in view of suppressing or delaying instabilities. The approach is global in the sense that both cross-stream and streamwise directions are discretized in the evolution operator. New light will therefore be shed on the streamwise properties of open-flows. In the case of oscillator flows, the unsteadiness is due to the existence of unstable global modes, i.e., unstable eigenfunctions of the linearized Navier–Stokes operator. The influence of nonlinearities on the dynamics is studied by deriving nonlinear amplitude equations, which accurately describe the dynamics of the flow in the vicinity of the bifurcation threshold. These equations also enable us to analyze the mean flow induced by the nonlinearities as well as the stability properties of this flow. The open-loop control of unsteadiness is then studied by a sensitivity analysis of the eigenvalues with respect to base-flow modifications. With this approach, we manage to a priori identify regions of the flow where a small control cylinder suppresses unsteadiness. Then, a closed-loop control approach was implemented for the case of an unstable open-cavity flow. We have combined model reduction techniques and optimal control theory to stabilize the unstable eigenvalues. Various reduced-order-models based on global modes, proper orthogonal decomposition modes, and balanced modes were tested and evaluated according to their ability to reproduce the input-output behavior between the actuator and the sensor. Finally, we consider the case of noise-amplifiers, such as boundary-layer flows and jets, which are stable when viewed in a global framework. The importance of the singular value decomposition of the global resolvent will be highlighted in order to understand the frequency selection process in such flows.
Biological Composites
Authors: Dunlop John W.C. , Fratzl Peter
Published: July 2010

Most natural materials are composites based on biopolymers and some minerals. Despite the relative paucity of these constituents, their combination yields materials with outstanding properties and a great variation in functionality. A particular characteristic of biological composites is their multifunctionality. The basis for achieving this property is usually a complex hierarchical architecture in which an adaptation to the function(s) is possible at different structural levels. Only a few biological composites have been thoroughly studied from a materials science perspective; nacre is a prominent example. Fueled by the increasing interest in bioinspired materials research, biological composites are now studied more widely, and it has become apparent that Nature often solves materials problems in an unexpected way. This review discusses some striking examples. Many more are likely to emerge in the near future.
Mechanical Principles of Biological Nanocomposites
Authors: Ji Baohua , Gao Huajian
Published: July 2010

Biological nanocomposites, such as bone, tooth, shell, and wood, exhibit exceptional mechanical properties. Much recent effort has been directed at exploring the basic mechanical principles behind the microstructures of these natural materials to provide guidelines for the development of novel man-made nanocomposites. This article reviews some of the recent studies on mechanical properties of biological nanocomposites, including their stiffness, strength, toughness, interface properties, and elastic stability. The discussion is focused on the mechanical principles of biological nanocomposites, including the generic nanostructure of hard-mineral crystals embedded in a soft protein matrix, the flaw-tolerant design of the hard phase, the role of the soft matrix, the hybrid interface between protein and mineral, and the structural hierarchy. The review concludes with some discussion of and outlook on the development of biomimicking synthetic materials guided by the principles found in biological nanocomposites.
Magnetoelectric Composites
Authors: Srinivasan G.
Published: July 2010

In a composite of magnetostrictive and piezoelectric phases, mechanical strain mediates magnetoelectric (ME) coupling between the magnetic and the electric subsystems. This review discusses recent advances in the physics of ME interactions in layered composites and nanostructures and potential device applications. The ME phenomena of importance are giant low-frequency interactions and coupling when the electric and/or the magnetic subsystems show resonance, including electromechanical resonance (EMR) in the piezoelectric phase, ferromagnetic resonance (FMR) in the magnetic phase, and magnetoacoustic resonance at the overlap of EMR and FMR. Potential device applications for the composites are magnetic-field sensors, dual electric-field- and magnetic-field-tunable microwave and millimeter-wave devices, and miniature antennas.
Inkjet Printing of Functional and Structural Materials: Fluid Property Requirements, Feature Stability, and Resolution
Authors: Derby Brian
Published: July 2010

Inkjet printing is viewed as a versatile manufacturing tool for applications in materials fabrication in addition to its traditional role in graphics output and marking. The unifying feature in all these applications is the dispensing and precise positioning of very small volumes of fluid (1–100 picoliters) on a substrate before transformation to a solid. The application of inkjet printing to the fabrication of structures for structural or functional materials applications requires an understanding as to how the physical processes that operate during inkjet printing interact with the properties of the fluid precursors used. Here we review the current state of understanding of the mechanisms of drop formation and how this defines the fluid properties that are required for a given liquid to be printable. The interactions between individual drops and the substrate as well as between adjacent drops are important in defining the resolution and accuracy of printed objects. Pattern resolution is limited by the extent to which a liquid drop spreads on a substrate and how spreading changes with the overlap of adjacent drops to form continuous features. There are clearly defined upper and lower bounds to the width of a printed continuous line, which can be defined in terms of materials and process variables. Finer-resolution features can be achieved through appropriate patterning and structuring of the substrate prior to printing, which is essential if polymeric semiconducting devices are to be fabricated. Low advancing and receding contact angles promote printed line stability but are also more prone to solute segregation or “coffee staining” on drying.
Metal Matrix Composites
Authors: Mortensen Andreas , Llorca Javier
Published: July 2010

In metal matrix composites, a metal is combined with another, often nonmetallic, phase to produce a novel material having attractive engineering attributes of its own. A subject of much research in the 1980s and 1990s, this class of materials has, in the past decade, increased significantly in variety. Copper matrix composites, layered composites, high-conductivity composites, nanoscale composites, microcellular metals, and bio-derived composites have been added to a palette that, ten years ago, mostly comprised ceramic fiber– or particle-reinforced light metals together with some well-established engineering materials, such as WC-Co cermets. At the same time, research on composites such as particle-reinforced aluminum, aided by novel techniques such as large-cell 3-D finite element simulation or computed X-ray microtomography, has served as a potent vehicle for the elucidation of the mechanics of high-contrast two-phase elastoplastic materials, with implications that range well beyond metal matrix composites.