bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement of strength and stiffness of Nylon 6 filaments through carbon nanotubes reinforcement
Authors: Mahfuz Hassan , Adnan Ashfaq , Rangari Vijay K. , Hasan Mohammad M. , Jeelani Shaik , Wright Wendelin J. , DeTeresa Steven J.
Published: February 2006

We report a method to fabricate carbon nanotube reinforced Nylon filaments through an extrusion process. In this process, Nylon 6 and multiwalled carbon nanotubes (MWCNT) are first dry mixed and then extruded in the form of continuous filaments by a single screw extrusion method. Thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies have indicated that there is a moderate increase in Tg without a discernible shift in the melting endotherm. Tensile tests on single filaments have demonstrated that Young’s modulus and strength of the nanophased filaments have increased by 220% and 164%, respectively with the addition of only 1wt.% MWCNTs. SEM studies and micromechanics based calculations have shown that the alignment of MWCNTs in the filaments, and high interfacial shear strength between the matrix and the nanotube reinforcement was responsible for such a dramatic improvement in properties.
In situ high-resolution transmission electron microscopy study of interfacial reactions of Cu thin films on amorphous silicon
Authors: Lee Sung Bo , Choi Duck-Kyun , Phillipp Fritz , Jeon Kyung-Sook , Kim Chang Kyung
Published: February 2006

Interfacial reactions of Cu with amorphous silicon (a-Si) in the Cu∕a-Si/glass system are studied by in situ high-resolution transmission electron microscopy at 550°C. Various Cu silicides, such as η-Cu3Si, Cu15Si4, and Cu5Si, and Cu particles are observed. The formation of the Cu particles can be attributed to a heating effect from electron beam irradiation. Around the Cu silicides, crystallization of a-Si occurs. Around the Cu particles, however, crystallization does not occur. Crystallization appears to be enhanced by Cu dissolved in a-Si.
In situ measurements of magnetoresistive effects in ferromagnetic microstructures by Lorentz microscopy
Authors: Haug T. , Vogl A. , Zweck J. , Back C. H.
Published: February 2006

We report on a four point resistance measurement inside a transmission electron microscope and during the imaging process which uses a special developed specimen holder. Lorentz microscopy allows us to observe the micromagnetic configuration of the ferromagnetic samples. Two different imaging techniques, Fresnel imaging and differential phase contrast, are used. The latter one allows lateral magnetic resolution down to 10nm. We present experiments on ferromagnetic nickel strips where we can show the direct correlation between the appearance of magnetic domains and anisotropic magnetoresistance.
Selective light emission from flexible organic light-emitting devices using a dot-nickel embedded indium tin oxide anode
Authors: Hsu Ching-Ming , Tsai Chung-Lin , Wu Wen-Tuan
Published: February 2006

This work demonstrates selective light emission from organic light-emitting diodes (OLEDs) with an Al/tris(8-hydroxyquinoline) aluminum N,N′-bis-(1-naphthyl)-N,N′-diphenyl-1, 1′biphenyl-4, 4′-diamine/nickel-embedded indium tin oxide (ITO)/ polyethylene teraphythalate film structure. Embedding Ni in the surfaces of ITO anodes can reduce the OLED turn-on voltage by 2.3V, allowing the OLED to be selectively emitted. This approach based on Ni-embedded ITO approach can prevent crosstalks in passive OLED addressing because the lateral electric current is negligible outside the Ni-embedded area. It also reduces the roughness of the ITO surface by polishing. Therefore, this method can simultaneously improve the optoelectrical characteristics and increase the lifetime of an OLED device.
Standing-wave spectrometer
Authors: Stiebig Helmut , Knipp Dietmar , Bunte Eerke
Published: February 2006

A standing-wave sensor was developed which facilitates the miniaturization of Fourier spectrometers down to the micrometer scale. The spectrometer concept is based on sampling a standing wave by an ultrathin and partially transmissive sensor. The active region of the sensor has a thickness of 30nm–40nm. The standing wave is created in front of a tunable mirror. Varying the position of the mirror results in a phase shift of the standing wave, a modulation of the intensity profile within the ultrathin sensor, and thus, in a modulation of the photocurrent. The spectral information of the incoming light can be determined by the Fourier transform of the sensor signal. The operation principle of the spectrometer is described and the influence of the device design on the spectral resolution of the spectrometer is discussed. Due to the simple linear setup of the sensor and the tunable mirror, the realization of one- and two-dimensional spectrometer arrays is feasible.
Ballistic rectification in an asymmetric mesoscopic cross junction
Authors: Knop M. , Wieser U. , Kunze U. , Reuter D. , Wieck A. D.
Published: February 2006

Ballistic rectification is demonstrated in a nanoscale waveguide cross junction consisting of a straight voltage stem channel and current-injecting branches which oppositely merge into the stem under an angle ϕ<90°. According to a simple billiardlike picture for both current directions, the injected electrons are deflected at the opposite boundary, thus charging one arm of the stem according to their preferential momentum component. The rectification efficiency has a maximum value of 2.6% and shows a characteristic voltage dependence, which is explained by the availability of unoccupied states in the voltage stem at low voltage and by carrier heating at high voltage.
Fullerene-organic nanocomposite: A flexible material platform for organic light-emitting diodes
Authors: Yuan Y. Y. , Han S. , Grozea D. , Lu Z. H.
Published: February 2006

Cu Pc : C 60 organic-nanocarbon composite coated metals (Au, Ag, and ITO) are found to form efficient hole injection anode structures for organic light-emitting diodes (OLEDs). A significant increase (∼ two times ) in current efficiency has been observed in OLEDs when the nanocomposite anode structures are used to replace the conventional CuPc/indium tin oxide hole injection structure. Moreover, the composite anode structures enable the use of simple metal electrodes for efficient and stable OLEDs. The composite provides, through a controlled variation in the C60 concentration, a flexible material platform in regulating the hole injection and transport through the various layers in an OLED.
Is indium tin oxide a suitable electrode in organic solar cells? Photovoltaic properties of interfaces in organic p∕n junction photodiodes
Authors: Jahng Woong Sang , Francis Anthony H. , Moon Hyunsik , Nanos John I. , Curtis M. David
Published: February 2006

The charge generation properties at all interfaces of a p∕n junction, bilayer photodiode have been investigated by means of the photoaction spectrum (PAS) as a function of applied bias. The organic photodiode was fabricated with a low-glass transition temperature (Tg) polysiloxane with pendant hydrazone groups as the p-type material and a perylene diimide derivative as the n-type material. The PAS under short circuit and reverse bias showed an antibatic response at the high-energy region (3.0–3.5eV), and a symbatic response at the low-energy region (2.0–3.0eV). However, under forward bias, the PAS showed the opposite behavior. These results are interpreted in terms of the band structure of tin-doped indium oxide (ITO) that prevents effective photoinjection of electrons at the polymer/ITO interface and the relative energy levels of the constituent materials.
Thermally crosslinked hole-transporting layers for cascade hole-injection and effective electron-blocking/exciton-confinement in phosphorescent polymer light-emitting diodes
Authors: Niu Yu-Hua , Liu Michelle S. , Ka Jae-Won , Jen Alex K.-Y.
Published: February 2006

A bilayer hole-injection/transport structure was prepared by thermally crosslinking two separate hole-transport layers (HTL). The resulting films possess excellent optical quality and solvent resistance. Cascade hole-injection and effective electron-blocking/exciton confinement can be achieved for light-emitting diodes (LEDs) using blue phosphorescent emitters, such asbis(4′,6′-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate. The first HTL was based on tetraphenyldiamine (TPD) has its highest occupied molecular orbit (HOMO) level lies at −5.3eV, and the second HTL with 4,4′,4″-tri(N-carbazolyl)triphenylamine has its HOMO level lies at −5.7eV. The preliminary results from blue LEDs using these cascade HTLs showed much improved device performance than those only use a single layer hole-transporting polymer.
Source - sink effects on grain weight of bread wheat, durum wheat, and triticale at different locations
Authors: Calderini Daniel F. , Reynolds M. P. , Slafer G. A.
Published: February 2006

Source limitation during grain filling is important for both management and breeding strategies of grain crops. There is little information on the sensitivity of grain weight of temperate cereals to variations in source–sink ratios, and no studies are available on the comparative behaviour of temperate cereals growing together in the same experiment. The objective of the current study was to evaluate, under field conditions, the response of grain weight to different source–sink ratios during grain filling in high-yielding cultivars of bread wheat, durum wheat, and triticale at 2 contrasting locations. Two experiments were carried out at C. Obregon and El Batan in Mexico. In each location, 6 genotypes (2 bread wheat, 2 durum wheat, 2 triticale) were evaluated. A week after anthesis, 2 source–sink (control and halved spikes) treatments were imposed. Location and genotype significantly (P < 0.01) affected grain yield and components. Significant grain weight increases (P < 0.05) were found only in 2 cases in El Batan. The highest response of 17% was found in triticale, with less than 10% in most of the other genotypes. The effect of genotype and location is discussed.
A comparison of the excretion rate of endogenous purine derivatives in the urine of Bos indicus and Bos taurus steers
Authors: Bowen M. K. , Poppi D. P. , McLennan S. R. , Doogan V. J.
Published: February 2006

Estimates of microbial crude protein (MCP) production by ruminants, using a method based on the excretion of purine derivatives in urine, require an estimate of the excretion of endogenous purine derivatives (PD) by the animal. Current methods allocate a single value to all cattle. An experiment was carried out to compare the endogenous PD excretion in Bos taurus and high-content B. indicus (hereafter, B. indicus) cattle. Five Holstein–Friesian (B. taurus) and 5 Brahman (> 75% B. indicus) steers (mean liveweight 326 ± 3.0 kg) were used in a fasting study. Steers were fed a low-quality buffel grass (Cenchrus ciliaris; 59.4 g crude protein/kg dry matter) hay at estimated maintenance requirements for 19 days, after which hay intake was incrementally reduced for 2 days and the steers were fasted for 7 days. The excretion of PD in urine was measured daily for the last 6 days of the fasting period and the mean represented the daily endogenous PD excretion. Excretion of endogenous PD in the urine of B. indicus steers was less than half that of the B. taurus steers (190 µmol/kg W0.75.day v. 414 µmol/kg W0.75.day; combined s.e. 37.2 µmol/kg W0.75.day; P < 0.001). It was concluded that the use of a single value for endogenous PD excretion is inappropriate for use in MCP estimations and that subspecies-specific values would improve precision.
Genetic variation in stem strength in field pea (Pisum sativum L.) and its association with compressed stem thickness
Authors: Beeck C. P. , Wroth J. , Cowling W. A.
Published: February 2006

We assessed genetic variation in stem strength in field pea (Pisum sativum L.) using physical and biological measures in order to develop selection criteria for breeding programs. A diverse group of 6 pea genotypes was subjected to 2 levels of disease (ascochyta leaf and stem blight), high and low. Stem samples were tested for physical stem strength (load at breaking point and flexion) using a universal testing machine. Stem diameter and compressed stem thickness were measured as biological indicators of stem strength. The genotypes varied significantly in physical and biological measures of stem strength, and in resistance to ascochyta blight. Load at breaking point was strongly associated with compressed stem thickness but only weakly associated with stem diameter. Significant variation in compressed stem thickness was present among pea genotypes, supporting this as an inexpensive, reliable, and quantitative measure for use in the field. There was no variation in stem lignin content among genotypes. Ascochyta blight resistance and stem strength, as assessed by load, flexion, or compressed stem thickness, were independent traits (the main effects of disease level and genotype × disease level interactions for load, flexion, and compressed stem thickness were non-significant). Therefore, concurrent genetic gains in both ascochyta resistance and stem strength should be possible in the same pea breeding population.
Contributions of glutenin and puroindoline genes to grain quality traits in southern Australian wheat breeding programs
Authors: Eagles H. A. , Cane Karen , Eastwood R. F. , Hollamby G. J. , Kuchel Haydn , Martin P. J. , Cornish G. B.
Published: February 2006

Glutenin genes were known to influence maximum dough resistance (Rmax), dough extensibility (extensibility), and dough development time, whereas puroindoline genes were known to influence grain hardness, flour water absorption (water absorption), and milling yield. These are important determinants of grain quality of wheat in Australia. This study was conducted to investigate the combined effect of these genes on Rmax, extensibility, dough development time, water absorption, and milling yield in a large dataset assembled from the breeding programs based at Horsham, Victoria; Roseworthy, South Australia; and Wagga Wagga, New South Wales; for at least 10 seasons.
The effect of the glutenin genes on Rmax, extensibility, and dough development time was confirmed, as was the effect of the puroindoline genes on water absorption and milling yield. In addition, puroindoline genes were shown to significantly affect extensibility and dough development time. The Pina-D1a/Pinb-D1b genotype increased extensibility, dough development time, and milling yield relative to the Pina-D1b/Pinb-D1a genotype. Both of these genotypes are present in cultivars classified as hard-grained in southern Australia. Therefore, the allelic composition of both glutenin and puroindoline genes is required to predict the grain quality of hard wheat in southern Australian breeding programs. The glutenin and puroindoline genes in combination accounted for more than 50% of the genotypic variance for these traits, except for milling yield, but a substantial proportion of the genotypic variation could not be attributed to these genes, indicating that other genes affecting the traits were present in the populations of these wheat-breeding programs.
Prion infection of mouse neurospheres
Authors: Giri Ranjit K. , Young Rebecca , Pitstick Rose , DeArmond Stephen J. , Prusiner Stanley B. , Carlson George A.
Published: February 2006

Only a few cell lines have been infected with prions, offering limited genetic diversity and sensitivity to several strains. Here we report that cultured neurospheres expressing cellular prion protein (PrP
C
) can be infected with prions. Neurosphere lines isolated from the brains of mice at embryonic day 13–15 grow as aggregates and contain CNS stem cells. We produced neurosphere cultures from FVB/NCr (FVB) mice, from transgenic (Tg) FVB mice that overexpress mouse PrP-A (Tg4053), and from congenic FVB mice with a targeted null mutation in the PrP gene (
Prnp
0/0
) and incubated them with the Rocky Mountain Laboratory prion strain. While monitoring the levels of disease-causing PrP (PrP
Sc
) at each passage, we observed a dramatic rise in PrP
Sc
levels with time in the Tg4053 neurosphere cells, whereas the level of PrP
Sc
decayed to undetectable levels in cell cultures lacking PrP. PrP
Sc
levels in cultures from FVB mice initially declined but then increased with passage. Prions produced in culture were transmissible to mice and produced disease pathology. Intracellular aggregates of PrP
Sc
were present in cells from infected cultures. The susceptibility of neurosphere cultures to prions mirrored that of the mice from which they were derived. Neurosphere lines from Tg4053 mice provide a sensitive
in vitro
bioassay for mouse prions; neurosphere lines from other Tg mice overexpressing PrP might be used to assay prions from other species, including humans.
MicroRNAs direct rapid deadenylation of mRNA
Authors: Wu Ligang , Fan Jihua , Belasco Joel G.
Published: February 2006

MicroRNAs (miRNAs) are ubiquitous regulators of eukaryotic gene expression. In addition to repressing translation, miRNAs can down-regulate the concentration of mRNAs that contain elements to which they are imperfectly complementary. Using miR-125b and let-7 as representative miRNAs, we show that in mammalian cells this reduction in message abundance is a consequence of accelerated deadenylation, which leads to rapid mRNA decay. The ability of miRNAs to expedite poly(A) removal does not result from decreased translation; nor does translational repression by miRNAs require a poly(A) tail, a 3′ histone stem-loop being an effective substitute. These findings suggest that miRNAs use two distinct posttranscriptional mechanisms to down-regulate gene expression.
Cortisol levels and very early pregnancy loss in humans
Authors: Nepomnaschy Pablo A. , Welch Kathleen B. , McConnell Daniel S. , Low Bobbi S. , Strassmann Beverly I. , England Barry G.
Published: February 2006

Maternal stress is commonly cited as an important risk factor for spontaneous abortion. For humans, however, there is little physiological evidence linking miscarriage to stress. This lack of evidence may be attributable to a paucity of research on maternal stress during the earliest gestational stages. Most human studies have focused on “clinical” pregnancy (>6 weeks after the last menstrual period). The majority of miscarriages, however, occur earlier, within the first 3 weeks after conception (≈5 weeks after the last menstrual period). Studies focused on clinical pregnancy thus miss the most critical period for pregnancy continuance. We examined the association between miscarriage and levels of maternal urinary cortisol during the first 3 weeks after conception. Pregnancies characterized by increased maternal cortisol during this period (within participant analyses) were more likely to result in spontaneous abortion (
P
< 0.05). This evidence links increased levels in this stress marker with a higher risk of early pregnancy loss in humans.
Between-subject transfer of emotional information evokes specific pattern of amygdala activation
Authors: Knapska Ewelina , Nikolaev Evgeni , Boguszewski Pawel , Walasek Grazyna , Blaszczyk Janusz , Kaczmarek Leszek , Werka Tomasz
Published: February 2006

Emotional states displayed by an animal or a human can seriously affect behavior of their conspecifics. The amygdala plays a crucial role in the processing of emotions. In this study, we describe an experimental rat model of between-subject transfer of emotional information and its effects on activation of the amygdala. The rats were kept in pairs, and one animal (designated as “demonstrator”) was treated to specific behavioral training of either foot-shock-reinforced context conditioning or just exposure to a novel context. We next examined the influence of the demonstrators on the exploratory behavior of their cagemates (called “observers”) and the observers’ performance of the acoustic startle response. We report that we can distinguish both groups of observers from the control animals (as shown by startle-response measure) and distinguish between observers (by means of indexing the exploration), with respect to whether they were paired with demonstrators treated to different experimental conditions. Furthermore, we show that the observers have most of their amygdala activated (as revealed by c-Fos mapping) to the same level as the demonstrators and, in the case of the central amygdala, to an even higher level. Moreover, the level of c-Fos expression in the observers reflected the specific behavioral treatment of the demonstrators with whom they were paired. Thus, in this study, we have shown that undefined emotional information transferred by a cohabitant rat can be evaluated and measured and that it evokes very strong and information-specific activation of the amygdala.
Psychology in Australian universities
Authors: Wilson Peter , Provost Stephen
Published: February 2006

All but three universities in Australia have departments or schools of psychology. In the older universities (e.g., the universities of Sydney, Melbourne, and Western Australia), the psychology departments evolved from philosophy departments in the late 1920s and early 1930s. There was a rapid expansion of universities in the 1960s, which led to the establishment of many new psychology departments. In a further expansion in the late 1980s, many former institutes of advanced education were afforded university status or were merged with existing universities. In these newer universities, psychology had been taught primarily to students in nursing and education, but these academic areas later evolved from “service” departments into larger and broader psychology departments. There is a strong system of accreditation of psychology departments, a function that is provided by the Australian Psychological Society. The APS conducts reviews of all departments of psychology on a 5‐year cycle. This system of accreditation was significantly strengthened in the mid‐1990s. Graduates who wish to become members of the APS must have completed their degrees within an accredited program (or the equivalent for applicants from other counties). Australian psychology programs are of three types. A 3‐year degree in psychology, often combined with other subjects such as teaching, is a popular major, but does not prepare psychologists. A 4‐year program, with a fourth‐year honours program requiring a thesis and study of ethics and practical applications, is required for those who wish to practise psychology. Graduate (postgraduate) degrees are also offered to prepare psychologists. Each university has some autonomy in the structure of the programs, and emphasis varies. Structure of courses also varies somewhat. Distance education and on‐line courses, although still controversial in Australia, are rapidly increasing in availability. More typically, courses are taught using lectures, group discussions, papers, presentations, and exams.
Learning and teaching psychology as a major subject in Germany
Authors: Hodapp Volker , Langfeldt Hans‐Peter
Published: February 2006

It was only in 1941 that a standardized curriculum and regulations for a professional psychology program as a major subject, including a nondoctoral final examination, were established in Germany. The curriculum and the examination requirements have since been modified from time to time. In the 1960s, only 18 universities offered psychology programs. There, 31 professors taught 2000 students; 20 years later, there were 350 professors, 30 universities, and 18,000 students. At present, we estimate that about 450 professors are teaching 32,000 students at 43 universities. On average, approximately 70% to 80% of the students are female. Although there are overall guidelines both for the curriculum and for the examinations, the local conditions of teaching and learning psychology differ. The largest psychological institutes have to cope with more than 1500 psychology majors, while the smallest one is attended by less than 300 students. Regulations define general and occupation‐related goals of study. The German psychology curriculum can currently be characterized as a generalist program. New developments are under way, including the restructuring of study, the introduction of the European Credit Transfer System (ECTS), the introduction of Bachelor's and Master's programs, and other changes within the German university system. As of 2004, however, the academic degree of the Diplom qualifies students to work in a psychology profession. Students acquire the knowledge and skills to recognize psychological problems and to formulate and realize solutions according to scientific principles. A major issue in teaching is the selection and development of methods for the analysis, verification, and evaluation of psychological activities.
Teaching undergraduate psychology in the Islamic Republic of Iran
Authors: Alipour Ahmad
Published: February 2006

Psychology was first included in curricula at some Iranian universities beginning in the 1920s. Since then, teaching psychology has developed rapidly, and undergraduate psychology programs are offered at 19 universities in Iran. Psychology has been available as a major since the mid‐1960s. The Bachelor of Science (BS) degree in psychology is awarded after 4 years study. Courses follow the credit‐hour and semester system and psychology programs leading to the BS require 130–135 credit hours of study, completed over about eight semesters. Credit hours refer to the number of hours each course meets per week during a semester. There are about 34,000 psychology students at the BS level in Iran now. These students study in four main fields: general, clinical, exceptional children, and industrial psychology. All courses are divided into general, basic, special, and selective categories. Psychology teachers in Iran have different approaches to the teaching‐learning process in psychology and use various methods appropriate for specific topics, although lectures are the most common. Different methods for assessing student learning are also used, but multiple‐choice exams are the most common method. Students can also continue their studies in psychology towards the MS and PhD degrees. There has been considerable growth of universities in the regional areas of Iran in recent years, and this trend has coincided with the development of distance‐education methods. Recently, in 2003, a law pertaining to psychology and counselling services was passed by the Islamic Iranian parliament. This law grants equal status to medical and psychological counselling services. This will be likely to increase the demand for psychologists in the workplace and result in additional programs oriented toward counselling services. Although there are several psychological associations in Iran, they do not participate in the preparation and administration of the curriculum.
Improvement of Intraoperative Antibiotic Prophylaxis in Prolonged Cardiac Surgery by Automated Alerts in the Operating Room
Authors: Zanetti Giorgio , Flanagan Hugh L. , Cohn Lawrence H. , Giardina Richard , Platt Richard
Published: February 2006

Objective:

To assess the impact of an automated intraoperative alert to redose prophylactic antibiotics in prolonged cardiac operations.

Design:

Randomized, controlled, evaluator-blinded trial.

Setting:

University-affiliated hospital.

Patients:

Patients undergoing cardiac surgery that lasted more than 4 hours after the preoperative administration of cefazolin, unless they were receiving therapeutic antibiotics at the time of surgery.

Intervention:

Randomization to an audible and visual reminder on the operating room computer console at 225 minutes after the administration of preoperative antibiotics (reminder group, n = 137) or control (n = 136). After another 30 minutes, the circulating nurse was required to indicate whether a follow-up dose of antibiotics had been administered.

Results:

Intraoperative redosing was significantly more frequent in the reminder group (93 of 137; 68%) than in the control group (55 of 136; 40%) (adjusted odds ratio, 3.31; 95% confidence interval, 1.97 to 5.56; P < .0001). The impact of the reminder was even greater when compared with the 6 months preceding the study period (129 of 480; 27%; P < .001), suggesting some spillover effect on the control group. Redosing was formally declined for 19 of the 44 patients in the reminder group without redosing. The rate of surgical-site infection in the reminder group (5 of 137; 4%) was similar to that in the control group (8 of 136; 6%; P = .42), but significantly lower than that in the pre-study period (48 of 480; 10%; P = .02).

Conclusion:

The use of an automatic reminder system in the operating room improved compliance with guidelines on perioperative antibiotic prophylaxis.
An Intranet-Based Automated System for the Surveillance of Nosocomial Infections: Prospective Validation Compared with Physicians' Self-Reports
Authors: Bouam Samir , Girou Emmanuelle , Brun-Buisson Christian , Karadimas Harry , Lepage Eric
Published: February 2006

Objective:

To examine the reliability of the data produced by an automated system for the surveillance of nosocomial infections.

Setting:

A 906-bed, tertiary-care teaching hospital.

Design:

Three surveillance techniques were concurrently performed in seven high-risk units during an 11-week period: automated surveillance (AS) based on the prospective processing of computerized medical records; laboratory-based ward surveillance (LBWS) based on the retrospective verification by ward clinicians of weekly reports of positive bacteriologic results; and a reference standard (RS) consisting of the infection control team reviewing case records of patients with positive bacteriology results. Bacteremia, urinary tract infections, and catheter-related infections were recorded for all inpatients. The performances (sensitivity, specificity, and time consumption) of AS and LBWS were compared with those of RS.

Results:

Of 548 positive bacteriology samples included during the study period, 229 (42%) were classified as nosocomial infections. The overall sensitivity was 91% and 59% for AS and LBWS, respectively. The two methods had the same overall specificity value (91%). Kappa measures of agreement were 0.81 and 0.54 for AS and LBWS, respectively. AS required less time to collect data (54 seconds per week per unit) compared with LBWS (7 minutes and 43 seconds per week per unit) and RS (37 minutes and 15 seconds per week per unit).

Conclusion:

Our results confirm that the retrospective review of charts and laboratory data by physicians lacks sensitivity for the surveillance of nosocomial infections. The intranet-based automated method developed for this purpose was more accurate and less time-consuming than the weekly, retrospective LBWS method.
Junctions of three quantum wires
Authors: Oshikawa Masaki , Chamon Claudio , Affleck Ian
Published: February 2006

We study a junction of three quantum wires enclosing a magnetic flux. The wires are
modelled as single-channel spinless Tomonaga–Luttinger liquids. This is the simplest
problem of a quantum junction between Tomonaga–Luttinger liquids in which Fermi
statistics enter in a non-trivial way. We study the problem using a mapping onto the
dissipative Hofstadter model, describing a single particle moving on a plane in a magnetic
field and a periodic potential coupled to a harmonic oscillator bath. Alternatively we study
the problem by identifying boundary conditions corresponding to the low energy fixed
points. We obtain a rich phase diagram including a chiral fixed point in which the
asymmetric current flow is highly sensitive to the sign of the flux and a phase in which
electron pair tunnelling dominates. We also study the effects on the conductance tensor of
the junction of contacting the three quantum wires to Fermi liquid reservoirs.
Disulfide Transfer between Two Conserved Cysteine Pairs Imparts Selectivity to Protein Oxidation by Ero1
Authors: Sevier Carolyn S. , Kaiser Chris A.
Published: February 2006

The membrane-associated flavoprotein Ero1p promotes disulfide bond formation in the endoplasmic reticulum (ER) by selectively oxidizing the soluble oxidoreductase protein disulfide isomerase (Pdi1p), which in turn can directly oxidize secretory proteins. Two redox-active disulfide bonds are essential for Ero1p oxidase activity: Cys100-Cys105 and Cys352-Cys355. Genetic and structural data indicate a disulfide bond is transferred from Cys100-Cys105 directly to Pdi1p, whereas a Cys352-Cys355 disulfide bond is used to reoxidize the reduced Cys100-Cys105 pair through an internal thiol-transfer reaction. Electron transfer from Cys352-Cys355 to molecular oxygen, by way of a flavin cofactor, maintains Cys352-Cys355 in an oxidized form. Herein, we identify a mixed disulfide species that confirms the Ero1p intercysteine thiol-transfer relay in vivo and identify Cys105 and Cys352 as the cysteines that mediate thiol-disulfide exchange. Moreover, we describe Ero1p mutants that have the surprising ability to oxidize substrates in the absence of Cys100-Cys105. We show the oxidase activity of these mutants results from structural changes in Ero1p that allow substrates increased access to Cys352-Cys355, which are normally buried beneath the protein surface. The altered activity of these Ero1p mutants toward selected substrates leads us to propose the catalytic mechanism involving transfer between cysteine pairs evolved to impart substrate specificity to Ero1p.
FUS1Regulates the Opening and Expansion of Fusion Pores between Mating Yeast
Authors: Nolan Scott , Cowan Ann E. , Koppel Dennis E. , Jin Hui , Grote Eric
Published: February 2006

Mating yeast cells provide a genetically accessible system for the study of cell fusion. The dynamics of fusion pores between yeast cells were analyzed by following the exchange of fluorescent markers between fusion partners. Upon plasma membrane fusion, cytoplasmic GFP and DsRed diffuse between cells at rates proportional to the size of the fusion pore. GFP permeance measurements reveal that a typical fusion pore opens with a burst and then gradually expands. In some mating pairs, a sudden increase in GFP permeance was found, consistent with the opening of a second pore. In contrast, other fusion pores closed after permitting a limited amount of cytoplasmic exchange. Deletion of FUS1 from both mating partners caused a >10-fold reduction in the initial permeance and expansion rate of the fusion pore. Although fus1 mating pairs also have a defect in degrading the cell wall that separates mating partners before plasma membrane fusion, other cell fusion mutants with cell wall remodeling defects had more modest effects on fusion pore permeance. Karyogamy is delayed by >1 h in fus1 mating pairs, possibly as a consequence of retarded fusion pore expansion.
The Vaccinia-related Kinases Phosphorylate the N′ Terminus of BAF, Regulating Its Interaction with DNA and Its Retention in the Nucleus
Authors: Nichols R. Jeremy , Wiebe Matthew S. , Traktman Paula
Published: February 2006

The vaccinia-related kinases (VRKs) comprise a branch of the casein kinase family whose members are characterized by homology to the vaccinia virus B1 kinase. The VRK orthologues encoded by Caenorhabditis elegans and Drosophila melanogaster play an essential role in cell division; however, substrates that mediate this role have yet to be elucidated. VRK1 can complement the temperature sensitivity of a vaccinia B1 mutant, implying that VRK1 and B1 have overlapping substrate specificity. Herein, we demonstrate that B1, VRK1, and VRK2 efficiently phosphorylate the extreme N′ terminus of the BAF protein (Barrier to Autointegration Factor). BAF binds to both DNA and LEM domain-containing proteins of the inner nuclear membrane; in lower eukaryotes, BAF has been shown to play an important role during the reassembly of the nuclear envelope at the end of mitosis. We demonstrate that phosphorylation of ser4 and/or thr2/thr3 abrogates the interaction of BAF with DNA and reduces its interaction with the LEM domain. Coexpression of VRK1 and GFP-BAF greatly diminishes the association of BAF with the nuclear chromatin/matrix and leads to its dispersal throughout the cell. Cumulatively, our data suggest that the VRKs may modulate the association of BAF with nuclear components and hence play a role in maintaining appropriate nuclear architecture.
WELFARE ANALYSIS OF PRIVATIZATION IN A MIXED MARKET WITH BARGAINING
Authors: JIANG LILY
Published: February 2006

The author analyzes the welfare effects of privatization in a mixed duopoly model in which the wage rate for the privatized firm is determined by Nash bargaining beforehand. The evaluations are based on three‐stage privatization frameworks respectively under two regimes: Cournot competition and a public firm acting as a Stackelberg leader. The author finds that the optimal degrees of privatization from the viewpoint of social welfare may be different for various types of competition. The article also shows that even optimal privatization set by a welfare‐maximization government may not guarantee welfare improvement, owing to the interference of wage bargaining. (JEL D60, D78, L32, L33)
HUNGARY'S EUROZONE ENTRY DATE: WHAT DO THE MARKETS THINK AND WHAT IF THEY CHANGE THEIR MINDS?
Authors: CSAJBÓK ATTILA , REZESSY ANDRÁS
Published: February 2006

This article investigates the potential impact of a shift in market expectations about a country's eurozone entry date on long‐term yields and the spot exchange rate in a simple uncovered interest parity (UIP) framework. The results suggest that the size of the reactions depend on how far the entry date is postponed, how far current inflation is from the Maastricht‐satisfying level, and whether the credibility of the central bank's target inflation path is sensitive to changes in the expected entry date. In the empirical part, the authors apply the framework for Hungary and draw some policy conclusions for the timing of ERM II entry. (JEL E44, E52, F33)
Mutations of intermediate effect are responsible for adaptation in evolvingPseudomonas fluorescenspopulations
Authors: Barrett Rowan D.H , Craig MacLean R , Bell Graham
Published: February 2006

The fixation of a beneficial mutation represents the first step in adaptation, and the average effect of such mutations is therefore a fundamental property of evolving populations. It is nevertheless poorly characterized because the rarity of beneficial mutations makes it difficult to obtain reliable estimates of fitness. We obtained 68 genotypes each containing a single fixed beneficial mutation from experimental populations ofPseudomonas fluorescens, evolving in medium with serine as the sole carbon source and estimated the selective advantage of each by competition with the ancestor. The distribution of selection coefficients is modal and closely resembles the Weibull distribution. The average selection coefficient (2.1) and beneficial mutation rate (3.8×10−8) are high relative to previous studies, possibly because the ancestral population grows poorly in serine-limited medium. Our experiment suggests that the initial stages of adaptation to stressful environments will involve the substitution of mutations with large effect on fitness.
Comparing amber fossil assemblages across the Cenozoic
Authors: Penney David , Langan A. Mark
Published: February 2006

To justify faunistic comparisons of ambers that differ botanically, geographically and by age, we need to determine that resins sampled uniformly. Our pluralistic approach, analysing size distributions of 671 fossilized spider species from different behavioural guilds, demonstrates that ecological information about the communities of two well-studied ambers is retained. Several lines of evidence show that greater structural complexity of Baltic compared to Dominican amber trees explains the presence of larger web-spinners. No size differences occur in active hunters. Consequently, we demonstrate for the first time that resins were trapping organisms uniformly and that comparisons of amber palaeoecosystem structure across deep time are possible.
Stable isotope evidence of diverse species-specific and individual wintering strategies in seabirds
Authors: Cherel Y , Phillips Richard A , Hobson Keith A , McGill Rona
Published: February 2006

Although there is increasing evidence that climatic variations during the non-breeding season shape population dynamics of seabirds, most aspects of their winter distribution and ecology remain essentially unknown. We used stable isotope signatures in feathers to infer and compare the moulting (wintering) habitat of subantarctic petrels breeding at two distant localities (South Georgia and Kerguelen). Petrels showed species-specific wintering habitat preferences, with a similar pattern of latitudinal segregation for all but one taxon. At both localities,
δ
13
C values indicated that blue petrels (
Halobaena caerulea
) moult in Antarctic waters, South Georgian diving petrels (
Pelecanoides georgicus
) in the vicinity of the archipelagos and/or in the Polar Frontal Zone and Antarctic prions (
Pachyptila desolata
) in warmer waters. In contrast, common diving petrels (
Pelecanoides urinatrix
) showed divergent strategies, with low and high intrapopulation variation at South Georgia and Kerguelen, respectively. Birds from Kerguelen dispersed over a much wider range of habitats, from coastal to oceanic waters and from Antarctica to the subtropics, whereas those from South Georgia wintered mainly in waters around the archipelago. This study is the first to show such striking between-population heterogeneity in individual wintering strategies, which could have important implications for likely demographic responses to environmental perturbation.
Mosquito repellents in frog skin
Authors: Williams C.R , Smith B.P.C , Best S.M , Tyler M.J
Published: February 2006

The search for novel insect repellents has been driven by health concerns over established synthetic compounds such as diethyl-
m
-toluamide (DEET). Given the diversity of compounds known from frog skin and records of mosquito bite and ectoparasite infestation, the presence of mosquito repellents in frogs seemed plausible. We investigated frog skin secretions to confirm the existence of mosquito repellent properties.
Litoria caerulea
secretions were assessed for mosquito repellency by topical application on mice. The secretions provided protection against host-seeking
Culex annulirostris
mosquitoes. Olfactometer tests using aqueous washes of skin secretions from
L. caerulea
and four other frog species were conducted to determine whether volatile components were responsible for repellency. Volatiles from
Litoria rubella
and
Uperoleia mjobergi
secretions were repellent to
C. annulirostris
, albeit not as repellent as a DEET control. The demonstration of endogenous insect repellents in amphibians is novel, and demonstrates that many aspects of frog chemical ecology remain unexplored.
Vibrational signalling in a Gondwanan relict insect (Hemiptera: Coleorrhyncha: Peloridiidae)
Authors: Hoch Hannelore , Deckert Jürgen , Wessel Andreas
Published: February 2006

Ancient, long-extinct floras and faunas can be reassembled through fossils and phylogenetics, and even palaeo-environments can be reconstructed with the aid of palaeoclimatology. However, very little is known about the sound-scape of the past. Of what kind were the first biologically meaningful sounds and vibrations ever emitted and perceived? The earliest signals in the history of life were probably produced by arthropods making use of the mechanical properties of their exoskeleton. Here, we report an observation of vibrational signalling in the coleorrhynchan
Hackeriella veitchi
, a representative of a Gondwanan relict insect lineage which is still extant in the Queensland rainforest. Our finding suggests that vibrational signalling by tymbal organs is ancestral for the Hemiptera (exclusive of Sternorrhyncha)—the song of the Coleorrhyncha was a likely element of the acoustic environment in the Permian moss forests and had possibly changed little since.
A polycrystal hysteresis model for ferroelectric ceramics
Authors: Su Y , Weng G.J
Published: February 2006

Most key elements of ferroelectric properties are defined through the hysteresis loops. For a ferroelectric ceramic, its loop is contributed collectively by its constituent grains, each having its own hysteresis loop when the ceramic polycrystal is under a cyclic electric field. In this paper, we propose a polycrystal hysteresis model so that the hysteresis loop of a ceramic can be calculated from the loops of its constituent grains. In this model a micromechanics-based thermodynamic approach is developed to determine the hysteresis behaviour of the constituent grains, and a self-consistent scheme is introduced to translate these behaviours to the polycrystal level. This theory differs from the classical phenomenological ones in that it is a micromechanics-based thermodynamic approach and it can provide the evolution of new domain concentration among the constituent grains. It also differs from some recent micromechanics studies in its secant form of self-consistent formulation and in its application of irreversible thermodynamics to derive the kinetic equation of domain growth. To put this two-level micromechanics theory in perspective, it is applied to a ceramic PLZT 8/65/35, to calculate its hysteresis loop between the electric displacement and the electric field (
D
versus
E
), and the butterfly-shaped longitudinal strain versus the electric field relation (
ϵ
versus
E
). The calculated results are found to be in good quantitative agreement with the test data. The corresponding evolution of new domain concentration
c
1
and the individual hysteresis loops of several selected grains—along with those of the overall polycrystal—are also illustrated.
A kinetic beam scheme for ideal quantum gas dynamics
Authors: Yang Jaw-Yen , Shi Yu-Hsin
Published: February 2006

A novel kinetic beam scheme for the ideal quantum gas is presented for the computation of quantum gas dynamical flows. The quantum Boltzmann equation approach is adopted and the local thermodynamic equilibrium quantum distribution is assumed. Both Bose–Einstein and Fermi–Dirac gases are considered. Formulae for one spatial dimension is first derived and the resulting beam scheme is tested for shock tube flows. Implementation of high-order methods is also outlined. We only consider the system in the normal phase consisting of particles in excited states and both the classical limit and the nearly degenerate limit are computed. The flow structures can all be accurately captured by the present beam scheme. Formulations for multiple spatial dimensions are also included.
Asymmetric Mathieu equations
Authors: Marathe Amol , Chatterjee Anindya
Published: February 2006

An inverted pendulum with asymmetric elastic restraints (e.g. a one-sided spring), when subjected to harmonic vertical base excitation, on linearizing trigonometric terms, is governed by an asymmetric Mathieu equation. This system is parametrically forced and strongly nonlinear (linearization for small motions is not possible). However, solutions are scaleable: if
x
(
t
) is a solution, then so is
αx
(
t
) for any real
α
>0. We numerically study the stability regions in the parameter plane of this system for a fixed degree of asymmetry in the elastic restraints. A Lyapunov-like exponent is defined and numerically evaluated to find these regions of stable and unstable behaviour. These numerics indicate that there are infinitely many possibilities of instabilities in this system that are missing in the usual or symmetric Mathieu equation. We find numerically that there are periodic solutions at the boundaries of stable regions in the parameter plane, analogous to the symmetric Mathieu equation. We compute and plot several of these solution branches, which provide a relatively simpler means of computing the stability transition curves of this system. We prove theoretically that such periodic solutions must exist on all stability boundaries. Our theoretical results apply to the asymmetric Hill's equation, of which the pendulum system is a special case. We demonstrate this with numerical studies of a more general asymmetric Mathieu equation.