bluuebunny/crossref_metadata_2025 huggingface dataset:
Direct ab initio molecular dynamics study on a microsolvated SN2 reaction of OH−(H2O) with CH3Cl
Authors: Tachikawa Hiroto
Published: October 2006

Reaction dynamics for a microsolvated SN2 reaction OH−(H2O)+CH3Cl have been investigated by means of the direct ab initio molecular dynamics method. The relative center-of-mass collision energies were chosen as 10, 15, and 25kcal∕mol. Three reaction channels were found as products. These are (1) a channel leading to complete dissociation (the products are CH3OH+Cl−+H2O: denoted by channel I), (2) a solvation channel (the products are Cl−(H2O)+CH3OH: channel II), and (3) a complex formation channel (the products are CH3OH⋯H2O+Cl−: channel III). The branching ratios for the three channels were drastically changed as a function of center-of-mass collision energy. The ratio of complete dissociation channel (channel I) increased with increasing collision energy, whereas that of channel III decreased. The solvation channel (channel II) was minor at all collision energies. The selectivity of the reaction channels and the mechanism are discussed on the basis of the theoretical results.
Cotton-Mouton polarimeter with HCN laser on CHS
Authors: Akiyama T. , Kawahata K. , Ito Y. , Okajima S. , Nakayama K. , Okamura S. , Matsuoka K. , Isobe M. , Nishimura S. , Suzuki C. , Yoshimura Y. , Nagaoka K. , Takahashi C. ,   CHS Experimental Group
Published: October 2006

Polarimeters based on the Cotton-Mouton effect hold promise for electron density measurements. We have designed and installed a Cotton-Mouton polarimeter on the Compact Helical System. The Cotton-Mouton effect is measured as the phase difference between probe and reference beams. In this system, an interferometric measurement can be performed simultaneously with the same probe chord. The light source is a HCN laser (wavelength of 337 μm). Digital complex demodulation is adopted for small phase analysis. The line averaged density evaluated from the polarimeter along a plasma center chord is almost consistent with that from the interferometer.
Decay dynamics of the long-range H¯Σg+1 state of D2 and H2: Experiment and theory
Authors: Ross Stephen C. , Yoshinari Toshio , Ogi Yoshihiro , Tsukiyama Koichi
Published: October 2006

We present accurate experimental measurements of the lifetimes of rovibrational levels of the long-range H¯Σg+1 state for both D2 and H2, obtained directly from the observation of the time-dependent decay of the fluorescence from these excited levels. These results improve upon and extend those of Reinhold et al. [J. Chem. Phys. 112, 10754 (2000)]. Several decay pathways are open to these levels including fluorescence, predissociation, and autoionization. We present theoretical results for each of these processes, each calculated using the simplest but still appropriate level of theory. In particular, the theoretical calculations provide a quantitative explanation of the dramatic vibrational dependence of the observed lifetimes, the isotope dependence of the lifetimes for levels well localized within the H¯ potential well and therefore not subject to significant tunneling, and an insight into the role of enhanced tunneling in autoionization. In these calculations each of the rovibrational levels of the H¯ state is treated individually, without having to engage in a global coupled-state calculation.
Control of fine particles by time-averaged external forces in plasmas
Authors: Iizuka Satoru , Sakuta Kazuma , Suzukawa Wataru , Kato Kohgi , Gohda Takuma
Published: October 2006

A technique for the control of fine particle behavior is developed and demonstrated experimentally. In this method positive pulses are applied to two point-electrodes placed with some distance in plasmas containing fine particles. When the positive pulses are applied to these electrodes alternatively with a repetition period that is shorter than the particle response time, the particles feel only time-averaged force because of their large mass and are gradually transported toward the middle point between two point-electrodes wherever they are distributed initially. This method is quite effective for converging fine particles in the plasma.
Explicit solutions for N-dimensional Schrödinger equations with position-dependent mass
Authors: Gönül B. , Koçak M.
Published: October 2006

With the consideration of spherical symmetry for the potential and mass function, one-dimensional solutions of nonrelativistic Schrödinger equations with spatially varying effective mass are successfully extended to arbitrary dimensions within the frame of recently developed elegant nonperturbative technique, where the BenDaniel-Duke effective Hamiltonian in one dimension is assumed like the unperturbed piece, leading to well-known solutions, whereas the modification term due to possible use of other effective Hamiltonians in one dimension and, together with the corrections coming from the treatments in higher dimensions, are considered as an additional term like the perturbation. Application of the model and its generalization for the completeness are discussed.
Plasma dragged microparticles as a method to measure plasma flows
Authors: Ticoş Cătălin M. , Wang Zhehui , Delzanno Gian Luca , Lapenta Giovanni
Published: October 2006

The physics of microparticle motion in flowing plasmas is studied in detail for plasmas with electron and ion densities ne,i∼1019m−3, electron and ion temperatures of no more than 15eV, and plasma flows on the order of the ion thermal speed, vf∼vti. The equations of motion due to Coulomb interactions and direct impact with ions and electrons, of charge variation, as well as of heat exchange with the plasma, are solved numerically for isolated particles (or dust grains) of micron sizes. It is predicted that microparticles can survive in plasma long enough, and can be dragged in the direction of the local ion flow. Based on the theoretical analysis, we describe a new plasma flow measurement technique called microparticle tracer velocimetry (mPTV), which tracks microparticle motion in a plasma with a high-speed camera. The mPTV can reveal the directions of the plasma flow vectors at multiple locations simultaneously and at submillimeter scales, which is hard to achieve by most other techniques. Thus, mPTV can be used to study plasma flows produced in the laboratory.
In situ investigation of the island nucleation of Ge on Si(001) using x-ray scattering methods
Authors: Schülli T. U. , Richard M.-I. , Renaud G. , Favre-Nicolin V. , Wintersberger E. , Bauer G.
Published: October 2006

The growth of Ge on Si(001) is investigated in situ at 500 and 600°C, combining grazing incidence diffraction, multiple wavelength anomalous diffraction, and small angle scattering. This allows probing simultaneously the island shape, strain state, composition, and the transition from wetting layer to island growth. At 500°C no intermixing occurs. The wetting layer is found to decrease by one atomic layer at the onset of island nucleation. At 600°C interdiffusion plays an important role in strain relaxation leading to a more stable wetting layer. Small angle scattering yields the island morphology and shows the transition from pyramids to multifacetted domes.
Influence of alloy composition on carrier transport and solar cell properties of hydrogenated microcrystalline silicon-germanium thin films
Authors: Matsui Takuya , Kondo Michio , Ogata Keisuke , Ozawa Tsuyoshi , Isomura Masao
Published: October 2006

The authors report on carrier transport properties and spectral sensitivities of hydrogenated microcrystalline silicon-germanium (μc-Si1−xGex:H) alloys fabricated by low-temperature (∼200°C) plasma-enhanced chemical vapor deposition over the wide compositional range. Hall-effect and conductivity measurements reveal a change from weak n-type to strong p-type conduction for x>0.75 and a monotonic decrease in photoconductivity upon Ge incorporation. In a p-i-n diode structure, the Ge incorporation into i layer reduces quantum efficiencies in the short wavelengths, indicating an increased photocarrier recombination at p∕i interface. Nevertheless, under reverse biased condition, a 0.9-μm-thick μc-Si0.6Ge0.4:H absorber yields a large photocurrent of >27mA∕cm2 (air mass 1.5 global) with spectral sensitivities extending into infrared wavelengths, offering a potential advantage over conventional microcrystalline silicon solar cells.
High performance thin film bulk acoustic resonator covered with carbon nanotubes
Authors: Dragoman M. , Muller A. , Neculoiu D. , Vasilache D. , Konstantinidis G. , Grenier K. , Dubuc D. , Bary L. , Plana R. , Flahaut E.
Published: October 2006

This letter presents experimental results concerning a thin film bulk acoustic wave resonator realized on a thin GaN membrane and covered with a thin film of double walled carbon nanotube mixture. The quality factor was measured before and after the coating of the resonator with the nanotube thin film. The quality factor has increased more than ten times when the resonator was coated with nanotubes, due to their high elasticity modulus and low density, which confers a much higher acoustic impedance of the resonator electrodes and thus confines much better the longitudinal acoustic standing waves inside the resonator.
Droplet formation in microchannels under static conditions
Authors: Wu Liang , Li Guann-Pyng , Xu Wei , Bachman Mark
Published: October 2006

Droplets generated by oil and water mixtures in microfluidic devices have become popular for generating nanovolume vessels for biochemical assays. The authors report a microfluidic technology that can create nanovolume droplets in a microfluidic channel under static (nonflow) conditions. The technique exploits interfacial surface tension and geometry of the channels to generate aqueous droplets of predetermined size at fixed locations. This results in a method of generating small drops in a microfluidic system at programed locations in a manner that is not strongly dependent on flow rate or viscosity.
Large piezoelectric strains from polarization graded ferroelectrics
Authors: Zhong S. , Ban Z.-G. , Alpay S. P. , Mantese J. V.
Published: October 2006

The potential applications of polarization graded ferroelectrics as high performance sensors and actuators are theoretically investigated. A static bending can be expected in polarization graded ferroelectric plates, forming a vertical displacement. This is due to the built-in strain gradient that arises from the grading of the composition and concomitantly, the spontaneous self-strain. Numerical results of two compositionally graded ferroelectrics, BaTiO3–Ba1−xSrxTiO3 and PbTiO3–Pb1−xZrxTiO3, show a high dynamic response of the displacement under an external electric field, yielding as much as ∼23% strain at 50kV∕cm in PbTiO3–Pb0.6Zr0.4TiO3, which is comparable to large displacement actuators formed from ceramic/ceramic and ceramic/metal multilayer mesomaterials.
Rapid nanopatterning of a Zr-based metallic glass surface utilizing focused ion beam induced selective etching
Authors: Kawasegi Noritaka , Morita Noboru , Yamada Shigeru , Takano Noboru , Oyama Tatsuo , Ashida Kiwamu , Taniguchi Jun , Miyamoto Iwao , Momota Sadao , Ofune Hitoshi
Published: October 2006

A simple and rapid method is proposed for nanoscale patterning on a metallic glass surface using focused ion beam irradiation followed by wet etching. It was found that the etch rate of a metallic glass surface irradiated with Ga+ ions could be drastically changed, and rapid patterning was possible with this method. Cross-sectional transmission electron microscopy observation reveals that the metallic glass substrate maintains an amorphous phase following irradiation. Etching enhancement was not observed for irradiation with Ar+ ions. The results indicate that enhancement of etching results from the presence of implanted Ga+ ions rather than a change in crystallography.
Determination of free carrier density and space charge layer variation in nanocrystalline In3+ doped tin oxides using Fourier transforminfrared spectroscopy
Authors: Drake Christina , Deshpande Sameer , Seal Sudipta
Published: October 2006

A correlation between the surface reactions and the electrical response of doped nano-metal-oxide-semiconductors exposed to reducing gas is established using Fourier transform infrared (FTIR) spectroscopy. The effect of processing temperature on the microstructure evolution and the electronic conduction of the nanocrystalline In–SnO2 is presented. Variation in the charge carrier density is correlated to the solid/gas reaction of In–SnO2 in the nanodomain using the Drude-Zener theory including Spitzer and Fan’s [Phys. Rev. 99, 1893 (1955)] correction to accommodate for the quantum effects. Higher gas sensitivity for nanocrystalline size less than twice the space charge layer thickness is observed using in situ FTIR.
Photon crystal waveguide-based surface plasmon resonance biosensor
Authors: Skorobogatiy Maksim , Kabashin Andrei V.
Published: October 2006

The concept of a photonic crystal waveguide-based surface plasmon resonance sensor is proposed, in which plasmons on a surface of a thin metal film are excited by a Gaussian-like leaky mode of an effectively single mode photonic crystal waveguide. The authors demonstrate that effective refractive index of a waveguide core mode can be designed to be considerably smaller than that of a core material, enabling efficient phase matching with plasmons at any wavelength of choice, while retaining highly sensitive response to changes in the refractive index of an analyte layer. This is attractive for the development of portable surface plasmon resonance biochemical sensors.
Bipolar transport observed through extraction currents on organic photovoltaic blend materials
Authors: Andersson L. Mattias , Zhang Fengling , Inganäs Olle
Published: October 2006

Both electron and hole mobilities have been simultaneously measured through charge extraction by linearly increasing voltage on polymer heterojunction solar cells with varying stoichiometry of polymer and acceptor. The polymer is a low band gap copolymer of fluorene, thiophene, and electron accepting groups named APFO-Green 5, and the acceptor is [6,6]-phenyl-C61-butyric acid methylester. Results are correlated to field effect transistor measurements on the same material system. A monotonous increase in mobility for both carrier types is observed with increased acceptor loading.
Ga
N
∕
Al
Ga
N
heterojunction infrared detector responding in 8–14 and 20–70μm ranges
Authors: Ariyawansa G. , Rinzan M. B. M. , Strassburg M. , Dietz N. , Perera A. G. U. , Matsik S. G. , Asghar A. , Ferguson I. T. , Luo H. , Liu H. C.
Published: October 2006

A GaN∕AlGaN heterojunction interfacial work function internal photoemission infrared detector responding in 8–14 and 20–70μm ranges has been demonstrated. Free carrier absorption based photoresponse shows a wavelength threshold of 14μm with a peak responsivity of 0.6mA∕W at 80K under −0.5V bias. A sharp peak in the 11–13.6μm range is observed superimposed on the free carrier response. In addition, the work demonstrates 54μm (5.5THz) operation of the detector based on 1s–2p± transition of Si donors in GaN. Possible approaches on improving the performance of the detector are also addressed.
Impact of Si substrate orientations on electrical properties of crystalline Gd2O3 thin films for high-K application
Authors: Laha Apurba , Osten H. J. , Fissel A.
Published: October 2006

The authors compare the properties of epitaxial Gd2O3 thin films grown on silicon substrates with three different orientations for high-K application. Pt∕Gd2O3∕Si(111) and Pt∕Gd2O3∕Si(110) metal oxide semiconductor heterostructures show promising electrical properties and hence, could be considered for future generation of complementary metal oxide semiconductor devices. Capacitance equivalent oxide thicknesses estimated from capacitance versus voltage characteristics are 0.97, 1.12, and 0.93nm for the films grown on Si(001), Si(111), and Si(110) substrates, respectively. The films exhibit good insulating property with leakage current densities of 0.4, 0.5, and 4.5mA∕cm2, respectively, at (Vg−VFBV)=−1V.
Electroluminescence mapping of CuGaSe2 solar cells by atomic force microscopy
Authors: Romero Manuel J. , Jiang C.-S. , Abushama J. , Moutinho H. R. , Al-Jassim M. M. , Noufi R.
Published: October 2006

The authors report on the observation of electroluminescence (EL) in CuGaSe2 solar cells using tapping-mode atomic force microscopy based on tuning-fork sensors. Individually injected current pulses are seen during intermittent contact driven by an external bias applied to the conducting tip. It follows that EL can be stimulated when the solar cell is forward biased during the contact cycle. Local L-V characteristics show evidence for EL, with a threshold voltage of 3.0–3.7V. Mapping of the photon emission suggests that grain boundaries effectively isolate grain interiors, which behave as individual light-emitting diodes.
Nanosecond laser ablation of gold nanoparticle films
Authors: Ko Seung H. , Choi Yeonho , Hwang David J. , Grigoropoulos Costas P. , Chung Jaewon , Poulikakos Dimos
Published: October 2006

Ablation of self-assembled monolayer protected gold nanoparticle films on polyimide was explored using a nanosecond laser. When the nanoparticle film was ablated and subsequently thermally sintered to a continuous film, the elevated rim structure by the expulsion of molten pool could be avoided and the ablation threshold fluence was reduced to a value at least ten times lower than the reported threshold for the gold film. This could be explained by the unusual properties of nanoparticle film such as low melting temperature, weak bonding between nanoparticles, efficient laser energy deposition, and reduced heat loss. Finally, submicron lines were demonstrated.
Use of cross-linkable polyfluorene in the fabrication of multilayer polyfluorene-based light-emitting diodes with improved efficiency
Authors: Charas A. , Alves H. , Alcácer L. , Morgado J.
Published: October 2006

The authors report the use of a cross-linkable polyfluorene to fabricate multilayer light-emitting diodes (LEDs), thereby avoiding the restriction to combine polymeric solutions in different solvents. In particular, we find that for LEDs fabricated with a hole-injection layer of poly(3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid (PEDOT), with magnesium cathodes and with poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT), as emissive layer, its electroluminescence efficiency increases from 2to5.5cd∕A upon insertion of the cross-linked polyfluorene between PEDOT and F8BT. This efficiency increase is attributed to an improvement of charge carrier balance within the F8BT emissive layer and a reduction of exciton quenching at PEDOT interface.
Metastable, epitaxial PrCo7 films with high energy product
Authors: Patra A. K. , Neu V. , Fähler S. , Groetzschel R. , Schultz L.
Published: October 2006

Epitaxial Pr–Co films with a nominal composition of Pr2Co17 have been prepared on a Cr buffered MgO (110) substrate. Pole figures and magnetic measurements reveal that these Pr–Co films crystallize in a metastable disordered hexagonal PrCo7 phase (TbCu7 type) rather than an ordered rhombohedral Pr2Co17 phase (Th2Zn17 type). Consequently high uniaxial anisotropy at room temperature is observed instead of the planar anisotropy expected for the rhombohedral phase. The energy density obtained in the nonequilibrium Pr–Co films is (BH)max=277kJ∕m3, which exceeds the (BH)max values of single phase Sm–Co films and Sm–Co∕Fe and Pr–Co∕Co multilayers.
Ionic control of ocular growth and refractive change
Authors: Crewther Sheila G. , Liang Helena , Junghans Barbara M. , Crewther David P.
Published: October 2006

The physiological mechanisms underlying the abnormal vitreal and ocular growth and myopic refractive errors induced under conditions of visual form deprivation in many animal species, including humans, are unknown. This study demonstrates, using energy dispersive x-ray microanalysis, a systematic pattern of changes in the elemental distribution of K, Na, and Cl across the entire retina in experimental form deprivation myopia and in the 5 days required for refractive normalization after occluder removal. In our report we link the ionic environment associated with physiological activity of the retina under a translucent occluder to refractive change and describe large but reversible environmentally driven increases in potassium, sodium, and chloride abundances in the neural retina. Our results are consistent with the notion of ionically driven fluid movements as the vector underlying the myopic increase in ocular size. New treatments for myopia, which currently affects nearly half of the human population, may result.
Obesity in young adulthood and later disability pension: A population-based cohort study of 366,929 Swedish men
Authors: Karnehed Nina , Rasmussen Finn , Kark Malin
Published: October 2006

Background: The prevalence of obesity has increased threefold among Swedish men during recent decades. Knowledge from Sweden on how obese men manage in working life and become disability pensioners is sparse. The aim of this nationwide and population-based cohort study was to investigate to what extent body mass index (BMI) in young adulthood predicts later disability pension. Method: All Swedish men born 1952—59, who had their weight and height measured at age 18 years in the compulsory military conscription examinations, were followed up longitudinally from 1990 to 2001 with regard to receiving disability pension. Data on own socioeconomic position (1985), education and marital status (1990), parental socioeconomic position (1960), and education (1970) were obtained from censuses. For 366,929 men (81% of the eligible men) the hazard ratio for receiving disability pension was calculated with Cox regression controlling for own education, parental education, childhood and adult socioeconomic position, marital status, morbidity, and type of municipality. Results: Obesity in young adulthood increased the risk for disability pension later in life (1.35, 95% CI 1.19, 1.52) compared with men of normal weight. The relationship between BMI and disability pension was J-shaped with higher risks for underweight (1.14, 95% CI 1.09, 1.20) and obese men. Conclusions: Obese men in Sweden are at higher risk of receiving disability pension. The relationship between BMI and disability pension is J-shaped. An important future task is to estimate the societal costs due to disability pension of obese people.
Patient experiences in relation to respondent and health service delivery characteristics: A survey of 26,938 patients attending 62 hospitals throughout Norway
Authors: Danielsen Kirsten , Garratt Andrew M. , Bjertnæs Øyvind Andresen , Pettersen Kjell I.
Published: October 2006

Aims: To assess the association between patient experiences, aspects of healthcare delivery, and patient characteristics for adult somatic inpatients attending hospitals throughout Norway. Methods: The Patient Experiences Questionnaire (PEQ) was mailed to 26,938 patients attending inpatient clinics at 62 Norwegian hospitals during 2002 and 2003 within a six-week period. Reminders were mailed at four weeks. Scores for the PEQ were regressed on whether the patient felt that he/she had received incorrect treatment, had spent the night in a corridor bed, had been an emergency or routine admission, his/her number of previous admissions, hospital teaching status, hospital size and location, health status, and sociodemographic variables. Results: A total of 13,700 (50.9%) patients responded. Patients who felt that they had received incorrect treatment had significantly poorer scores for all 10 PEQ dimensions. Those spending the night in a corridor bed had significantly poorer scores for six dimensions. Emergency admissions and the previous number of inpatient stays were significantly associated with poorer experiences for 10 and 7 dimensions respectively. Hospital size and university status had negative relationships with scores for six and four dimensions respectively. Conclusions: Whether the patient felt that he/she had received the incorrect treatment had by far the strongest association with patient experiences. Future studies of patient experiences and satisfaction should include this variable. As found in previous research, patient experiences were significantly associated with age and health status.
Lumican, a small leucine‐rich proteoglycan substituted with keratan sulfate chains is expressed and secreted by human melanoma cells and not normal melanocytes
Authors: Sifaki M. , Assouti M. , Nikitovic D. , Krasagakis K. , Karamanos N. K. , Tzanakakis G. N.
Published: October 2006

Melanoma is a frequent and therapy‐resistant human disease. Malignant melanocytes modulate their microenvironment in order to penetrate the dermal/epidermal junction and eventually invade the dermis. The small leucine‐rich proteoglycans (SLRPs) constitute important constituents of the dermis extracellular matrix (ECM), participating in both the structural and the functional organization of the skin. The role of a keratan sulphate SLRP lumican, has recently been investigated in the growth and metastasis of several cancers. In this study, the expression of lumican was studied in two human melanoma cell lines (WM9, M5) as well as in normal neonatal human melanocytes (HEMN) using real time PCR, western blotting with antibodies against the protein core and keratan sulfate, and treatments with specific enzymes. Both human metastatic melanoma cell lines were found to express lumican mRNA and effectively secrete lumican in a proteoglycan form, characterized to be substituted mostly with keratan sulfate chains. Lumican mRNA was not detected in normal melanocytes. This is the first time that the synthesis and secretion of lumican in human melanoma cell lines is reported. The role of this proteoglycan in the development and progression of malignant melanoma has to be further investigated.
iubmb Life, 58: 606‐610, 2006
MT1‐MMP: A key regulator of cell migration in tissue
Authors: Itoh Yoshifumi
Published: October 2006

Controlled cell migration is a fundamental and critical event in many physiological processes. However once control is lost, cell migration facilitates disease progression such as seen in cancer metastasis, atherosclerosis, and rheumatoid arthritis. One of the critical proteinases involved in cell migration is membrane‐type 1 matrix metalloproteinase (MT1‐MMP/MMP‐14). MT1‐MMP degrades extracellular matrix to make a path for cells to migrate, sheds cell surface molecules to give migratory signals, and activates ERK (extracellular signal‐regulated protein kinase) enhancing cell migration. For MT1‐MMP to promote cell migration, it needs to act in co‐ordination with other cell migration machinery. Understanding such regulatory links may provide insights into the development of novel disease therapies.
iubmb Life, 58: 589‐596, 2006
The Clinical Assessment, Treatment, and Prevention of Lyme Disease, Human Granulocytic Anaplasmosis, and Babesiosis: Clinical Practice Guidelines by the Infectious Diseases Society of America
Authors: Wormser Gary P. , Dattwyler Raymond J. , Shapiro Eugene D. , Halperin John J. , Steere Allen C. , Klempner Mark S. , Krause Peter J. , Bakken Johan S. , Strle Franc , Stanek Gerold , Bockenstedt Linda , Fish Durland , Dumler J. Stephen , Nadelman Robert B.
Published: October 2006

Evidence-based guidelines for the management of patients with Lyme disease, human granulocytic anaplasmosis (formerly known as human granulocytic ehrlichiosis), and babesiosis were prepared by an expert panel of the Infectious Diseases Society of America. These updated guidelines replace the previous treatment guidelines published in 2000 (Clin Infect Dis 2000; 31[Suppl 1]:1–14). The guidelines are intended for use by health care providers who care for patients who either have these infections or may be at risk for them. For each of these Ixodes tickborne infections, information is provided about prevention, epidemiology, clinical manifestations, diagnosis, and treatment. Tables list the doses and durations of antimicrobial therapy recommended for treatment and prevention of Lyme disease and provide a partial list of therapies to be avoided. A definition of post–Lyme disease syndrome is proposed.
Experimental study of pedestrian counterflow in a corridor
Authors: Kretz Tobias , Grünebohm Anna , Kaufman Maike , Mazur Florian , Schreckenberg Michael
Published: October 2006

In this work the results of a pedestrian counterflow experiment in a corridor of width 2 m
are presented. 67 participants were divided into two groups with varying relative and
absolute size and walked in opposite directions through a corridor. The video footage taken
from the experiment was evaluated for passing times, walking speeds, fluxes and lane
formation, including symmetry breaking. The results include comparatively large fluxes and
speeds as well as a maximal asymmetry between left- and right-hand traffic. The sum of
flow and counterflow in any case turns out to be larger than the flow in all situations
without counterflow.
New Light on Chromotherapy: Grakov′s ‘Virtual Scanning’ System of Medical Assessment and Treatment
Authors: Hankey Alex , Ewing Elena
Published: October 2006

Virtual Scanning incorporates novel uses of colored light into its system of health assessment and therapy. Independent investigations of its effectiveness in Russia and the UK have revealed unique abilities to correct incipient and fully developed chronic conditions. As such it forms an important new addition to the field of Chromotherapy. It differs from most others, in that its development depended on discoveries in neuroscience by its inventor, and subsequent application of new models in computational neuroscience.
Traditional Phytochemistry: Identification of Drug by ‘Taste’
Authors: Joshi Kalpana , Hankey Alex , Patwardhan Bhushan
Published: October 2006

Ayurveda, the system of traditional medicine from India, holds that ‘Rasa’, a concept roughly corresponding to taste, is a basis for identifying pharmacological properties of plants and other materia medica used in Dravyaguna—its system of phytomedicine. This idea has recently found support in studies of ibuprofen, the pharmacological properties of which are similar to those of oleocanthal, because the two substances have very similar tastes. This paper discusses a possible scientific approach to understanding the Ayurvedic (hypo)thesis in terms of the stereochemical basis of both pharamaco‐activity and taste, and the numbers of possible pharmaco‐active compounds that ‘Rasa’ may be able to distinguish. We conclude that molecules binding to a specific enzyme active site should have their own ‘Rasa’, and that the number of different subjectively experienced ‘tastes’ is more than enough to distinguish between molecular shapes binding to all enzyme active sites in the body.
Sex-role reversed nuptial feeding reduces male kleptoparasitism of females in Zeus bugs (Heteroptera; Veliidae)
Authors: Arnqvist Göran , Jones Therésa M , Elgar Mark A
Published: October 2006

Males of a variety of taxa occasionally steal food secured by their mates. In some spiders and insects, males rely entirely on this form of intraspecific kleptoparasitism for their subsistence. However, this male strategy may be costly for females and a variety of different female counteradaptations have been proposed. In Zeus bugs (
Phoreticovelia
spp.), males ride on the back of their mates for extended periods and females produce a gland secretion that males feed on. By experimentally occluding the dorsal glands in females and varying food availability, we show that nuptial feeding by females reduces the extent to which the males kleptoparasitize their mates. We suggest that females have, at least in part, evolved this unique form of nuptial feeding as a counteradaptation to reduce the rate of kleptoparasitism by males.
Sexual dichroism and pigment localization in the wing scales of
Pieris rapae
butterflies
Authors: Giraldo M.A , Stavenga D.G
Published: October 2006

The beads in the wing scales of pierid butterflies play a crucially important role in wing coloration as shown by spectrophotometry and scanning electron microscopy (SEM). The beads contain pterin pigments, which in
Pieris rapae
absorb predominantly in the ultraviolet (UV). SEM demonstrates that in the European subspecies
Pieris rapae rapae
, both males and females have dorsal wing scales with a high concentration of beads. In the Japanese subspecies
Pieris rapae crucivora
, however, only the males have dorsal wing scales studded with beads, and the dorsal scales of females lack beads. Microspectrophotometry of single scales without beads yields reflectance spectra that increase slightly and monotonically with wavelength. With beads, the reflectance is strongly reduced in the UV and enhanced at the longer wavelengths. By stacking several layers of beaded scales, pierid butterflies achieve strong colour contrasts, which are not realized in the dorsal wings of female
P. r. crucivora
. Consequently,
P. r. crucivora
exhibits a strong sexual dichroism that is absent in
P. r. rapae
.
Macroevolutionary dynamics in environmental space and the latitudinal diversity gradient in New World birds
Authors: Diniz-Filho José Alexandre Felizola , Rangel Thiago Fernando L.V.B , Bini Luis Mauricio , Hawkins Bradford A
Published: October 2006

Correlations between species richness and climate suggest non-random occupation of environmental space and niche evolution through time. However, the evolutionary mechanisms involved remain unresolved. Here, we partition the occupation of environmental space into intra- and inter-clade components to differentiate a model based on pure conservation of ancestral niches with higher diversification rates in the tropics, and an adaptive radiation model based on shifts in adaptive peaks at the family level allowing occupation of temperate regions. We examined these mechanisms using within- and among-family skewness components based on centroids of 3560 New World bird species across four environmental variables. We found that the accumulation of species in the tropics is a result of both processes. The components of adaptive radiation have family level skewness of species' distributions strongly structured in space, but not phylogenetically, according to the integrated analyses of spatial filters and phylogenetic eigenvectors. Moreover, stronger radiation components were found for energy variables, which are often used to argue for direct climatic effects on diversity. Thus, the correspondence between diversity and climate may be due to the conservation of ancestral tropical niches coupled with repeated broad shifts in adaptive peaks during birds' evolutionary history more than by higher diversification rates driven by more energy in the tropics.
A molecular phylogeny of annelids
Authors: Rousset Vincent , Pleijel Fredrik , Rouse Greg W. , Erséus Christer , Siddall Mark E.
Published: October 2006

We present parsimony analyses of annelids based on the largest taxon sample and most extensive molecular data set yet assembled, with two nuclear ribosomal genes (18S rDNA and the D1 region of 28S rDNA), one nuclear protein coding‐gene (Histone H3) and one mitochondrial ribosomal gene (16S rDNA) from 217 terminal taxa. Of these, 267 sequences are newly sequenced, and the remaining were obtained from GenBank. The included taxa are based on the criteria that the taxon must have 18S rDNA or at least two other loci. Our analyses show that 68% of annelid family ranked taxa represented by more than one taxon in our study are supported by a jackknife value > 50%. In spite of the size of our data set, the phylogenetic signal in the deepest part of the tree remains weak and the majority of the currently recognized major polychaete clades (except Amphinomida and Aphroditiformia) could not be recovered. Terbelliformia is monophyletic (with the exclusion of Pectinariidae, for which only 18S data were available), whereas members of taxa such as Phyllodocida, Cirratuliformia, Sabellida and Scolecida are scattered over the trees. Clitellata is monophyletic, although Dinophilidae should possibly be included, and Clitellata has a sister group within the polychaetes. One major problem is the current lack of knowledge on the closest relatives to annelids and the position of the annelid root. We suggest that the poor resolution in the basal parts of the trees presented here may be due to lack of signal connected to incomplete data sets both in terms of terminal and gene sampling, rapid radiation events and/or uneven evolutionary rates and long‐branch attraction.

© The Willi Hennig Society 2006.
What determines conditionality in ant–Hemiptera interactions? Hemiptera habitat preference and the role of local ant activity
Authors: GOVE AARON D. , RICO‐GRAY VICTOR
Published: October 2006

Abstract1. This paper describes spatial variation in density of a mutualist Hemiptera, and attempts to elucidate an understanding of the spatial variation in conditionality of its mutualism with ants.

2. Aggregations of the membracid treehopper,Campylenchiasp., occurred more frequently, and with higher number of individuals, in isolated trees as compared with their occurrence in the same tree species in wooded patches.

3. Using treehopper aggregations as the level of replication, there was a habitat × ant presence interaction associated with colony survival time. However, when the median survival time of all aggregations within each tree was used, only an additive effect of both habitat type and ant presence were apparent. This suggests that treehopper aggregations in some isolated trees experienced more benefit from ant presence than other trees.

4. The ant:treehopper ratio averaged over each tree was correlated with effect of ant presence on survivorship (survival time without ants/survival time with ants). Therefore, conditionality in the ant–membracid mutualism appears related to ant attendance level at the scale of individual trees.

5. Ant attendance at treehopper aggregations in isolated and matorral trees did not differ, and therefore there is no clear mechanism by which ants create the contrast in treehopper densities between the two habitat types.

6. The main force shaping initial treehopper densities in the two habitats is likely plant quality. Results suggest that growing situation (or more specifically plant health) is likely a good predictor of membracid density, while general ant activity within a tree is the best indicator of interaction strength.
Aspartyl‐phosphate phosphatases deactivate the response regulator components of the sporulation signal transduction system in Bacillus subtilis
Authors: Perego Marta , Glaser Philippe , Hoch James A.
Published: October 2006

Bacteria use two‐component signal transduction systems to sense and respond to their environment. A sensor kinase and a response‐regulator transcription factor work in concert by phosphorylation/dephosphorylation through kinase and phosphatase activities to maintain a level of phosphorylated response regulator commensurate with the level of signal input. Signal input can be accommodated through stimulation of the kinase activity or the phosphatase activity of the two‐component system. With some notable exceptions, the sensor kinases recognize a single stimulatory ligand. A new dimension in the regulation of two‐component signal transduction systems was discovered in the Rap phosphatases which dephosphorylate the Spo0F response‐regulator of Bacillus subtilis independent of the sensor kinases. This family of phosphatases is encoded by at least six chromosomal genes. Although not all of the phosphatases of the family have activity on phosphorylated Spo0F, the two best‐characterized members, RapA and RapB, prevent sporulation by dephosphorylating this response regulator component of the phosphorelay. Phosphatase activity of RapA is regulated by a gene, phrA, in the same transcriptional unit, that encodes a peptide secreted from the cell which may serve as a quorum sensor. Most of the Rap phosphatase operons have a gene coding for a protein with some similarity to PhrA in their transcription units, but it is uncertain whether all of these play a role in regulation. The Rap phosphatases are postulated to be a mechanism for allowing signals other than those that affect the sensor kinases to regulate the signal transduction pathway. They may have been recruited to help regulate sporulation because the multiple signals regulating this process may out‐strip the recognition capacity of the kinases.
Stationary phase in Saccharomyces cerevisiae
Authors: Werner‐Washburne Margaret , Braun Edward L. , Crawford Matthew E. , Peck Vickie M.
Published: October 2006

Like other microorganisms, the yeast Saccharomyces cerevisiae responds to starvation by arresting growth and entering stationary phase. Because most microorganisms exist under conditions of nutrient limitation, the ability to tolerate starvation is critical for survival. Molecular analyses have identified changes in transcription, translation, and protein modification in stationary‐phase cells. At the level of translation, the pattern of newly synthesized proteins in stationary‐phase cells is surprisingly similar to the pattern of proteins synthesized during exponential growth. When limited for different nutrients, yeast strains may not enter stationary phase but opt for pathways such as pseudohyphal growth. If nutrient limitation continues, the end‐point is likely to be a stationary‐phase cell. Based on the results of recent studies, we propose a model for entry into stationary phase in which G0 arrest is separable from acquisition of the ability to survive long periods of time without added nutrients.
The SMR family: a novel family of multidrug efflux proteins involved with the efflux of lipophilic drugs
Authors: Paulsen Ian T. , Skurray Ronald A. , Tam Roland , Saier Milton H. , Turner Raymond J. , Weiner Joel H. , Goldberg Edward B. , Grinius Leonas L.
Published: October 2006

The sequenced members of a novel family of small, hydrophobic, bacterial multidrug‐resistance efflux proteins, which we have designated the small multidrug resistance (SMR) protein family, are identified and analysed. Two distinct clusters of proteins were identified within this family: (i) small multidrug efflux systems; and (ii) Sug proteins, potentially involved in the suppression of groEL mutations. Hydropathy and residue distribution analyses of this family suggest a structural model in which the polypeptide chain spans the membrane four times as mildly amphipathic α‐helices. The roles of specific residues, a possible mechanistic model of drug efflux, and the primary physiological role(s) of the SMR proteins are discussed.
Alteration of haem‐attachment and signal‐cleavage sites for Paracoccus denitrificans cytochrome c550 probes pathway of c‐type cytochrome biogenesis in Escherichia coli
Authors: Sambongi Yoshihiro , Stoll Raphael , Ferguson Stuart J.
Published: October 2006

Paracoccus denitrificans cytochrome c550 is expressed as a periplasmic holo‐protein in Escherichia coli; amino acid substitutions of cysteine residues in the haembinding motif (Cys‐X‐X‐Cys‐His), either together or singly, prevented covalent attachment of haem but not polypeptide translocation into the periplasm. When the three alanine residues at positions ‐3 to ‐1 in the native signal‐cleavage site were deleted, or alanine at ‐1 was changed to glutamine, signal cleavage was at alternative sites (after only ten residues in the latter case), but haem attachment still occurred. When the same three alanines were changed to Asp‐Glu‐Asp, a membrane‐associated apo product that had retained the complete signal sequence was detected. These and other results presented here indicate that (i) haem attachment is not required for the apo‐cytochrome c550 export to the periplasm; (ii) haem cannot attach to apocytochrome c550 when attached to the cytoplasmic membrane, suggesting that signal‐sequence cleavage precedes periplasmic haem attachment, which can occur at as few as six residues from the mature N‐terminus; and (iii) two cysteines are required for haem attachment, possibly because a disulphide bond is an intermediate. The gene for Saccharomyces cerevisiae mitochondrial iso‐1‐cytochrome c was expressed as a holo‐protein in E. coli when fused with the signal sequence plus the first 10 residues of the mature cytochrome c550, indicating that the E. coli cellular apparatus for the c‐type cytochrome biogenesis has a broad substrate specificity.
Identification of a second family of high‐molecular‐weight adhesion proteins expressed by non‐typable Haemophilus influenzae
Authors: Barenkamp Stephen J. , Geme Joseph W. St.
Published: October 2006

We previously reported that two surface‐exposed high‐molecular‐weight proteins, HMW1 and HMW2, expressed by a prototypic strain of non‐typable Haemophilus influenzae (NTHI), mediate attachment to human epithelial cells. These proteins are members of a family of highly immunogenic proteins common to 70–75% of NTHI strains. NTHI strains that lack HMW1/ HMW2‐like proteins remain capable of efficient attachment to cultured human epithelial cells, suggesting the existence of additional adhesion molecules. We reasoned that characterization of high‐molecular‐weight immunogenic proteins from an HMW1/HMW2‐deficient strain might identify additional adhesion proteins. A genomic library was prepared in λEMBL3 with chromosomal DNA from non‐typable Haemophilus strain 11, a strain that lacks HMW1/HMW2‐like proteins. The library was screened immunologically with convalescent serum from a child naturally infected with strain 11, and phage clones expressing high‐molecular‐weight recombinant proteins were identified by Western blot analysis. One clone was identified that expressed a protein with an apparent molecular mass greater than 200 kDa. Transformation of non‐adherent Escherichia coli strain DH5α with plasmids containing the genetic locus encoding this protein gave rise to E. colitransformants that adhered avidly to Chang conjunctival cells. Subcloning and mutagenesis studies localized the DNA conferring the adherence phenotype to a 4.8 kbp fragment, and nucleotide sequence analysis further localized the gene encoding the adhesion protein to a 3.3 kbp open reading frame predicted to encode a protein of 114kDa. The gene was designated hia for Haemophilus influenzae adhesin. Southern analysis revealed an hia homologue in 13 of 15 HMW1/HMW2‐deficient non‐typable H. influenzae strains. In contrast, the hia gene was not present in any of 23 non‐typable H. influenzae strains which expressed HMW1/HMW2‐like proteins. Identification of this second family of high‐molecular‐weight adhesion proteins suggests the possibility of developing vaccines based upon a combination of HMW1/HMW2‐like proteins and Hia‐like proteins which would be protective against disease caused by most or all non‐typable H. influenzae
Aperiplasmic protein (Skp) of Escherichia coli selectively binds a class of outer membrane proteins
Authors: Chen Robert , Henning Ulf
Published: October 2006

A search was performed for a periplasmic molecular chaperone which may assist outer membrane proteins of Escherichia coli on their way from the cytoplasmic to the outer membrane. Proteins of the periplasmic space were fractionated on an affinity column with sepharose‐bound outer membrane porin OmpF. A 17kDa polypeptide was the predominant protein retained by this column. The corresponding gene was found in a gene bank; it encodes the periplasmic protein Skp. The protein was isolated and it could be demonstrated that it bound outer membrane proteins, following SDS‐PAGE, with high selectivity. Among these were OmpA, OmpC, OmpF and the maltoporin LamB. The chromosomal skp gene was inactivated by a deletion causing removal of most of the signal peptide plus 107 residues of the 141‐residue mature protein. The mutant was viable but possessed much‐reduced concentrations of outer membrane proteins. This defect was fully restored by a plasmid‐borne skp gene which may serve as a periplasmic chaperone.