bluuebunny/crossref_metadata_2025 huggingface dataset:
What determines Alnus‐associated ectomycorrhizal community diversity and specificity? A comparison of host and habitat effects at a regional scale
Authors: Roy Mélanie , Rochet Juliette , Manzi Sophie , Jargeat Patricia , Gryta Hervé , Moreau Pierre‐Arthur , Gardes Monique
Published: March 2013

Global‐scale analyses of ectomycorrhizal (ECM) fungi communities emphasize host plant families as the main drivers of diversity. This study aims to test, on Alnus–ECM communities, which fungi are said to be ‘host‐specific’, to what extent host species, habitat and distance explain their alpha and beta diversity variations, and their specificity.

In France, ECM communities associated with two subgenera and five species of Alnus, were sampled on 165 trees from 39 lowland to subalpine sites. In all, 1178 internal transcribed spacer (ITS) sequences of ECM fungi clustered in 86 molecular operational taxonomic units (MOTUs).

The species richness was low but still variable, and the evenness of communities was lower on organic soils and in Corsica. Similarity between communities was influenced both by host, soil parameters, altitude and longitude, but not by climate and distance. A large majority of ‘specific’ fungi were shared between host species within a subgenus, and showed habitat preferences within the subgenus distribution range.

Our study confirms that Alnus ECM communities are low in diversity, highly conserved at a regional scale, and partly shared between congeneric host species. A large part of alpha and beta diversity variations remained unexplained, and other processes may shape these communities.
Dissecting the impact of CO2 and pH on the mechanisms of photosynthesis and calcification in the coccolithophore Emiliania huxleyi
Authors: Bach Lennart T. , Mackinder Luke C. M. , Schulz Kai G. , Wheeler Glen , Schroeder Declan C. , Brownlee Colin , Riebesell Ulf
Published: March 2013

Coccolithophores are important calcifying phytoplankton predicted to be impacted by changes in ocean carbonate chemistry caused by the absorption of anthropogenic CO2. However, it is difficult to disentangle the effects of the simultaneously changing carbonate system parameters (CO2, bicarbonate, carbonate and protons) on the physiological responses to elevated CO2.

Here, we adopted a multifactorial approach at constant pH or CO2 whilst varying dissolved inorganic carbon (DIC) to determine physiological and transcriptional responses to individual carbonate system parameters.

We show that Emiliania huxleyi is sensitive to low CO2 (growth and photosynthesis) and low bicarbonate (calcification) as well as low pH beyond a limited tolerance range, but is much less sensitive to elevated CO2 and bicarbonate. Multiple up‐regulated genes at low DIC bear the hallmarks of a carbon‐concentrating mechanism (CCM) that is responsive to CO2 and bicarbonate but not to pH.

Emiliania huxleyi appears to have evolved mechanisms to respond to limiting rather than elevated CO2. Calcification does not function as a CCM, but is inhibited at low DIC to allow the redistribution of DIC from calcification to photosynthesis. The presented data provides a significant step in understanding how E. huxleyi will respond to changing carbonate chemistry at a cellular level.
The Arabidopsis exocyst subunit SEC3A is essential for embryo development and accumulates in transient puncta at the plasma membrane
Authors: Zhang Ying , Immink Richard , Liu Chun‐Ming , Emons Anne Mie , Ketelaar Tijs
Published: March 2013

The exocyst is a protein complex that is essential for polarized secretion in mammals and fungi. Although the exocyst is essential for plant development, its precise function has not been elucidated. We studied the role of exocyst subunit SEC3A in plant development and its subcellular localization.

T‐DNA insertional mutants were identified and complemented with a SEC3A‐green fluorescent protein (GFP) fusion construct. SEC3A‐GFP localization was determined using confocal microscopy.

sec3a mutants are defective in the globular to heart stage transition in embryogenesis. SEC3A‐GFP has similar cell plate localization to the other plant exocyst subunits. In interphase cells, SEC3A‐GFP localizes to the cytoplasm and to the plasma membrane, where it forms immobile, punctate structures with discrete lifetimes of 2–40 s. These puncta are equally distributed over the cell surface of root epidermal cells and tip growing root hairs. The density of puncta does not decrease after growth termination of these cells, but decreases strongly when exocytosis is inhibited by treatment with brefeldin A.

SEC3A does not appear to be involved in polarized secretion for cell expansion in tip growing root hairs. The landmark function performed by SEC3 in mammals and yeast is likely to be conserved in plants.
Interleukin‐4RA gene polymorphism is associated with oral mucous membrane pemphigoid
Authors: Carrozzo M , Dametto E , Fasano ME , Broccoletti R , Carbone M , Rendine S , Amoroso A
Published: March 2013

Objective

The aim of this study was to analyse whether the polymorphisms of several pro‐ and anti‐inflammatory cytokines may influence the susceptibility to predominantly oral Mucous membrane pemphigoid (MMP) in a Northern Italian population.

Material and Methods

DNA was obtained from 41 MMP patients (29 with exclusively oral pemphigoid [OP]) and 140 unrelated bone marrow donors. Thirteen cytokine genes with 22 single‐nucleotide polymorphisms (SNP) were studied by a sequence‐specific PCR assay.

Results

There was no significant difference between the patients taken together and healthy controls for any cytokine gene polymorphism studied. However, the allele A of the IL‐4 receptor A (IL‐4RA) was significantly more frequent in OP than controls (P < 0.05), causing an increased frequency of genotype A/A in OP patients (89.7 vs 67.9, odds ratio: 4.11, 95% confidence intervals 1.18–14.28, P = 0.023, Pc = 0.046).

Conclusion

IL‐4RA‐1902 A/A genotype has been associated with a reduced response to IL‐4 and has been found in 90% OP patient. Giving the supposed importance of IL‐4 in MMP fibrotic process, our results can partially explain the low likelihood of scarring in OP patients.
A randomized controlled comparison of the Bonfils fiberscope and the GlideScope Cobalt AVL video laryngoscope for visualization of the larynx and intubation of the trachea in infants and small children with normal airways
Authors: Kaufmann Jost , Laschat Michael , Hellmich Martin , Wappler Frank
Published: March 2013

Background

The Bonfils fiberscope (BF) used without the assistance of a laryngoscope failed to improve the view of direct laryngoscopy in children with normal airways. We hypothesized that if BF is supported by a laryngoscope—as recommended by its inventor—it can provide comparably good visualization of the glottis as the GlideScope® Cobalt AVL video laryngoscope (GS).

Methods

We included 100 children with normal airways in a randomized controlled trial. The study consisted of assessing the airway by direct laryngoscopy (DL), followed by intubation using either the BF or the GlideScope. Main outcome measures were the quality of visualization of the larynx by the percentage of glottis opening seen (POGO) and the time needed for intubation of the trachea.

Results

Visualization of the larynx (POGO) using the BF was significantly better than with DL (P = 0.016) or with GS (P = 0.001). The DL provided an allover better visualization than GS, although this difference was not significant and solely attributable to children weighing <15 kg. Intubation was successful in all cases with both devices. The time needed for intubation was shorter using the BF (36 ± 8 s) than with the GlideScope (49 ± 12 s, P < 0.001).

Conclusion

The Bonfils fiberscope significantly improved the view on the larynx compared with direct laryngoscopy and the GlideScope and enables shorter intubation time than with the GlideScope.
Steady‐state models of photosynthesis
Authors: VON CAEMMERER SUSANNE
Published: March 2013

In the challenge to increase photosynthetic rate per leaf area mathematical models of photosynthesis can be used to help interpret gas exchange measurements made under different environmental conditions and predict underlying photosynthetic biochemistry. To do this successfully it is important to improve the modelling of temperature dependencies of CO2 assimilation and gain better understanding of internal CO2 diffusion limitations. Despite these shortcomings steady‐state models of photosynthesis provide simple easy to use tools for thought experiments to explore photosynthetic pathway changes such as redirecting photorespiratory CO2, inserting bicarbonate pumps into C3 chloroplasts or inserting C4 photosynthesis into rice. Here a number of models derived from the C3 model by Farquhar, von Caemmerer and Berry are discussed and compared.
Cinemeducation: Teaching Family Assessment Skills Using Full‐Length Movies
Authors: Wilson Astrid H. , Blake Barbara J. , Taylor Gloria A. , Hannings Glenda
Published: March 2013

A thorough family assessment provides a foundation for the nursing process when working with families. Therefore, nurses, along with other health care providers must develop expertise in conducting family assessments to provide the best possible care within the community. This article describes an innovative educational strategy using movies to teach family assessment skills and puts forth recommendations for future research to provide evidence to support this teaching modality.
The retinoic acid‐producing capacity of gut dendritic cells and macrophages is reduced during persistent T. muris infection
Authors: Hurst R. J. M. , Else K. J.
Published: March 2013

Trichuris muris is an intestinal nematode that invades the colonic epithelium triggering a mucosal inflammation. Vitamin A and its active metabolite retinoic acid are strongly linked with the modulation of gut immune responses. Here, we describe the temporal changes in the expression of aldehyde dehydrogenase (ALDH) enzymes, responsible for converting dietary‐absorbed vitamin A into the immuno‐modulatory retinoic acid in lamina propria leucocytes post‐infection. We show that ALDH enzymes are expressed by both colonic macrophages and dendritic cells. Further, during an on‐going T. muris infection, ALDH expression is repressed from uninfected levels and only recovers to normal levels following expulsion of the parasite. These results suggest that local regulation of cellular levels of retinoic acid is an important component of infection‐driven inflammation.
Bacterial lipid modification enhances immunoprophylaxis of filarial abundant larval transcript‐2 protein in Mastomys model
Authors: Sharmila S. , Christiana I. , Kiran P. , Reddy M. V. R. , Sankaran K. , Kaliraj P.
Published: March 2013

As in many other parasitic diseases, efficacious vaccine for lymphatic filariasis has been elusive for want of new approaches leaving billions of people either debilitated or at risk. With multiple B‐ and T‐cell epitopes, the abundant larval transcript‐2 (ALT‐2) of the filarial worm, Brugia malayi, has been shown to be a promising immunoprophylactic target. To enhance its efficacy, it was lipid modified using our recently developed protein engineering tool, which then offered 30% more immunoprotection (49 vs. 79%) in Mastomys coucha model. Sustained high levels of IFN‐γ (about 100 times) and high antibody titres (10‐fold) elicited by lipid‐modified ALT‐2, as compared to the native form, indicated the maintenance of Th1/Th2 balance that is impaired in filariasis. Thus, this study provides the basis for developing efficacious vaccines for filariasis and other parasitic diseases by exploiting bacterial lipid modification.
Combination treatment of elevated UVB radiation, CO2 and temperature has little effect on silver birch (Betula pendula) growth and phytochemistry
Authors: Lavola Anu , Nybakken Line , Rousi Matti , Pusenius Jyrki , Petrelius Mari , Kellomäki Seppo , Julkunen‐Tiitto Riitta
Published: March 2013

Elevations of carbon dioxide, temperature and ultraviolet‐B (UBV) radiation in the growth environment may have a high impact on the accumulation of carbon in plants, and the different factors may work in opposite directions or induce additive effects. To detect the changes in the growth and phytochemistry of silver birch (Betula pendula) seedlings, six genotypes were exposed to combinations of ambient or elevated levels of CO2, temperature and UVB radiation in top‐closed chambers for 7 weeks. The genotypes were relatively similar in their responses, and no significant interactive effects of three‐level climate factors on the measured parameters were observed. Elevated UVB had no effect on growth, nor did it alter plant responses to CO2 and/or temperature in combined treatments. Growth in all plant parts increased under elevated CO2, and height and stem biomass increased under elevated temperature. Increased carbon distribution to biomass did not reduce its allocation to phytochemicals: condensed tannins, most flavonols and phenolic acids accumulated under elevated CO2 and elevated UVB, but this effect disappeared under elevated temperature. Leaf nitrogen content decreased under elevated CO2. We conclude that, as a result of high genetic variability in phytochemicals, B. pendula seedlings have potential to adapt to the tested environmental changes. The induction in protective flavonoids under UVB radiation together with the positive impact of elevated CO2 and temperature mitigates possible UVB stress effects, and thus atmospheric CO2 concentration and temperature are the climate change factors that will dictate the establishment and success of birch at higher altitudes in the future.
Power and PulsedDoppler Evaluation of Prostatic Artery Blood Flow in Normal and Benign Prostatic Hyperplasia–Affected Dogs
Authors: Zelli R , Orlandi R , Troisi A , Cardinali L , Polisca A
Published: March 2013

Contents

This study was carried out with the objectives to test the differences in the haemodynamic characteristics of the prostatic artery in normal and benign prostatic hyperplasia (BPH)–affected dogs usingDoppler ultrasonography. In sixteen male German shepherd dogs, prostatic volume was detected and prostatic biopsy was performed. The prostatic artery blood flow parameters determined were as follows: peak systolic velocity (PSV), end diastolic velocity (EDV), Resistive Index (RI) and Pulsatility Index. The powerDoppler mode was used for colour flow mapping of the prostatic artery. InPWmode at marginal locations, the waveforms recorded showed a continuous pattern typical of the high‐resistance vessels, while in subcapsular locations, the waveforms recorded were continuous characteristic of the low‐resistance vessel. Peak systolic velocity and EDV in both locations were significantly higher in BPH group (p < 0.001) than normal group (p < 0.05). Pixel number in BPH group in both locations was significantly higher (p < 0.05) compared to the normal group. This study shows thatDoppler ultrasonography represents a valid and non‐invasive method for the characterization of the blood flow in the prostatic artery in dogs affected with BPH. Moreover, statistically significant differences of blood flow velocities in prostatic artery in normal and BPH‐affected dogs were detected. The RI was not able to differentiate normal dogs from dogs affected byBPHand therefore is not a parameter usable for diagnostic purposes, while PowerDoppler could represent an additional diagnostic tool.
The role of social memory in natural resource management: insights from participatory video
Authors: Mistry Jayalaxshmi , Berardi Andrea , Haynes Lakeram , Davis Delano , Xavier Rebecca , Andries Johnny
Published: March 2013

This research looked at the role of social memory for adaptive natural resource management within indigenous communities of the North Rupununi social‐ecological system (SES) in Guyana. Secondary data from historic texts and archives were first used to build a social and ecological history of the North RupununiSES. Current social memory ‘in use’ was then surfaced through a participatory video (PV) process led by the indigenous community. From this, a compendium of key narratives of the communities' social memory was identified and modes of social memory creation, transmittance and modification were revealed. These highlighted the role of social memory in identity formation and self representation, how social memory maintains and reinforces community connectedness and collectiveness, and howPVsupports indigenous ways of communication, especially the visual. The study provides some valuable insights into the dynamic nature of the North RupununiSESsocial memory, how it is used to make sense of the world, and howPVcan be used as a tool for surfacing and recording social memory.
EFFECTS OF CORN OIL ADMINISTERED ORALLY ON CONSPICUITY OF ULTRASONOGRAPHIC SMALL INTESTINAL LESIONS IN DOGS WITH LYMPHANGIECTASIA
Authors: Pollard Rachel E. , Johnson Eric G. , Pesavento Patricia A. , Baker Tomas W. , Cannon Allison B. , Kass Philip H. , Marks Stanley L.
Published: March 2013

Lymphangiectasia is one of the causes of protein‐losing enteropathy in dogs and characteristic ultrasonographic small intestinal lesions have been previously described. The purpose of this study was to determine whether corn oil administered orally (COAO) would result in increased conspicuity of these characteristic small intestinal ultrasonographic lesions in dogs with lymphangiectasia. Affected dogs were included if they underwent corn oil administered orally and had a surgical full‐thickness intestinal biopsy diagnosis of lymphangiectasia. Control dogs had normal clinical examination and standard laboratory test findings. Ultrasound images of duodenum, jejunum, and ileum were obtained prior to and 30, 60, 90, and 120 min after corn oil administered orally for all dogs. Parameters recorded for each ultrasound study were intestinal wall thickness, mucosal echogenicity, and presence or absence of hyperechoic mucosal striations (HMS) and a parallel hyperechoic mucosal line (PHML). Nine affected and five controls dogs were included in the study. Seven of the nine dogs with lymphangiectasia had hyperechoic mucosal striations prior to corn oil administered orally. Jejunal hyperechoic mucosal striations were significantly associated with lymphangiectasia at multiple time points (P < 0.05) and were best identified in dogs with lymphangiectasia 60 or 90 min after corn oil administered orally. Increased mucosal echogenicity was observed in all dogs at multiple time points after corn oil administered orally. A parallel hyperechoic mucosal line was present in the jejunum in 4/5 healthy and 6/9 dogs with lymphangiectasia at one or more time points after corn oil administered orally. Findings indicated that corn oil administered orally improves conspicuity of characteristic ultrasonographic lesions in dogs with lymphangiectasia, however some of these lesions may also be present in healthy dogs that recently received a fatty meal.
BrachyView: Proof‐of‐principle of a novel in‐body gamma camera for low dose‐rate prostate brachytherapy
Authors: Petasecca M. , Loo K. J. , Safavi‐Naeini M. , Han Z. , Metcalfe P. E. , Meikle S. , Pospisil S. , Jakubek J. , Bucci J. A. , Zaider M. , Lerch M. L. F. , Qi Y. , Rosenfeld A. B.
Published: March 2013

Purpose:

The conformity of the achieved dose distribution to the treatment plan strongly correlates with the accuracy of seed implantation in a prostate brachytherapy treatment procedure. Incorrect seed placement leads to both short and long term complications, including urethral and rectal toxicity. The authors present BrachyView, a novel concept of a fast intraoperative treatment planning system, to provide real‐time seed placement information based on in‐body gamma camera data. BrachyView combines the high spatial resolution of a pixellated silicon detector (Medipix2) with the volumetric information acquired by a transrectal ultrasound (TRUS). The two systems will be embedded in the same probe so as to provide anatomically correct seed positions for intraoperative planning and postimplant dosimetry. Dosimetric calculations are based on the TG‐43 method using the real position of the seeds. The purpose of this paper is to demonstrate the feasibility of BrachyView using the Medipix2 pixel detector and a pinhole collimator to reconstruct the real‐time 3D position of low dose‐rate brachytherapy seeds in a phantom.

Methods:

BrachyView incorporates three Medipix2 detectors coupled to a multipinhole collimator. Three‐dimensionally triangulated seed positions from multiple planar images are used to determine the seed placement in a PMMA prostate phantom in real time. MATLAB codes were used to test the reconstruction method and to optimize the device geometry.

Results:

The results presented in this paper show a 3D position reconstruction accuracy of the seed in the range of 0.5–3 mm for a 10–60 mm seed‐to‐detector distance interval (Z direction), respectively. The BrachyView system also demonstrates a spatial resolution of 0.25 mm in the XY plane for sources at 10 mm distance from Medipix2 detector plane, comparable to the theoretical value calculated for an equivalent gamma camera arrangement. The authors successfully demonstrated the capability of BrachyView for real‐time imaging (using a 3 s data acquisition time) of different brachytherapy seed configurations (with an activity of 0.05 U) throughout a 60 × 60 × 60 mm3 Perspex prostate phantom.

Conclusions:

The newly developed miniature gamma camera component of BrachyView, with its high spatial resolution and real time capability, allows accurate 3D localization of seeds in a prostate phantom. Combination of the gamma camera with TRUS in a single probe will complete the BrachyView system.
Performance of a high‐sensitivity dedicated cardiac SPECT scanner for striatal uptake quantification in the brain based on analysis of projection data
Authors: Park Mi‐Ae , Moore Stephen C. , Müller Stefan P. , McQuaid Sarah J. , Kijewski Marie Foley
Published: March 2013

Purpose:

The authors have previously reported the advantages of high‐sensitivity single‐photon emission computed tomography (SPECT) systems for imaging structures located deep inside the brain. DaTscan (Isoflupane I‐123) is a dopamine transporter (DaT) imaging agent that has shown potential for early detection of Parkinson disease (PD), as well as for monitoring progression of the disease. Realizing the full potential of DaTscan requires efficient estimation of striatal uptake from SPECT images. They have evaluated two SPECT systems, a conventional dual‐head gamma camera with low‐energy high‐resolution collimators (conventional) and a dedicated high‐sensitivity multidetector cardiac imaging system (dedicated) for imaging tasks related to PD.

Methods:

Cramer–Rao bounds (CRB) on precision of estimates of striatal and background activity concentrations were calculated from high‐count, separate acquisitions of the compartments (right striata, left striata, background) of a striatal phantom. CRB on striatal and background activity concentration were calculated from essentially noise‐free projection datasets, synthesized by scaling and summing the compartment projection datasets, for a range of total detected counts. They also calculated variances of estimates of specific‐to‐nonspecific binding ratios (BR) and asymmetry indices from these values using propagation of error analysis, as well as the precision of measuring changes in BR on the order of the average annual decline in early PD.

Results:

Under typical clinical conditions, the conventional camera detected 2 M counts while the dedicated camera detected 12 M counts. Assuming a normal BR of 5, the standard deviation of BR estimates was 0.042 and 0.021 for the conventional and dedicated system, respectively. For an 8% decrease to BR = 4.6, the signal‐to‐noise ratio were 6.8 (conventional) and 13.3 (dedicated); for a 5% decrease, they were 4.2 (conventional) and 8.3 (dedicated).

Conclusions:

This implies that PD can be detected earlier with the dedicated system than with the conventional system; therefore, earlier identification of PD progression should be possible with the high‐sensitivity dedicated SPECT camera.
Dose response of selected ion chambers in applied homogeneous transverse and longitudinal magnetic fields
Authors: Reynolds M. , Fallone B. G. , Rathee S.
Published: March 2013

Purpose:

The magnetic fields of an integrated MR‐Linac system will alter the paths of electrons that produce ions in the ionization chambers. The dose response of selected ion chambers is evaluated in the presence of varying transverse and longitudinal magnetic fields. The investigation is useful in calibration of therapeutic x‐ray beams associated with MR‐Linac systems.

Methods:

The Monte Carlo code PENELOPE was used to model the irradiation of NE2571, and PR06C ionization chambers in the presence of a transverse and longitudinal (with respect to the photon beam) magnetic fields of varying magnitude. The long axis of each chamber was simulated both parallel and perpendicular to the incident photon beam for each magnetic field case. The dose deposited in each chamber for each case was compared to the case with zero magnetic field by means of a ratio. The PR06C chamber's response was measured in the presence of a transverse magnetic field with field strengths ranging from 0.0 to 0.2 T to compare to simulated results.

Results:

The simulations and measured data show that in the presence of a transverse magnetic field there is a considerable dose response (maximum of 11% near 1.0 T in the ion chambers investigated, which depends on the magnitude of magnetic field, and relative orientation of the magnetic field, radiation beam, and ion chamber. Measurements made with the PR06C chamber verify these results in the region of measurement. In contrast, a longitudinal magnetic field produces only a slight increase in dose response (2% at 1.5 T) that rises slowly with increasing magnetic field and is seemingly independent of chamber orientation. Response trends were similar for the two ion chambers and relative orientations considered, but slight variations are present from chamber to chamber.

Conclusions:

Care must be taken when making ion chamber measurements in a transverse magnetic field. Ion chamber responses vary not only with transverse field strength, but with chamber orientation and type, and can be considerable. Longitudinal magnetic fields influence ion chamber responses relatively little (2% at 1.5 T), and only at field strengths in excess of 1.0 T.
Synchronization of a thermoacoustic oscillator by an external sound source
Authors: Penelet G. , Biwa T.
Published: March 2013

Since the pioneering work of Christiaan Huygens on the sympathy of pendulum clocks, synchronization phenomena have been widely observed in nature and science. In this paper, we describe a simple experiment, with a thermoacoustic oscillator driven by a loudspeaker, which exhibits several aspects of synchronization. Both the synchronization region of leading order around the oscillator's natural frequency f0 and regions of higher order (around f0∕2 and f0∕3) are measured as functions of the loudspeaker voltage and frequency. We also show that increasing the coupling between the loudspeaker and the oscillator gives rise under some circumstances to the death of self-sustained oscillations (quenching). Moreover, two additional set of experiments are performed: the first investigates a feedback loop in which the signal captured by the microphone is delivered to the loudspeaker through a phase-shifter; the second investigates the nontrivial interaction between the loudspeaker and the oscillator when the latter acts as a relaxation oscillator (spontaneous and periodic onset/damping of self-sustained oscillations). The experiment is easy to build and highly demonstrative; it might be of interest for classroom demonstrations or an instructional lab dealing with nonlinear dynamics.
The rise and fall of spinning tops
Authors: Cross Rod
Published: March 2013

The motion of four different spinning tops was filmed with a high-speed video camera. Unlike pointed tops, tops with a rounded peg precess initially about a vertical axis that lies well outside the top, and then spiral inward until the precession axis passes through a point close to the center-of-mass. The center-of-mass of a top with a rounded peg can rise as a result of rolling rather than sliding friction, contrary to the explanation normally given for the rise of spinning tops. A tippe top was also filmed and was observed to jump vertically off a horizontal surface several times while the center-of-mass was rising, contrary to the usual assumption that the normal reaction force on a tippe top remains approximately equal to its weight. It was found that the center-of-mass of a tippe top rises as a result of rolling friction at low spin frequencies and as a result of sliding friction at high spin frequencies. It was also found that, at low spin frequencies, a tippe top can precess at two different frequencies simultaneously.
Elucidating the stop bands of structurally colored systems through recursion
Authors: Amir Ariel , Vukusic Peter
Published: March 2013

Interference is the source of some of the spectacular colors of animals and plants in nature. In some of these systems, the physical structure consists of an ordered array of layers with alternating high and low refractive indices. This periodicity leads to an optical band structure that is analogous to the electronic band structure encountered in semiconductor physics: specific bands of wavelengths (the stop bands) are perfectly reflected. Here, we present a minimal model for optical band structure in a periodic multilayer structure and solve it using recursion relations. The stop bands emerge in the limit of an infinite number of layers by finding the fixed point of the recursion. We compare to experimental data for various beetles, whose optical structure resembles the proposed model. Thus, using only the phenomenon of interference and the idea of recursion, we are able to elucidate the concept of band structure in the context of the experimentally observed high reflectance and iridescent appearance of structurally colored beetles.
Paleomagnetic Excursions as Magnetostratigraphic Horizons: A Cautionary Note
Authors: Verosub Kenneth L.
Published: March 2013

Sediments from certain environments with high rates of deposition are not remagnetized after they have been deformed. The paleomagnetic signature from a zone of deformation can be misinterpreted as evidence for globally coherent fluctuations in the earth's magnetic field.
Photoinduced Polymerization of Solid C
60
Films
Authors: Rao A. M. , Zhou Ping , Wang Kai-An , Hager G. T. , Holden J. M. , Wang Ying , Lee W.-T. , Bi Xiang-Xin , Eklund P. C. , Cornett D. S. , Duncan M. A. , Amster I. J.
Published: March 2013

The irradiation of oxygen-free, face-centered-cubic C
60
films with visible or ultraviolet light phototransformed C
60
into a different solid phase. Results from laser desorption mass spectroscopy, scanning electron microscopy, Raman and infrared spectroscopy, optical absorption, and luminescence indicate that a photopolymerization of the fullerene molecules within the film occurred.
Electrochemical Processing of Conducting Polymer Fibers
Authors: Li Shulong , Macosko Christopher W. , White Henry S.
Published: March 2013

An electrochemical method for growing macroscopic fibers of electrically conductive poly(3-methylthiophene) is described. Single fibers of uniform diameter (∼0.1 to 0.7 millimeter) and length greater than 10 centimeters are grown in a capillary flow cell by electrochemical oxidation of the monomer, 3-methylthiophene. The shapes and diameters of the resulting fibers are determined by the fluid flow pattern in the cell. Straight fibers, sawtooth-shaped fibers, and fibers with tapered necks can be grown by varying the capillary shape.
Host Exopolysaccharide Quantity and Composition Impact Erwinia amylovora Bacteriophage Pathogenesis
Authors: Roach Dwayne R. , Sjaarda David R. , Castle Alan J. , Svircev Antonet M.
Published: March 2013

Erwinia amylovorabacteriophages (phages) belonging to theMyoviridaeandPodoviridaefamilies demonstrated a preference for either high-exopolysaccharide-producing (HEP) or low-exopolysaccharide-producing (LEP) bacterial hosts when grown on artificial medium without or with sugar supplementation.Myoviridaephages produced clear plaques on LEP hosts and turbid plaques on HEP hosts. The reverse preference was demonstrated by mostPodoviridaephages, where clear plaques were seen on HEP hosts. Efficiency of plating (EOP) was determined by comparing phage growth on the original isolation host to the that on the LEP or HEP host. Nine of 10Myoviridaephages showed highest EOPs on LEP hosts, and 8 of 11Podoviridaephages had highest EOPs on HEP hosts. Increasing the production of EPS on sugar-supplemented medium or decreasing production by knocking out the synthesis of amylovoran or levan, the two EPSs produced byE. amylovora, indicated that these components play crucial roles in phage infection. Amylovoran was virtually essential for proliferation of mostPodoviridaephages when phage population growth was compared to the wild type. Decreased levan production resulted in a significant reduction of progeny from phages in theMyoviridaefamily. Thus,Podoviridaephages are adapted to hosts that produce high levels of exopolysaccharides and are dependent on host-produced amylovoran for pathogenesis.Myoviridaephages are adapted to hosts that produce lower levels of exopolysaccharides and host-produced levan.
Characterization of a Lactobacillus gasseri JCM 1131
T
Lipoteichoic Acid with a Novel Glycolipid Anchor Structure
Authors: Shiraishi Tsukasa , Yokota Shin-ichi , Morita Naoki , Fukiya Satoru , Tomita Satoru , Tanaka Naoto , Okada Sanae , Yokota Atsushi
Published: March 2013

We determined the chemical structure of lipoteichoic acid (LTA) from
Lactobacillus gasseri
JCM 1131
T
. The repeating unit was comprised of glycerolphosphate and 2-alanylglycerolphosphate. The glycolipid anchor was tetrahexosylglycerol with two or three acyl groups. To our knowledge, this is the first demonstration of a tetrahexose structure in an LTA glycolipid anchor.
Insights into the Assembly of the Alginate Biosynthesis Machinery in Pseudomonas aeruginosa
Authors: Rehman Zahid U. , Wang Yajie , Moradali M. Fata , Hay Iain D. , Rehm Bernd H. A.
Published: March 2013

Pseudomonas aeruginosa
is an opportunistic pathogen of particular significance to cystic fibrosis patients. This bacterium produces the exopolysaccharide alginate, which is an indicator of poor prognosis for these patients. The proteins required for alginate polymerization and secretion are encoded by genes organized in a single operon; however, the existence of internal promoters has been reported. It has been proposed that these proteins form a multiprotein complex which extends from the inner to outer membrane. Here, experimental evidence supporting such a multiprotein complex was obtained via mutual stability analysis, pulldown assays, and coimmunoprecipitation. The impact of the absence of single proteins or subunits on this multiprotein complex, i.e., on the stability of potentially interacting proteins, as well as on alginate production was investigated. Deletion of
algK
in an alginate-overproducing strain, PDO300, interfered with the polymerization of alginate, suggesting that in the absence of AlgK, the polymerase and copolymerase subunits, Alg8 and Alg44, are destabilized. Based on mutual stability analysis, interactions between AlgE (outer membrane), AlgK (periplasm), AlgX (periplasm), Alg44 (inner membrane), Alg8 (inner membrane), and AlgG (periplasm) were proposed. Coimmunoprecipitation using a FLAG-tagged variant of AlgE further demonstrated its interaction with AlgK. Pulldown assays using histidine-tagged AlgK showed that AlgK interacts with AlgX, which in turn was also copurified with histidine-tagged Alg44. Detection of AlgG and AlgE in PAO1 supported the existence of internal promoters controlling expression of the respective genes. Overall experimental evidence was provided for the existence of a multiprotein complex required for alginate polymerization and secretion.
Assessing the Inactivation of Mycobacterium avium subsp.
paratuberculosis
during Composting of Livestock Carcasses
Authors: Tkachuk Victoria L. , Krause Denis O. , McAllister Tim A. , Buckley Katherine E. , Reuter Tim , Hendrick Steve , Ominski Kim H.
Published: March 2013

Mycobacterium avium
subsp.
paratuberculosis
causes Johne's disease (JD) in ruminants, with substantial economic impacts on the cattle industry. Johne's disease is known for its long latency period, and difficulties in diagnosis are due to insensitivities of current detection methods. Eradication is challenging as
M. avium
subsp.
paratuberculosis
can survive for extended periods within the environment, resulting in new infections in naïve animals (W. Xu et al., J. Environ. Qual. 38:437-450, 2009). This study explored the use of a biosecure, static composting structure to inactivate
M. avium
subsp.
paratuberculosis. Mycobacterium smegmatis
was also assessed as a surrogate for
M. avium
subsp.
paratuberculosis
. Two structures were constructed to hold three cattle carcasses each. Naturally infected tissues and ground beef inoculated with laboratory-cultured
M. avium
subsp.
paratuberculosis
and
M. smegmatis
were placed in nylon and plastic bags to determine effects of temperature and compost environment on viability over 250 days. After removal, samples were cultured and growth of both organisms was assessed after 12 weeks. After 250 days,
M. avium
subsp.
paratuberculosis
was still detectable by PCR, while
M. smegmatis
was not detected after 67 days of composting. Furthermore,
M. avium
subsp.
paratuberculosis
remained viable in both implanted nylon and plastic bags over the composting period. As the compost never reached a homogenous thermophilic (55 to 65°C) state throughout each structure, an
in vitro
experiment was conducted to examine viability of
M. avium
subsp.
paratuberculosis
after exposure to 80°C for 90 days. Naturally infected lymph tissues were mixed with and without compost. After 90 days,
M. avium
subsp.
paratuberculosis
remained viable despite exposure to temperatures typically higher than that achieved in compost. In conclusion, it is unlikely composting can be used as a means of inactivating
M. avium
subsp.
paratuberculosis
associated with cattle mortalities.
Characterization of Undermethylated Sites in Vibrio cholerae
Authors: Dalia Ankur B. , Lazinski David W. , Camilli Andrew
Published: March 2013

The activities of DNA methyltransferases are important for a variety of cellular functions in bacteria. In this study, we developed a modified high-throughput technique called
methyl
h
omopolymer
t
ail
m
ediated
seq
uencing (methyl HTM-seq) to identify the undermethylated sites in the
Vibrio cholerae
genome for the two DNA methyltransferases, Dam, an adenine methyltransferase, and VchM, a cytosine methyltransferase, during growth in rich medium
in vitro
. Many of the undermethylated sites occurred in intergenic regions, and for most of these sites, we identified the transcription factors responsible for undermethylation. This confirmed the presence of previously hypothesized DNA-protein interactions for these transcription factors and provided insight into the biological state of these cells during growth
in vitro
. DNA adenine methylation has previously been shown to mediate heritable epigenetic switches in gene regulation. However, none of the undermethylated Dam sites tested showed evidence of regulation by this mechanism. This study is the first to identify undermethylated adenines and cytosines genomewide in a bacterium using second-generation sequencing technology.
PelA Deacetylase Activity Is Required for Pel Polysaccharide Synthesis in Pseudomonas aeruginosa
Authors: Colvin Kelly M. , Alnabelseya Noor , Baker Perrin , Whitney John C. , Howell P. Lynne , Parsek Matthew R.
Published: March 2013

The Pel polysaccharide serves as an intercellular adhesin for the formation and maintenance of biofilms in the opportunistic pathogenPseudomonas aeruginosa. Pel biosynthesis requires the products of a seven-gene operon,pelA-pelG, all of which are necessary for Pel-dependent biofilm formation and Pel-related phenotypes. One of the genes,pelA, encodes a protein with a predicted polysaccharide deacetylase domain. In this work, the role of the putative deacetylase domain in Pel production was examined. We first established that purified recombinant PelA hydrolyzed the pseudosubstratep-nitrophenyl acetatein vitro, and site-specific mutations of predicted deacetylase active-site residues reduced activity greater than 10-fold. Additionally, these mutants were deficient in Pel-dependent biofilm formation and wrinkly colony morphologyin vivo. Subcellular fractionation experiments demonstrate that PelA localizes to both the membrane and periplasmic fractions. Finally, antiserum against the Pel polysaccharide was generated, and PelA deacetylase mutants do not produce Pel-reactive material. Taken together, these results suggest that the deacetylase activity of PelA is important for the production of the Pel polysaccharide.
DisseminatedNocardiainfection in a renal transplant patient: the pitfalls of diagnosis and management
Authors: Jorna Thomas , Taylor Joanne
Published: March 2013

This case report describes the progress of an immunosuppressed renal transplant patient who presented with signs and symptoms of community acquired pneumonia. He did not respond to conventional therapy and underwent further investigation. Definitive diagnosis proved challenging. On the basis of multiple investigation results he was treated variously for bacterial, viral and tuberculous infections. At one point it was thought pulmonary malignancy was likely. After excision of a subcutaneous nodule, microscopy and culture confirmed diagnosis of disseminatedNocardia farcinica. This case demonstrates the difficulty in diagnosing this rare infection in immunocompromised patients, the problems posed by concomitant infection and the potential hazards of multiple drug interactions. On initiation of optimum antimicrobial therapy and with safe levels of immunosuppression our patient made full recovery without any loss in graft function.
DisseminatedMycobacterium haemophiluminfection in a 72-year-old patient with rheumatoid arthritis on infliximab
Authors: Collins C Scott , Terrell Christine , Mueller Paul
Published: March 2013

Mycobacterium haemophilumis a slow growing, aerobic, fastidious mycobacterium requiring hemin and a temperature of 30–32° C for optimal growth that is ubiquitous in nature. Disease in immunocompromised adults typically manifests as skin lesions such as papules, pustules and ulcerations. This organism also causes lymphadenitis in immunocompetent children. Antitumour necrosis factor-α (anti-TNF-α) therapy with agents such as infliximab, etanercept and adalimumab is increasingly being used for immunosuppression in patients with various autoimmune conditions. These agents are known to place patients at increased risk for tuberculosis and other granulomatous diseases. However, little is known about illness caused byM haemophilumin patients on immunosuppression with anti-TNF-α therapy. We describe a case of disseminatedM haemophilummanifesting as skin lesions in a 72-year-old man with rheumatoid arthritis on infliximab and methotrexate.
Recurrent atypical fibroxanthoma of the limbus
Authors: Ullrich Katja , Wells Jane , Brennan Catriona , Craig Jamie
Published: March 2013

We report an unusual presentation of recurrent atypical fibroxanthoma of the limbus. Clinical and histological appearances, as well as management are discussed and the current literature is reviewed.
Pustular vasculitis
Authors: Selvan Shilpa , Shakir Rebecca , Chan Antoni
Published: March 2013

We present a rare case of pustular vasculitis secondary to streptococcal infection. The majority of cases described in the literature predominantly involve the dorsal hands, and may subsequently spread to involve the lower limbs. However, our case demonstrates a rare case where primary involvement of the lower limbs was present with secondary involvement at the dorsum of the hands. The patient responded well to intravenous methylprednisolone reflected both clinically and by his acute phase response.
Citrobacter koseri: an unusual cause of pyogenic liver abscess
Authors: Gupta Monica , Sharma Alka , Singh Ram , Lehl S S
Published: March 2013

Liver abscess is a common pathology in the Indian subcontinent and usually results from amoebic or bacterial infection. Pyogenic abscesses usually occur in those with underlying predisposing factors like intra-abdominal infections, biliary infections or comorbidities like malignancy, immunosuppression, diabetes mellitus and previous biliary surgery or interventional endoscopy.Citrobacteris an unusual cause of pyogenic liver abscess and may occur in the setting of underlying comorbidities. We report a 56-year-old man with diabetes (operated for periampullary carcinoma 20 years ago), who presented with a history of fever for 1 week and on evaluation was found to haveCitrobacter koseri-related hepatic abscess. The patient was managed with parenteral antibiotics, repeated aspiration of liver abscess and pigtail drainage.
Cross-sectional study of sociodemographic patterning of risk factors for cardiovascular disease in three isolated-based subgroups of the Uyghur population in Xinjiang, China
Authors: Jiang Jingmei , Wufuer Mayila , Simayi Amuti , Nijiati Muyesai , Fan Ming , Zhu Pengcheng , Chen Fenghui , Shan Guangliang , Xue Fang , Tian Xiaobing , Li Feng , Hou Lei , Han Wei , Cheng Zuheng , Qiu Changchun
Published: March 2013

Objective

To explore the sociodemographic patterning of risk factors for cardiovascular disease (CVD) in three isolated-based subgroups of the Uyghur population in Xinjiang, China.

Design

A cross-sectional study. Between 2005 and 2008, a non-probability sampling design method was used to select three specific groups of the Uyghur rural populations based on their potential socioeconomic status (ie, isolated, semi-isolated and open-environment status).

Setting

Three communities (named Desert, Turpan and Yuli Rob) in Southern Xinjiang autonomous region, China.

Participants

1656 people were included in this study. The inclusion criteria were that all participants were 18 years or older, they were descendants of at least three generations living in the same region, and there was no history of intermarriage.

Main outcome measures

The prevalence of CVD risk factors (ie, tobacco use, alcohol use, obesity, dyslipidemia, hypertension, diabetes, etc) was assessed.

Results

Compared with the Desert and Turpan communities, Yuli Rob had the highest levels of obesity, dyslipidemia and hypertension, and the Desert had the lowest levels of CVD risk factors. Age standardisation slightly altered the estimates, though the patterns remained unchanged. Some unique characteristics were also found. For example, the Desert group displayed significantly lower high-density lipoprotein cholesterol (HDLC) level compared with Yuli Rob and Turpan groups. The mean values were 0.63, 1.06 and 1.45 mmol/l for men and 0.64, 1.22 and 1.51 mmol/l for women (p<0.0001). The HDLC levels in the Desert group increased with increase in body mass index and fasting glucose levels, which was inconsistent with previous studies.

Conclusions

Identifying the unique CVD risk factors of the ethnic-specific populations is very important in development of tailored strategies for the prevention of CVD.