bluuebunny/crossref_metadata_2025 huggingface dataset:
Lemierre's and Lemierre's-like syndromes in association with infectious mononucleosis
Authors: Chacko E M , Krilov L R , Patten W , Lee P J
Published: July 2010

Objective:

This study aimed to review cases of Lemierre's and Lemierre's-like syndromes in paediatric patients, to examine a possible association with Epstein–Barr virus as a predisposing factor, and to assess the impact of this virus on the severity of illness.

Methods:

We performed a retrospective analysis of data from the in-patient database at Winthrop University Hospital, from January 2001 to October 2007. We reviewed clinical and laboratory findings as well as the outcome of infection in patients aged 21 years or less with a diagnosis of Lemierre's syndrome. An additional case of Lemierre's-like syndrome was also included. The illness severity and duration of in-patient management of those testing positive for heterophile antibody were then compared with the same parameters in patients who tested negative.

Results:

Of the five patients diagnosed with Lemierre's syndrome, two had concomitant acute infection with Epstein–Barr virus. Additionally, a 19-year-old adolescent was admitted during this period with acute infectious mononucleosis, Fusobacterium necrophorum sepsis, sinusitis, frontal lobe abscess and ophthalmic vein thrombosis. The clinical presentation of all patients included fever, sore throat, and ear or neck pain. The duration of symptoms ranged from two days to three weeks prior to admission. The patients with acute Epstein–Barr virus infection had been diagnosed with infectious mononucleosis prior to admission, and tested positive for heterophile antibody. These patients subsequently underwent more extensive in-patient treatment, including intensive care management and ventilator support. The patients who tested negative for heterophile antibody experienced a milder course of illness, with a shorter duration of in-patient management.

Conclusion:

Two patients diagnosed with Lemierre's syndrome, and a third with Fusobacterium necrophorum sepsis, had coexisting acute Epstein–Barr virus infection. Patients who tested positive for heterophile antibody experienced a more severe course of illness. These observations suggest a possible association between Epstein–Barr virus infection and the severity of concomitant Lemierre's syndrome.
Distinguishing resident from transient species along marine artificial reefs
Authors: Boisnier Etienne , Sagawa Tatsuyuki , Komatsu Teruhisa , Takagi Norimasa
Published: July 2010

Even if artificial reef studies heavily refer to the distinction between resident and transient species, there is still no widely-shared available method to distinguish objectively these two groups. Such an absence makes any comparison between studies difficult. This study aims to test whether the four objective distinction methods successfully applied to a 21-year-long time-series on fish assemblage in an English estuary may be as successful when applied to marine artificial reefs. For such a purpose, we tested each distinction tool separately with reference to four different artificial reef fish assemblage datasets. Three of them were drawn from the literature. Results indicate that none of these tools, used either individually or collectively, provide an efficient solution to distinguish resident species for the four datasets considered. We suggest that one of the major reasons for this failure may lie in the relative sampling size. Nonetheless, as these four datasets are representative of the datasets generally reported in the literature, tools capable of distinguishing reliably and efficiently resident from transient species along artificial reefs have yet to be developed. However, such a development requires fish residence to be previously and accurately defined by artificial reef scientists and managers.
Validating an ecological model with fisheries management applications: the relationship between loggerhead by-catch and distance to the coast
Authors: Báez José C. , Real Raimundo , Bellido Jesús , Macias David , de la Serna José M. , Camiñas Juan A.
Published: July 2010

On the one hand, a recent study on sea turtle by-catch during surface longline fishing targeting swordfish in the western Mediterranean Sea showed that sea turtle by-catch is independent of fishing effort and other technological factors. When the distance to the coast increases, there is a higher probability of catching a loggerhead turtle. The authors proposed to avoid fisheries further than 35 nautical miles (approximately 65 km) from the coast. However, the proposed 35 nautical miles limit could be useful where the continental shelf is narrow, as in the Balearic Sea, and useless where it widens. On the other hand, ecological model validation is considered essential for management application. The objective of the present paper is to validate the new fisheries loggerhead by-catch model in different areas outside the Balearic Sea with wider continental shelves, aimed at maintaining sustainable fishing activity compatible with the conservation of the loggerhead populations. Our present results validate the previous model, and stress the importance of the eco-geographical variable distance to the coast in understanding the loggerhead by-catch (or incidental capture) per unit effort for the longline fisheries targeting swordfish.
Factors influencing cercarial emergence and settlement in the digenean trematodeParorchis acanthus(Philophthalmidae)
Authors: Prinz K. , Kelly T.C. , O'Riordan R.M. , Culloty S.C.
Published: July 2010

The trematodeParorchis acanthusis widely distributed and exhibits a broad host spectrum, with larval stages occurring in marine gastropods and adult flukes parasitizing on various seabird species. Unlike the majority of digeneans, its cercariae do not invade a second intermediate host but encyst on a substrate in the open. In a series of laboratory experiments, we investigated factors influencing cercarial emergence and settlement ofP. acanthus. Emergence of cercariae from the gastropod intermediate hostNucella lapillusincreased with increasing temperature, whereas cercarial encystment success decreased. Numbers of emerged cercariae were highest in the presence of light and water. However, although in much lower numbers, cercariae were also released fromN. lapillusand successfully encysted under relatively dry conditions. Cercariae were found to settle predominantly on filtering blue musselsMytilus edulis, suggesting that cercarial concentration on the valves is largely facilitated by the bivalve's inhalation current. After being inhaled, cercariae actively emerged from the mussels using their suckers and subsequently encysted on the shells, preferably along the rim of the valves. Barnacle epibiontsSemibalanus balanoideswere observed to impair cercarial settlement on mussels, by disturbing or preying on cercariae. Whilst settlement success of cercariae onM. edulisincreased with increasing mussel density, intensity of encysted metacercariae decreased. Furthermore, cercariae settled more efficiently on small than on large mussels. Our findings suggest that the transmission ofP. acanthuscercariae is regulated by a range of abiotic and biotic factors, with filtering activity of mussels playing a key role by enhancing accumulation of cercariae on a substrate suitable for transmission to the bird final host.
The population of Errina aspera (Hydrozoa: Stylasteridae) of the Messina Strait (Mediterranean Sea)
Authors: Salvati Eva , Angiolillo Michela , Bo Marzia , Bavestrello Giorgio , Giusti Michela , Cardinali Andrea , Puce Stefania , Spaggiari Costanza , Greco Silvestro , Canese Simonepietro
Published: July 2010

Errina aspera is the only species belonging to the family Stylasteridae known from the Mediterranean Sea. The distribution of this species includes the Messina Strait, the Gibraltar Strait and the Atlantic coast of Morocco. In spite of the taxonomic and biogeographical importance of this species, no studies were conducted on its population structure in the Messina Strait. Here we report a study carried out with the aid of a ROV on a horizontal transect 350 m long at a depth comprised between 83 and 105 m where an extremely dense population of this stylasterid (101.4 ± 13.3 m−2) was recorded. The main components of the benthic community other than E. aspera are the coralline alga Lithothamnion philippii and the white zoanthid Epizoanthus sp. The colonies of E. aspera have a height ranging between 1.2 and 18.8 cm (4.1 ± 0.1 cm on average); they generally show a bi-dimensional, fan shaped morphology, but three-dimensional, brush-like specimens are also observed. The size–frequency distribution of the colony height is unimodal with a mode in the classes of 3–5 cm and a long tail of rare large colonies suggesting that the current may act as a limiting factor for the colony growth. The association with the gastropod ovulid Pedicularia sicula is confirmed.
Identification and characterization of a surface-associated, subtilisin-like serine protease inTrichomonas vaginalis
Authors: HERNÁNDEZ-ROMANO PABLO , HERNÁNDEZ ROBERTO , ARROYO ROSSANA , ALDERETE JOHN F. , LÓPEZ-VILLASEÑOR IMELDA
Published: July 2010

Trichomonas vaginalisis a protozoan parasite causing trichomonosis, a sexually transmitted infection in humans. This parasite has numerous proteases, most of which are cysteine proteases that appear to be involved in adherence and cytotoxicity of host cells. In this report we identify and characterize a putative subtilisin-like serine protease (SUB1). Thesub1gene encodes a 101-kDa protein.In silicoanalyses predict signal and pro-peptides at the N-terminus, and a transmembrane helix at the carboxy-terminal region. Thesub1gene was found as single copy by Southern analysis, albeit additional serine protease related genes are annotated in theT. vaginalisgenome. The expression ofsub1could only be detected by RT-PCR and Ribonuclease Protection Assays, suggesting a low abundant mRNA. Thesub1gene transcription start site was correctly assigned by RPA. The transcript abundance was found to be modulated by the availability of iron in the growth medium. Antibodies raised to a specific SUB1 peptide recognized a single protein band (~82 kDa) in Western blots, possibly representing the mature form of the protein. Immunofluorescence showed SUB1 on the trichomonad surface, and in dispersed vesicles throughout the cytoplasm. A bioinformatic analysis of genes annotated as serine proteases in theT. vaginalisgenome is also presented. To our knowledge this is the first putative serine protease experimentally described forT. vaginalis.
Discrimination of fish populations using parasites: Random Forests on a ‘predictable’ host-parasite system
Authors: PÉREZ-DEL-OLMO A. , MONTERO F. E. , FERNÁNDEZ M. , BARRETT J. , RAGA J. A. , KOSTADINOVA A.
Published: July 2010

We address the effect of spatial scale and temporal variation on model generality when forming predictive models for fish assignment using a new data mining approach, Random Forests (RF), to variable biological markers (parasite community data). Models were implemented for a fish host-parasite system sampled along the Mediterranean and Atlantic coasts of Spain and were validated using independent datasets. We considered 2 basic classification problems in evaluating the importance of variations in parasite infracommunities for assignment of individual fish to their populations of origin: multiclass (2–5 population models, using 2 seasonal replicates from each of the populations) and 2-class task (using 4 seasonal replicates from 1 Atlantic and 1 Mediterranean population each). The main results are that (i) RF are well suited for multiclass population assignment using parasite communities in non-migratory fish; (ii) RF provide an efficient means for model cross-validation on the baseline data and this allows sample size limitations in parasite tag studies to be tackled effectively; (iii) the performance of RF is dependent on the complexity and spatial extent/configuration of the problem; and (iv) the development of predictive models is strongly influenced by seasonal change and this stresses the importance of both temporal replication and model validation in parasite tagging studies.
‘Sporting Moscow’: stadia buildings and the challenging of public space in the post-war Soviet Union
Authors: KÖHRING ALEXANDRA
Published: July 2010

The Moscow Luzhniki stadia (1954–56) were constructed at the beginning of Khrushchev's reforms as a representative object to launch a rejuvenated and modernized socialism. The article seeks to situate the stadia complex in the crucial processes of urban transformation that occurred in the post-war Soviet Union; in questioning the Stalin monumental style, the planning of Luzhniki opened a more relational understanding of public space to Soviet people.
Research in urban history: recent theses on nineteenth- and early twentieth-century municipal administration
Authors: COUPERUS STEFAN
Published: July 2010

The ways in which the organization of local government and the practice of political power locally have changed over time has attracted heightened interest from urban and administrative historians over recent decades. Much of this burgeoning interest has paralleled the concurrent decline in the status and powers of local government since the 1980s. In recent years, a shifting focus from government to governance has allowed the historian to re-conceptualize approaches to urban political power. Urban governance denotes a wider system of government by encapsulating the complex range of actors, interests and resources, which straddle the public, private and voluntary sectors, each with a vested interest in the way that political power is organized and practised locally. By broadening their approach to urban political power, urban historians have, since the late 1980s, elicited new perspectives on municipal administration, reattaching it with the national and juridical frameworks of analysis from which it had been fractured. In general, this growing number of local, regional and cross-national historical studies hints at a more complex and interesting municipal dimension which transcends previously impermeable divisions between the private and the public spheres, between political democracy and administrative bureaucracy, between the central state and municipal administration, and between national and transnational contexts of administrative thought and practice.
Choice cuts: parsing policymakers’ pursuit of patient empowerment from an individual perspective
Authors: Schlesinger Mark
Published: July 2010

In this commentary I explore several ways in which the psychology of individual decision-making shapes consumers’ choices in medical settings and the potential for choice-based policies to improve the performance of the health care system. This analysis draws some crucial distinctions among the various pathways though which policymakers expect choice to improve outcomes and the various forms of support that might enhance patients’ engagement with choice. I also consider how choice-promoting policies interact with other strategies for patient empowerment and depend crucially on the ways in which individual patients develop the capacity to make sense of their experiences with medical care. Drawing largely on data and studies from medical consumerism in the US, I identify a number of choice ‘pathologies’ that might compromise the influence or beneficial effects of choice-promoting initiatives. Though these limitations are unlikely to turn public officials away from their consumerist policy aspirations, identifying the realistic limitations of such initiatives makes clear the need to complement them with other strategies for enhancing patients’ well being and encouraging a more responsive health care system.
Free‐running ground‐based photometric array imaging of transient luminous events
Authors: Newsome R. T. , Inan U. S.
Published: July 2010

We present observations of transient luminous events (TLEs) recorded during a summer TLE observation campaign in 2008 at Langmuir Laboratory near Socorro, New Mexico. The campaign featured observations made by a free‐running, ground‐based multianode photometric array called the Photometric Imager of Precipitated Electron Radiation (PIPER). As a photometric array, PIPER has high (40 μs) temporal resolution and enough spatial resolution (16 anodes per photometer) to make it particularly useful in the study of fast TLEs like elves and halos. As a free‐running instrument, there are no missed detections and no unwanted sampling bias introduced by triggering. As a ground‐based instrument, it can follow individual storms over the course of their lifetime rather than randomly sampling over large numbers of storms as required by space‐based instruments. During the campaign, 143 sprites, 803 elves, and 166 halos were observed over six storms, resulting in averaged elve‐to‐sprite and halo‐to‐sprite occurrence ratios of 5.6:1 and 1.2:1, respectively. There was considerable variability in the elve‐to‐sprite occurrence ratio from storm to storm, ranging from a low of 3.7:1 to a high of 13.4:1. Overall, 78.2% of the elves and 55.4% of the halos were associated with negative cloud‐to‐ground lightning strikes (−CGs); no sprites associated with −CGs were observed. Additionally, 40 events in which pairs of elves occur in rapid succession, events we refer to as elve doublets, were observed in several storms. The duration between elves in the elve doublet events was typically 120 μs. The causative mechanism for these events is still under deliberation.
Elevated bacterial abundance and exopolymers in saline frost flowers and implications for atmospheric chemistry and microbial dispersal
Authors: Bowman J. S. , Deming J. W.
Published: July 2010

Frost flowers (FF) have been studied for their potential influence on ice‐surface reflectivity and roles in atmospheric chemistry, but not as microbial habitats. We examined FF grown in a freezer laboratory from a bacteria‐containing saline solution and FF formed naturally in the coastal (April) and central Arctic Ocean (September). All FF contained bacteria (up to 3.46 × 106 ml−1 in natural FF) with densities 3–6‐fold higher than in underlying ice. Bacterial abundance correlated strongly with salinity in FF (p values ≤ 0.001), a correlation that held for all components of the surface‐ice environment (p < 0.0001, coastal samples). Concentrations of extracellular polysaccharides were also elevated in FF and brine skim relative to underlying ice (up to 74‐fold higher). Here we consider implications of finding microbes and exopolymers within the chemically reactive surface‐ice environment to the photolytic production of oxidants and long‐range transport of potential ice‐nucleating particles in the atmosphere.
On the origin of continental precipitation
Authors: Gimeno Luis , Drumond Anita , Nieto Raquel , Trigo Ricardo M. , Stohl Andreas
Published: July 2010

About 9 out of 10 liters of water evaporated from the oceans every year precipitates back onto oceans. However, the remaining 10% that get transported to continents play an irreplaceable role feeding the land branch of the hydrological cycle. Here we use an objective 3‐D Lagrangian model (FLEXPART) to detect major oceanic moisture source areas and the associated continental regions significantly influenced by each moisture source. Our results reveal a highly asymmetrical supply of oceanic moisture to the continents, with the Northern Atlantic subtropical ocean source impacting the continents considerably more than the large Southern Indian and North Pacific sources. Also, the small Mediterranean Sea and Red Sea basins are important moisture sources for relatively large land areas. The Indian subcontinent receives moisture from six different major oceanic source regions. Future changes in meteorological conditions over the oceanic moisture source regions may have an impact on water availability for many river basins.
Structural insight into the oxidation‐sensing mechanism of the antibiotic resistance of regulator MexR
Authors: Chen Hao , Yi Chengqi , Zhang Jin , Zhang Wenru , Ge Zhiyun , Yang Cai‐Guang , He Chuan
Published: July 2010

MexR functions as the primary regulator of the mexAB–oprM multidrug efflux expression in Pseudomonas aeruginosa. It has been shown that MexR senses oxidative stress by interprotomer disulphide bond formation between redox‐active cysteines. This oxidation induces MexR to dissociate from the promoter DNA, thus activating the transcriptional expression of efflux pump genes. In this study, we present the crystal structure of MexR in its oxidized form at a resolution of 2.1 Å. This crystal structure reveals the mechanism by which oxidative signal allosterically derepresses the MexR‐controlled transcription activation.
Zinc-finger nucleases: new strategies to target the rat genome
Authors: Geurts Aron M. , Moreno Carol
Published: July 2010

The importance of genetic laboratory models, such as mice and rats, becomes evident when there is a poor understanding of the nature of human disease. Many rat models for human disease, created over the years by phenotype-driven strategies, now provide a foundation for the identification of their genetic determinants. These models are especially valuable with the emerging need for validation of genes found in genome-wide association studies for complex diseases. The manipulation of the rat genome using engineered zinc-finger nucleases now introduces a key technology for manipulating the rat genome, which is broadly applicable. The ability to generate knockout rat models using zinc-finger nuclease technology will now enable its full emergence as an exceptional physiological and genetic research model.
Effect of tetragonal distortion on ferroelectric domain switching: A case study on La-doped BiFeO3–PbTiO3 ceramics
Authors: Leist Thorsten , Granzow Torsten , Jo Wook , Rödel Jürgen
Published: July 2010

The ferroelectric and piezoelectric properties of (1−x)BiFeO3–xPbTiO3 (BF-PT) ceramics were investigated as a function of tetragonal distortion. The latter was adjusted by employing La-doping (0–30 at %) while keeping the material near the morphotropic phase boundary by varying x between 0.35 and 0.46. This allows changing the c/a ratio of tetragonal BF-PT in the range from 1.10–1.01 and consequently alters the level of compatibility stresses. It was found that the c/a ratio has a significant influence on domain switching as inferred from electric field induced polarization, strain hysteresis, and Rayleigh measurements. Specifically, a threshold c/a ratio of about 1.045 was identified below which the electric field induced domain mobility increases sharply.
A generalization of the cumulant expansion. Application to a scale-invariant probabilistic model
Authors: Rodríguez A. , Tsallis C.
Published: July 2010

As well known, cumulant expansion is an alternative way to moment expansion to fully characterize probability distributions provided all the moments exist. If this is not the case, the so-called escort mean values (or q-moments) have been proposed to characterize probability densities with divergent moments [C. Tsallis et al., J. Math. Phys. 50, 043303 (2009)]. We introduce here a new mathematical object, namely, the q-cumulants, which, in analogy to the cumulants, provide an alternative characterization to that of the q-moments for the probability densities. To illustrate the technical details of the procedure, we apply this new scheme to further study a recently proposed family of scale-invariant discrete probabilistic models [A. Rodríguez et al., J. Stat. Mech.: Theory Exp. 2008, P09006; R. Hanel et al., Eur. Phys. J. B 72, 263 (2009)] having q-Gaussians as limiting probability distributions.
LuAG:Ce fibers for high energy calorimetry
Authors: Dujardin C. , Mancini C. , Amans D. , Ledoux G. , Abler D. , Auffray E. , Lecoq P. , Perrodin D. , Petrosyan A. , Ovanesyan K. L.
Published: July 2010

The main objective of this contribution is to point out the potentialities of cerium doped LuAG single crystal as pixels and fibers. We first show that after optimization of growth conditions using Bridgman technology, this composition exhibits very good performances for scintillating applications (up to 26 000 photons/MeV). When grown with the micropulling down technology, fiber shapes can be obtained while the intrinsic performances are preserved. For the future high energy experiments requiring new detector concepts capable of delivering much richer informations about x- or gamma-ray energy deposition, unusual fiber shaped dense materials need to be developed. We demonstrate in this frame that cerium doped LuAG is a serious candidate for the next generation of ionizing radiation calorimeters.
Effect of substrate orientation on lattice relaxation of epitaxial BiFeO3 thin films
Authors: Kan Daisuke , Takeuchi Ichiro
Published: July 2010

We have investigated detailed structural properties of epitaxial BiFeO3 thin films grown on (001), (110), and (111) SrTiO3 substrates in thicknesses up to 1 μm. X-ray reciprocal space mappings reveal that the fabricated films have crystal structures and the strain relaxation dictated by the substrate orientation. The rhombohedral structure, which is observed in the bulk form, is maintained only when the film is grown on the (111)-oriented substrate. The films grown on the (001) and (110)-oriented substrates have a lower structural symmetry than the rhombohedral one, namely a monoclinic structure. Two different processes are observed for the relaxation of the epitaxial strain from the substrate: they are (1) changes in lattice constants and (2) changes in the distortion angle in the BiFeO3 lattice. In the presence of a biaxial strain along the {100} axis, the relaxation in the distortion angle is inhibited, causing a gradual change in the lattice constants. As the number of the {100} axes on the substrate surface is decreased, the distortion angle relaxation becomes the dominant process, making the lattice parameters fully relaxed. We also find that the tilting of the crystallographic domain structures takes place concomitant with the angle relaxation process. These results indicate the strong influence of the substrate orientation on the structural properties of epitaxially-grown BiFeO3 thin films.
Power spectrum analysis with least-squares fitting: Amplitude bias and its elimination, with application to optical tweezers and atomic force microscope cantilevers
Authors: Nørrelykke Simon F. , Flyvbjerg Henrik
Published: July 2010

Optical tweezers and atomic force microscope (AFM) cantilevers are often calibrated by fitting their experimental power spectra of Brownian motion. We demonstrate here that if this is done with typical weighted least-squares methods, the result is a bias of relative size between −2/n and +1/n on the value of the fitted diffusion coefficient. Here, n is the number of power spectra averaged over, so typical calibrations contain 10%–20% bias. Both the sign and the size of the bias depend on the weighting scheme applied. Hence, so do length-scale calibrations based on the diffusion coefficient. The fitted value for the characteristic frequency is not affected by this bias. For the AFM then, force measurements are not affected provided an independent length-scale calibration is available. For optical tweezers there is no such luck, since the spring constant is found as the ratio of the characteristic frequency and the diffusion coefficient. We give analytical results for the weight-dependent bias for the wide class of systems whose dynamics is described by a linear (integro)differential equation with additive noise, white or colored. Examples are optical tweezers with hydrodynamic self-interaction and aliasing, calibration of Ornstein–Uhlenbeck models in finance, models for cell migration in biology, etc. Because the bias takes the form of a simple multiplicative factor on the fitted amplitude (e.g. the diffusion coefficient), it is straightforward to remove and the user will need minimal modifications to his or her favorite least-squares fitting programs. Results are demonstrated and illustrated using synthetic data, so we can compare fits with known true values. We also fit some commonly occurring power spectra once-and-for-all in the sense that we give their parameter values and associated error bars as explicit functions of experimental power-spectral values.
Silicon based microfluidic cell for terahertz frequencies
Authors: Baragwanath A. J. , Swift G. P. , Dai D. , Gallant A. J. , Chamberlain J. M.
Published: July 2010

We present a detailed analysis of the design, fabrication and testing of a silicon based, microfluidic cell, for transmission terahertz time-domain spectroscopy. The sensitivity of the device is tested through a range of experiments involving primary alcohol/water mixtures. The dielectric properties of these solutions are subsequently extracted using a Nelder–Mead search algorithm, and are in good agreement with literature values obtained via alternative techniques. Quantities in the order of 2 μmol can be easily distinguished for primary alcohols in solution, even with the subwavelength optical path lengths used. A further display of the device sensitivity is shown through the analysis of commercial whiskeys, where there are clear, detectable differences between samples. Slight absorption variations were identified between samples of the same commercial brand, owing to a 2.5% difference in their alcoholic content. Results from data taken on subsequent days after system realignment are also presented, confirming the robustness of the technique, and the data extraction algorithm used. One final experiment, showing the possible use of this device to analyze aqueous biological samples is detailed; where biotin, a molecule known for its specific terahertz absorptions, is analyzed in solution. The device sensitivity is once again displayed, where quantities of 3 nmol can be clearly detected between samples.
Heat flow model for pulsed laser melting and rapid solidification of ion implanted GaAs
Authors: Kim Taeseok , Pillai Manoj R. , Aziz Michael J. , Scarpulla Michael A. , Dubon Oscar D. , Yu Kin M. , Beeman Jeffrey W. , Ridgway Mark C.
Published: July 2010

In order to further understand the pulsed-laser melting (PLM) of Mn and N implanted GaAs, which we have used to synthesize thin films of the ferromagnetic semiconductor Ga1−xMnxAs and the highly mismatched alloy GaNxAs1−x, we have simulated PLM of amorphous (a-) and crystalline (c-) GaAs. We present a numerical solution to the one-dimensional heat equation, accounting for phase-dependent reflectivity, optical skin depth, and latent heat, and a temperature-dependent thermal conductivity and specific heat. By comparing the simulations with experimental time-resolved reflectivity and melt depth versus laser fluence, we identify a set of thermophysical and optical properties for the crystalline, amorphous, and liquid phases of GaAs that give reasonable agreement between experiment and simulation. This work resulted in the estimation of thermal conductivity, melting temperature and latent heat of fusion of a-GaAs of 0.008 W/cm K at 300 K, 1350 K, and 2650 J/cm3, respectively. These materials properties also allow the prediction of the solidification velocity of crystalline and ion-amorphized GaAs.
Progress in breeding perennial grains
Authors: Cox T. S. , Van Tassel D. L. , Cox C. M. , DeHaan L. R.
Published: July 2010

Annual cereal, legume and oilseed crops remain staples of the global food supply. Because most annual crops have less extensive, shorter-lived root systems than do perennial species, with a correspondingly lower capacity to manage nutrients and water, annual cropping systems tend to suffer higher levels of soil erosion and generate greater water contamination than do perennial systems. In an effort to reduce soil degradation and water contamination simultaneously – something that neither no-till nor organic cropping alone can accomplish – researchers in the United States, Australia and other countries have begun breeding perennial counterparts of annual grain and legume crops. Initial cycles of hybridization, propagation and selection in wheat, wheatgrasses, sorghum, sunflower and Illinois bundleflower have produced perennial progenies with phenotypes intermediate between wild and cultivated species, along with improved grain production. Further breeding cycles will be required to develop agronomically adapted perennial crops with high grain yields.
The risk of vegetative water deficit in early-sown faba bean (Vicia faba L.) and its implications for crop productivity in a Mediterranean-type environment
Authors: French R. J.
Published: July 2010

Farmers in Mediterranean-type environments should plant annual crops as early as possible to maximise yield. Greater rainfall variability at the start of the growing season potentially exposes early-sown crops to water deficit, which may be severe enough to cause crop mortality or to reduce potential productivity. This paper shows that in a typical Mediterranean-type environment at Merredin, Western Australia, much longer dry periods between rainfall events are likely in April rather than in May or June, but with a sowing rule based on farmer behaviour the likelihood of damaging water deficit is small. Soil water at sowing is a good indicator of this likelihood.
The implications of early water deficit for crop productivity were investigated for faba bean in two experiments at Merredin in 1997 and 1998. In 1997 simulated plant available water in the top 40 cm (PAW40) at sowing was 24 mm and 8-week-old plants displayed severe wilting after 6 weeks without rain. There was no crop mortality even after 8 weeks without rain and plants recovered quickly when rewatered. Water deficit reduced grain yield through lower evapotranspiration since withholding water reduced total supply but also because severely stressed plants could not extract water from as deep in the soil as less stressed plants. In 1998 simulated PAW40 at sowing was 41 mm and no wilting was observed when water was withheld for 8 weeks. Apparent transpiration efficiency was not affected by mild water deficit in either year, but was reduced by 35% by delaying sowing in 1998. This was due to higher atmospheric vapour pressure deficit during reproductive growth of the later-sown crop. These results suggest that delaying sowing in faba bean is more likely to reduce faba bean grain yield unless there is a strong likelihood of severe water deficit soon after sowing. This likelihood can be judged from the amount of soil water at sowing.
Evaluation of chicory cultivars and accessions for forage in south-eastern Australia
Authors: Li Guangdi D. , Nie Zhongnan , Bonython Amanda , Boschma Suzanne P. , Hayes Richard C. , Craig Andrew D. , Lodge Greg M. , Clark Bronwen , Dear Brian S. , Smith Alison B. , Harden Steven , Hughes Steve J.
Published: July 2010

The comparative herbage production and persistence of 7 chicory cultivars and 14 accessions collected from diverse regions of the world were evaluated over 3 years in 5 agro-ecological environments across New South Wales (NSW), Victoria (Vic.) and South Australia (SA). Results showed that all cultivars had higher herbage yields than the accessions, but varied greatly among sites. Averaged across all cultivars, total herbage yields were up to 24.6 t DM/ha over 3 years at the Hamilton, Vic. site, but as low as 6.9 and 5.7 t DM/ha at the Wagga Wagga and Bookham, NSW sites, respectively, where chicory only persisted for 2 years. In contrast, the average herbage yield of all accessions was only one-half of that produced by the cultivars at the Hamilton site and about one-third of that at the other 4 sites. All cultivars and accessions persisted well under the favourable climate conditions experienced at the Hamilton site. In contrast, severe drought in 2006 resulted in the death of chicory swards at the Wagga Wagga and Bookham sites, and substantial declines in persistence at the Manilla, NSW and Willalooka, SA sites. Nevertheless, accessions collected from Australia and Asia were more persistent than some of the cultivars and may provide opportunities to select genotypes better adapted to intermittently dry mixed farming systems in south-eastern Australia. Our findings indicated that the current cultivars were best suited to sites similar to the Hamilton site in the winter-dominant, higher rainfall zone of south-eastern Australia. Under these conditions chicory was likely to be productive and persistent for 4 years or longer. In the drier mixed farming zone, chicory may be more suitable in shorter (2–3-year) pasture phases. Further research is required to identify those factors contributing to poor persistence.
Winning territorial disputes selectively enhances androgen sensitivity in neural pathways related to motivation and social aggression
Authors: Fuxjager Matthew J. , Forbes-Lorman Robin M. , Coss Dylan J. , Auger Catherine J. , Auger Anthony P. , Marler Catherine A.
Published: July 2010

Winning aggressive disputes can enhance future fighting ability and the desire to seek out additional contests. In some instances, these effects are long lasting and vary in response to the physical location of a fight. Thus, in principle, winning aggressive encounters may cause long-term and context-dependent changes to brain areas that control the output of antagonistic behavior or the motivation to fight (or both). We examined this issue in the territorial California mouse (
Peromyscus californicus
) because males of this species are more likely to win fights after accruing victories in their home territory but not after accruing victories in unfamiliar locations. Using immunocytochemistry and real-time quantitative PCR, we found that winning fights either at home or away increases the expression of androgen receptors (AR) in the medial anterior bed nucleus of the stria terminalis, a key brain area that controls social aggression. We also found that AR expression in brain regions that mediate motivation and reward, nucleus accumbens (NAcc) and ventral tegmental area (VTA), increases only in response to fights in the home territory. These effects of winning were likely exclusive to the neural androgenic system because they have no detectible impact on the expression of progestin receptors. Finally, we demonstrated that the observed changes in androgen sensitivity in the NAcc and VTA are positively associated with the ability to win aggressive contests. Thus, winning fights can change brain phenotype in a manner that likely promotes future victory and possibly primes neural circuits that motivate individuals to fight.
Arpc1b, a centrosomal protein, is both an activator and substrate of Aurora A
Authors: Molli Poonam R. , Li Da-Qiang , Bagheri-Yarmand Rozita , Pakala Suresh B. , Katayama Hiroshi , Sen Subrata , Iyer Jyoti , Chernoff Jonathan , Tsai Ming-Ying , Nair Sujit S. , Kumar Rakesh
Published: July 2010

Here we provide evidence in support of an inherent role for Arpc1b, a component of the Arp2/3 complex, in regulation of mitosis and demonstrate that its depletion inhibits Aurora A activation at the centrosome and impairs the ability of mammalian cells to enter mitosis. We discovered that Arpc1b colocalizes with γ-tubulin at centrosomes and stimulates Aurora A activity. Aurora A phosphorylates Arpc1b on threonine 21, and expression of Arpc1b but not a nonphosphorylatable Arpc1b mutant in mammalian cells leads to Aurora A kinase activation and abnormal centrosome amplification in a Pak1-independent manner. Together, these findings reveal a new function for Arpc1b in centrosomal homeostasis. Arpc1b is both a physiological activator and substrate of Aurora A kinase and these interactions help to maintain mitotic integrity in mammalian cells.
An example concerning the Menger-Urysohn formula
Authors: van Mill Jan , Pol Roman
Published: July 2010

We construct subsets

A
A

,

B
B

of the Euclidean space

R

4

\mathbb {R}^{4}

such that

dim

(
A
∪
B
)
>

dim

(
A
×
B
)
+
1

\hbox {dim}(A\cup B)>\hbox {dim}(A \times B)+1

. This provides a counterexample to a conjecture by E. Ščepin for subspaces of

R

4

\mathbb {R}^{4}

.
Constantive Mal’cev clones on finite sets are finitely related
Authors: Aichinger Erhard
Published: July 2010

We show that on a finite set there are at most countably many constantive clones that contain a Mal’cev operation, and each such clone can be described by a single finitary relation. Thus, modulo polynomial equivalence and renaming of the elements, there are only countably many finite algebras that contain a Mal’cev term.
Spectral method on quadrilaterals
Authors: Ben-yu Guo , Hong-li Jia
Published: July 2010

In this paper, we investigate the spectral method on quadrilaterals. We introduce an orthogonal family of functions induced by Legendre polynomials, and establish some results on the corresponding orthogonal approximation. These results play important roles in the spectral method for partial differential equations defined on quadrilaterals. As examples of applications, we provide spectral schemes for two model problems and prove their spectral accuracy in Jacobi weighted Sobolev space. Numerical results coincide well with the analysis. We also investigate the spectral method on convex polygons whose solutions possess spectral accuracy. The approximation results of this paper are also applicable to other problems.
Equations for the modular curve 𝑋₁(𝑁) and models of elliptic curves with torsion points
Authors: Baaziz Houria
Published: July 2010

We describe an algorithm for constructing plane models of the modular curve

X
1

(
N
)

X_1(N)

and discuss the resulting equations when

N
≤
51

N\leq 51

.
The smallest Perron numbers
Authors: Wu Qiang
Published: July 2010

A Perron number is a real algebraic integer

α

\mathbf {\alpha }

of degree

d
≥
2

d \geq 2

, whose conjugates are

α

i

\mathbf {\alpha } _{i}

, such that

α

>

max

2
≤
i
≤
d

|

α

i

|

\mathbf {\alpha } >\max _{2 \leq i \leq d} \vert \mathbf {\alpha } _{i} \vert

. In this paper we compute the smallest Perron numbers of degree

d
≤
24

d \leq 24

and verify that they all satisfy the Lind-Boyd conjecture. Moreover, the smallest Perron numbers of degree 17 and 23 give the smallest house for these degrees. The computations use a family of explicit auxiliary functions. These functions depend on generalizations of the integer transfinite diameter of some compact sets in

C

\mathbb {C}
Analysis of a finite PML approximation to the three dimensional elastic wave scattering problem
Authors: Bramble James , Pasciak Joseph , Trenev Dimitar
Published: July 2010

We consider the application of a perfectly matched layer (PML) technique to approximate solutions to the elastic wave scattering problem in the frequency domain. The PML is viewed as a complex coordinate shift in spherical coordinates which leads to a variable complex coefficient equation for the displacement vector posed on an infinite domain (the complement of the scatterer). The rapid decay of the PML solution suggests truncation to a bounded domain with a convenient outer boundary condition and subsequent finite element approximation (for the truncated problem).

We prove existence and uniqueness of the solutions to the infinite domain and truncated domain PML equations (provided that the truncated domain is sufficiently large). We also show exponential convergence of the solution of the truncated PML problem to the solution of the original scattering problem in the region of interest. We then analyze a Galerkin numerical approximation to the truncated PML problem and prove that it is well posed provided that the PML damping parameter and mesh size are small enough. Finally, computational results illustrating the efficiency of the finite element PML approximation are presented.
Asymptotics of greedy energy points
Authors: García A. López , Saff E.
Published: July 2010

For a symmetric kernel

k
:
X
×
X
→

R

∪
{
+
∞
}

k:X\times X \rightarrow \mathbb {R}\cup \{+\infty \}

on a locally compact metric space

X
X

, we investigate the asymptotic behavior of greedy

k
k

-energy points

{

a

i

}

1

∞

\{a_{i}\}_{1}^{\infty }

for a compact subset

A
⊂
X

A\subset X

that are defined inductively by selecting

a

1

∈
A

a_{1}\in A

arbitrarily and

a

n
+
1

a_{n+1}

so that
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="sigma-summation Underscript i equals 1 Overscript n Endscripts k left-parenthesis a Subscript n plus 1 Baseline comma a Subscript i Baseline right-parenthesis equals inf Underscript x element-of upper A Endscripts sigma-summation Underscript i equals 1 Overscript n Endscripts k left-parenthesis x comma a Subscript i Baseline right-parenthesis">

∑

i
=
1

n

k
(

a

n
+
1

,

a

i

)
=

inf

x
∈
A

∑

i
=
1

n

k
(
x
,

a

i

)

\sum _{i=1}^{n}k(a_{n+1},a_{i})=\inf _{x\in A}\sum _{i=1}^{n}k(x,a_{i})

. We give sufficient conditions under which these points (also known as Leja points) are asymptotically energy minimizing (i.e. have energy

∑

i
≠
j

N

k
(

a

i

,

a

j

)

\sum _{i\neq j}^{N}k(a_{i},a_{j})

as

N
→
∞

N\rightarrow \infty

that is asymptotically the same as
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="script upper E left-parenthesis upper A comma upper N right-parenthesis colon equals min left-brace sigma-summation Underscript i not-equals j Endscripts k left-parenthesis x Subscript i Baseline comma x Subscript j Baseline right-parenthesis colon x 1 comma ellipsis comma x Subscript upper N Baseline element-of upper A right-brace">

E

(
A
,
N
)
:=
min
{

∑

i
≠
j

k
(

x

i

,

x

j

)
:

x

1

,
…
,

x

N

∈
A
}

\mathcal {E}(A,N):=\min \{\sum _{i\neq j}k(x_{i},x_{j}):x_{1},\ldots ,x_{N}\in A\}

), and have asymptotic distribution equal to the equilibrium measure for

A
A

. For the case of Riesz kernels

k

s

(
x
,
y
)
:=

|

x
−
y

|

−
s

k_{s}(x,y):=|x-y|^{-s}

,

s
>
0

s>0

, we show that if

A
A

is a rectifiable Jordan arc or closed curve in

R

p

\mathbb {R}^{p}

and

s
>
1

s>1

, then greedy

k

s

k_{s}

-energy points are not asymptotically energy minimizing, in contrast to the case

s
>
1

s>1

. (In fact, we show that no sequence of points can be asymptotically energy minimizing for

s
>
1

s>1

.) Additional results are obtained for greedy

k

s

k_{s}

-energy points on a sphere, for greedy best-packing points (the case

s
=
∞

s=\infty

), and for weighted Riesz kernels. For greedy best-packing points we provide a simple counterexample to a conjecture attributed to L. Bos.
A new multiscale finite element method for high-contrast elliptic interface problems
Authors: Chu C.-C. , Graham I. , Hou T.-Y.
Published: July 2010

We introduce a new multiscale finite element method which is able to accurately capture solutions of elliptic interface problems with high contrast coefficients by using only coarse quasiuniform meshes, and without resolving the interfaces. A typical application would be the modelling of flow in a porous medium containing a number of inclusions of low (or high) permeability embedded in a matrix of high (respectively low) permeability. Our method is

H
1

H^1

- conforming, with degrees of freedom at the nodes of a triangular mesh and requiring the solution of subgrid problems for the basis functions on elements which straddle the coefficient interface but which use standard linear approximation otherwise. A key point is the introduction of novel coefficient-dependent boundary conditions for the subgrid problems. Under moderate assumptions, we prove that our methods have (optimal) convergence rate of

O
(
h
)

O(h)

in the energy norm and

O
(

h
2

)

O(h^2)

in the

L
2

L_2

norm where

h
h

is the (coarse) mesh diameter and the hidden constants in these estimates are independent of the “contrast” (i.e. ratio of largest to smallest value) of the PDE coefficient. For standard elements the best estimate in the energy norm would be

O

(

h

1

/

2
−
ε

)

\mathcal {O}(h^{1/2-\varepsilon })

with a hidden constant which in general depends on the contrast. The new interior boundary conditions depend not only on the contrast of the coefficients, but also on the angles of intersection of the interface with the element edges.