bluuebunny/crossref_metadata_2025 huggingface dataset:
Incorporating spatial variation of nitrification and denitrification rates into whole‐lake nitrogen dynamics
Authors: Bruesewitz Denise A. , Tank Jennifer L. , Hamilton Stephen K.
Published: June 2012

Despite dramatic increases in nitrogen (N) loading to fresh waters and growing scientific attention on the changing N cycle, measurements of nitrification and denitrification rates in lakes are lacking. In particular, we know little about how these processes vary spatially within a lake, and how this potential spatial variation contributes to a lake's N dynamics. We measured sediment nitrification and denitrification rates at 40 sites in Gull Lake, Michigan (USA), and found that the shallow edge sediments (<2 m deep) of the lake were hot spots of N transformation. Nitrification rates were comparable in sediments at all depths, while sediment denitrification rates were highest in the shallow edge habitat, and lowest in the profundal sediments (<2 m and >10 m deep, respectively). We scaled‐up our sediment transformation rates across the lake to illustrate spatial variability in nitrification and denitrification. For whole‐lake nitrification, the contribution of shallow edge, littoral, and profundal sediments followed in proportion to lake surface area of each habitat. In contrast, the contribution of each of these areas to whole‐lake denitrification was not proportional to their respective surface areas, and instead was equal across the 3 habitat types, with each area contributing roughly 30% of the total N loss via denitrification. Spatially representative characterization of nitrification and denitrification in lentic ecosystems requires incorporation of the spatial variation in these transformations with a particular focus on littoral sediments, and this is often overlooked in studies of lentic N cycling. Furthermore, anthropogenic changes to lake shorelines that influence N cycling in littoral sediments may have a disproportionate effect on whole‐lake ecosystem function.
O-GlcNAcylation and oxidation of proteins: is signalling in the cardiovascular system becoming sweeter?
Authors: Lima Victor V. , Spitler Kathryn , Choi Hyehun , Webb R. Clinton , Tostes Rita C.
Published: June 2012

O-GlcNAcylation is an unusual form of protein glycosylation, where a single-sugar [GlcNAc (N-acetylglucosamine)] is added (via β-attachment) to the hydroxyl moiety of serine and threonine residues of nuclear and cytoplasmic proteins. A complex and extensive interplay exists between O-GlcNAcylation and phosphorylation. Many phosphorylation sites are also known glycosylation sites, and this reciprocal occupancy may produce different activities or alter the stability in a target protein. The interplay between these two post-translational modifications is not always reciprocal, as some proteins can be concomitantly phosphorylated and O-GlcNAcylated, and the adjacent phosphorylation or O-GlcNAcylation can regulate the addition of either moiety. Increased cardiovascular production of ROS (reactive oxygen species), termed oxidative stress, has been consistently reported in various chronic diseases and in conditions where O-GlcNAcylation has been implicated as a contributing mechanism for the associated organ injury/protection (for example, diabetes, Alzheimer's disease, arterial hypertension, aging and ischaemia). In the present review, we will briefly comment on general aspects of O-GlcNAcylation and provide an overview of what has been reported for this post-translational modification in the cardiovascular system. We will then specifically address whether signalling molecules involved in redox signalling can be modified by O-GlcNAc (O-linked GlcNAc) and will discuss the critical interplay between O-GlcNAcylation and ROS generation. Experimental evidence indicates that the interactions between O-GlcNAcylation and oxidation of proteins are important not only for cell regulation in physiological conditions, but also under pathological states where the interplay may become dysfunctional and thereby exacerbate cellular injury.
A consistent approach for the treatment of Fermi acceleration in time-dependent billiards
Authors: Karlis A. K. , Diakonos F. K. , Constantoudis V.
Published: June 2012

The standard description of Fermi acceleration, developing in a class of time-dependent billiards, is given in terms of a diffusion process taking place in momentum space. Within this framework, the evolution of the probability density function (PDF) of the magnitude of particle velocities as a function of the number of collisions n is determined by the Fokker-Planck equation (FPE). In the literature, the FPE is constructed by identifying the transport coefficients with the ensemble averages of the change of the magnitude of particle velocity and its square in the course of one collision. Although this treatment leads to the correct solution after a sufficiently large number of collisions have been reached, the transient part of the evolution of the PDF is not described. Moreover, in the case of the Fermi-Ulam model (FUM), if a standard simplification is employed, the solution of the FPE is even inconsistent with the values of the transport coefficients used for its derivation. The goal of our work is to provide a self-consistent methodology for the treatment of Fermi acceleration in time-dependent billiards. The proposed approach obviates any assumptions for the continuity of the random process and the existence of the limits formally defining the transport coefficients of the FPE. Specifically, we suggest, instead of the calculation of ensemble averages, the derivation of the one-step transition probability function and the use of the Chapman-Kolmogorov forward equation. This approach is generic and can be applied to any time-dependent billiard for the treatment of Fermi-acceleration. As a first step, we apply this methodology to the FUM, being the archetype of time-dependent billiards to exhibit Fermi acceleration.
Hierarchical transformation of Hamiltonians with linear and quadratic couplings for nonadiabatic quantum dynamics: Application to the ππ*/nπ* internal conversion in thymine
Authors: Picconi David , Lami Alessandro , Santoro Fabrizio
Published: June 2012

We face with the general problem of defining a reduced number of effective collective coordinates to describe accurately the short-time nonadiabatic dynamics of large semirigid systems, amenable to a description in terms of coupled harmonic potential energy surfaces. We present a numeric iterative protocol to define a hierarchical representation of the Hamiltonian taking into account both linear and quadratic intra- and inter-state couplings (QVC, quadratic vibronic coupling model), thus generalizing the method introduced recently in the literature [E. Gindensperger, H. Köppel, and L. S. Cederbaum, J. Chem. Phys. 126, 034106 (2007)]10.1063/1.2426342 for the linear vibronic coupling (LVC) model. This improvement allows to take into account the effect of harmonic frequency changes and Duschinsky mixings among the different electronic states, providing a route to upgrade the models for nonadiabatic harmonic systems to those nowadays routinely used for the simulation of vibronic spectra of adiabatic systems (negligible nonadiabatic couplings). We apply our method to the study of ππ* → nπ* internal conversion in thymine, analysing the differences in LVC and QVC predictions both for the absorption spectrum and the dynamics of electronic populations.
Spin-dependent polaron recombination in conjugated polymers
Authors: Sun Zhen , Stafström Sven
Published: June 2012

We simulate the interchain polaron recombination process in conjugated polymer systems using a nonadiabatic molecular dynamics method, which allows for the coupled evolution of the nuclear degrees of freedom and multiconfigurational electronic wavefunctions. Within the method, the appropriate spin symmetry of the electronic wavefunction is taken into account, thus allowing us to distinguish between singlet and triplet excited states. It is found that the incident polarons can form an exciton, form a bound interchain polaron pair, or pass each other, depending on the interchain interaction strength and the strength of an external electric field. Most importantly, we found that the formation of singlet excitons is considerably easier than triplet excitons. This shows that in real organic light emitting devices, the electroluminescence quantum efficiency can exceed the statistical limitation value of 25%, in agreement with experiments.
New detection system and signal processing for the tokamak ISTTOK heavy ion beam diagnostic
Authors: Henriques R. B. , Nedzelskiy I. S. , Malaquias A. , Fernandes H.
Published: June 2012

The tokamak ISTTOK havy ion beam diagnostic (HIBD) operates with a multiple cell array detector (MCAD) that allows for the plasma density and the plasma density fluctuations measurements simultaneously at different sampling volumes across the plasma. To improve the capability of the plasma density fluctuations investigations, a new detection system and new signal conditioning amplifier have been designed and tested. The improvements in MCAD design are presented which allow for nearly complete suppression of the spurious plasma background signal by applying a biasing potential onto special electrodes incorporated into MCAD. The new low cost and small size transimpedance amplifiers are described with the parameters of 400 kHz, 107 V/A, 0.4 nA of RMS noise, adequate for the plasma density fluctuations measurements.
Free volume dilatation in polymers by ortho-positronium
Authors: Winberg P. , Eldrup M. , Maurer F. H. J.
Published: June 2012

The possibility of positronium induced free volume cavity expansion in some polymers above the glass transition temperature was investigated using experimental positron annihilation lifetime data from the literature for polydimethylsiloxane, polyisobutylene, and polybutadiene as function of temperature. The results suggest that free volume sites can expand towards an equilibrium size, determined as the equilibrium Ps-bubble size defined earlier for low-molecular-weight liquids. The expansion can be explained by the increase of molecular mobility and hence decrease of relaxation times, which at the higher temperatures approach the o-Ps lifetimes. Nanoscale viscosities were estimated using Navier-Stokes equation and were found to be several orders of magnitude lower than the macroscopic viscosity at the same temperature.
A theory for time-dependent solvation structure near solid-liquid interface
Authors: Iida Kenji , Sato Hirofumi
Published: June 2012

We propose a theory to describe time-dependent solvation structure near solid-liquid interface. Recently, we have developed two-dimensional-reference interaction site model to describe solvation structure near solid-liquid interface at the equilibrium state. In the present study, the theory is extended to treat dynamical aspect of the solvation; site-site Smoluchowski-Vlasov equation and surrogate Hamiltonian description are utilized to deal with the time-dependency. This combination enables us to access a long-time behavior of solvation dynamics. We apply the theory to a model system consisting of an atomistic wall and water solvent, and discuss the hydration structure dynamics near the interface at the molecular-level.
Epitaxial two dimensional aluminum films on silicon (111) by ultra-fast thermal deposition
Authors: Levine Igal , Yoffe Alexander , Salomon Adi , Li Wenjie , Feldman Yishay , Vilan Ayelet
Published: June 2012

Aluminum thin films are known for their extremely rough surface, which is detrimental for applications such as molecular electronics and photonics, where protrusions cause electrical shorts or strong scattering. We achieved atomically flat Al films using a highly non-equilibrium approach. Ultra-fast thermal deposition (UFTD), at rates >10 nm/s, yields RMS roughness of 0.4 to 0.8 nm for 30–50 nm thick Al films on variety of substrates. For UFTD on Si(111) substrates, the top surface follows closely the substrate topography (etch pits), indicating a 2D, layer-by-layer growth. The Al film is a mixture of (100) and (111) grains, where the latter are commensurate with the in-plane orientation of the underlying Si (epitaxy). We show the use of these ultra-smooth Al films for highly reproducible charge-transport measurements across a monolayer of alkyl phosphonic acid as well as for plasmonics applications by directly patterning them by focused ion beam to form a long-range ordered array of holes. UFTD is a one-step process, with no need for annealing, peeling, or primer layers. It is conceptually opposite to high quality deposition methods, such as MBE or ALD, which are slow and near-equilibrium processes. For Al, though, we find that limited diffusion length (and good wetting) is critical for achieving ultra-smooth thin films.
Flash heating in the diamond cell: Melting curve of rhenium
Authors: Yang Liuxiang , Karandikar Amol , Boehler Reinhard
Published: June 2012

A new method for measuring melting temperatures in the laser-heated diamond cell is described. This method circumvents previous problems associated with the sample instability, thermal runaway, and chemical reactions. Samples were heated with a single, 20 milliseconds rectangular pulse from a fiber laser, monitoring their thermal response with a fast photomultiplier while measuring the steady state temperature with a CCD spectrometer. The samples were recovered and analyzed using scanning electron microscopy. Focused ion beam milling allowed to examine both the lateral and the vertical solid-liquid boundaries. Ambient pressure tests reproducibly yielded the known melting temperatures of rhenium and molybdenum. Melting of Re was measured to 50 GPa, a 5-fold extension of previous data. The refractory character of Re is drastically enhanced by pressure, in contrast to Mo.
CuI interlayers in lead phthalocyanine thin films enhance near-infrared light absorption
Authors: Jung Kim Hyo , Shim Hyun-Sub , Whan Kim Ji , Hwi Lee Hyun , Kim Jang-Joo
Published: June 2012

The insertion of a CuI interlayer improved the preferential alignment of lead phthalocyanine (PbPc) molecules in the monoclinic phase, as demonstrated by x-ray diffraction analysis of ultra-thin (5 nm) and thin (30 nm) PbPc films. CuI triclinic phases were not observed. The improved preferential alignment and crystallinity in the monoclinic phase enhanced near-infrared photon absorption. The power conversion efficiency of a PbPc/C60 planar heterojunction organic photovoltaic device fabricated using the CuI templating layer structure could be improved from 1.3% to 2.5%.
Correlation between electronic structure and magnetic properties of Fe-doped ZnO films
Authors: Chen Tiexin , Cao Liang , Zhang Wenhua , Zhang Wang , Han Yuyan , Zheng Zhiyuan , Xu Faqiang , Kurash Ibrahim , Qian Haijie , Wang Jia’ou
Published: June 2012

Fe-doped ZnO films with different Fe concentrations that display ferromagnetism at room temperature have been prepared by plasma assisted molecular beam epitaxy (p-MBE) techniques. Synchrotron-based measurements of photoemission spectroscopy (PES), x-ray absorption spectroscopy (XAS), resonant photoemission spectroscopy (RPES), and superconducting quantum interference device (SQUID) were performed to investigate the electronic structure and magnetic properties of the films. It was found by Fe 2p PES and XAS that the dominant valence state of Fe ions is Fe3+ and that the configuration of Fe ions varies from tetrahedral sites to octahedral sites as the Fe concentration increases. Results of RPES indicate that the electronic states related to Fe2+ also exist near the Fermi level and that the distribution of Fe 3d electronic states in the valence band varies with different Fe concentrations. Correlations of the magnetic properties with the electronic structure of Fe-ZnO films have established that the electronic states related to Fe2+ and localized defects like Zn vacancies play an important role for ferromagnetism of Fe-ZnO films, while Fe3+ ions at octahedral sites destabilize the ferromagnetic interactions.
Interstitial doping induced superconductivity at 15.3 K in Nb5Ge3 compound
Authors: Bortolozo A. D. , dos Santos C. A. M. , Jardim R. F. , Ritter C. , Devishvili A. , Rotter M. , Gandra F. G. , Machado A. J. S.
Published: June 2012

It is reported superconductivity in Nb5Ge3C0.3, an interstitial carbide compound. The temperature dependence of the electrical resistivity, ac-susceptibility, and heat capacity (HC) indicate that a bulk type-II superconductivity appears at TC = 15.3 K. Magneto-resistance measurements suggest an upper critical field of BC2 ∼ 10.6 T and a coherence length of ξ ∼ 55 Å at zero temperature. Neutron diffraction analyzes locate the carbon atoms at the interstitial 2b site of the Mn5Si3 type-structure. Heat capacity data below TC are well described by BCS theory. The size of the jump at TC is in good agreement with the superconducting volume fraction observed in susceptibility measurements. A Debye temperature and Sommerfeld constant were also extracted from heat capacity data as 343 K and 34 mJ/mol K2, respectively.
Loss of insulin-induced activation of TRPM6 magnesium channels results in impaired glucose tolerance during pregnancy
Authors: Nair Anil V. , Hocher Berthold , Verkaart Sjoerd , van Zeeland Femke , Pfab Thiemo , Slowinski Torsten , Chen You-Peng , Schlingmann Karl Peter , Schaller André , Gallati Sabina , Bindels René J. , Konrad Martin , Hoenderop Joost G.
Published: June 2012

Hypomagnesemia affects insulin resistance and is a risk factor for diabetes mellitus type 2 (DM2) and gestational diabetes mellitus (GDM). Two single nucleotide polymorphisms (SNPs) in the epithelial magnesium channel TRPM6 (V
1393
I, K
1584
E) were predicted to confer susceptibility for DM2. Here, we show using patch clamp analysis and total internal reflection fluorescence microscopy, that insulin stimulates TRPM6 activity via a phosphoinositide 3-kinase and Rac1-mediated elevation of cell surface expression of TRPM6. Interestingly, insulin failed to activate the genetic variants TRPM6(V
1393
I) and TRPM6(K
1584
E), which is likely due to the inability of the insulin signaling pathway to phosphorylate TRPM6(T
1391
) and TRPM6(S
1583
). Moreover, by measuring total glycosylated hemoglobin (TGH) in 997 pregnant women as a measure of glucose control, we demonstrate that TRPM6(V
1393
I) and TRPM6(K
1584
E) are associated with higher TGH and confer a higher likelihood of developing GDM. The impaired response of TRPM6(V
1393
I) and TRPM6(K
1584
E) to insulin represents a unique molecular pathway leading to GDM where the defect is located in TRPM6.
Control of electron transport routes through redox-regulated redistribution of respiratory complexes
Authors: Liu Lu-Ning , Bryan Samantha J. , Huang Fang , Yu Jianfeng , Nixon Peter J. , Rich Peter R. , Mullineaux Conrad W.
Published: June 2012

In cyanobacteria, respiratory electron transport takes place in close proximity to photosynthetic electron transport, because the complexes required for both processes are located within the thylakoid membranes. The balance of electron transport routes is crucial for cell physiology, yet the factors that control the predominance of particular pathways are poorly understood. Here we use a combination of tagging with green fluorescent protein and confocal fluorescence microscopy in live cells of the cyanobacterium
Synechococcus elongatus
PCC 7942 to investigate the distribution on submicron scales of two key respiratory electron donors, type-I NAD(P)H dehydrogenase (NDH-1) and succinate dehydrogenase (SDH). When cells are grown under low light, both complexes are concentrated in discrete patches in the thylakoid membranes, about 100–300 nm in diameter and containing tens to hundreds of complexes. Exposure to moderate light leads to redistribution of both NDH-1 and SDH such that they become evenly distributed within the thylakoid membranes. The effects of electron transport inhibitors indicate that redistribution of respiratory complexes is triggered by changes in the redox state of an electron carrier close to plastoquinone. Redistribution does not depend on de novo protein synthesis, and it is accompanied by a major increase in the probability that respiratory electrons are transferred to photosystem I rather than to a terminal oxidase. These results indicate that the distribution of complexes on the scale of 100–300 nm controls the partitioning of reducing power and that redistribution of electron transport complexes on these scales is a physiological mechanism to regulate the pathways of electron flow.
Anti–IL-7 receptor-α reverses established type 1 diabetes in nonobese diabetic mice by modulating effector T-cell function
Authors: Lee Li-Fen , Logronio Kathryn , Tu Guang Huan , Zhai Wenwu , Ni Irene , Mei Li , Dilley Jeanette , Yu Jessica , Rajpal Arvind , Brown Colleen , Appah Charles , Chin Sherman Michael , Han Bora , Affolter Timothy , Lin John C.
Published: June 2012

Genetic variation in the IL-7 receptor-α (IL-7R) gene is associated with susceptibility to human type 1 diabetes (T1D). Here we investigate the therapeutic efficacy and mechanism of IL-7Rα antibody in a mouse model of T1D. IL-7Rα antibody induces durable, complete remission in newly onset diabetic mice after only two to three injections. IL-7 increases, whereas IL-7Rα antibody therapy reduces, the IFN-γ–producing CD4+(TH1) and IFN-γ–producing CD8+T cells. Conversely, IL-7 decreases and IL-7Rα antibody enhances the inhibitory receptor Programmed Death 1 (PD-1) expression in the effector T cells. Programmed Death 1 blockade reversed the immune tolerance mediated by the IL-7Rα antibody therapy. Furthermore, IL-7Rα antibody therapy increases the frequency of regulatory T cells without affecting their suppressor activity. The durable efficacy and the multipronged tolerogenic mechanisms of IL-7Rα antibody therapy suggest a unique disease-modifying approach to T1D.
Elevated urinary neutrophil gelatinase‐associated lipocalcin after acute heart failure treatment is associated with worsening renal function and adverse events
Authors: Collins Sean P. , Hart Kimberly W. , Lindsell Christopher J. , Fermann Gregory J. , Weintraub Neal L. , Miller Karen F. , Roll Susan N. , Sperling Matthew I. , Sawyer Douglas B. , Storrow Alan B.
Published: June 2012

Aims

Reliable detectors of worsening renal function (WRF) in Emergency Department (ED) patients with acute heart failure (AHF) are limited. We hypothesized that initial urinary neutrophil gelatinase‐associated lipocalcin (NGAL) levels, and changes in urinary NGAL levels after initial ED AHF therapy, would be associated with WRF and adverse events.

Methods and results

Urinary NGAL upon ED presentation and 12–24 h after ED treatment was measured in a cohort of ED patients with AHF. NGAL was corrected for urinary creatinine (uCr). WRF was defined as RIFLE stages 1, 2, or 3, or a creatinine increase of ≥0.3 mg/dL. Patients were prospectively followed for 5‐ and 30‐day adverse cardiovascular events. The 399 patients had a median age of 63 years, 50% were Caucasian, and 62% were male. Those with WRF at 72–96 h were more likely to have a higher initial NGAL value (71 vs. 32 ng NGAL/mg uCr) (P = 0.005), and a higher NGAL level at 12–24 h after ED therapy (107 vs. 25ng NGAL/mg uCr, P < 0.001). In a multivariable model, NGAL at 12–24 h remained a significant predictor of WRF (P = 0.012). Of all variables available 12–24 h after initial therapy, the only significant predictor of 30‐day events was an elevated urinary NGAL level (P = 0.02).

Conclusions

Urinary NGAL levels determined 12–24 h after ED therapy are significantly associated with both WRF at 72–96 h and 30‐day adverse events. This suggests that early management strategies may have an impact on subsequent WRF and outcomes. If confirmed, NGAL may have a role for guiding therapeutic decisions.
Resting heart rate and incident heart failure in apparently healthy men and women in the EPIC‐Norfolk study
Authors: Pfister Roman , Michels Guido , Sharp Stephen J. , Luben Robert , Wareham Nick J. , Khaw Kay‐Tee
Published: June 2012

Aims

Increasing levels of resting heart rate are associated with increased risk of developing hypertension and cardiovascular disease, and seem to play a role in the progression of heart failure. The shape of the association between resting heart rate and risk of developing heart failure has not been examined in healthy individuals of the general population.

Methods and results

Hazard ratios (HRs) of heart failure comparing categories of resting heart rate [51–60 b.p.m. (reference), 61–70 b.p.m., 71–80 b.p.m., 81–90 b.p.m., and 91–100 b.p.m.] were calculated in apparently healthy men (9805) and women (12 321) aged 39–79 participating in the ‘European Prospective Investigation into Cancer and Nutrition’ (EPIC) study in Norfolk. During a mean follow‐up of 12.9 years, 1356 incident cases of heart failure occurred. In participants without potential heart rate‐modifying medication, age‐ and sex‐adjusted incidence rates of heart failure were 3.3, 3.7, 4.0, 5.1, and 5.5 per 1000 person‐years for increasing categories of resting heart rate; compared with the reference category, HRs and 95% confidence intervals (CI) for increasing categories of resting heart rate were 1.08 (0.88–1.34), 1.17 (0.94–1.46), 1.39 (1.08–1.79), and 1.42 (1.00–2.03), respectively, in multivariable analysis adjusting for age, sex, body mass index, systolic blood pressure, prevalent diabetes, cholesterol concentration, social class, educational level, smoking, and physical activity. Within the reference range of resting heart rate (50–100 b.p.m.) each 10 b.p.m. increase was associated with an 11% increase in hazard of heart failure in multivariable analysis. The results did not change materially after adjusting for myocardial infarction and coronary heart disease events during follow up (1.12, 1.06–1.18).

Conclusion

Resting heart rate shows a graded association with hazard of heart failure in apparently healthy men and women which is not mediated by coronary heart disease. Further study is needed to examine the underlying mechanisms.
Aphelenchoides bicaudatusfrom Ornamental Nurseries in Taiwan and Its Relationship with Some Agricultural Crops
Authors: Jen Fan-Yu , Tsay Tung-Tsuan , Chen Peichen
Published: June 2012

Aphelenchoides bicaudatus nematodes were identified in planting materials and water samples from 35 floral ornamental nurseries in Taiwan. A pure line of the nematode was established from the bulk samples collected, and the nematode was identified as A. bicaudatus on the basis of morphometric data and the 18S gene sequence (GU984233). Host range tests were conducted by inoculating A. bicaudatus onto Phalaenopsis spp. strawberry, rice, bird's-nest fern, cyclamen, dendrobium, African violet, and saxifrage (all reported hosts of A. besseyi). Symptoms did not develop during the 4 weeks following inoculation. However, after staining, both eggs and nematodes inside plant tissue of Phalaenopsis roots, strawberry leaf buds, and rice sheath indicated that A. bicaudatus had established in these hosts. These results revealed a potential new host–parasite relationship of A. bicaudatus, and suggest that this nematode may infect these economically important hosts.
Model and test in a fungus of the probability that beneficial mutations survive drift
Authors: Gifford Danna R. , de Visser J. Arjan G. M. , Wahl Lindi M.
Published: June 2012

Determining the probability of fixation of beneficial mutations is critically important for building predictive models of adaptive evolution. Despite considerable theoretical work, models of fixation probability have stood untested for nearly a century. However, recent advances in experimental and theoretical techniques permit the development of models with testable predictions. We developed a new model for the probability of surviving genetic drift, a major component of fixation probability, for novel beneficial mutations in the fungus
Aspergillus nidulans
, based on the life-history characteristics of its colony growth on a solid surface. We tested the model by measuring the probability of surviving drift in 11 adapted strains introduced into wild-type populations of different densities. We found that the probability of surviving drift increased with mutant invasion fitness, and decreased with wild-type density, as expected. The model accurately predicted the survival probability for the majority of mutants, yielding one of the first direct tests of the extinction probability of beneficial mutations.
Transcriptional and Metabolic Analysis of Senescence Induced by Preventing Pollination in Maize
Authors: Sekhon Rajandeep S. , Childs Kevin L. , Santoro Nicholas , Foster Cliff E. , Buell C. Robin , de Leon Natalia , Kaeppler Shawn M.
Published: June 2012

Transcriptional and metabolic changes were evaluated during senescence induced by preventing pollination in the B73 genotype of maize (Zea mays). Accumulation of free glucose and starch and loss of chlorophyll in leaf was manifested early at 12 d after anthesis (DAA), while global transcriptional and phenotypic changes were evident only at 24 DAA. Internodes exhibited major transcriptomic changes only at 30 DAA. Overlaying expression data onto metabolic pathways revealed involvement of many novel pathways, including those involved in cell wall biosynthesis. To investigate the overlap between induced and natural senescence, transcriptional data from induced senescence in maize was compared with that reported for Arabidopsis (Arabidopsis thaliana) undergoing natural and sugar-induced senescence. Notable similarities with natural senescence in Arabidopsis included up-regulation of senescence-associated genes (SAGs), ethylene and jasmonic acid biosynthetic genes, APETALA2, ethylene-responsive element binding protein, and no apical meristem transcription factors. However, differences from natural senescence were highlighted by unaltered expression of a subset of the SAGs, and cytokinin, abscisic acid, and salicylic acid biosynthesis genes. Key genes up-regulated during sugar-induced senescence in Arabidopsis, including a cysteine protease (SAG12) and three flavonoid biosynthesis genes (PRODUCTION OF ANTHOCYANIN PIGMENT1 (PAP1), PAP2, and LEUCOANTHOCYANIDIN DIOXYGENASE), were also induced, suggesting similarities in senescence induced by pollination prevention and sugar application. Coexpression analysis revealed networks involving known senescence-related genes and novel candidates; 82 of these were shared between leaf and internode networks, highlighting similarities in induced senescence in these tissues. Insights from this study will be valuable in systems biology of senescence in maize and other grasses.
Therapy‐related classical Hodgkin lymphoma after a primary haematological malignancy: a report on 13 cases
Authors: Cheminant Morgane , Galicier Lionel , Brière Josette , Boutboul David , Micléa Jean‐Michel , Venon Marie‐Dominique , Robin Marie , Thieblemont Catherine , Brice Pauline
Published: June 2012

The risk of developing Hodgkin lymphoma (HL) is increased in immunodeficiencies or during the treatment of some autoimmune diseases. The development of new therapeutic agents has highlighted the risk of unusual lymphoid proliferations, particularly classical HL (cHL). We report the clinicopathological findings of 13 cHL arising in patients treated for a primary haematological malignancy. Eight patients had received an immunomodulator, protein tyrosine‐kinase inhibitor or monoclonal antibody, which may have contributed to the cHL development. Most patients had disseminated disease with poor prognostic factors at cHL diagnosis. Despite the initial presentation, good outcomes were achieved with standard cHL chemotherapy.
Combined modality therapy versus chemotherapy alone as an induction regimen for primary central nervous system lymphoma: a decision analysis
Authors: Prica Anca , Chan Kelvin , Cheung Matthew C.
Published: June 2012

In immunocompetent patients with primary central nervous system (CNS) lymphoma, combined modality therapy (CMT) using high‐dose methotrexate and whole brain radiotherapy has improved response rates compared to chemotherapy alone. The trade‐off is delayed and potentially devastating treatment‐related neurotoxicity. A Markov decision‐analytic model compared CMT to chemotherapy alone in patients with primary CNS lymphoma. Baseline probabilities were derived from a systematic literature review. Outcomes were life expectancy and quality‐adjusted life expectancy. Sensitivity analyses were performed. The life expectancy was 2·69 years for CMT and 2·77 years for chemotherapy alone. The quality‐adjusted life expectancies for the two strategies were 1·70 and 1·67 quality‐adjusted life years (QALYs) respectively. In younger patients <60 years of age, CMT yielded a quality‐adjusted life expectancy of 2·71 QALYs, compared to 2·09 QALYs for chemotherapy alone, yielding an expected benefit with CMT of 0·62 QALYs or 7·4 quality‐adjusted months. There was no difference between the strategies in the older group. The model was robust to key variables for the younger group. The preferred induction strategy for younger patients appears to be CMT, maximizing life expectancy, and QALYs. This analysis confirms that the preferred strategy for older patients is chemotherapy alone.
Shoot atmospheric contact is of little importance to aeration of deeper portions of the wetland plant Meionectes brownii; submerged organs mainly acquire O2 from the water column or produce it endogenously in underwater photosynthesis
Authors: RICH SARAH MEGHAN , PEDERSEN OLE , LUDWIG MARTHA , COLMER TIMOTHY DAVID
Published: June 2012

Partial shoot submergence is considered less stressful than complete submergence of plants, as aerial contact allows gas exchange with the atmosphere. In situ microelectrode studies of the wetland plant Meionectes brownii showed that O2 dynamics in the submerged stems and aquatic roots of partially submerged plants were similar to those of completely submerged plants, with internal O2 concentrations in both organs dropping to less than 5 kPa by dawn regardless of submergence level. The anatomy at the nodes and the relationship between tissue porosity and rates of O2 diffusion through stems were studied. Stem internodes contained aerenchyma and had mean gas space area of 17.7% per cross section, whereas nodes had 8.2%, but nodal porosity was highly variable, some nodes had very low porosity or were completely occluded (ca. 23% of nodes sampled). The cumulative effect of these low porosity nodes would have impeded internal O2 movement down stems. Therefore, regardless of the presence of an aerial connection, the deeper portions of submerged organs sourced most of their O2 via inwards diffusion from the water column during the night, and endogenous production in underwater photosynthesis during the daytime.
The effectiveness of systemic antimicrobial treatment in canine superficial and deep pyoderma: a systematic review
Authors: Summers Jennifer F. , Brodbelt David C. , Forsythe Peter J. , Loeffler Anette , Hendricks Anke
Published: June 2012

Aim – To identify and evaluate existing evidence for the effectiveness of systemic antimicrobial treatments for naturally occurring superficial and deep canine pyoderma.

Method – Electronic searches of PubMed, MEDLINE and CAB Direct were carried out (25 May 2011) without date or language restrictions. Proceedings of ESVD/ECVD, AAVD/ACVD, NAVDF and WCVD annual congresses were searched. Unpublished studies were sought via the Veterinary Dermatology discussion list and Veterinary Information Network.

Results – Seventeen full‐length, peer‐reviewed controlled trials reporting clinical outcomes of systemic antimicrobial treatment for canine pyoderma were identified. Outcomes specific to superficial or deep pyoderma were reported in nine and five studies, respectively. Five studies reported outcomes only for nondifferentiated pyoderma depth. Heterogeneity of study designs and outcome measures made meta‐analysis inappropriate. A good level of evidence was identified supporting the high efficacy of subcutaneously injected cefovecin in superficial pyoderma and for oral amoxicillin–clavulanic acid in deep pyoderma. A fair level of evidence was identified for moderate to high efficacy of oral amoxicillin–clavulanic acid, clindamycin, cefadroxil, trimethoprim–sulphamethoxazole and sulfadimethoxine–ormetoprim in superficial pyoderma and oral pradofloxacin, oral cefadroxil and subcutaneously injected cefovecin in deep pyoderma. Eleven trials reported observations of adverse effects in treated pyoderma cases by intervention group; four dogs were withdrawn owing to the severity of adverse effects.

Conclusions – There is a need for greater numbers of adequately sized, blinded, randomized controlled trials evaluating systemic antimicrobial interventions for canine pyoderma. Improved differentiation between superficial and deep pyoderma in outcome reporting, outcome measure standardization and association of outcomes with causative bacterial species and their resistance patterns are required.
First Report of Bacilliform Badnavirus‐like Virus Particles in Red Clover
Authors: Fránová Jana , Jakešová Hana
Published: June 2012

A virus detected in symptomatic Trifolium pratense L. plants in the Czech Republic had bacilliform virions which in thin sections occurred solely in phloem tissues and measured 220–500 nm by 30–31.5 nm. The virus was mechanically transmitted to Nicotiana occidentalis Wheeler, accession 37B. The partial nucleotide sequence (540 bp; accession number JX069965) with similarity to open reading frame III of the badnavirus genome was amplified from total genomic DNA, extracted from the plants. The new sequence had 74.4% nucleotide identity to that of Ananas comosus endogenous virus in the polyprotein gene covering reverse transcriptase. The results suggest that the Czech isolate from clover should be regarded as a new member of the genus Badnavirus, for which the name Red clover bacilliform virus is suggested. This is the first report of a tentative member of Badnavirus genus occurring in forage crops.
Comparison of safety and tolerability with continuous (exenatide once weekly) or intermittent (exenatide twice daily) GLP‐1 receptor agonism in patients with type 2 diabetes
Authors: Ridge T. , Moretto T. , MacConell L. , Pencek R. , Han J. , Schulteis C. , Porter L.
Published: June 2012

Aims

Exenatide is a glucagon‐like peptide‐1 receptor agonist shown to improve glycaemic control in patients with type 2 diabetes (T2DM). Intermittent exenatide exposure is achieved with the twice‐daily formulation (ExBID), while the once‐weekly formulation (ExQW) provides continuous exenatide exposure. This integrated, retrospective analysis compared safety and tolerability of ExQW vs. ExBID in patients with T2DM.

Methods

Data were pooled from two open‐label, randomized, comparator‐controlled, trials directly comparing ExQW (N = 277) to ExBID (N = 268). Between‐group differences in adverse event (AE) and hypoglycaemia incidences were calculated. Incidence over time and duration of selected AEs (nausea, vomiting, and injection‐site‐related AEs) were also summarized.

Results

The most common AEs were nausea, diarrhoea, injection‐site pruritus, and vomiting. Nausea and vomiting occurred less frequently with ExQW vs. ExBID, peaking at initiation (ExQW) or at initiation and dose escalation (ExBID), and decreasing over time. Few patients discontinued because of gastrointestinal‐related AEs. Injection‐site AEs were more common with ExQW but decreased over time in both groups. No major hypoglycaemia occurred; minor hypoglycaemia occurred with low incidence in patients not using concomitant sulphonylurea, with no difference between ExQW and ExBID. Serious AEs and discontinuations because of AEs were reported with similar frequency in both groups.

Conclusions

Both exenatide formulations were generally safe and well‐tolerated, with ExQW associated with less nausea and vomiting but more injection‐site AEs. Continuous vs. intermittent exposure did not impact the overall tolerability profile of exenatide, with no evidence of prolonged duration or worsened intensities of AEs with continuous exposure.
Selwyn, Neil et al (2010) Primary schools and ictContinuum (London) isbn978‐18553‐9578‐7 185 pp £24.99http://www.continuumbooks.com/CompanionWebsites/book‐homepage.aspx?BookId=158591
Authors: Thomas Michael
Published: June 2012

Primary schools and ict addresses the integration of information technology into primary school education in the UK. Using a mixed methods approach, it builds a unique case study of learner perspectives and outlines recommendations for the sector.

If the content of this book is likely to be relevant to you, I recommend that you borrow a copy for a while.

Michael Thomas
Maki, Peggy L (2010) Assessing for learningStylus (Sterling VA, & Eurospan, London) isbn978‐1‐57922‐441‐7 330 pp £26.50http://stylus.styluspub.com/Books/BookDetail.aspx?productID=235072
Authors: Cowan John
Published: June 2012

Target readers based in the US who are interested in current developments in higher education institutional procedures there will find this source clear and well informed. If such content is likely to be relevant to you, I recommend that you arrange to borrow a copy for a while. Possible readers in Europe and Australasia who are attracted by the title will find the text parochialand worryingly lacking in awareness of developments outside the US. Also, it is more concerned with assessment of learning, than with assessment for learning. If you are not based in the US, I would not advise you to purchase or borrow.

John Cowan
Conforming to and Resisting Dominant Gender Norms: How Male and Female Nursing Students Do and Undo Gender
Authors: McDonald James
Published: June 2012

Much existing research has shown that men are able to construct and enact masculine identities in female‐dominated occupational contexts. However, few studies have examined the experiences of both men and women in these occupations. Furthermore, few studies attend to how men and women in these occupations both conform to and resist gender norms. In this study, I draw on the undoing gender frameworks developed by Deutsch and Butler to address the limitations mentioned above. Most notably, this study attends to the ways in which male and female nursing students do gender by conforming to dominant gender norms, as well as undo gender by resisting these norms. The main contribution of this study is thus to show the multiple ways through which gender can be done and undone in the professional training of both male and female nurses. The results of this study demonstrate the importance of attending to both women and men in research on female‐dominated occupations and of examining both similarities and differences in the gender performances of men and women.
Routine outcomes monitoring as part of children and young people's Improving Access to Psychological Therapies (CYP IAPT) – improving care or unhelpful burden?
Authors: Wolpert Miranda , Fugard Andrew J.B. , Deighton Jessica , Görzig Anke
Published: June 2012

This brief commentary article considers the implications of intensive outcome monitoring which is central to children and young people's Improving Access to Psychological Therapies (CYP IAPT) in England and Wales. Services are being provided with a range of free software solutions to enable data collection, and guidance on interpretation of the measures, but there will still be some burden of data entry and collation for already overstretched services. It may be that the utility of the feedback will go some way to offset the sense of burden but this remains to be seen. Whether commissioners and others will rise to the challenge of supporting this aspect may prove crucial to the success or otherwise of such intensive ROM use. Many aspects of the CYP IAPT approach are new and whilst drawing on experience from earlier pilots of session by session monitoring in CAMHS both in the UK and abroad, and from Adult IAPT, there is likely to be much for us to learn. Time will tell whether the approach helps to improve the care children and young people receive but we are cautiously optimistic.
Anticoagulation for the treatment of thrombotic complications in patients with cirrhosis
Authors: Rodriguez‐Castro Kryssia I. , Simioni Paolo , Burra Patrizia , Senzolo Marco
Published: June 2012

Cirrhotic patients can develop thrombotic complications, which in this group of patients occur with a greater frequency than in the general population. Portal vein thrombosis (PVT) is the most common thrombotic phenomenon, although deep venous thrombosis and pulmonary embolism can also occur. Risk factors for thrombosis include inherited and acquired deficiency of factors involved in anticoagulation mechanisms, venous stasis of the portal vein owing to architectural derangement of the liver and possibly local factors related to the endothelium. Clinical manifestations of PVT range from asymptomatic disease to a life‐threatening complication, and although it is no longer considered an absolute contraindication for liver transplant, its presence may require challenging surgical techniques, which entail greater morbidity. Anticoagulation therapy is henceforth an important strategy to treat cirrhotic patients with PVT, although experience in this group of patients is limited. Vitamin K antagonists and low‐molecular‐weight heparin have been used successfully, achieving recanalization of the thrombosed vessel in patients with cirrhosis; however, the precise drug regimen management and monitoring has not be fully explored in this group of patients.
Ictal involvement of the nigrostriatal system in subtle seizures of ring chromosome 20 epilepsy
Authors: Meletti Stefano , Vignoli Aglaia , Benuzzi Francesca , Avanzini Pietro , Ruggieri Andrea , Pugnaghi Matteo , Nichelli Paolo , Canevini Maria Paola
Published: June 2012

Studies in animal models and patients with epilepsy have suggested that basal ganglia circuits may control epileptic seizures and that striatal dopaminergic transmission may play a role in seizure modulation and interruption. Chromosome 20 [r(20)] syndrome is a well‐defined chromosomal disorder characterized by epilepsy, mild‐to‐moderate mental retardation, and lack of recognizable dysmorphic features. Epilepsy is often the most important clinical manifestation of the syndrome, with prolonged episodes of nonconvulsive status epilepticus suggesting dysfunction in the seizure control system. We present the ictal blood oxygen level–dependent (BOLD) changes in brief seizures recorded by means of electroencephalography–functional magnetic resonance imaging (EEG‐fMRI) coregistration in a patient with [r(20)] syndrome. We observed ictal BOLD increments in a cortical‐subcortical network involving substantia nigrastriatum and frontal cortex. At present, this is the first functional neuroimaging evidence of the involvement of the nigrostriatal system during ictal EEG discharges in [r(20)] syndrome supporting a role of the basal ganglia circuits in human epileptic seizures.
Phenotypic presentation of the Ser63Del MPZ mutation
Authors: Miller Lindsey J. , Patzko Agnes , Lewis Richard A. , Shy Michael E.
Published: June 2012

Mutations in MPZ cause CMT1B, the second most frequent cause of CMT1. Elegant studies with Ser63del mice suggest that Ser63del MPZ is retained in the ER where it activates the unfolded protein response (UPR) that contributes to the neuropathy. Clinical information about patients with this mutation is limited. We present clinical and electrophysiological data on a large multigenerational family with CMT1B caused by Ser63del MPZ. The patients have a classical CMT1 phenotype that is much less severe than that of patients with Arg98Cys MPZ that also activates the UPR. These results suggest that clinical presentation along cannot predict which MPZ mutations will be retained in the ER and activate the UPR.