bluuebunny/crossref_metadata_2025 huggingface dataset:
Countering cultural hegemony: Audience research in the Arab world
Authors: Mellor Noha
Published: July 2014

The article provides a critical review of Arab scholarship on audience studies, focusing on the themes and different traditions adopted by Arab scholars, such as positivism versus cultural studies. Drawing on several examples of audience studies in the Arab world, I argue that this type of research has been influenced by the call to document and counter western cultural hegemony. While the majority of these studies quantitatively measure media consumption in terms of time used on these media and type of programmes watched, the underpinning assumption is the need to counter the negative impact of imported cultural programmes on Arab audiences, particularly youth. I argue that Arab researchers here are situated as experts detached from the audiences, thereby positioning themselves in a knowledge hierarchy above the subjects of their research. The review shows the implied view of Arab audiences as passive receivers of information, and potential victims of the recent technological innovation of communication.
Las nuevas carreras de medicina como símbolo: entre la legitimidad académica y la señalización de mercado
Authors: Fernandez Darraz Enrique , Bernasconi Andres
Published: July 2014

La educación médica es compleja, altamente regulada, y generalmente deficitaria. ¿Por qué una universidad habría de abrir una escuela de Medicina? Entre 1990 y 2010, el número de escuelas de Medicina en Chile aumentó de 6 a 28. Este crecimiento tuvo lugar conjuntamente con un aumento de cuatro veces en la matrícula total en educación superior, y un aumento de tres veces en los estudiantes de Medicina. La expansión de la educación médica no puede explicarse solamente en base al aumento en el acceso a la educación superior y a un incremento en la demanda por estudios de Medicina. También se requirió un aumento en la oferta de estudios de este tipo. ¿Por qué se crearon nuevas escuelas de Medicina en las universidades chilenas? ¿Sólo para crear más plazas para futuros médicos? A través de este estudio basado en entrevistas, buscamos recuperar la justificación de la creación de nuevas escuelas de Medicina en Chile en las últimas dos décadas, e interpretar los resultados bajo dos prismas teóricos: el nuevo institucionalismo organizacional, por un lado, y la teoría de la señalización (signaling), por el otro. En los relatos de los protagonistas de estos procesos encontramos evidencia tanto de la búsqueda de legitimidad académica como de la intención de dar una señal al mercado, así como una comprensión de la manera en que estos propósitos se apoyan recíprocamente, en tanto el principal beneficio anticipado por los promotores de las nuevas escuelas de Medicina fue el aumento en la reputación académica de la universidad, la cual, a su vez, serviría para reforzar su posición competitiva con respecto a otras universidades.
El peso real de la deuda de estudios. Análisis cualitativo de la trayectoria de endeudamiento de los jóvenes deudores del sistema de financiamiento universitario Corfo
Authors: Perez-Roa Lorena
Published: July 2014

A partir de un estudio cualitativo realizado con jóvenes adultos -entre 25 y 36 años- deudores de los créditos de pregrado otorgados por la Corporación de Fomento de la Producción (en adelante Corfo )y  residentes en Santiago de Chile, el presente trabajo se ocupa de analizar sus trayectoria de endeudamiento educacional. Los principales hallazgos dan cuenta de las proyecciones económicas y profesionales que los deudores asumen cuando acceden al crédito, las estrategias familiares desarrolladas para obtener y responder al crédito y las difíciles consecuencias personales y familiares que ha significado para los deudores responder a las exigencias de rembolso del crédito.
Error Analysis for the Finite Element Approximation of Transmission Eigenvalues
Authors: Cakoni Fioralba , Monk Peter , Sun Jiguang
Published: July 2014

In this paper
we consider the transmission eigenvalue problem corresponding to acoustic scattering by a bounded isotropic inhomogeneous object in two dimensions. This is a non-self-adjoint eigenvalue problem for a quadratic pencil of operators. In particular we are concerned with theoretical error analysis of a finite element method for computing the eigenvalues and corresponding eigenfunctions. Our analysis of convergence makes use of Osborn's perturbation theory for eigenvalues of non-self-adjoint compact operators. Some numerical examples are presented to confirm our theoretical error analysis.
Positive solutions of periodic type boundary value problems for first order singular functional differential equations
Authors: Kiguradze Ivan , Sokhadze Zaza
Published: July 2014

For first order singular functional differential equations, optimal sufficient conditions for the existence of positive solutions of periodic type boundary value problems are established.
Identification of a novel PHEX mutation in a Chinese family with X-linked hypophosphatemic rickets using exome sequencing
Authors: Yuan Lamei , Wu Song , Xu Hongbo , Xiao Jingjing , Yang Zhijian , Xia Hong , Liu An , Hu Pengzhi , Lu Anjie , Chen Yulan , Xu Fengping , Deng Hao
Published: July 2014

Familial hypophosphatemic rickets (HR), the most common inherited form of rickets, is a group of inherited renal phosphate wasting disorders characterized by growth retardation, rickets with bone deformities, osteomalacia, poor dental development, and hypophosphatemia. The purpose of this study was to identify the genetic defect responsible for familial HR in a four-generation Chinese Han pedigree by exome sequencing and Sanger sequencing. Clinical features include skeletal deformities, teeth abnormalities, hearing impairments and variable serum phosphate level in patients of this family. A novel deletion mutation, c.1553delT (p.F518Sfs*4), was identified in the X-linked phosphate regulating endopeptidase homolog gene (PHEX). The mutation is predicted to result in prematurely truncated and loss-of-function PHEX protein. Our data suggest that exome sequencing is a powerful tool to discover mutation(s) in HR, a disorder with genetic and clinical heterogeneity. The findings may also provide new insights into the cause and diagnosis of HR, and have implications for genetic counseling and clinical management.
Teaching a subject on leadership and intrapersonal development: some personal reflections
Authors: Dorcas Allen
Published: July 2014

A 14-week university course on Leadership and Intrapersonal development was taught in the fall of 2011 to a group of 49 undergraduate students. The teacher reflects on different aspects of the course, his experience as a teacher, his views on how the course impacted him and his students, and the need for such a course at the university. It was concluded that the course is an excellent platform to develop more critical-minded students who are better equipped to tackle university studies and life in general.
Perceived benefits of a university subject on leadership and intrapersonal development
Authors: Shek Daniel T.L. , Leung Janet T.Y.
Published: July 2014

This paper examines the perceived benefits of a university subject on leadership and intrapersonal development (“Tomorrow’s Leaders” at The Hong Kong Polytechnic University) from the perspective of the students. Based on the reflections of 62 students, several perceived benefits of the subject were identified, including promotion of self-understanding, enhancement of intrapersonal and interpersonal qualities, improvement of relationships with peers and their families, cultivation of new perspectives towards life, development of moral and ethical decision-making capacities, having better adjustment to the university life, acquisition of knowledge and skills to become effective leaders, and building up of competencies that will be useful in their future lives and career. These findings illustrate the importance of an effective university subject that attempts to promote the holistic development of young people.
A methodology for solving the one-dimensional mono-energetic
transport equation in homogeneous semi-infinite medium
Authors: Samin Adib , Ciccarello Travis , Cao Lei
Published: July 2014

In this paper,
we implement and verify an algorithm based on the
eigendecomposition method to solve the one-dimensional mono-energetic
transport equation in a semi-infinite medium with isotropic scattering.
Using our algorithm, we produce approximate closed-form expressions for the
solution. Moreover, the algorithm does not utilize a Laplace transform,
offers reasonable accuracy, and displays rapid convergence using a
relatively small number of quadrature points.
Complexity in language and in law
Authors: Sampson Geoffrey
Published: July 2014

Two kinds of objection are made to the claim that some languages are simpler than others. Many linguists have asserted that, as a matter of empirical observation, all languages are roughly equal in complexity, but very little evidence has been cited. A more weighty objection is that the claim is meaningless because the complexity of different languages is incommensurable. It may not be numerically quantifiable; but a comparison with the evolution of legal systems shows that that does not make claims of differential complexity meaningless.
Network science as a method of measuring language complexity
Authors: Vitevitch Michael
Published: July 2014

The physical, mathematical, and information sciences have developed a number of ways to measure complexity and complex systems in the social, biological, and physical domains. One way of measuring complex systems that might be useful to language scientists is the set of tools from the interdisciplinary field known as network science. A number of studies that have used the tools of network science to examine various aspects of language and language processing are summarized. It is acknowledged that much work must be done to use the tools of network science to address the debate about the (equal) complexity of languages. However, this work may prove useful to language scientists interested in the (equal) complexity of languages, as well as in other topics about language. Furthermore, the distinct structural characteristics observed in networks of several languages to date may also prove useful to network scientists as they try to understand how certain structural characteristics influence network dynamics in other domains. Language scientists are urged to embrace the techniques of network science to address the question of the complexity of languages.
Correlation between neopterin levels in premature infants with sepsis and the signs and symptoms of neonatal sepsis using the Töllner sepsis score
Authors: Anggara Mohamad Yanuar , Gurnida Dida Akhmad , Effendi Sjarif Hidajat
Published: July 2014

Neonatal sepsis in premature infants is difficult to diagnose, and available markers are still varied. Neopterin is a derivative of pyrazino-pyrimidine produced by macrophages when stimulated by interferon γ. This study aimed to measure and compare the concentration of serum neopterin between groups of neonates with and without sepsis, and its correlation with Töllner’s sepsis score (TSS). This analytic observational study with a cross-sectional design included 46 premature infants with (n=23) and without neonatal sepsis (n=23). Data analysis using the Mann-Whitney U-test was performed to compare the levels of neopterin in premature infants with and without neonatal sepsis, and the Spearman rank correlation test to determine the correlation between neopterin levels and TSS. Neopterin levels in the sepsis group were higher than in the non-sepsis group (116 vs. 41.1 nmol/L; p<0.001). This study also showed a positive correlation between neopterin levels in premature infants with neonatal sepsis and TSS (r=0.776, p<0.001). Neopterin levels were higher in premature infants with neonatal sepsis than in those without it and positively correlated with TSS.
QT-AIM analysis of neutral pterin and its anionic and cationic forms
Authors: Reibnegger Gilbert
Published: July 2014

Quantum theory of atoms in molecules (QT-AIM) allows detailed insight into the electronic structure of molecules by analysis of the gradient vector field of the electronic density distribution function. First results of a QT-AIM analysis of neutral pterin as well as its anionic and cationic forms in aqueous solution are reported based on density functional theory using B3LYP/6–311+G(2d,p)//6–31G(d) level of theory. Besides reporting QT-AIM results of the atomic partial charges and bond orders of the molecules, their electron density functions, Laplacians and electrostatic potential functions are also shown. The results demonstrate the rather extensive delocalization of both negative and positive extra charges predominantly over the pyrimidine moiety of the pterin ring system and allow a precise quantitation of the effects of addition or elimination of a proton on the bonding structure. Quantum chemical techniques in combination with QT-AIM procedures are thus well-suited to describing the bonding structure as well as the major atomic and bonding features of neutral pterin and its cationic and anionic forms. Moreover, the data demonstrate that the chosen level of theory yields chemically reasonable results while not being computationally too expensive, thus providing a sound basis for further theoretical chemical work on pteridines.
Dynamic regulation of phenylalanine hydroxylase
Authors: Fuchs Julian E. , Fuchs Dietmar , Liedl Klaus R.
Published: July 2014

Phenylalanine hydroxylase (PAH) is the key enzyme in phenylalanine metabolism, catalyzing its oxidative breakdown to tyrosine. Its function in the committed step of amino acid metabolism requires strict regulation. Thus, several regulatory mechanisms are central for an understanding of PAH at the atomistic level. The enzyme is activated by incubation with phenylalanine and inhibited by tetrahydrobiopterin binding. Furthermore, phosphorylation of Ser-16 in the regulatory domain influences enzyme turnover. All major regulatory processes in PAH are connected to the conformational changes within a protein and its oligomeric assembly. The underlying dynamic processes in the enzyme are tackled by a variety of experimental and computational approaches. We especially emphasize the computational approaches, aiming to unravel the changes in the molecular dynamics of PAH that govern allosteric regulation. State-of-the-art molecular dynamics simulations provide access to the conformational transitions in biological macromolecules at the microsecond time scale and beyond. Thus, in silico strategies are promising for the identification of the complex allosteric mechanisms governing PAH activity in vivo.
The Interaction of Bio-Molecules with Lipid Membranes Studied by X-ray Diffraction
Authors: Rheinstädter Maikel , Toppozini Laura , Dies Hannah
Published: July 2014

For the past 100 years, X-ray diffraction has been a powerful and
indispensable tool to study the structure of matter. The challenge
when studying molecular ordering in biological materials is their
inherent disorder and strong fluctuations, which often suppress the
formation of Bragg peaks. In the case of membranes, X-rays can detect
molecules inside and confined between membranes. In this article we
review examples to highlight the capabilities and accomplishments of
X-ray scattering for the determination of membrane structure. X-ray
diffraction gives quantitative information about partitioning of
a small molecule, ethanol, in lipid bilayers. By taking
amyloid-β peptides as examples, it is demonstrated that the
position of peptides in lipid membranes can be determined with high
precision. Confinement between membranes can organize molecules, as is
the case for a mono-nucleotide, adenosine monophosphate, and the
resulting pattern might be important to understand the formation of
short RNA strands. With new approaches and techniques, and the
increasingly powerful and capable devices, X-ray diffraction will
continue to be the work horse for the determination of molecular
structure in biological materials.
Mechanical Behavior Analysis of Asphalt Mixture in Meso-Scale Considering Locally Effective Material
Authors: Dong Zejiao , Gong Xiangbing , Xiao Guiqing , Sun Rongrong
Published: July 2014

Both conventional asphalt mix design and current pavement structure design method, known as macro research techniques, cannot take all micro–meso-parameters into consideration. The relationship between meso-structural information and macroscopic mechanical responses was established by using locally effective material method. First, elastic properties of asphalt mortar were obtained based on the resilient modulus test, and an appropriate moving window size was used to calculate the coarse aggregate volume fraction, which was treated as a locally homogenous distribution. Additionally, accounting for the generation of homogenous materials, a locally effective material method was implemented by a mechanical approach method for different asphalt mixtures, and then effective models for finite-element method (FEM) were established. Finally, effective models were calibrated within a small displacement domain based on the digital image correlation monitoring test, and then the FEM results illustrated the different mechanical responses, which show a more reasonable distribution than original models. In conclusion, although effective FEM model are locally equivalent materials, this approach is an effective method without lacking of the ability to figure out these meso-structural differences among various asphalt mixtures.
Small Specimen Test Techniques: 6th Volume
Authors: Sokolov Mikhail A. , Lucon Enrico
Published: July 2014

Description

Get 16 peer-reviewed papers that were presented at a symposium held January 29-31, 2014 in Houston, TX. The symposium was sponsored by ASTM International Committee E10 on Nuclear Technology and Applications and Subcommittee E10.02 Behavior and Use of Nuclear Structural Materials. The Symposium Chairpersons and STP Editors are Mikhail A. Sokolov, Oak Ridge National Lab, Oak Ridge, TN, USA and Enrico Lucon, National Institute of Standards and Technology, Boulder, CO, USA.
Sox2, a marker for stem‐like tumor cells in skin squamous cell carcinoma and hedgehog subgroup medulloblastoma
Authors: Becher Oren J , Holland Eric C
Published: July 2014

Heterogeneity within tumors is becoming increasingly recognized as an important cause of treatment failure in cancer. Two recent studies use fate‐mapping and limiting dilution transplantation assays to identify SRY (sex determining region Y)‐box 2 (Sox2) as cancer stem‐cell marker and driver of cancer stemness.
A New Dataset of Spermatogenic vs. Oogenic Transcriptomes in the Nematode Caenorhabditis elegans
Authors: Ortiz Marco A , Noble Daniel , Sorokin Elena P , Kimble Judith
Published: July 2014

The nematode Caenorhabditis elegans is an important model for studies of germ cell biology, including the meiotic cell cycle, gamete specification as sperm or oocyte, and gamete development. Fundamental to those studies is a genome-level knowledge of the germline transcriptome. Here, we use RNA-Seq to identify genes expressed in isolated XX gonads, which are approximately 95% germline and 5% somatic gonadal tissue. We generate data from mutants making either sperm [fem-3(q96)] or oocytes [fog-2(q71)], both grown at 22°. Our dataset identifies a total of 10,754 mRNAs in the polyadenylated transcriptome of XX gonads, with 2748 enriched in spermatogenic gonads, 1732 enriched in oogenic gonads, and the remaining 6274 not enriched in either. These spermatogenic, oogenic, and gender-neutral gene datasets compare well with those of previous studies, but double the number of genes identified. A comparison of the additional genes found in our study with in situ hybridization patterns in the Kohara database suggests that most are expressed in the germline. We also query our RNA-Seq data for differential exon usage and find 351 mRNAs with sex-enriched isoforms. We suggest that this new dataset will prove useful for studies focusing on C. elegans germ cell biology.
Soft Selective Sweeps in Complex Demographic Scenarios
Authors: Wilson Benjamin A , Petrov Dmitri A , Messer Philipp W
Published: July 2014

Adaptation from de novo mutation can produce so-called soft selective sweeps, where adaptive alleles of independent mutational origin sweep through the population at the same time. Population genetic theory predicts that such soft sweeps should be likely if the product of the population size and the mutation rate toward the adaptive allele is sufficiently large, such that multiple adaptive mutations can establish before one has reached fixation; however, it remains unclear how demographic processes affect the probability of observing soft sweeps. Here we extend the theory of soft selective sweeps to realistic demographic scenarios that allow for changes in population size over time. We first show that population bottlenecks can lead to the removal of all but one adaptive lineage from an initially soft selective sweep. The parameter regime under which such “hardening” of soft selective sweeps is likely is determined by a simple heuristic condition. We further develop a generalized analytical framework, based on an extension of the coalescent process, for calculating the probability of soft sweeps under arbitrary demographic scenarios. Two important limits emerge within this analytical framework: In the limit where population-size fluctuations are fast compared to the duration of the sweep, the likelihood of soft sweeps is determined by the harmonic mean of the variance effective population size estimated over the duration of the sweep; in the opposing slow fluctuation limit, the likelihood of soft sweeps is determined by the instantaneous variance effective population size at the onset of the sweep. We show that as a consequence of this finding the probability of observing soft sweeps becomes a function of the strength of selection. Specifically, in species with sharply fluctuating population size, strong selection is more likely to produce soft sweeps than weak selection. Our results highlight the importance of accurate demographic estimates over short evolutionary timescales for understanding the population genetics of adaptation from de novo mutation.
Shared Genetic Pathways Contribute to the Tolerance of Endogenous and Low-Dose Exogenous DNA Damage in Yeast
Authors: Lehner Kevin , Jinks-Robertson Sue
Published: July 2014

DNA damage that escapes repair and blocks replicative DNA polymerases is tolerated by bypass mechanisms that fall into two general categories: error-free template switching and error-prone translesion synthesis. Prior studies of DNA damage responses in Saccharomyces cerevisiae have demonstrated that repair mechanisms are critical for survival when a single, high dose of DNA damage is delivered, while bypass/tolerance mechanisms are more important for survival when the damage level is low and continuous (acute and chronic damage, respectively). In the current study, epistatic interactions between DNA-damage tolerance genes were examined and compared when haploid yeast cells were exposed to either chronic ultraviolet light or chronic methyl methanesulfonate. Results demonstrate that genes assigned to error-free and error-prone bypass pathways similarly promote survival in the presence of each type of chronic damage. In addition to using defined sources of chronic damage, rates of spontaneous mutations generated by the Pol ζ translesion synthesis DNA polymerase (complex insertions in a frameshift-reversion assay) were used to infer epistatic interactions between the same genes. Similar epistatic interactions were observed in analyses of spontaneous mutation rates, suggesting that chronic DNA-damage responses accurately reflect those used to tolerate spontaneous lesions. These results have important implications when considering what constitutes a safe and acceptable level of exogenous DNA damage.
Pre-Exercise Participation Cardiovascular Screening in a Heterogeneous Cohort of Adult Cancer Patients
Authors: Kenjale Aarti A. , Hornsby Whitney E. , Crowgey Theresa , Thomas Samantha , Herndon James E. , Khouri Michel G. , Lane Amy R. , Bishop Caroline E. , Eves Neil D. , Peppercorn Jeffrey , Douglas Pamela S. , Jones Lee W.
Published: July 2014

Background.

The purpose of this study was to investigate the extent of pre-exercise participation (“preparticipation”) health screening in a heterogeneous cohort of adult cancer patients.

Methods.

Patients (n = 413) with histologically confirmed solid or hematologic malignancy were categorized into preparticipation health screening risk stratification based on American College Sports Medicine (ACSM) recommendations. Risk of an exercise-related event was evaluated during a symptom-limited cardiopulmonary exercise test (CPET) with 12-lead electrocardiography (ECG).

Results.

Participant risk was categorized as low risk (n = 59, 14%), moderate risk (n = 217, 53%), and high risk (n = 137, 33%). Mean peak oxygen consumption was 21.7 ± 6.7 mL/kg−1 per minute−1 or 19.5 ± 21.7% below age- and sex-predicted sedentary values. No major serious adverse events or fatal events were observed during CPET procedures. A total of 31 positive ECG tests were observed, for an event rate of 8%. ACSM risk stratification did not predict the risk of a positive test. Age, statin use, antiplatelet therapy use, cardiovascular disease, prior treatment with anthracycline or radiation therapy, and being sedentary were predictors of a positive test (all p < .10).

Conclusion.

The patient risk-stratification profile strongly suggests that the use of formalized preparticipation health screening is required in all oncology scenarios; however, risk of an exercise-induced event is low, suggesting that the use of exercise testing is not required for pre-exercise clearance in the majority of patients.
Current Issues in Malignant Pleural Mesothelioma Evaluation and Management
Authors: Ai Jing , Stevenson James P.
Published: July 2014

Malignant pleural mesothelioma (MPM) is an uncommon disease most often associated with occupational asbestos exposure and is steadily increasing in worldwide incidence. Patients typically present at an older age, with advanced clinical stage and other medical comorbidities, making management quite challenging. Despite great efforts, the prognosis of MPM remains poor, especially at progression after initial treatment. Macroscopic complete resection of MPM can be achieved through extrapleural pneumonectomy (EPP) or extended (ie, radical) pleurectomy (e-P/D) in selected patients and can result in prolonged survival when incorporated into a multimodality approach. Given the morbidity associated with surgical resection of MPM, optimizing identification of appropriate patients is essential. Unfortunately, most patients are not candidates for EPP or e-P/D due to advanced stage, age, and/or medical comorbidity. Pemetrexed and platinum combination chemotherapy has become the cornerstone of therapy for patients with unresectable disease because the combination is associated with improved survival and quality of life in treated patients. However, MPM eventually becomes resistant to initial therapy, and benefit to further lines of therapy has not been substantiated in randomized clinical trials. Translational research has provided exciting insights into tumorigenesis, biomarkers, and immune response in MPM, leading to the development of multiple novel therapeutic agents that are currently in clinical trials. These advances hold the promise of a new era in the treatment of MPM and suggest that this disease will not be left behind in the war on cancer.
Effect of superplasticiser and sodium tripolyphosphate on fluidity of cement paste
Authors: Tan Hongbo , Huang Jian , Ma Baoguo , Li Xiangguo
Published: July 2014

The effect of sodium tripolyphosphate (STPP) on the fluidity of cement paste with lignin sulfonate (LS), sulfonated naphthalene formaldehyde condensate (FDN) and polycarboxylate ether (PCE) superplasticiser (SP) was studied. The adsorption amounts of LS, FDN and PCE were assessed using UV spectrophotometry and total organic carbon analysis; the concentration of Ca2+ions in solution and the adsorption amounts of STPP were tested with plasma emission spectrometry and the electrokinetic properties of the cement particles were confirmed using ζ-potential measurements. Based on analysis of the adsorption amounts, the Ca2+concentration, ζ-potential and fluidity of cement paste, the competitive adsorption between SPs and STPP was investigated. The result shows that SP and STPP can all adsorb onto the surface of cement particles and there is competitive adsorption between STPP and SP. STPP prevents Ca2+releasing and pre-empts the adsorption sites of SP; it causes a reduction in the adsorption amount of SP and increases the ζ-potential of cement particles. The SP also reduces the adsorption amount of STPP. Competitive adsorption causes changes in fluidity and fluidity loss. STPP can improve the initial fluidity and reduce fluidity loss of cement paste with LS or FDN. With PCE and STPP, the initial fluidity can be improved, but fluidity loss increases; this is due to the different molecular structure of the SPs. It is thus suggested that STPP can be used with LS and FDN to improve fluidity and reduce fluidity loss, but it is a disadvantage when used with PCE.
Biofilm Removal and Antimicrobial Activity of Two Different Air‐Polishing Powders: An In Vitro Study
Authors: Drago Lorenzo , Del Fabbro Massimo , Bortolin Monica , Vassena Christian , De Vecchi Elena , Taschieri Silvio
Published: July 2014

Background: Biofilm removal plays a central role in the prevention of periodontal and peri‐implant diseases associated with microbial infections. Plaque debridement may be accomplished by air polishing using abrasive powders. In this study, a new formulation consisting of erythritol and chlorhexidine is compared with the standard glycine powder used in air‐polishing devices. Their in vitro antimicrobial and antibiofilm effects on Staphylococcus aureus, Bacteroides fragilis, and Candida albicans are investigated.

Methods: Biofilm was allowed to grow on sandblasted titanium disks and air polished with glycine or erythritol‐chlorhexidine powders. A semiquantitative analysis of biofilm by spectrophotometric assay was performed. A qualitative analysis was also carried out by confocal laser scanning microscopy. Minimum inhibitory concentrations and minimum microbicidal concentrations were evaluated, together with the microbial recovery from the residual biofilm after air‐polishing treatment.

Results: The combination of erythritol and chlorhexidine displayed stronger antimicrobial and antibiofilm activity than glycine against all microbial strains tested.

Conclusion: Air polishing with erythritol‐chlorhexidine seems to be a viable alternative to the traditional glycine treatment for biofilm removal.
Calibrating Corn Color from Aerial Photographs to Predict Sidedress Nitrogen Need
Authors: Scharf Peter C. , Lory John A.
Published: July 2014

Supplemental N need of corn (Zea mays L.) and other crops can vary substantially within and among fields. Corn color is sensitive to N status and may provide a means to accurately match N fertilizer rates to spatially variable N needs. Our objective was to calibrate the relationship between corn color measured in aerial photographs and sidedress N need. Economic optimum N rate (EONR) at sidedress was determined in 18 yield response experiments located in production cornfields. Low‐altitude, high‐resolution aerial photographs were taken at growth stage V6 or V7 with two types of film: color positive and color infrared. The EONR ranged from 0 to 336 kg N ha−1. For both types of film, corn color was a significant predictor of EONR at sidedress but only when expressed relative to the color of well‐fertilized corn in the same field and when no N had been applied at planting. Predictions were more accurate using color film than color‐infrared film. Removal of soil pixels from the true‐color aerial images greatly strengthened the relationship between measured color and EONR: R2 values ranged from 0.27 to 0.31 for single colors measured from the entire image and from 0.60 to 0.79 after the removal of soil pixels. Our results demonstrate that corn color measured in aerial photographs can be used to predict sidedress N need. Obstacles to practical use in guiding variable‐rate sidedressing include: no N can be applied at planting, a high‐N reference strip is needed, and soil pixels must be removed from the image.
Nitrogen Use Efficiency and Apparent Nitrogen Recovery of Kentucky Bluegrass, Smooth Bromegrass, and Orchardgrass
Authors: Zemenchik Robert A. , Albrecht Kenneth A.
Published: July 2014

Nitrogen rate, grass species, and soil type may affect the efficiency of N fertilizer use by cool‐season perennial grasses of the North‐Central USA. Knowing how these factors affect apparent N recovery (ANR) and N use efficiency (NUE) could help producers reduce N losses into water resources and improve economic returns. Estimated ANR and NUE were determined for monoculture Kentucky bluegrass (Poa pratensis L.), smooth bromegrass (Bromus inermis Leyss.), and orchardgrass (Dactylis glomerata L.) in three separate experiments conducted from 1994 to 1996 on Plano silt loam (Typic Argiudoll) and Rozetta silt loam (Typic Hapludalf) near Arlington and Lancaster WI, respectively. Swards were managed in a three‐harvest system and given N fertilizer split‐applied at annual rates of 0, 56, 112, 168, 224, and 336 kg N ha−1. As expected, total forage dry matter (DM) yield increased for all species with increased N rate. Mean ANR at either location ranged from 0.28 to 0.47 kg N (kg N applied)−1 for Kentucky bluegrass, 0.17 to 0.44 for smooth bromegrass, and 0.32 to 0.50 for orchardgrass. Similarly, mean NUE ranged from 12 to 18 kg forage DM (kg N)−1 for Kentucky bluegrass, 9 to 16 for smooth bromegrass, and from 11 to 28 for orchardgrass. Relatively stable ANR values during drought, greater annual DM yields, and a more seasonally uniform growth habit suggest that orchardgrass may be the most prodigious N user among the species studied and would provide the least risk for N losses to the environment.
Accumulation of Microbial Biomass within Particulate Organic Matter of Aging Golf Greens
Authors: Kerek Mine , Drijber Rhae A. , Powers William L. , Shearman Robert C. , Gaussoin Roch E. , Streich Anne Marie
Published: July 2014

Microbial biomass (MB) is a key variable controlling soil organic matter dynamics in soil. Currently, there is little information on the amount and significance of MB in highly managed golf greens. Our objective was to determine the amount and distribution of MB within soil structural components of golf greens and its relationship to the location of organic substrates. During 1996, 47 greens were sampled from 12 golf courses within Nebraska (USA). Microbial biomass, determined as extractable lipid phosphate on field‐moist soils, increased linearly with age of green . In 1997 and 1999, selected greens were resampled and separated into mineral fraction (MF) and particulate organic matter (POM) fraction using a sodium metatungstate (NMT; ). Then, POM was separated into light (L‐POM) and heavy (H‐POM) fractions using NMT . Amount of MB of whole soil and POM was linearly related to green age (r2 = 0.76 and 0.68, respectively). Amount of MB in MF was not related to green age. The portion of total soil MB associated with POM increased significantly from 25.6% for an 8‐yr‐old green to 77.8% for a 28‐yr‐old green. Carbon in fulvic acid and humic acid increased with green age from 0.5 to 1.7 and 0.6 to 2.6 g kg−1 soil, respectively. As humus is a relatively stable form of soil organic matter, we hypothesized that humus accumulation within POM renders both POM and associated MB more resistant to degradation; thus, they accumulate.
A Regression Model to Predict Soybean Cultivar Yield Performance at Late Planting Dates
Authors: Board James E.
Published: July 2014

Proper cultivar selection increases yield for late‐planted soybean [Glycine max (L.) Merr.] in soybean–wheat (Triticum aestivum L.) double‐cropping systems in the southeastern USA. In cases where identification of high‐yielding cultivars for late planting is not practical by traditional combine‐harvest of large plots (e.g., a cultivar trial with many entries or progeny selection from a breeding program), regression models using simple characteristics obtained from small plots are a possible alternative. The objective of this study was to validate two regression models determined from previous research for their accuracy at identifying high‐yielding cultivars in independent studies. Field studies were conducted near Baton Rouge, LA (30° N lat.), on a Commerce silt loam (fine‐silty, mixed, nonacid, thermic Aeric Fluvaquents) involving a late‐planted cultivar study with 46 entries, 1994 to 1996, and a second study, 1995 to 1996, involving 19 cultivars grown under stressed (undrained waterlogged site) and nonstressed conditions (drained site, free of waterlogging). Results indicated that a regression model based on total dry matter at R5, plant height, and length of the seed‐filling period (SFP) consistently identified high‐yielding cultivars across the two studies (70–100% accuracy) and was also highly correlated with plot yield (r2 = 0.86) The second model, involving only plant height and length of the SFP, was less accurate. In conclusion, regression models using easily obtainable morphological and/or developmental characteristics can be used to identify high‐yielding cultivars at late planting dates.
Do Species Mixtures Increase Above‐ and Belowground Resource Capture in Woody and Herbaceous Tropical Legumes?
Authors: Gathumbi Stanley M. , Ndufa James K. , Giller Ken E. , Cadisch Georg
Published: July 2014

The rotation of crops with planted, N2‐fixing legumes is a promising agroforestry innovation for replenishing soil fertility in the tropics. We postulated that woody and herbaceous legumes with different growth and rooting patterns could be mixed to optimize above‐ and belowground resource capture. The objective of this study was to evaluate the effect of species interactions on resource utilization by legumes grown in mixtures on a Kandiudalfic Eutrudox in western Kenya. Four woody legume shrubs—pigeonpea [Cajanus cajan(L.) Millsp.], sesbania [Sesbania sesban(L.) Merr.], crotalaria (Crotalaria grahamianaWight and Arn.), and tephrosia (Tephrosia vogeliiHook F.)—grown in monoculture and mixed stands were evaluated for light interception, soil N and water uptake, and biomass production. Siratro [Macroptilium atropurpureum(DC.) Urb.] and groundnut (Arachis hypogaeaL.) were undersown in woody legume stands. Total aboveground biomass production ranged from 9 to 13 Mg ha−1for monoculture and 8 to 15 Mg ha−1for mixtures of woody legumes. Total N in woody‐legume stands ranged from 100 to 178 kg N ha−1. Biomass and plant N were not significantly different among woody‐legume treatments. However, undersowing siratro as a supplement increased stand productivity and recycled biomass N. Species complementarity in topsoil and subsoil utilization of mineral N was observed in crotalaria + sesbania and pigeonpea + tephrosia mixed stands. Dense soil cover created by siratro led to better conservation of soil water. Results indicated that the tested mixtures provide a better risk management strategy through compensatory growth potential. Greatest opportunities for intensifying resource utilization appear to exist through undersowing a creeping legume with an open‐canopy woody legume.
Corn Production as Affected by Tillage System and Starter Fertilizer
Authors: Vetsch Jeffrey A. , Randall Gyles W.
Published: July 2014

Potential agronomic and soil conservation benefits of modified no‐till (NT) systems make them appealing for corn (Zea mays L.) production in the northern Corn Belt where adoption of NT has been limited due to yield reductions on these colder soils. A 4‐yr (1997–2000) experiment was conducted on a high P– and K–testing Port Byron silt loam (fine silty, mixed, mesic typic Hapludoll) to determine the effects of four tillage systems [no‐till (NT), Rawson zone till (ZT), fall strip till (ST), and conventional tillage practice (CT)] on corn production and cone index (CI; penetrometer resistance) in continuous corn and corn following soybean [Glycine max (L.) Merr.]. Eight treatments, four tillage systems (main plots) with starter fertilizer at rates of 0 and 168 kg ha−1 of a 9–10–24, were arranged in a split‐plot design with four replicates. Surface residue coverage after planting was maintained at high levels (>40%) with NT, ZT, and ST, whereas coverage averaged only 25% with the CT practice. Cone index during the period of early plant growth was significantly less for the ZT and ST systems compared with the NT and CT systems, but CI did not exceed 1.3 MPa. Four‐year average yields of continuous corn grain ranked according to tillage were CT > ZT = ST > NT. A significant tillage × year interaction indicated equal yields for CT and NT in the first 2 yr but 1.0 to 1.2 Mg ha−1 less with NT in the last 2 yr. Tillage system did not significantly affect corn grain yields following soybean when averaged across years. Starter fertilizer increased yields by 0.5 Mg ha−1 on this high‐testing soil for all tillage systems in both crop rotations. Surface residue and corn yields following corn and soybean can be optimized using modified NT systems (ZT and ST) and starter fertilizer in these well‐drained, loess soils.
Harvest Date and Hybrid Influence on Corn Forage Yield, Quality, and Preservation
Authors: Darby Heather M. , Lauer Joseph G.
Published: July 2014

The selection of corn (Zea mays L.) hybrids and the timing of harvest are important management considerations for dairy and livestock operations. Objectives of this study were to determine the effect of harvest date on yield and quality of corn hybrids and to describe the relationship between harvest date and the yield and quality of corn forage, silage, and stover. During 1998 and 1999, four hybrids were harvested at eight different harvest times between 521 and 1224 growing degree units (GDUs) after planting. Few hybrid or hybrid × harvest date effects were observed. As GDUs accumulated, dry matter yield increased from 8 to 25 Mg ha−1. Lowest concentrations of neutral detergent fiber (NDF) and acid detergent fiber (ADF) and highest concentrations of in vitro true digestibility (IVTD) occurred when forage was harvested between 700 and 650 g kg−1 moisture (1025 and 1186 GDUs after planting). Potential milk yield indices of milk Mg−1 corn forage (794 kg) and milk ha−1 corn forage (19 049 Mg) were reached when corn was harvested between 670 and 630 g kg−1 moisture. In general, silage had 15% lower concentrations of NDF, 8% lower IVTD, 48% lower cell wall digestibility, 7% lower crude protein, and 15% higher concentrations of ADF than unfermented fresh forage. Harvesting can be accomplished until 580 g kg−1 moisture while maintaining 95% of the maximum yield and milk ha−1
Reinfection of Tall Fescue Cultivars with Non‐Ergot Alkaloid–Producing Endophytes
Authors: Bouton Joe H. , Latch Garrick C. M. , Hill Nicholas S. , Hoveland Carl S. , McCann Mark A. , Watson Richard H. , Parish Jane A. , Hawkins Larry L. , Thompson Frederick N.
Published: July 2014

For tall fescue (Festuca arundinaceaSchreb.) in the southeastern USA, persistence and yield are directly related to infection with a fungal endophyte [Neotyphodium coenophialum(Morgan‐Jones & Gams.) Glenn, Bacon, & Hanlin comb. nov.]. However, most endophyte‐infected (E+) tall fescue cultivars produce toxic ergot alkaloids resulting in poor weight gain and reproduction in grazing livestock. The objective of this paper was to assess the strategy of reinfecting ‘Jesup’ and ‘Georgia 5’ tall fescue with non‐ergot alkaloid–producing endophyte strains. Different cultivar–strain combinations were tested against the E+ and endophyte‐free (E−) versions of the same cultivars for stand survival and dry matter yield; in separate experiments, they were assessed for toxicity in lambs (Ovis aries). Most cultivar–strain combinations produced no ergot alkaloids but varied in ability to transmit through seed. The best combination, Jesup (AR542), possessed yield and stand survival better (P< 0.05) than the E− checks and equivalent (P< 0.05) to the E+ checks. Lambs gained an average of 124 g/d on both cultivars containing AR542, which was equivalent to gains on E− forage but approximately 57% greater than gains on E+ forage. Animals consuming forage from E− or non‐ergot‐producing strains did not exhibit depressed serum prolactin or elevated body temperatures of animals on E+ forage. The strategy of reinfecting tall fescue cultivars with naturally occurring, non‐ergot‐producing endophytes appears promising for removing toxicity symptoms and retaining agronomic performance, but intense screening is needed to identify the best cultivar–strain combinations.
Plant Population and Row‐Spacing Effects on Early Soybean Production Systems in the Mid‐Atlantic USA
Authors: Holshouser David L. , Whittaker Joshua P.
Published: July 2014

Limited information is available on early soybean [Glycine max (L.) Merr.] production systems (ESPS) in the Mid‐Atlantic USA. Furthermore, the effects of intermittent drought stress on the response of ESPS to plant population and row‐spacing alterations have not been fully explored. The objective of this research was to determine if increasing plant population and decreasing row spacing could increase yield of ESPS in the Mid‐Atlantic USA where intermittent drought is a major environmental limitation. Two maturity group (MG) III and two MG IV soybean cultivars were planted using row spacings of 23 and 46 cm and five populations ranging from 103 000 to 850 000 plants ha−1 at four locations that varied in levels of drought stress. With little drought stress, no response of soybean yield to plant population occurred. A population of 208 000 plants ha−1 was adequate for maximum yields at a site having only a brief period of stress; populations over 600 000 plants ha−1 were required to maximize yield where drought stress limited leaf area production. Narrowing row spacing increased mean leaf area index (LAI) by 0.15 and 0.30 units and yield by 100 and 290 kg ha−1 in low and moderate stress environments, respectively. Maturity group IV cultivars were better able to compensate for moisture stress periods because the stress occurred during earlier development stages compared with MG III cultivars. This research indicated that increasing LAI in ESPS via increased plant populations or narrow row spacing may increase ESPS yield, especially in environments of early season intermittent drought stress.