bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification and Characterization of Phosphoribosylpyrophosphate Synthetase from Rubber Tree Latex
Authors: Gallois R. , Prevot J. C. , Clement A. , Jacob J. L. 
Published: October 2016

Abstract
Phosphoribosylpyrophosphate synthetase (PRS; EC 2.7.6.1) from Hevea brasiliensis Mull. Arg. latex was located in the cytosol. After purification, its apparent molecular weight under nondenaturing conditions was estimated at 200,000 [plus or minus] 10,000; a single band at 57,000 [plus or minus] 3,000 was detected after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The enzyme seemed to be a homotetramer. Its affinity constants were estimated at 200 [plus or minus] 30 [mu]M for adenosine triphosphate and 40 [plus or minus] 2 [mu]M for ribose-5-phosphate. The purified enzyme proved to be functional in a paraphysiological medium (cytosol deproteinized by ultrafiltration). Optimum pH was 7.5 in buffer and 6.5 in a paraphysiological medium. No PRS activity was detected in the absence of the Mg2+ ion. Of the numerous compounds tested, only Mn2+, phosphoribosylpyrophosphate, and inorganic phosphate affected the enzymatic reaction. Mn2+ (inhibitor constant = 20 [mu]M) and phosphoribosylpyrophosphate (inhibitor constant = 30 [mu]M) were inhibitors. PRS responded allosterically (Hill's coefficient = 2.3) to ribulose-5-phosphate in the presence of a physiological concentration of inorganic phosphate (10 mM). These results are set in the physiological context of laticifers.
Evidence for Chewing Insect-Specific Molecular Events Distinct from a General Wound Response in Leaves
Authors: Korth K. L. , Dixon R. A. 
Published: October 2016

Abstract
The timing of transcript accumulation of several wound-induced genes is different in insect-damaged and mechanically damaged leaves. Transcripts for the proteinase inhibitor II and 3-hydroxy-3-methylglutaryl-coenzyme A reductase genes accumulate more rapidly in potato (Solanum tuberosum L.) leaves chewed on by caterpillars than in leaves damaged mechanically. The timing of maximum transcript accumulation was not affected by the degree of damage inflicted by the insect larvae. When applied to a mechanical wound site, regurgitant isolated from Manduca sexta larvae causes transcript accumulation profiles to shift to parallel those in insect-damaged tissue. Whether obtained from larvae fed either potato leaves or a nonplant diet, insect regurgitant fed through the petiole of detached leaves also induces accumulation of these transcripts. The transcript accumulation-inducing activity of regurgitant is enhanced by heating at 100[deg]C. Our data suggest that a heat-stable, insect-derived elicitor functions to induce the rapid accumulation of transcripts that may be involved in plant defense against herbivores. Distinct signal transduction pathways that can distinguish between insect damage and abiotic damage might therefore exist in plants.
Evidence from Polygene Mapping for a Causal Relationship between Potato Tuber Dormancy and Abscisic Acid Content
Authors: Simko I. , McMurry S. , Yang H. M. , Manschot A. , Davies P. J. , Ewing E. E. 
Published: October 2016

Abstract
In previous studies polygene mapping of a backcross population derived from haploid potato (Solanum tuberosum) and a diploid wild species (Solanum berthaultii) showed at least eight quantitative trait loci (QTLs) associated with tuber dormancy. The same population was mapped for abscisic acid (ABA) content in tubers so that any QTLs identified could be compared with those detected previously. At least three distinct loci on three chromosomes (2, 4, and 7) were associated with variation in ABA content. One of the QTLs was detected only as a main (single locus) effect, and two QTLs were found through two-locus interaction analysis (epistasis). Interaction between QTLs at markers TG234 (chromosome 2) and TG155 (chromosome 4) explained 20% of total phenotypic variance for this trait. The interaction closely resembled one previously detected for dormancy, suggesting an association between high ABA content and long tuber dormancy. Although relationships between ABA level and dormancy could be demonstrated through polygene mapping, there was no indication of a relationship between these traits when they were subjected to a conventional correlation test. This illustrates the usefulness of polygene mapping as a tool to identify possible associations between hormone levels and plant development.
Visualization of Freezing Behaviors in Leaf and Flower Buds of Full-Moon Maple by Nuclear Magnetic Resonance Microscopy
Authors: Ishikawa M. , Price W. S. , Ide H. , Arata Y. 
Published: October 2016

Abstract
1H-Nuclear magnetic resonance (NMR) microscopy was used to study the freezing behavior of wintering buds of full-moon maple (Acer japonicum Thunb.). The images obtained predominantly reflected the density of mobile (i.e. non-ice) protons from unfrozen water. A comparison of NMR images taken at different subfreezing temperatures revealed which tissues produced high- and low-temperature exotherms in differential thermal analyses. In leaf and lower buds of A. japonicum, the scales and stem bark tissues were already frozen by -7[deg]C, but the primordial inflorescence and terminal primordial shoots remained supercooled at -14[deg]C, and the lateral primordial shoots were unfrozen even at -21[deg]C. The freezing of these supercooled tissues was associated with their loss of viability. The size of the supercooled primordial shoots and inflorescences was gradually reduced with decreasing temperature, indicating extraorgan freezing in these tissues. During this process the formation of dark regions beneath the primordia and subsequent gradual darkening in the basal part of supercooled primordia were visible. As the lateral shoot primordia were cooled, the unfrozen area was considerably reduced. Since the lateral primordia remained viable down to -40[deg]C, with no detectable low-temperature exotherms, they probably underwent type I extraorgan freezing. Deep supercooling in the xylem was clearly imaged. NMR microscopy is a powerful tool for noninvasively visualizing harmonized freezing behaviors in complex plant organs.
Properties of Two Outward-Rectifying Channels in Root Xylem Parenchyma Cells Suggest a Role in K+ Homeostasis and Long-Distance Signaling
Authors: Wegner L. H. , De Boer A. H. 
Published: October 2016

Abstract
Xylem parenchyma cells (XPCs) control the composition of the transpiration stream in plants and are thought to play a role in long-distance signaling as well. We addressed the regulation, selectivity, and dependence on the apoplastic ion concentrations of two types of outward rectifiers in the plasma membrane of XPCs, to assess the physiological role of these conductances. In whole-cell recordings, the membrane conductance at depolarization was under the control of cytosolic Ca2+: at physiological Ca2+ levels (150 nM) the K+ outward-rectifying conductance (KORC) predominated, whereas at elevated Ca2+ levels (5 [mu]M), only the nonselective outward-rectifying conductance (NORC) was active. No such regulatory effect of Ca2+ was observed in inside-out experiments. The voltage dependence of whole-cell KORC currents strongly depended on apoplastic K+ concentration: an increase in apoplastic K+ resulted in a positive shift of the current-voltage curve, roughly following the shift in Nernst potential of K+. KORC is impermeable to Na+, but does translocate Ca2+ in addition to K+. In contrast to KORC, NORC selected poorly among monovalent cations and anions, the relative permeability PC+/PA- being about 1.9. Gating of NORC was largely unaffected by the level of K+ in the bath. Under all ionic conditions tested, NORC tail currents or single-channel currents reversed close to 0 mV. Using an in vivo xylem-perfusion technique, tetraethylammonium (an inhibitor of KORC) was shown to block K+ transport to the shoot. These data support the hypothesis that release of K+ to the xylem sap is mediated by KORC. The molecular properties of these two conductances are discussed in the light of the distinct physiological role of XPCs.
Finite element analysis and improved design of large-scale belt-conveyor drums
Authors: Mihailidis Athanassios , Savaidis George , Bouras Emmanouil , Athanasopoulos Emmanouil , Ganavaras Nikolaos , Topalidis Ioannis , Karageorgos Dimitrios , Rampidis Ilias 
Published: October 2016

Purpose
Large-scale belt-conveyor systems are extensively used in open mines to continuously transport bulk material. Conveyor pulleys are critical components and failures have significant financial consequences due to extended downtime. Aiming at increasing their durability, two critical spots are identified: the drum and the welds between end-plates and drum. Alternative designs have been evaluated. The paper aims to discuss these issues.

Design/methodology/approach
Loads on the driving drum are determined from measurements of the bearing force and the motor power. The friction interaction between belt and drum is described by the creep model and its impact is evaluated by comparing the results obtained for low and typical values of friction coefficient. Alternative designs are analysed using finite element method with optimised variable density mesh. The stress field and the deformations are calculated and evaluated.

Findings
Friction affects the torque transmission capacity and force distribution, but it is shown that in this case it has almost no impact on the maximum von Mises stress which occurs on the inside surface of the drum; therefore fatigue cracks initiated there, cannot be visually detected. A reinforcing diaphragm is added at the mid-plane to reduce the stress. A new, improved design is proposed to eliminate welds between the end-plates and the drum.

Research limitations/implications
The new proposed design has to be tested in the field to ultimately validate its higher durability.

Originality/value
The impact of the friction of the belt on the drum is demonstrated. The reinforcement resulting from a mid-plane diaphragm is quantitatively evaluated and assessed. A new improved pulley design is proposed aiming at significantly increased operational life compared to the one of the current design.
Cutting forces prediction and thermal distribution considering various cutting parameters and wear progression in drilling
Authors: Mirisidis Ioannis 
Published: October 2016

Purpose
The purpose of this paper is to develop a finite element method (FEM) supported simulation of drilling process applied to superficially hardened steels and assess the heat treatments effect on the optimum drilling conditions (feed rate, speed, etc.).

Design/methodology/approach
A three-dimensional model was developed simulating the drilling procedure while experimental data, concerning the chip geometry and force components, were used to validate the model. The developed simulation will allow systematically insight on the tools wear progression induced by the developed temperature and stress fields. Two different cases of simulation were examined. A typical simulation was investigated, which erected with all the standard features found in the FEM simulation software. In the second case, all the experimental data were introduced.

Findings
The simulation results revealed that the advanced developed FEM model describes sufficiently the real chip geometry. Moreover, the FEM calculations provide an effective tool for predicting occurring temperatures, strain and stresses and thus for approaching the real loads of the cutting tool during drilling.

Originality/value
This paper fulfills an identified need to study the drilling simulation.
Effects of business school student’s study time on the learning process
Authors: Tetteh Godson Ayertei 
Published: October 2016

PurposeThis paper aims to clarify the relationship between the student’s study time and the learning process in the higher education system by adapting the total quality management (TQM) principles-process approach. Contrary to Deming’s (1982) constancy of purpose to improve the learning process, some students in higher education postpone their studies till the last few weeks of an examination.Design/methodology/approachThe paper opted for an experimental study with three different classes of business school students. The experimental research question was “Do student’s study time (massed or distributed spacing) has an impact on the learning process?”FindingsResults indicated that students in the “Strictly supervised study time” group improved on their learning process more than the “Not Strictly Supervised study time” and the control group. It is important for students to manage their own learning activities and follow a regular study time and constantly improve their learning process as proposed by Deming (1982).Research limitations/implicationsThis study used restricted to undergraduate business school students in a university in Ghana, and may not necessarily be applicable universally. One other limitation was that the authors did not control for lecturer’s expectancies and how these may have influenced the students’ learning process. Another potential limitation was that TQM was the only subject area used for this study.Practical implicationsThis objective of the study is to use the TQM principles of process approach, the Learning Theory and the Learning Strategies from the Motivated Strategies for Learning Questionnaire (MSLQ) – Pintrichet al.(1991) – to support theoretical and practical implications of the relationship between the student’s study time and the learning process. The results imply that students must take a more active role in their learning by having a regular study time.Originality/valueCurrently, to the best of the authors’ knowledge, there are not many experiment-based studies on a student’s study time using the MSLQ-Pintrichet al.(1991) approach. This study contributes to the literature by examining how a student’s study time (massed or distributed spacing) has an impact on the learning process.
Segmenting students based on study abroad motivations, attitudes, and preferences
Authors: Janda Swinder 
Published: October 2016

PurposeThe purpose of this paper is to create a segmentation scheme to better understand different student groups based on their motivations, attitudes and preferences related to studying abroad.Design/methodology/approachThe study uses a two-step approach – in phase one, a series of 15 semi-structured interviews are conducted with students in an effort to uncover depth information related to key motivations, attitudes and preferences related to study abroad. This is followed up by phase two which uses the data from phase one to develop and administer an online survey to collect quantitative data related to student study abroad perceptions.FindingsResults indicate that there are two broad segments of students based on their study abroad motivations, attitudes and preferences. The larger segment, termed the “externally-motivated familiarity seekers”, represents 62 per cent of students, while the smaller segment, labeled the “internally-motivated adventure seekers” represents 38 per cent of students. Further results show that the majority of students are interested in short-term study abroad.Research limitations/implicationsThe study was conducted at one University in the Midwestern region of the USA. Further research using samples from different geographic areas would help improve efficacy of the results.Practical implicationsThe results have significant value for higher education institutions focused on optimizing their study abroad offerings to bring about a program-student fit that will create additional value for a variety of students.Originality/valueThis study is intended to understand key student motivations and preferences related to study abroad and as such provide higher educational institutions with practical insights that they can use to offer the right types of study abroad programs that will enhance value for a variety of students.
Intraspecific trait variation across multiple scales: the leaf economics spectrum in coffee
Authors: Martin Adam R. , Rapidel Bruno , Roupsard Olivier , Van den Meersche Karel , de Melo Virginio Filho Elias , Barrios Mirna , Isaac Marney E. 
Published: October 2016

Summary

Understanding species differences in plant functional traits has been critical in developing a mechanistic understanding of terrestrial ecological processes. Greater attention is now being placed on understanding the extent, causes and consequences of intraspecific trait variation (ITV).

ITV is especially important in governing ecological processes in cropping systems, where only a small number of species or genotypes exist in high abundances. However, it remains unclear if key principles of trait‐based ecology – namely the leaf economics spectrum (LES) – also describe intraspecific variation in crop functional biology. There also remains a need to understand whether ITV within crops is random, or structured across environmental, management‐related or biological levels of organization in agroecosystems.

We employed a nested design field survey to evaluate ITV in leaf traits in coffee (Coffea arabica), one of the world's most widespread tropical crops. We evaluated ITV in eight physiological, morphological and chemical leaf traits, across five nested categorical levels (sites, management systems, spatial location, plant identity, branch identity). We compared patterns of LES trait covariation in coffee, to interspecific patterns observed across over 700 wild plant species.

Patterns of bivariate and multivariate ITV in coffee were broadly consistent with, but considerably weaker than, interspecific patterns associated with the LES, indicating that crops may systematically diverge from global patterns of trait trade‐offs observed in wild plants.

Physiological traits varied most widely (coefficient of variation (cv) 42–107%), followed by morphological traits (cv = 15–38%) and chemical traits (cv = 3–11%). Physiological ITV was best explained by the site in which a coffee plant was growing (17–55% explained), while ITV for chemical traits was best explained by management treatments within sites (25–36%); morphological ITV was higher even at the individual tree level or branch level and remained largely unexplained.

Our results support the hypothesis that artificial selection and high‐resource agricultural environments lead crops to systematically deviate from patterns of leaf trait covariation observed across wild plants species. Coupled with an understanding of how different traits vary systematically across multiple levels of biological organization, these findings help integrate ITV into future analyses of agroecosystem structure and function.

A lay summary is available for this article.
Plant communication in a widespread goldenrod: keeping herbivores on the move
Authors: Morrell Kimberly , Kessler André 
Published: October 2016

Summary

Plant communication has been documented in over 35 plant species spanning 16 families to date; however, the underlying mechanisms through which it shapes plants' ecological interactions remain less clear.

Using a combination of field/laboratory bioassays, headspace volatile and leaf chemical analyses in tall goldenrod (Solidago altissima), we tested the hypothesis that plant‐to‐plant communication affects the performance, feeding and movement behaviour of herbivores by changing plants' chemical phenotypes.

We found that plant communication accelerates herbivore movement between host plants while simultaneously reducing herbivory. This suggests that plant communication can limit herbivore loads by keeping herbivores on the move between host plants.

We demonstrate that volatile chemicals emitted from herbivore‐attacked plants are sufficient to explain metabolic responses in and ecological consequences for the exposed neighbour plant. Volatile profiles of beetle (Trirhabda virgata)‐damaged and undamaged plants show substantial compositional differences, especially in sesquiterpene emission, indicating that these differences have the potential to provide neighbouring plants with specific information about herbivores in the vicinity.

Despite qualitative and phenological differences in plants' metabolic responses to herbivory‐induced volatile organic compounds (VOCs) and feeding herbivores, herbivores nonetheless respond similarly to directly damaged plants and plants exposed to VOCs from damaged neighbours as if they were of equivalently poor quality.

This study suggests that by enlarging the spatial scale at which induced resistance affects the distribution of plant chemical phenotypes in plant populations, VOC‐mediated plant communication alters the movement behaviour and performance of herbivores.

A lay summary is available for this article.
Disparities in Diabetes Care Quality by English Language Preference in Community Health Centers
Authors: Leung Lucinda B. , Vargas‐Bustamante Arturo , Martinez Ana E. , Chen Xiao , Rodriguez Hector P. 
Published: October 2016

ObjectiveTo conduct a parallel analysis of disparities in diabetes care quality among Latino and Asian community health center (CHC) patients by English language preference.Study Setting/Data CollectionClinical outcomes (2011) and patient survey data (2012) for Type 2 diabetes adults from 14 CHCs (n = 1,053).Study DesignWe estimated separate regression models for Latino and Asian patients by English language preference for Clinician & Group—Consumer Assessment of Healthcare Providers and System, Patient Assessment of Chronic Illness Care, hemoglobin A1c, and self‐reported hypoglycemic events. We used the Blinder–Oaxaca decomposition method to parse out observed and unobserved differences in outcomes between English versus non‐English language groups.Principal FindingsAfter adjusting for socioeconomic and health characteristics, disparities in patient experiences by English language preference were found only among Asian patients. Unobserved factors largely accounted for linguistic disparities for most patient experience measures. There were no significant differences in glycemic control by language for either Latino or Asian patients.ConclusionsGiven the importance of patient retention in CHCs, our findings indicate opportunities to improve CHC patients' experiences of care and to reduce disparities in patient experience by English preference for Asian diabetes patients.
Dermatofibrosarcoma Protuberans: A comprehensive review on the spectrum of clinico‐radiological presentations
Authors: Sung Tony HT , Tam Annie CW , Khoo Jennifer LS 
Published: October 2016

SummaryDermatofibrosarcoma Protuberans (DFSP) is a rare malignant soft‐tissue neoplasm which is often misdiagnosed due to its indolent clinical course and non‐specific radiological appearances. An observation case series was conducted with retrospective review of clinical and radiological data of DFSP patients presenting to a major tertiary hospital in Hong Kong for radiological assessment between November 2006 and February 2016. Seven patients with confirmed histological diagnosis of DFSP were included. Tumour sizes at presentation ranged from 1 to 5 cm, most commonly (n = 6) occurred over chest wall and abdominal wall. History of previous local trauma or surgery was identified in the majority of cases (n = 4). There was poor correlation between pre‐imaging clinical diagnoses and pathological diagnoses. Local recurrence and tumour de‐differentiation with sarcomatous changes occurred in the minority of cases (n = 2). A common radiological ‘claw’ sign at the lesion/skin interface formed by elongated appendages of the tumour superficially was appreciated in most cases (n = 6). A history of previous local trauma or surgery serves as a possible etiological factor for the development of DFSP. High clinical suspicion for the entity is essential in its detection and differentiation from simple wound complications and local recurrence of other benign lesions. The radiological ‘claw’ sign at the lesion/skin interface might serve as a tell‐tale sign for cutaneous tumour involvement. A comprehensive analysis of imaging findings in conjunction with individual clinical presentations is the key to accurate diagnoses and proper management.