bluuebunny/crossref_metadata_2025 huggingface dataset:
Complex liquid-crystal nanostructures in semiflexible ABC linear triblock copolymers: A self-consistent field theory
Authors: Li Shiben , Jiang Ying , Chen Jeff Z. Y.
Published: November 2016

We show that two series of ABC linear triblock copolymers possess sequences of order-to-order phase transitions between microphase-separated states, as the degree of flexibility of the semiflexible middle B-blocks varies. The spatial and orientational symmetries of these phases, some of them containing liquid-crystal ordering, are analysed in comparison with related structures previously determined experimentally and theoretically. A theoretical framework based on the self-consistent field treatment of the wormlike-chain model, which incorporates the Flory-Huggins and Maier-Saupe interactions in the free energy, is used here as a basic foundation for numerical calculations. We suggest that tuning the flexibility parameter, which reduces to the concept of degree of polymerization in the coil-like limit and characterizes the chain-persistency in the rod-like limit, provides a promising approach that can be used to design the resulting microphase-separated structures in semiflexible copolymer melts.
Aberration-free and functionality-switchable meta-lenses based on tunable metasurfaces
Authors: Xu He-Xiu , Ma Shaojie , Luo Weijie , Cai Tong , Sun Shulin , He Qiong , Zhou Lei
Published: November 2016

Constructing a meta-lens with tunable meta-atoms with varactor diodes incorporated, we can precisely control the phase profile of the meta-lens by varying the external voltages imparted on the diodes, such that the dispersion-induced phase distortions at off-working frequencies can be rectified and the functionality of the meta-lens can be dynamically changed. As an illustration, we design and fabricate a tunable meta-lens in the microwave regime and employ both experiments and numerical simulations to demonstrate the aberration-free and dynamically switchable focusing performances of the meta-lens. Our approach paves the road to achieve dispersion-corrected and switchable manipulations of electromagnetic waves in the microwave regime.
Communication: Chemisorption of muonium on gold nanoparticles: A sensitive new probe of surface magnetism and reactivity
Authors: Dehn M. H. , Arseneau D. J. , Böni P. , Bridges M. D. , Buck T. , Cortie D. L. , Fleming D. G. , Kelly J. A. , MacFarlane W. A. , MacLachlan M. J. , McFadden R. M. L. , Morris G. D. , Wang P.-X. , Xiao J. , Zamarion V. M. , Kiefl R. F.
Published: November 2016

Chemisorption of muonium onto the surface of gold nanoparticles has been observed. Muonium (μ+e−), a light hydrogen-like atom, reacts chemically with uncapped 7 nm gold nanoparticles embedded in mesoporous silica (SBA-15) with a strong temperature-dependent rate. The addition rate is fast enough to allow coherent spin transfer into a diamagnetic muon state on the nanoparticle surface. The muon is well established as a sensitive probe of static or slowly fluctuating magnetic fields in bulk matter. These results represent the first muon spin rotation signal on a nanoparticle surface or any metallic surface. Only weak magnetic effects are seen on the surface of these Au nanoparticles consistent with Pauli paramagnetism.
Image pixel device using integrated organic electronic components
Authors: Swathi K. , Narayan K. S.
Published: November 2016

We report a solution processed, monolithically integrated device similar to an imaging pixel element used in complementary metal-oxide semiconductor (CMOS) based cameras. This integrated pixel essentially consists of a pair of organic photodiode (OPD) and organic field effect transistor (OFET). The signal generated by the light responsive OPD drives the OFET to different output states to quantify the light intensity. The prerequisite of a low operating voltage OFET (<2 V) was achieved using a bottom-gate, top-contact OFET consisting of a high mobility polymer semiconductor and a self-assembled hybrid dielectric layer. A bulk heterojunction blend was used as the photo-active layer in the OPD along with suitable buffer layers for charge extraction. The material parameters were optimized to realize a suitable structure which clearly demonstrated the interplay of the OPD and OFET operations, thereby forming a roadmap for all-organic CMOS arrays.
Carrier localization effects in GaAs1−xSbx/GaAs heterostructures
Authors: Maros Aymeric , Faleev Nikolai N. , Bertoni Mariana I. , Honsberg Christiana B. , King Richard R.
Published: November 2016

We investigated the structural and optical properties of GaAs1−xSbx/GaAs heterostructures grown by molecular beam epitaxy on GaAs (001) substrates for Sb concentration up to 12% by means of high-resolution X-ray diffraction and photoluminescence. The correlation between our structural and optical analysis revealed that compositional fluctuations induced localized states which trap carriers at low temperature. Under low excitation power, the photoluminescence (PL) spectra are composed of two competing peaks in the temperature range of 30–80 K. The lower energy peak is associated with transitions from localized states in the band-tail of the density of states while the higher energy peak corresponds to transitions from free carriers. A model based on a redistribution process of localized excitons was used to reproduce the S-shape behavior of the temperature dependent PL. Reducing the growth temperature from 500 °C to 420 °C suppressed the S-shape behavior of the PL indicating a reduction in compositional variation.
Effect of perpendicular magnetic field on bubble-like magnetic solitons driven by spin-polarized current with Dzyaloshinskii–Moriya interaction
Authors: Song Chengkun , Jin Chendong , Zhang Senfu , Chen Shujun , Wang Jianbo , Liu Qingfang
Published: November 2016

The topological properties of bubble-like magnetic solitons can be modified by interfacial Dzyaloshinskii-Moriya interaction (DMI). In this paper, the dynamic responses of bubble-like magnetic solitons nucleated in the free layer of the spin-torque nano-oscillators (STNOs) are investigated in the presence of DMI and the perpendicular magnetic field by using micromagnetic simulations. We observed that the oscillation frequency of bubble-like magnetic solitons can be manipulated by the perpendicular magnetic field. Moreover, the magnetic structures keep stable in small DMI. With an increase in the DMI strength, rich kinds of bubble-like magnetic solitons appear at different spin-polarized current and perpendicular magnetic field. These results provide a further understanding of bubble-like magnetic solitons structures and direct applications in STNOs.
Open-Chain Crown-Ether-Derived Two-Photon Fluorescence Probe for Real-Time Dynamic Biopsy of Mercury Ions
Authors: Huang Chibao , Zhang Daohai , Qu Junle , Liu Xiaonan , Zhao Guanglian , Yuan Tingxiang , Liu Yang
Published: November 2016

A novel two-photon fluorescence probe for Hg2+ derived from bis(styryl)terephthalonitrile, as a two-photon fluorophore, and bis[2-(2-hydroxyethyl sulfanyl) ethyl]amino group (ionophore), as a novel Hg2+ ligand, was developed. The probe possesses small molecule size, large two-photon absorption cross-section (1067 GM) in H2O, non-cytotoxic effect, long wavelength emission at 588 nm, large Stokes shift (121 nm), excellent photostability, high water solubility, good cell permeability, and pH insensitivity in the biologically relevant range. The probe can selectively detect Hg2+ ions in live cells and living tissues without interference from other metal ions and the membrane-bound probes, and its quenching constant is 8.73 × 105 M–1.
Corrigendum to: Integrated transcriptomics and metabolomics reveal induction of hierarchies of resistance genes in potato against late blight
Authors: Yogendra Kalenahalli N. , Kushalappa Ajjamada C.
Published: November 2016

Late blight caused by Phytophthora infestans is a devastating disease affecting potato production worldwide. The quantitative resistance is durable, but the underlying molecular and biochemical mechanisms are poorly understood, limiting its application in breeding. Integrated transcriptomics and metabolomics approach was used for the first time to study the hierarchies of molecular events occurring, following inoculation of resistant and susceptible potato genotypes with P. infestans. RNA sequencing revealed a total of 4216 genes that were differentially expressed in the resistant than in the susceptible genotype. Genes that were highly expressed and associated with their biosynthetic metabolites that were highly accumulated, through metabolic pathway regulation, were selected. Quantitative real-time PCR was performed to confirm the RNA-seq expression levels. The induced leucine-rich repeat receptor-like kinases (LRR-RLKs) are considered to be involved in pathogen recognition. These receptor genes are considered to trigger downstream oxidative burst, phytohormone signalling-related genes, and transcription factors that regulated the resistance genes to produce resistance related metabolites to suppress the pathogen infection. It was noted that several resistance genes in metabolic pathways related to phenylpropanoids, flavonoids, alkaloids and terpenoid biosynthesis were strongly induced in the resistant genotypes. The pathway specific gene induction provided key insights into the metabolic reprogramming of induced defence responses in resistant genotypes.
‘It depends on the consultation’: revisiting use of family members as interpreters for general practice consultations – when and why?
Authors: Hilder Jo , Gray Ben , Dowell Anthony , Macdonald Lindsay , Tester Rachel , Stubbe Maria
Published: November 2016

Family members continue to be used as interpreters in medical consultations despite the well-known risks. This paper examines participant perceptions of this practice in three New Zealand clinics chosen for their frequent use of interpreters and their skill in using them. It is based on a detailed study of 17 video-recorded interpreted consultations and 48 post-consultation interviews with participants (5 doctors, 16 patients and 12 interpreters, including 6 family members). All participants expressed satisfaction with the communication. Analysis of the interviews explored what participants liked or valued about family member interpreters (FMIs). Key themes were the FMIs’ personal relationship and knowledge, patient comfort, trust, cultural norms, time efficiency and continued help outside the consultation. General practitioners (GPs) expressed awareness of potential risks and how to manage them, in contrast to patients and FMIs. Although the use of professional interpreters needs to be strongly promoted, a well-informed decision to use a family member is appropriate in some situations. GPs need to be well trained in how to assess and manage the risks. Rather than striving for ‘best practice’ (i.e. universal use of professional interpreters), it is better to aim for ‘good practice’ where a considered judgement is made about each situation on an individual basis.
Variation and change in Italian phonology
Authors: Krämer Martin
Published: November 2016

In this paper I discuss the influence of language acquisition and borrowing on the reorganisation of grammar and lexicon in the development from Latin into Italian. We will have a look at the historical sequencing of the introduction of new phonological processes, velar palatalization, mid vowel breaking, and lateral palatalization, and how they conspire to create new contrasts or reintroduce contrasts that have been subject to neutralisation. The amphichronic analysis proposed here brings together insights from acquisition and loanword phonology in Optimality Theory to explain the historical development.
Attrition at the interfaces in bilectal acquisition (Italian/Gallipolino)
Authors: Colonna Dahlman Roberta , Kupisch Tanja
Published: November 2016

The aim of this study is to investigate whether native speakers of Gallipolino, bilectals who have acquired Gallipolino as L1 (together with standard Italian) in their childhood, who have left Gallipoli after puberty and currently use standard Italian as their primary language, display effects of attrition with respect to subordinate clauses embedded under the complementizers ku and ka. Our hypothesis is that complementizer selection in Gallipolino exhibits emergent optionality (that leads to ungrammaticality) due to influence of standard Italian. To test this hypothesis, a grammaticality judgment task has been designed and administered to 14 participants.
Electroencephalographic evidence of vowels computation and representation in human auditory cortex
Authors: Grimaldi Mirko , Manca Anna Dora , Sigona Francesco , Di Russo Francesco
Published: November 2016

By exploiting the N1 component of the auditory event related potentials we aimed to measure and localize the processing involving the spectro-temporal and the abstract featural representation. We investigated the electroencephalography patterns of 11 Salento Italian speakers discriminating their native five stressed vowels [i, ε, a, ɔ, u]. Findings showed two distinct N1 sub-components: the N1a peaking at 125–135 ms, localized in the bilateral primary auditory cortex (BA41), and the N1b peaking at 145–155 ms, localized in the superior temporal gyrus (BA22) with a strong leftward lateralization. Crucially, while high vowels elicited higher amplitudes than non-high vowels both in the N1a and N1b, back vowels generated later responses than non-back vowels in the N1b only. Overall, these findings suggest a hierarchical processing where from the N1a to the N1b the acoustic analysis shift progressively toward the computation and representation of phonological features.
Chitin oligosaccharide deacetylase from Shewanella baltica ATCC BAA-1091
Authors: Hirano Takako , Shiraishi Haruka , Ikejima Masafumi , Uehara Rie , Hakamata Wataru , Nishio Toshiyuki
Published: November 2016

Chitin oligosaccharide deacetylase (COD) from bacteria that have been examined so far typically comprise two carbohydrate-binding domains (CBDs) and one polysaccharide deacetylase domain. In contrast, Shewanella baltica ATCC BAA-1091 COD (Sb-COD) has only one CBD, yet exhibits chitin-binding properties and substrate specificities similar to those of other CODs.
Application study of 1,2-α-l-fucosynthase: introduction of Fucα1-2Gal disaccharide structures on N-glycan, ganglioside, and xyloglucan oligosaccharide
Authors: Sugiyama Yuta , Katoh Toshihiko , Honda Yuji , Gotoh Aina , Ashida Hisashi , Kurihara Shin , Yamamoto Kenji , Katayama Takane
Published: November 2016

We have recently generated a highly efficient 1,2-α-l-fucosynthase (BbAfcA N423H mutant) by protein engineering of 1,2-α-l-fucosidase from Bifidobacterium bifidum JCM 1254. This synthase could specifically introduce H-antigens (Fucα1-2Gal) into the non-reducing ends of oligosaccharides and in O-linked glycans in mucin glycoprotein. In the present study, we show an extended application of the engineered 1,2-α-l-fucosynthase by demonstrating its ability to insert Fuc residues into N- and O-glycans in fetuin glycoproteins, GM1 ganglioside, and a plant-derived xyloglucan nonasaccharide. This application study broadens the feasibility of this novel H-antigen synthesis technique in functional glycomics.
Long-Term Forensic Mental Health Services: An Exploratory Comparison of 18 European Countries
Authors: Sampson Stephanie , Edworthy Rachel , Völlm Birgit , Bulten Erik
Published: November 2016

The objective of this study was to explore current provisions within forensic mental health inpatient services for people who require longer-term care within Europe. We used a structured questionnaire and follow-up semi-structured interviews with experts in forensic psychiatry in 18 European countries. All experts interviewed acknowledged the issue of ‘long-stay’ in forensic psychiatry with patient characteristics including chronic mental disorder, treatment-resistance and violent behavior. Formal and informal definitions of ‘long-stay’ varied widely between countries. Eight experts stated that long-stay services are currently available in their country. Of the countries without long-stay services, five experts expressed a need develop them. Improved quality of life and promotion of wellbeing were emphasized as the fundamental treatment philosophy. Even without an agreed definition of ‘long-stay’, it is clear that a proportion of mentally disordered offenders (MDOs) are ‘stuck’ in ‘the system’. Experts shared common concerns in terms of political pressures to contain dangerous MDOs for ensuring public safety as well as ethical debates regarding long-term forensic mental health care. Further research is required to promote dialogue between and within countries to address the balance of patient' rights and public safety, and to produce longitudinal and economic analyses of existing long-stay forensic service provisions.
Study of instability driving inward particle flux during the formation of transport barriers at the edge of the HL-2A tokamak
Authors: Kong D.F. , Lan T. , Liu A.D. , Yu C.X. , Zhao H.L. , Shen H.G. , Yan L.W. , Dong J.Q. , Xu M. , Zhao K.J. , Cheng J. , Duan X.R. , Liu Y. , Chen R. , Sun X. , Xie J.L. , Li H. , Liu W.D.
Published: November 2016

An electrostatic coherent mode with a frequency of

20
∼
100

kHz can be observed during the formation of transport barriers in high-confinement-mode plasma in the HL-2A tokamak, using reciprocating Langmuir probes. The mode drives a strong inward particle flux measured directly with four-tip probes with values comparable to the particle flux at the striking point in the divertor, which has also been validated by the measurement of other diagnostics. Several characteristics simultaneously indicate that the mode is an ion mode excited at the edge, which plays an important role in the formation of transport barriers besides particle diffusion.
Biological Psychiatry of Cancer and Cancer Treatment
Authors: Hodgkiss Andrew
Published: November 2016

As long-term cancer survival becomes a widely shared experience, the quality of life of people living with and beyond a cancer diagnosis is increasingly important. Optimizing the prevention and treatment of any psychiatric consequences of certain tumours and treatments is now central to high-quality cancer care. This book—a rather original addition to the oncology and psycho-oncology literature—aims to equip oncology clinicians with the knowledge to more expertly prevent, detect, and manage the ‘organic’ psychiatric disorders experienced by people with cancer. It will also serve as a valuable introduction to contemporary oncology for psychiatrists.

The psychiatry of cancer is a distinct subject within the wider field of psycho-oncology. Psychiatric disorders arising through direct biological mechanisms from particular tumours or cancer treatments is a narrower topic still, but one in which oncologists are required to have expertise. This book considers in detail the psychiatric aspects of pro-inflammatory cytokines, endocrine paraneoplastic syndromes, onconeuronal antibodies, brain irradiation, hormone deprivation, glucocorticoid treatment, conventional chemotherapies, and molecularly targeted agents.
Early Prescription Opioid Use for Musculoskeletal Disorders and Work Outcomes
Authors: Carnide Nancy , Hogg-Johnson Sheilah , Côté Pierre , Irvin Emma , Van Eerd Dwayne , Koehoorn Mieke , Furlan Andrea D.
Published: November 2016

Objectives:

Musculoskeletal disorders (MSDs) are a common source of work disability. Opioid prescribing for MSDs has been on the rise, despite a lack of data on effectiveness. The objective of this study was to conduct a systematic review to determine whether early receipt of opioids is associated with future work outcomes among workers with MSDs compared with other analgesics, no analgesics, or placebo.

Methods:

MEDLINE, EMBASE, CINAHL, and CENTRAL were searched from inception to 2014 and reference lists were scanned. Studies were included if opioids were prescribed within 12 weeks of MSD onset. Eligible outcomes included absenteeism, work status, receiving disability payments, and functional status. Two reviewers independently reviewed articles for relevance, risk of bias, and data extraction using standardized forms. Data synthesis using best evidence synthesis methods was planned.

Results:

Five historical cohort studies met the inclusion criteria, all including workers filing wage compensation claims. Four studies demonstrated a significant association between early opioids and prolonged work disability. One study found a shorter time between prescriptions to be associated with shorter work disability. However, all studies were found to be at a high risk of bias and a best evidence synthesis could not be conducted. The main limitations identified were with exposure measurement and control of confounding.

Discussion:

Current literature suggests that opioids provided within the first 12 weeks of onset of an MSD are associated with prolonged work disability. However, the conclusions of these studies need testing in a high-quality study that addresses the methodological shortcomings identified in the current review.
Effective Utilization of Computerized Curricular Assistive Tools in Improving NCLEX-RN Pass Rates for a Baccalaureate Nursing Program
Authors: Shoemaker Joy R. , Chavez Ruth A. , Keane Patricia , Butz Susan , Yowler Susan K.
Published: November 2016

Achieving satisfactory first-time pass rates on the national nursing licensure examination represents a challenge for nursing programs across the United States. The consequences of examination failure for first-time test takers can be devastating, both emotionally and financially. Nursing programs are evaluated by national higher-education credentialing bodies and state boards of nursing based on the first-time pass rate of their students. One Midwestern nursing program faced unsatisfactory first-time pass rates and developed strategies for improving first-time pass rates over a 3-year period. The nursing program utilized several strategies documented in the literature but found implementing computerized curricular assistive tools that complemented the nursing program’s curriculum to be most effective. In addition, changing faculty and student culture on preparation for the national licensure examination was beneficial to all involved in the process.
Evaluation of Functional Visual Acuity in Glaucoma Patients
Authors: Ozeki Naoki , Yuki Kenya , Shiba Daisuke , Tsubota Kazuo
Published: November 2016

Purpose:

We evaluated the association between functional visual acuity (FVA) and visual fields in glaucoma patients.

Patients and Methods:

Forty-seven patients with glaucoma were enrolled (28 men, 19 women; mean age: 65.2±7.3 y; range: 38 to 82 y), and their 94 eyes were studied. Inclusion criteria were having glaucomatous optic disc abnormalities, visual field loss with glaucoma, and a best-corrected visual acuity in each eye of 1.0 (equivalent to Snellen 20/20) or better. FVA and visual maintenance ratio evaluations were made with an AS-28 FVA measurement system. To assess FVA, Landolt optotypes were displayed sequentially for 2 seconds each, and the size was reduced when the patient gave the correct answer. Humphrey automated perimetry was performed to determine mean deviation (MD) and foveal threshold, and these values were used to evaluate associations between FVA and visual field. Mean and SD was calculated for all parameters for statistical comparisons.

Results:

The MD values were −10.1±7.3 (range: −29.87 to 1.05) dB, and foveal thresholds were 34.8±2.8 (mean±SD, range: 25 to 41) dB. The logMAR FVA values were 0.14±0.17 (range: −0.14 to 0.73), and the visual maintenance ratios were 0.92±0.06 (range: 0.73 to 1.02). Linear regression analysis of the logMAR FVA values and visual field gave a MD of R=0.26 (P=0.01), and a foveal threshold of R=0.51 (P<0.001). The corresponding figures for the visual maintenance ratio and visual field were MD: R=0.25 (P=0.01) and foveal threshold: R=0.48 (P<0.001).

Conclusions:

The results of the current study showed that the logMAR FVA and visual maintenance ratio correlated moderately with foveal threshold.
Future directions in chimeric antigen receptor T cell therapy
Authors: Maude Shannon L.
Published: November 2016

Purpose of review

The impact of immunotherapy has grown exponentially in the past 5 years. Principle illustrations are encouraging results with engineered T cells expressing a chimeric antigen receptor (CAR). This experimental therapy is developing simultaneously in pediatric and adult clinical trials, making this field particularly relevant and exciting for pediatric oncologists.

Recent findings

CAR-modified T cells targeting CD19 have produced dramatic antitumor responses in patients with relapsed/refractory B cell acute lymphoblastic leukemia. Clinical trials from several institutions, in both children and adults, using distinct CAR T cell products have demonstrated similar high complete remission rates of 61–93%, with durable remissions observed. Although the development of CARs for other malignancies has lagged behind, research into novel approaches to overcome inherent challenges is promising.

Clinical trials of CAR-modified T cells have produced unprecedented results and are anticipated to have a broader impact as this approach expands into other indications, including other cancers and frontline therapy. The potential for long-term disease control, if fully realized, will have a transformative impact on the field.
Laboratory X-ray characterization of a surface acoustic wave on GaAs: the critical role of instrumental convolution
Authors: Largeau Ludovic , Camara Ibrahima , Duquesne Jean-Yves , Gourdon Catherine , Rovillain Pauline , Thevenard Laura , Croset Bernard
Published: November 2016

Surface acoustic waves of micrometre wavelength travelling on a monocrystal give diffraction satellites around each Bragg peak in an X-ray diffraction diagram. By using a four-crystal monochromator, a secondary two-crystal analyser and masks reducing the footprint to the part of the crystal containing the acoustic modulation, it is possible to observe these satellites on a GaAs (001) surface using a laboratory diffractometer. The finite extension of the satellite diffraction rods and of the crystal truncation rod perpendicular to the surface leads to geometrical correction factors when convoluted with the instrumental resolution function, which had previously been ignored. The calculation of these geometrical correction factors in the framework of the kinematic approximation allows the determination of the surface acoustic wave amplitude, and the study of its attenuation and its dependence on radiofrequency power and duty cycle. The ability to perform such determinations with a laboratory diffractometer should prove useful in optimizing surface acoustic waves, which are presently used in a broad range of condensed matter physics studies.
Small-angle scattering and morphologies of ultra-flexible microemulsions
Authors: Prevost Sylvain , Lopian Tobias , Pleines Maximilian , Diat Olivier , Zemb Thomas
Published: November 2016

The phase diagrams of ternary mixtures of partly miscible solvents containing a hydrotropic co-solvent exhibit a variable miscibility gap and one critical point. This work investigates the entire monophasic region far from and near to the miscibility gap in octan-1-ol/ethanol/water, for which ultra-flexible microemulsions (UFMEs) are observed by small-angle scattering techniques. SWAXS (combined small- and wide-angle X-ray scattering) allows the elucidation of these types of structure. Three distinct areas can be identified in the phase diagram, with scattering data resembling those from direct, bicontinuous and reverse local structures. These UFMEs are far more polydisperse than their surfactant-based counterparts. Water-rich and solvent-rich domains are only delimited by a small excess of hydrotrope, instead of a well defined surfactant layer of fixed area per molecule. It is shown that all scattering spectra obtained for the nanostructured compositions can be modelled by a simple unified analytical model composed of two uncorrelated contributions. The main one is the Ornstein–Zernike formula for composition fluctuations which gives information about the pseudo-phase domain size. The second is a Lorentzian that captures the structure of at least one of the coexisting pseudo-phases. No Porod law can be measured in the SAXS domain. The proposed expression gives access to two characteristic sizes as well as one inter-aggregate distance.
Ambivalent Precarity: Career Trajectories and Temporalities in Highly Skilled Sports Labor Migration from West Africa to Northern Europe
Authors: Agergaard Sine , Ungruhe Christian
Published: November 2016

Transnational migrants are often considered to be the core of the new global precariat. On the one hand, migrants are particularly likely to become precariats, due to the outsourcing of precarious work to migrant workers and the attribution of precarious citizenship status to migrants. On the other hand, labor migrants’ accounts show that this precarity is not exclusively based on oppression, misery, and exploitation, but that labor migration is also driven by hope and the imagination of a better future; hardships may even open up new opportunities. This article aims to scrutinize the ambivalence of precarity and the ways in which precarization processes also appear in highly skilled labor migration (in this case sought‐after jobs as transnational athletes). The article draws on material from multisited field studies among aspiring and current soccer migrants. The experiences and conditions are described for female and male soccer players who originate from various West African settings and move to Northern European locations. The analysis finds ambivalent precarization processes at various points of the career. The temporality of precarization processes becomes apparent when comparing the large number of young men and women who strive to migrate to the few individuals who become professional players abroad but often struggle with occupational challenges after their careers. The article ends by suggesting an engagement with the ambivalences of precarious work in future studies, both in sport and other vocational sectors.
Biochemical magnetic resonance imaging of knee articular cartilage: T1rho and T2 mapping as cartilage degeneration biomarkers
Authors: Le Jenna , Peng Qi , Sperling Karen
Published: November 2016

Osteoarthritis (OA) is a disease whose hallmark is the degeneration of articular cartilage. There is a worsening epidemic of OA in the United States today, with considerable economic costs. In order to develop more effective treatments for OA, noninvasive biomarkers that permit early diagnosis and treatment monitoring are necessary. T1rho and T2 mapping are two magnetic resonance imaging techniques that have shown great promise as noninvasive biomarkers of cartilage degeneration. Each of the two techniques is endowed with advantages and disadvantages: T1rho can discern earlier biochemical changes of OA than T2 mapping, while T2 mapping is more widely available and can be incorporated into existing imaging protocols in a more time‐efficient manner than T1rho. Both techniques have been applied in numerous instances to study how cartilage is affected by OA risk factors, such as age and exercise. Additionally, both techniques have been repeatedly applied to the study of posttraumatic OA in patients with torn anterior cruciate ligaments.
The Inter‐Religious Council of Sierra Leone as Peace Facilitator in Post‐1991 Sierra Leone
Authors: Anne Hurd Hilary
Published: November 2016

This essay represents the first in‐depth study of “faith‐based diplomacy” or “religious peacebuilding” in Sierra Leone. Building largely upon personal interviews with religious leaders and ex‐combatants, the study explores the role of the Inter‐Religious Council of Sierra Leone (IRCSL) as peace facilitator during three phases of Sierra Leone's civil war and aftermath (1991–present) and identifies what types of actions and strategies the IRCSL pursued in each phase. Employing Scott Appleby's typology of conflict transformation, it shows the important—yet uneven—influence of faith‐based peacemaking in Sierra Leone and concludes that both the IRCSL's reputation for “neutrality” and international support enabled its success.
… but you are not German.” – Afro‐German culture and literature in the German language classroom
Authors: Schenker Theresa , Munro Robert
Published: November 2016

Units and classes dedicated to multiculturalism in Germany have predominantly focused on Turkish‐German literature and culture. Afro‐Germans have been a minority whose culture and literature have only marginally been included in German classes, even though Afro‐Germans have been a part of Germany for centuries and have undergone efforts at establishing themselves as an organized cultural group. This article argues for a stronger focus on Afro‐German culture in German classes by providing a brief overview of Afro‐German history, outlining a sample class unit on Afro‐German poetry, and introducing an extensive list of Afro‐German texts and texts about Afro‐Germans in Germany that can be used at different levels of German. The article offers relevant background information for instructors interested in including units on the Afro‐German experience in their classes and suggests texts in a variety of genres for all language levels.
Numerical Investigation of Flow Structure and Heat Transfer Produced by a Single Highly Confined Bubble in a Pressure-Driven Channel Flow
Authors: Willard John R. , Hollingsworth D. Keith
Published: November 2016

Confined bubbly flows in millimeter-scale channels produce significant heat transfer enhancement when compared to single-phase flows. This enhancement has been demonstrated in experimental studies, and some of these studies conclude that the enhancement persists even in the absence of active nucleation sites and bubble growth. This observation leads to the hypothesis that the enhancement is driven by a convective phenomenon in the liquid phase around the bubble instead of sourcing from microlayer evaporation or active nucleation. Presented here is a numerical investigation of flow structure and heat transfer due to a single bubble moving through a millimeter-scale channel in the absence of phase change. The simulation includes thermal boundary conditions designed to match those of a recent experiment. The channel is horizontal with a uniform-heat-generation upper boundary condition and an adiabatic lower boundary condition. The Lagrangian framework allows the simulation of a channel of arbitrary length using this smaller computational domain. The fluid phases are modeled using the Volume-of-Fluid method with full geometric reconstruction of the liquid/gas interface. The liquid around the bubble moves as a low-Reynolds-number unsteady laminar flow.

In a square region from the trailing edge of the contact line to one nominal bubble diameter behind the bubble, the area-averaged Nusselt number is, at its greatest, 4.7 times the value produced by a single-phase flow. Bubble shape and speed compare well to observations from the recent experiment.

The heat transfer enhancement can be attributed to flow structures created by bubble motion. Multiple regions have been observed and are differentiated by their respective vortex characteristics. The primary region exists directly behind the bubble and exhibits the highest enhancement in heat transfer. It contains channel-spanning vortices that move cold fluid along the centerline and edge of the vortices from near the far wall of the channel to the heated wall. The cold fluid delivered by this motion tends to thin the thermal gradient region near the wall and directly behind the bubble and results in the highest local heat transfer coefficients. This vortex drives a bulk exchange of fluid across the channel and elongates the area of heat transfer enhancement to several bubble diameters. The secondary region is a set of vortices that exist to the side and slightly behind the bubble. These vortices rotate at a shallow angle to the primary flow direction and are weaker than those in the other regions.
Gas Phase Distribution Effects on Heat Transfer in Upward Vertical Bubbly Channel Flows
Authors: Hinkle Haden , Law Deify
Published: November 2016

Two-phase (non-boiling) flows have been shown to increase heat transfer in channel flows as compared with single-phase flows. The present work explores the effects of gas phase distribution such as volume fraction and bubble size on the heat transfer in upward vertical channel flows. A two-dimensional (2D) channel flow of 10 cm wide by 100 cm high is studied numerically. Numerical simulations are performed using the commercial computational fluid dynamics (CFD) code ANSYS FLUENT. The bubble size is characterized by the Eötvös number. The volume fraction and the Eötvö number are varied parametrically to investigate their effects on Nusselt number of the two-phase flows. All simulations are compared with a single-phase flow condition.
Numerical Study on the Performance of a Tube With Inserted Porous Media of Various Thermal Conductivities
Authors: Khan Tariq Amin , Li Wei
Published: November 2016

Numerical study is performed on the effect of thermal conductivity of porous media (k) on the Nusselt number (Nu) and performance evaluation criteria (PEC) of a tube. Two-dimensional axisymmetric forced laminar and fully developed flow is assumed. Porous medium partially inserted in the core of a tube is investigated under varied Darcy number (Da), i.e., 10−6 ≤ Da ≤ 10−2. The range of Re number used is 100 to 2000 and the conductivity of porous medium is 1.4 to 202.4 W/(m.K) with air as the working fluid. The momentum equations are used to describe the fluid flow in the clear region. The Darcy-Forchheimer-Brinkman model is adopted for the fluid transport in the porous region. The mathematical model for energy transport is based on the one equation model which assumes a local thermal equilibrium between the fluid and the solid phases. Results are different from the conventional thoughts that porous media of higher thermal conductivity can enhance the performance (PEC) of a tube. Due to partial porous media insertion, the upstream parabolic velocity profile is destroyed and the flow is redistributed to create a new fully develop velocity profile downstream. The length of this flow redistribution to a new developed laminar flow depends on the Da number and the hydrodynamic developing length increases with increasing Da number. Moreover, the temperature profile is also readjusted within the tube. The Nu and PEC numbers have a nonlinear trend with varying k. At very low Da number and at a lower k, the Nu number decreases with increasing Re number while at higher k, the Nu number first increases to reach its peak value and then decreases. At higher Re number, the results are independent of k. However, at a higher Da number, the Nu and PEC numbers significantly increases at low Re number while slightly increases at higher Re number. Hence, the change in Nu and PEC numbers neither increases monotonically with k, nor with Re number. Investigation of PEC number shows that at very low Da number (Da = 10−6), inserting porous media of a low k is effective at low Re number (Re ≤ 500) while at high Re number, using porous material is not effective for the overall performance of a tube. However, at a relatively higher Da number (Da = 10−2), high k can be effective at higher Re number. Moreover, it is found that the results are not very sensitive to the inertia term at lower Da number.
Effect of Prandtl Number on the Heat Transfer From a Rotating Disk: An Experimental Study
Authors: Helcig Christian , aus der Wiesche Stefan
Published: November 2016

Heat transfer coefficients were experimentally determined for a free rotating disk in still air and water. These were obtained with an electrically heated disk placed in a cylindrical pool. The accuracy of the employed experimental apparatus was assessed by heat transfer measurements in air. For this fluid, an excellent agreement with reliable literature data was found. Essentially new experimental data were obtained for water as fluid. Based upon the experimental data, the validity of theoretical correlations and the effect of the Prandtl number on the convective heat transfer from a rotating disk were discussed. It was found that in laminar water flow, the value of the correlation exponent for the Prandtl number is practically identical to 1/2 as theoretically predicted in 1948 by Dorfman. In turbulent flow, its value is better given by 1/3 as in case of the classical turbulent boundary layer theory.
Numerical Modelling of Natural Convection Driven Melting for an Inclined/Finned Rectangular Enclosure
Authors: Kabbara Moe , Kheirabadi Ali C. , Groulx Dominic
Published: November 2016

This paper presents a numerical study aimed at understanding the impact of the mushy zone constant, Amush, on simulated phase change heat transfer with varying geometries (inclination angles, and fin additions). This parameter is found in the Carman-Koseny equation, which is used in the modified heat capacity-porosity formulation for modeling phase change; this approach models fluid flow within the mushy region as flow through a porous medium. The melting of dodecanoic acid inside a rectangular thermal storage unit was simulated in COMSOL Multiphysics 4.4 with Amush being varied for each geometry. The predicted numerical melt front positions were directly compared to published experimental results [18–20]. Results have shown that the influence of Amush on the melting rate of the PCM is reduced with increasing inclination angles of the enclosure; where the melt interface is perpendicular to the direction of gravity. This has been attributed to the reduced velocity magnitudes that appear near the melt interface in such geometries. The addition of the fins showed that near the fin region Amush does not play an important role. However, it was observed that the model over predicts the velocity near the fin in the one fin model, which caused a mismatch between numerical and experimental results.
Flow and Heat Transfer Study of an Impinging Piezoelectric Fan Over a Vertical Surface
Authors: Habibi Parsa Shadi , Ghaffari Omidreza , Solovitz Stephen , Arik Mehmet
Published: November 2016

Piezoelectric fans are low-form-factor cooling devices, which have gained recent attention for electronics cooling. These devices feature a vibrating blade, which sheds vortices from its tip during its motion. The performance of a piezoelectric fan is based on its location, orientation, and operating condition. Thus, we investigated the heat transfer and flow field of an impinging flow produced by a piezoelectric fan.

The heat transfer tests are conducted using a vertical, 2.54 cm × 2.54 cm copper heater, which is configured with the piezoelectric fan positioned along its centerline. The fan is operated at its fundamental frequency of 60 Hz, where it achieves maximum heat transfer and fan deflection. There is significant heat transfer degradation with increasing heater-to-fan spacing and off-resonance operating conditions.

To better understand this thermal performance, we require information about the flow field produced by this pulsating flow. Hence, we performed particle image velocimetry (PIV) measurements of the flow field for free and impinging cases with different heater-to-fan spacing. We used instantaneous and time-averaged PIV to depict the response in a region within approximately two times the fan oscillation amplitude. In this region, there was a stagnation flow close to the heater, which would result in significant heat transfer. However, this flow also featured high-magnitude velocity vectors towards the sides of the heater rather than towards its center, which would likely result in non-uniform heat transfer.
Heat Transfer Enhancement in Split and Recombine Flow Configurations: A Numerical and Experimental Study
Authors: Jarrahi Mojtaba , Thermeau Jean-Pierre , Peerhossaini Hassan
Published: November 2016

Heat transfer enhancement in laminar regime by split and recombine (SAR) mechanism, based on the baker’s transformation, is investigated. Two different heat exchangers, called SAR1 and SAR2, are studied. Their geometries are inspired from the previous studies reported in the literature. The working fluid on both, shell and tube side, is water and the temperature on the shell side is kept constant. Experiments are carried out for the Reynolds number range 100<Re<3000 when the Prandtl number is between 4.5 and 7.5. The results show that the convective heat transfer coefficient in the first element of heat exchanger SAR1 is higher than that in the second one, i.e. SAR2. However, the variation in the convective heat transfer coefficient from the first to the third element along the heat exchanger SAR2 is less significant than that observed for SAR1. Moreover, SAR2 causes a higher pressure drop, especially when Re>1000, and provides a less uniform temperature field at the outlet.
Non-Boiling Heat Transfer of Air/Water Mist Flow in a Square Duct With Orthogonal Ribs
Authors: Huang Yi-Hsuan , Chen Chiao-Hsin , Liu Yao-Hsien
Published: November 2016

Heat transfer of mist flow in a rib-roughened square duct was experimentally determined using infrared thermography. The mist flow was generated by introducing fine dispersed water droplets into the air stream. A constant heat flux was applied to the surface during the test and the surface temperature was kept below the boiling point. The heat transfer measurement was performed on a heated surface located inside a vertical square duct with a hydraulic diameter of 4cm. The air/water mist flow was carried upward by air flow from a blower placed at the bottom of the duct. The flow passed through a flow straightener and entered the heated region of the square duct. The Reynolds numbers of the carrier fluid were 7900, 16000 and 24000.

The results showed that mist flow cooling achieved higher heat transfer rates compared to the air cooling. Thin liquid films formed on the heated surface by the mist flow and the evaporation from the droplets and liquid film contributed to a higher heat removal rate. The heat transfer enhancement on the smooth surface by the mist flow was 4 to 6 times higher compared to the air flow.

Rib turbulators were typically applied in channel walls for heat transfer enhancement in gas turbine blades or heat exchangers. Ribs caused flow reattachment and promoted flow mixing. The higher Nusselt number induced by flow reattachment can be visualized using infrared thermography. For the ribbed case, the heat transfer contours were reported based the regions between ribs. Square brass ribs were used and the rib height-to-hydraulic diameter ratio was 0.05. The rib pitch-to-height ratios were 10 and 20 in the current study.

For the mist flow in the ribbed duct, the intense flow mixing and secondary flow caused by the ribs blew away liquid films on the surface. The heat transfer enhancement near the reattachment region was mainly influenced by the droplet impingement on the surface. In the ribbed duct, the heat transfer enhancement from using the mist flow was 2.5 to 3.5 times higher compared to the air flow.