bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethylene Propylene Rubber Polyampholytes and their Blends with Polypropylene as an Alternative to Chemically Cross‐Linked Thermoplastic Elastomers and Thermoplastic Vulcanizates
Authors: Powell Andrew , Kontopoulou Marianna , Hojabr Sassan
Published: July 2013

An ethylene propylene rubber polyampholyte (EPR‐g‐PA) containing zwitterionic ammonium carboxylate grafts is prepared by reacting maleated EPR (EPR‐g‐MAn) with a tertiary amino alcohol, 2‐[2‐(dimethylamino)ethoxy]ethanol (DMAEE). EPR‐g‐PA has equivalent viscoelastic properties to an EPR that is lightly cross‐linked using a peroxide cure, but with a higher strain hardening coefficient and elongation at break. EPR‐g‐PA has similar adhesion to metals and improved adhesion to other ionomers, whereas the adhesive strength to a polyamide substrate is reduced compared to the EPR‐g‐MAn. The in situ reaction of EPR‐g‐MAn with DMAEE during blending with PP produced a blend with superior impact properties compared to the thermoplastic vulcanizate (TPV) blend of peroxide cross‐linked EPR‐g‐MAn and PP.
Rare disease centers for periodic paralysis: China versus the United States and United Kingdom
Authors: Ke Qing , Qi Ming , Wu Weiping , Luo Benyan , Hanna Michael , Herr Barbara , Griggs Robert C. ,   the Consortium for Investigation of Neurological Channelopathies (CINCH)
Published: July 2013

Introduction: We have developed a rare disease center in China. Methods: In this study we analyzed how patients with periodic paralysis accessed centers in China vs. in the USA and UK. Results: A total of 116 patients with periodic paralysis were evaluated in Beijing and Hangzhou (2003–2012). These patients traveled long distances for outpatient specialist care without an appointment or physician referral. In contrast, at the University of Rochester in the USA, >90% of patients were referred from physicians throughout the country by identifying physician expertise or by referrals from a patient advocacy group. In the UK, a single center, supported by the National Health Service, provides assessment/genetic testing for all UK patients. Conclusions: Rare disease centers in China require: (1) establishing a center for clinical characterization of the disease (e.g., periodic paralysis); (2) establishing a genetic diagnostic platform; (3) placing the center at a major city hospital; and (4) facilitating patient access through internet websites. Muscle Nerve 49: 171–174, 2014
Feature selection for motor unit potential train characterization
Authors: Abdelmaseeh Meena , Smith Benn , Stashuk Daniel
Published: July 2013

Introduction: Ten new features of motor unit potential (MUP) morphology and stability are proposed. These new features, along with 8 traditional features, are grouped into 5 aspects: size, shape, global complexity, local complexity, and stability. Methods: We used sequential forward and backward search strategies to select subsets of these 18 features to discriminate accurately between muscles whose MUPs are predominantly neurogenic, myopathic, or normal. Results and Conclusions: Results based on 8102 motor unit potential trains (MUPTs) extracted from 4 different limb muscles (n = 336 total muscles) demonstrate the usefulness of these newly introduced features and support an aspect‐based grouping of MUPT features. Muscle Nerve 49: 680–690, 2014
Structure and NMR properties of 6‐substituted‐5,6‐dihydrobenzo[c]phenanthridine alkaloids
Authors: Kadam Shivaji S. , Maier Lukáš , Šolomek Tomáš , Nečas Marek , Šmejkal Karel , Dostál Jiří , Sklenář Vladimír , Marek Radek
Published: July 2013

We report a preparation of new 6‐substituted‐5,6‐dihydrobenzo[c]phenanthridines by the reaction of azoles with quaternary benzo[c]phenanthridine alkaloids sanguinarine and chelerythrine. The prepared compounds have been characterized by NMR spectroscopy, mass spectrometry, and single‐crystal X‐ray diffraction. Conformational behaviors of carbazole derivatives in solution have been investigated by low‐temperature NMR experiments. Barriers to rotation around newly formed C6–N bonds were determined to be 12–13 kcal/mol. Quantum chemical calculations have been used to reproduce the experimental observations. Large structural effects on several 1H NMR resonances were observed experimentally, analyzed by Density Functional Theory (DFT) calculations at B3LYP/6‐311+G(d,p)/PCM level, and interpreted by ring‐current effects of the benzo[c]phenanthridine and carbazole units. Copyright © 2013 John Wiley & Sons, Ltd.
Withdrawing life‐extending drugs at the end of life
Authors: Abel Julian
Published: July 2013

Our series on stopping drugs provides practical advice on why, when and how to withdraw drug therapy. Here the author discusses the reasons for discontinuing life‐extending medications during end‐of‐life care.
Current choice of treatment for hypo‐ and hyperthyroidism
Authors: Weetman Anthony
Published: July 2013

Thyroid dysfunction is a common disorder and most cases of hypothyroidism are managed in general practice. Our Drug review discusses the currently available drug treatments for hypo‐ and hyperthyroidism, followed by sources of further information in Resources.
Mirabegron: new treatment for OAB with fewer side‐effects
Authors: Chaplin Steve , Chapple Christopher
Published: July 2013

Mirabegron (Betmiga) is a new class of drug for the treatment of overactive bladder. In our New products review, Steve Chaplin presents the clinical data relating to its efficacy and adverse events, and Professor Chapple discusses its place in treatment compared with anticholinergics.
Investigation of carrier spill‐over in InGaN‐based light‐emitting diodes by temperature dependences of resonant photoluminescence and open‐circuit voltage
Authors: Han Dong‐Pyo , Kang Min‐Goo , Oh Chan‐Hyoung , Kim Hyunsung , Kim Kyu‐Sang , Shin Dong‐Soo , Shim Jong‐In
Published: July 2013

In InGaN‐based light‐emitting diodes (LEDs), carrier leakage to the outside of the active quantum wells (QWs) has been considered as one of the dominant carrier loss mechanisms at high current densities. In order to verify the carrier spill‐over phenomenon, we compared the electroluminescence (EL) efficiency, the resonant photoluminescence (PL) efficiency, and the open‐circuit voltage as functions of current, temperature, and excitation laser power. Very similar tendencies were experimentally observed among the three physical quantities, which implied that carriers were spilt over out of the QWs even in the resonant PL experiment.
Density functional theory study of the impact of tin doping on oxygen diffusion in Czochralski silicon
Authors: Gao Chao , Ma Xiangyang , Yang Deren
Published: July 2013

The impact of tin (Sn) doping on interstitial oxygen (Oi) diffusion in Czochralski silicon is investigated by density functional theory (DFT) calculations. Two aspects are taken into consideration: (i) Sn induced lattice strain and lattice expansion; (ii) direct and vacancy‐mediated interaction between Sn and Oi atoms. The calculations show that the interstitial oxygen migration energy barrier increases with increasing lattice constant which grows with the concentration of Sn. Structure analysis indicates that the geometric parameters such as the bond length and the angle of SiOSi configuration also increase with the lattice constant, which is considered to be the origin of the increased energy barrier for oxygen diffusion. SnO pair formation is found to be energetically unfavorable, while the SnVO complexes have a large binding energy. Sn is however able to trap Oi atoms by stimulating vacancy generation around it, which increases the oxygen diffusion energy barrier as well. It is thus predicted that oxygen diffusion in silicon with a high concentration of Sn atoms will be retarded.
Efficiency enhancement of Cu(In,Ga)Se2 thin‐film solar cells by a post‐deposition treatment with potassium fluoride
Authors: Laemmle Anke , Wuerz Roland , Powalla Michael
Published: July 2013

Alkali‐free Cu(In,Ga)Se2(CIGS) absorbers grown on Mo‐coated alumina (Al2O3) substrates were doped with potassium (K) after CIGS growth by a potassium fluoride (KF) post‐deposition treatment (PDT). The addition of K to the absorber leads to a strong increase in cell efficiency from 10.0% for the K‐free cell to 14.2% for the K‐doped cell, mainly driven by an increase in the open‐circuit voltage Voc and the fill factor FF, and to an increase in the net charge carrier density. Hence K doping by KF‐PDT is comparable to doping with Na.

magnified image

J –V characteristics of a CIGS solar cell with KF‐PDT (red solid line) and of a K‐free reference cell without treatment (black dashed line). The solar cell treated with K shows a strong increase in Voc and FF compared to the solar cell without K.

(© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unusual domain configurations and local piezoresponse in the [720]‐cut BaTiO3 single crystal
Authors: Zeng H. R. , Sun F. , Zhao K. Y. , Li F. X. , Zhang X. W. , Chu R. Q. , Luo H. S. , Li G. R.
Published: July 2013

The domain configurations and local piezoresponse property of the [720]‐cut BaTiO3 single crystal and [001]‐oriented BaTiO3 crystal were investigated by high‐resolution piezoresponse force microscopy. Large differences in their surface topography features, domain configurations and local piezoresponse were found between [720]‐cut and [001]‐oriented BaTiO3 crystals. The large surface bending angle due to ferroelastic domain walls leads to a high strain energy appearing in the [720]‐cut BaTiO3, further resulting in unique band‐like topographic features, needle domains for stress compensation and locally ultrahigh piezoelectric response as well. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quality Changes of Extra Virgin Olive Oil Packaged in Coloured Polyethylene Terephthalate Bottles Stored Under Different Lighting Conditions
Authors: Rizzo Valeria , Torri Luisa , Licciardello Fabio , Piergiovanni Luciano , Muratore Giuseppe
Published: July 2013

In this paper, the influence of light storage and the exposure on quality parameters of a monovarietal extra virgin olive oil packaged in polyethylene terephthalate (PET) bottles were investigated. Coloured PET bottles (clear, green, orange, white and blue) were stored under different artificial lighting conditions in order to simulate the market environment (one fluorescent cool white lamp) and to perform an accelerated test (four fluorescent cool white lamps); storage in the dark was considered as a control. Total peroxide value, polyphenols, chlorophyll and carotenoids contents were, among the ones tested, the quality indexes most affected by lighting and were useful to investigate the bottle colour influence. Concerning the global quality of olive oil, under one fluorescent lamp, the best performances were obtained using blue and white PET bottles; whereas under accelerated conditions, the differences in the protection efficacy offered by the differently coloured bottles were reduced. Copyright © 2013 John Wiley & Sons, Ltd.
Four‐dimensional tensor equations for a classical fluid in an external gravitational field
Authors: Charron Martin , Zadra Ayrton , Girard Claude
Published: July 2013

A four‐dimensional tensor formalism suitable for the equations of motion of a classical fluid in the presence of a given external gravitational field is presented. The formalism allows for arbitrary time‐dependent transformations of spatial coordinates. Some well‐known conservation laws are derived in covariant form. The metric tensor and the associated Christoffel symbols are calculated for coordinate systems useful in meteorology. The vertical momentum equation employed in the Canadian operational weather forecasting model is obtained using the proposed tensor formalism.
Hydrogen isotope ratio mass spectrometry and high‐resolution/high‐accuracy mass spectrometry in metabolite identification studies: Detecting target compounds for sports drug testing
Authors: Thevis Mario , Piper Thomas , Horning Stevan , Juchelka Dieter , Schänzer Wilhelm
Published: July 2013

RATIONALE

In sports drug testing, comprehensive studies on the metabolism of therapeutic agents with misuse potential are necessary to identify metabolites that provide utmost retrospectivity and specificity. By commonly employed approaches minor and/or long‐term metabolites in urine might remain undetected. Hence, an alternative strategy to unambiguously identify the majority of urinary metabolites including low‐abundance representatives is desirable.

METHODS

Urine samples were collected for 20 days during an elimination study with an oral dose of 5 mg of 17α‐C2H3‐metandienone. The specimens were processed according to established sample preparation procedures (including fractionation and deconjugation) and subjected to gas chromatography/hydrogen isotope ratio mass spectrometry (GC/IRMS) analysis. Due to the deuteration of the administered drug, urinary metabolites bearing the deuterium label yield abundant and specific signals on the GC/IRMS instrument resulting from the substantially altered 2H/1H ratio. The sample aliquots were measured by gas chromatography/time‐of‐flight (GC/Q‐TOF) mass spectrometry using identical GC conditions, allowing high‐resolution/high‐accuracy mass data to be obtained on all urinary metabolites previously identified by IRMS.

RESULTS

Within the IRMS chromatograms, labeled metabolites were identified up to 20 days after administration at urinary concentration down to 0.25 ng/mL. More than 50 metabolites were observed with the earlier described long‐term metabolite of metandienone, 18‐nor‐17β‐hyroxymethyl,17α‐methyl‐androst‐1,4,13‐trien‐3‐one, being the most prominent glucuronidated metabolite in the studied time window. In the sulfoconjugated steroids fraction, a yet unknown metabolite was observed at m/z 283.1997 comprising the experimentally determined elemental composition of C20H212H3O.

CONCLUSIONS

Combining IRMS with high‐resolution mass spectrometry considerably facilitates and accelerates metabolite identification of deuterium‐labeled compounds in urine. Of particular relevance in doping control, the principle is applicable also to other arenas of drug research, allowing the preparation and administration of e.g. radioactively labeled substances to be omitted. © 2013 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd.
Ionospheric observations of underground nuclear explosions (UNE) using GPS and the Very Large Array
Authors: Park Jihye , Helmboldt Joseph , Grejner‐Brzezinska Dorota A. , von Frese Ralph R. B. , Wilson Thomas L.
Published: July 2013

Observations from Global Positioning System (GPS) receivers and the Very Large Array (VLA) radio telescope recorded traveling ionospheric disturbances (TID) from underground nuclear explosions (UNEs), detonated in September 1992. The slant TEC (STEC) data derived from GPS observations were processed for all ray paths to isolate TIDs. For the TIDs from the Hunters Trophy test on 18 September 1992 and the Divider test on 23 September 1992, the propagated mean velocities of the TIDs were about 573 m/s and 740 m/s with standard deviations of 85 m/s and 135 m/s, respectively. For the VLA observations, the spectral analysis produced three‐dimensional fluctuation spectral cubes for the Hunters Trophy event. The arrival time of the TID at the VLA implied a propagation speed of 570–710 m/s. This study suggests the global availability of GNSS tracking networks and new low‐frequency (VHF) radio telescopes may offer a method of UNE detection and characterization, which could complement the International Monitoring System (IMS).
Misunderstanding Metatheorizing
Authors: Edwards Mark G.
Published: July 2013

Metatheorizing is an important but generally poorly understood genre of social science inquiry that has particular relevance to systems research. In this paper, I define and present the major characteristics of metatheoretical research, discuss why it is neglected as a form of research and how it is often misunderstood and inadequately represented in the systems and management science literature. I illustrate the discussion with some examples of misunderstanding of metatheorizing from the systems science literature. I also make some recommendations for how researchers can improve their own metatheorizing and so, hopefully, help this important form of research become more widely acknowledged and critically appreciated. Copyright © 2013 John Wiley & Sons, Ltd.
Enrichment of human embryonic stem cell-derived NKX6.1-expressing pancreatic progenitor cells accelerates the maturation of insulin-secreting cells in vivo
Authors: Rezania Alireza , Bruin Jennifer E. , Xu Jean , Narayan Kavitha , Fox Jessica K. , O'Neil John J. , Kieffer Timothy J.
Published: July 2013

Human embryonic stem cells (hESCs) are considered a potential alternative to cadaveric islets as a source of transplantable cells for treating patients with diabetes. We previously described a differentiation protocol to generate pancreatic progenitor cells from hESCs, composed of mainly pancreatic endoderm (PDX1/NKX6.1-positive), endocrine precursors (NKX2.2/synaptophysin-positive, hormone/NKX6.1-negative), and polyhormonal cells (insulin/glucagon-positive, NKX6.1-negative). However, the relative contributions of NKX6.1-negative versus NKX6.1-positive cell fractions to the maturation of functional β-cells remained unclear. To address this question, we generated two distinct pancreatic progenitor cell populations using modified differentiation protocols. Prior to transplant, both populations contained a high proportion of PDX1-expressing cells (∼85%–90%) but were distinguished by their relatively high (∼80%) or low (∼25%) expression of NKX6.1. NKX6.1-high and NKX6.1-low progenitor populations were transplanted subcutaneously within macroencapsulation devices into diabetic mice. Mice transplanted with NKX6.1-low cells remained hyperglycemic throughout the 5-month post-transplant period whereas diabetes was reversed in NKX6.1-high recipients within 3 months. Fasting human C-peptide levels were similar between groups throughout the study, but only NKX6.1-high grafts displayed robust meal-, glucose- and arginine-responsive insulin secretion as early as 3 months post-transplant. NKX6.1-low recipients displayed elevated fasting glucagon levels. Theracyte devices from both groups contained almost exclusively pancreatic endocrine tissue, but NKX6.1-high grafts contained a greater proportion of insulin-positive and somatostatin-positive cells, whereas NKX6.1-low grafts contained mainly glucagon-expressing cells. Insulin-positive cells in NKX6.1-high, but not NKX6.1-low grafts expressed nuclear MAFA. Collectively, this study demonstrates that a pancreatic endoderm-enriched population can mature into highly functional β-cells with only a minor contribution from the endocrine subpopulation.
In situ mechanotransduction via vinculin regulates stem cell differentiation
Authors: Holle Andrew W. , Tang Xinyi , Vijayraghavan Deepthi , Vincent Ludovic G. , Fuhrmann Alexander , Choi Yu Suk , Álamo Juan C. , Engler Adam J.
Published: July 2013

Human mesenchymal stem cell (hMSC) proliferation, migration, and differentiation have all been linked to extracellular matrix stiffness, yet the signaling pathway(s) that are necessary for mechanotransduction remain unproven. Vinculin has been implicated as a mechanosensor in vitro, but here we demonstrate its ability to also regulate stem cell behavior, including hMSC differentiation. RNA interference-mediated vinculin knockdown significantly decreased stiffness-induced MyoD, a muscle transcription factor, but not Runx2, an osteoblast transcription factor, and impaired stiffness-mediated migration. A kinase binding accessibility screen predicted a cryptic MAPK1 signaling site in vinculin which could regulate these behaviors. Indeed, reintroduction of vinculin domains into knocked down cells indicated that MAPK1 binding site-containing vinculin constructs were necessary for hMSC expression of MyoD. Vinculin knockdown does not appear to interfere with focal adhesion assembly, significantly alter adhesive properties, or diminish cell traction force generation, indicating that its knockdown only adversely affected MAPK1 signaling. These data provide some of the first evidence that a force-sensitive adhesion protein can regulate stem cell fate.
Performance limitations for nanowire/nanoribbon biosensors
Authors: Rajan Nitin K. , Duan Xuexin , Reed Mark A.
Published: July 2013

Field‐effect transistor‐based biosensors (bioFETs) have shown great promise in the field of fast, ultra‐sensitive, label‐free detection of biomolecules. Reliability and accuracy, when trying to measure small concentrations, is of paramount importance for the translation of these research devices into the clinical setting. Our knowledge and experience with these sensors has reached a stage where we are able to identify three main aspects of bioFET sensing that currently limit their applications. By considering the intrinsic device noise as a limitation to the smallest measurable signal, we show how various parameters, processing steps and surface modifications, affect the limit of detection. We also introduce the signal‐to‐noise ratio of bioFETs as a universal performance metric, which allows us to gain better insight into the design of more sensitive devices. Another aspect that places a limit on the performance of bioFETs is screening by the electrolyte environment, which reduces the signal that could be potentially measured. Alternative functionalization and detection schemes that could enable the use of these charge‐based sensors in physiological conditions are highlighted. Finally, the binding kinetics of the receptor–analyte system are considered, both in the context of extracting information about molecular interactions using the bioFET sensor platform and as a fundamental limitation to the number of molecules that bind to the sensor surface at steady‐state conditions and to the signal that is generated. Some strategies to overcome these limitations are also proposed. Taken together, these performance‐limiting issues, if solved, would bring bioFET sensors closer to clinical applications. WIREs Nanomed Nanobiotechnol 2013, 5:629–645. doi: 10.1002/wnan.1227

This article is categorized under:

Diagnostic Tools > Biosensing

Diagnostic Tools > Diagnostic Nanodevices
Reprogramming cells and tissue patterning via bioelectrical pathways: molecular mechanisms and biomedical opportunities
Authors: Levin Michael
Published: July 2013

Transformative impact in regenerative medicine requires more than the reprogramming of individual cells: advances in repair strategies for birth defects or injuries, tumor normalization, and the construction of bioengineered organs and tissues all require the ability to control large‐scale anatomical shape. Much recent work has focused on the transcriptional and biochemical regulation of cell behavior and morphogenesis. However, exciting new data reveal that bioelectrical properties of cells and their microenvironment exert a profound influence on cell differentiation, proliferation, and migration. Ion channels and pumps expressed in all cells, not just excitable nerve and muscle, establish resting potentials that vary across tissues and change with significant developmental events. Most importantly, the spatiotemporal gradients of these endogenous transmembrane voltage potentials (Vmem) serve as instructive patterning cues for large‐scale anatomy, providing organ identity, positional information, and prepattern template cues for morphogenesis. New genetic and pharmacological techniques for molecular modulation of bioelectric gradients in vivo have revealed the ability to initiate complex organogenesis, change tissue identity, and trigger regeneration of whole vertebrate appendages. A large segment of the spatial information processing that orchestrates individual cells' programs toward the anatomical needs of the host organism is electrical; this blurs the line between memory and decision‐making in neural networks and morphogenesis in nonneural tissues. Advances in cracking this bioelectric code will enable the rational reprogramming of shape in whole tissues and organs, revolutionizing regenerative medicine, developmental biology, and synthetic bioengineering. WIREs Syst Biol Med 2013, 5:657–676. doi: 10.1002/wsbm.1236

This article is categorized under:

Developmental Biology > Developmental Processes in Health and Disease

Laboratory Methods and Technologies > Imaging

Developmental Biology > Stem Cell Biology and Regeneration
A hybrid stochastic Galerkin method for uncertainty quantification applied to a conservation law modelling a clarifier‐thickener unit
Authors: Bürger R. , Kröker I. , Rohde C.
Published: July 2013

The continuous sedimentation process in a clarifier‐thickener can be described by a scalar nonlinear conservation law for the local solids volume fraction. The flux density function is discontinuous with respect to spatial position due to feed and discharge mechanisms. Typically, the feed flow cannot be given deterministically and efficient numerical simulation requires a concept for quantifying uncertainty. In this paper uncertainty quantification is expressed by a new hybrid stochastic Galerkin (HSG) method that extends the classical polynomial chaos approximation by multiresolution discretization in the stochastic space. The new approach leads to a deterministic hyperbolic system for a finite number of stochastic moments which is however partially decoupled and thus allows efficient parallelisation. The complexity of the problem is further reduced by stochastic adaptivity. For the approximate solution of the resulting high‐dimensional system a finite volume scheme is introduced. Numerical experiments cover one‐ and two‐dimensional situations.
A microscale second gradient approximation of the damage parameter of quasi‐brittle heterogeneous lattices
Authors: Rinaldi A. , Placidi L.
Published: July 2013

Lattice models are powerful tools to investigate damage processes in quasi‐brittle material by a microscale perspective. Starting from prior work on a novel rational damage theory for a 2D heterogenous lattice, this paper explores the connection between the series of critical strains at which the microcracks form (i.e. lattice links fail) and the second gradient of the microscale displacement field. Taking a simple tensile test as a representative case study for this endeavour, the analysis of accurate numerical results provides evidence that the second gradient of the microscale displacement field (notably the quantity | ∇ (∂ ux/∂ x)| for the specific example elaborated here) conveys indeed crucial information about the microcracks formation process and can be conveniently used to introduce simplifications of the rational theory that are of relevance by practical purposes as full field strain measurements become routinely possible with digital imaging correlation techniques. Note worthy, the results support the new view that the damage evolution is a three regimes process (I dilute damage, II homogeneous interaction, III localization.) The featured connection with the second gradient of the microscale displacement field is applicable in regions II–III, where microcracks interactions grow stronger and the lattice transitions to the softening regime. The potential impact of these findings towards the formulation of new and physically based CDM models, which are consistent with the reference discrete microscale theory, cannot be overlooked and is pointed out.
Harmonic vibrations of nanosized piezoelectric bodies with surface effects
Authors: Nasedkin A.V. , Eremeyev V.A.
Published: July 2013

We consider the harmonic and eigenvalue problems for piezoelectric nanodimensional bodies with account for surface stresses and surface electric charges. For harmonic problem new mathematical model is suggested, which generalizes the model of the piezoelectric medium with damping properties, boundary conditions of contact type and surface effects. The classical and generalized (weak) statements for harmonic and eigenvalue problems are formulated in the extended and reduced forms. The spectral properties of the eigenvalue problems with account for surface effects are determined. A variational minimal principle is constructed which is similar to the well‐known variational principle for problems for pure elastic and piezoelectric media. The discreteness of the spectrum and completeness of the eigenvectors are proved. As a consequence of variational principle, the properties of the natural frequencies increase or decrease are established for changing the mechanical, electric and “surface” boundary conditions and the moduli of piezoelectric body. The finite element approaches are described for determination of the natural frequencies, the resonance and antiresonance frequencies and harmonic behavior of nanosized piezoelectric bodies with account for surface effects.
Isobavachalcone and bavachinin from Psoraleae Fructus modulate Aβ42 aggregation process through different mechanisms in vitro
Authors: Chen Xiumin , Yang Yanfang , Zhang Yingtao
Published: July 2013

Spontaneous aggregation of Aβ is a key factor in the development of Alzheimer's disease. In searching for Aβ aggregation inhibitors from traditional Chinese herbal medicines, we identified two active compounds from Psoraleae Fructus, namely isobavachalcone and bavachinin. We further demonstrated that the two compounds modulate Aβ42 aggregation process through different mechanisms. Isobavachalcone significantly inhibits both oligomerization and fibrillization of Aβ42, whereas bavachinin inhibits fibrillization and leads to off‐pathway aggregation. Both of the compounds attenuated Aβ42‐induced toxicity in a SH‐SY5Y cell model. These findings may provide valuable information for new drug development and Alzheimer's therapy in the future.
VAR-BASED OPTIMAL PARTIAL HEDGING
Authors: Cong Jianfa , Tan Ken Seng , Weng Chengguo
Published: July 2013

Hedging is one of the most important topics in finance. When a financial market is complete, every contingent claim can be hedged perfectly to eliminate any potential future obligations. When the financial market is incomplete, the investor may eliminate his risk exposure by superhedging. In practice, both hedging strategies are not satisfactory due to their high implementation costs, which erode the chance of making any profit. A more practical and desirable strategy is to resort to the partial hedging, which hedges the future obligation only partially. The quantile hedging of Föllmer and Leukert (Finance and Stochastics, vol. 3, 1999, pp. 251–273), which maximizes the probability of a successful hedge for a given budget constraint, is an example of the partial hedging. Inspired by the principle underlying the partial hedging, this paper proposes a general partial hedging model by minimizing any desirable risk measure of the total risk exposure of an investor. By confining to the value-at-risk (VaR) measure, analytic optimal partial hedging strategies are derived. The optimal partial hedging strategy is either a knock-out call strategy or a bull call spread strategy, depending on the admissible classes of hedging strategies. Our proposed VaR-based partial hedging model has the advantage of its simplicity and robustness. The optimal hedging strategy is easy to determine. Furthermore, the structure of the optimal hedging strategy is independent of the assumed market model. This is in contrast to the quantile hedging, which is sensitive to the assumed model as well as the parameter values. Extensive numerical examples are provided to compare and contrast our proposed partial hedging to the quantile hedging.
Forage degradability, rumen bacterial adherence and fibrolytic enzyme activityin vitro: effect of pH or glucose concentration
Authors: FARENZENA R. , KOZLOSKI G. V. , MEZZOMO M. P. , FLUCK A. C.
Published: July 2013

A set of independent assays were conducted to assess the effects of either pH or glucose concentration on forage degradation, bacterial adherence and on fibrolytic enzyme activityin vitro. For measuring degradation and bacterial adherence, ryegrass (Lolium multiflorum) and bermudagrass (Cynodon dactylon) samples were incubatedin vitrofor 24 h in the medium at different pH (5·5, 6·0, 6·5 or 7·0) or with different initial glucose concentrations (0, 1000, 2000 and 3000 mg/l). For fibrolytic enzyme activity evaluation, forage samples were incubatedin situand the extracted enzymes were incubatedin vitrounder the different pH and glucose treatment conditions. The amount of bacteria adhering to samples and the degradability of dry matter (DM) and neutral detergent fibre (NDF) were higher for ryegrass than for bermudagrass, were not affected by glucose concentration and were linearly and positively affected by increased pH. On average, carboxymethylcellulase (CMCase) and xylanase activities were higher for ryegrass than for bermudagrass in the pH assay, whereas the differences between forages were not significant in the glucose assay. For both forage species, the quadratic effect of pH or glucose concentration on CMCase and xylanase activities was significant. Maximum activity of both enzymes was observed at pH 6·0 or at glucose concentration of 2000 mg/l. In conclusion, forage degradation was affected negatively by decreased ruminal pH due to reduced bacterial adherence. In turn, the pH or glucose effect on fibrolytic enzyme activity was not related to their effects on bacterial adherence or forage degradation, indicating that forage degradation is more dependent on the degree of microbial colonization than on the specific activity of bacterial enzymes.
Operation Abolition: Defending the Civil Liberties of the “Un-American,” 1957–1961
Authors: MARTIN RUTH
Published: July 2013

In response to the House Un-American Activities Committee's attacks on legal defenders of political nonconformists, the six-year-old Emergency Civil Liberties Committee organized a publicity and test-case campaign to highlight the dubious constitutionality of HUAC's methods. Their drive to abolish HUAC helped to transform the defence of the constitutional rights of suspected subversives or “un-Americans” by undermining the governmental structures of the Second Red Scare. The ECLC's activity also prompted a shift in the policy of the nation's largest civil liberties group, the American Civil Liberties Union, in favour of abolition. HUAC's response of a mass propaganda campaign represented the culmination of a period when they sought to crush “un-American” dissent, inadvertently elevating the ECLC to a position of national prominence in the struggle for Cold War civil liberties.
Prenatal and childhood antecedents of suicide: 50-year follow-up of the 1958 British Birth Cohort Study
Authors: Geoffroy M.-C. , Gunnell D. , Power C.
Published: July 2013

Background

We aimed to elucidate early antecedents of suicide including possible mediation by early child development.

Method

Using the 1958 birth cohort, based on British births in March 1958, individuals were followed up to adulthood. We used data collected at birth and at age 7 years from various informants. Suicides occurring up to 31 May 2009 were identified from linked national death certificates. Multivariable Cox proportional hazard models were used to investigate risk factors.

Results

Altogether 12399 participants (n = 44 suicides) had complete data. The strongest prenatal risk factors for suicide were: birth order, with risk increasing in later-born children [ptrend = 0.063, adjusted hazard ratio (HR)], e.g. for fourth- or later-born children [HR = 2.27, 95% confidence interval (CI) 0.90–5.75]; young maternal age (HR = 1.18, 95% CI 0.34–4.13 for ⩽19 years and HR = 0.41, 95% CI 0.19–0.91 for >29 years, ptrend = 0.034); and low (<2.5 kg) birth weight (HR = 2.48, 95% CI 1.03–5.95). The strongest risk factors at 7 years were externalizing problems in males (HR = 2.96, 95% CI 1.03–8.47, ptrend = 0.050) and number of emotional adversities (i.e. parental death, neglected appearance, domestic tension, institutional care, contact with social services, parental divorce/separation and bullying) for which there was a graded association with risk of suicide (ptrend = 0.033); the highest (HR = 3.12, 95% CI 1.01–9.62) was for persons with three or more adversities.

Conclusions

Risk factors recorded at birth and at 7 years may influence an individual's long-term risk of suicide, suggesting that trajectories leading to suicide have roots in early life. Some factors are amenable to intervention, but for others a better understanding of causal mechanisms may provide new insights for intervention to reduce suicide risk.
Structure of viruses: a short history
Authors: Rossmann Michael G.
Published: July 2013

This review is a partially personal account of the discovery of virus structure and its implication for virus function. Although I have endeavored to cover all aspects of structural virology and to acknowledge relevant individuals, I know that I have favored taking examples from my own experience in telling this story. I am anxious to apologize to all those who I might have unintentionally offended by omitting their work.

The first knowledge of virus structure was a result of Stanley's studies of tobacco mosaic virus (TMV) and the subsequent X-ray fiber diffraction analysis by Bernal and Fankuchen in the 1930s. At about the same time it became apparent that crystals of small RNA plant and animal viruses could diffract X-rays, demonstrating that viruses must have distinct and unique structures. More advances were made in the 1950s with the realization by Watson and Crick that viruses might have icosahedral symmetry. With the improvement of experimental and computational techniques in the 1970s, it became possible to determine the three-dimensional, near-atomic resolution structures of some small icosahedral plant and animal RNA viruses. It was a great surprise that the protecting capsids of the first virus structures to be determined had the same architecture. The capsid proteins of these viruses all had a ‘jelly-roll’ fold and, furthermore, the organization of the capsid protein in the virus were similar, suggesting a common ancestral virus from which many of today's viruses have evolved. By this time a more detailed structure of TMV had also been established, but both the architecture and capsid protein fold were quite different to that of the icosahedral viruses. The small icosahedral RNA virus structures were also informative of how and where cellular receptors, anti-viral compounds, and neutralizing antibodies bound to these viruses. However, larger lipid membrane enveloped viruses did not form sufficiently ordered crystals to obtain good X-ray diffraction. Starting in the 1990s, these enveloped viruses were studied by combining cryo-electron microscopy of the whole virus with X-ray crystallography of their protein components. These structures gave information on virus assembly, virus neutralization by antibodies, and virus fusion with and entry into the host cell. The same techniques were also employed in the study of complex bacteriophages that were too large to crystallize. Nevertheless, there still remained many pleomorphic, highly pathogenic viruses that lacked the icosahedral symmetry and homogeneity that had made the earlier structural investigations possible. Currently some of these viruses are starting to be studied by combining X-ray crystallography with cryo-electron tomography.
Capitolia
Authors: Quinn Josephine Crawley , Wilson Andrew
Published: July 2013

Capitolia, temples to the triad of divinities Iuppiter Optimus Maximus, Iuno Regina and Minerva Augusta, are often considered part of the standard urban ‘kit’ of Roman colonies. Their placement at one end of the forum is sometimes seen as schematizing and replicating in miniature the relationship between the Capitolium at Rome and the Forum Romanum below it. Reliably attested Capitolia are, however, rarer in the provinces than this widespread view assumes and there seems to be no relationship between civic status and the erection of a Capitolium. Indeed, outside Italy there are very few Capitolia other than in the African provinces, where nearly all known examples belong to the second or early third century a.d., mostly in the Antonine period. This regional and chronological clustering demands explanation, and since it comes too late to be associated with the foundation of colonies, and there is no pattern of correlation with upgrades in civic status, we propose that the explanation has to do with the growing power and influence of North African élites, who introduced the phenomenon from Rome. Rather than being a form of temple imposed from the centre on the provinces, Capitolia were adopted by provincial élites on the basis of their relationship with Rome.
Situating Science in Global History: Local Exchanges and Networks of Circulation
Authors: Roberts Lissa
Published: July 2013

In response to increasing academic interest, Cambridge University Press launched a new journal in 2006, entitled the Journal of Global History. To inaugurate the endeavour, the editors asked economic historian Patrick O'Brien to write an introductory essay to serve as a prolegomenon for this newly invigorated field of study. O'Brien began by noting that it is no mere coincidence that interest in global history should be growing, given the global challenges entailed in current-day economic, political and environmental issues. From this perspective, we might take “global history” to refer both to the field's geographical reach and its attempts to relate a global range of seemingly diverse phenomena. Both understandings require us to stretch beyond the narrow specialisms in which we were trained and invite increasing willingness to collaborate. Along these lines, O'Brien applauded those historians who have reached outside their own discipline to draw on the insights and methods of the natural sciences, as well as natural scientists whose work is shedding new light on historical development.
Implementation without control: the role of the private water companies in establishing constant water in nineteenth-century London
Authors: HILLIER JOSEPH
Published: July 2013

The switch from intermittent to constant water supply in London in the late nineteenth century has attracted little attention. This article argues that this transition, the basis of the modern water system, was a considerable undertaking. System-builders (London's private water companies) faced a permissive regulatory environment and a population that could be ambivalent about constant water. While the water companies tried to encourage standardization through contract agreements and inspection, their lack of domestic access encouraged technical fragmentation. Local socio-political relations influenced the form of the constant water system, with consequences for future consumption practices.
Making Cairo modern? Innovation, urban form and the development of suburbia, c. 1880–1922
Authors: MOORE JAMES
Published: July 2013

Cairo has often been seen as a ‘dual city’ divided between a ‘modern’ European city and a historic ‘traditional’ core. This article challenges this view through a historical exploration of suburban Cairo, a subject neglected by mainstream urban historians. A comparative examination of Ismailiyah, Garden City, Zamalek, Maadi, Helwan and Heliopolis illustrates that these suburbs took very different forms and reflected a wide range of historical and contemporary architectural tastes and design perspectives. Not all suburban developments were products of modern technical innovations and by 1922 no suburb had a majority of European residents. The use of the term ‘modern’ to characterize Cairo's suburbs therefore has the tendency to privilege western concepts of the modern and obscure the complexities of suburban social and economic development.
‘Bustling, crowding, and pushing’: pickpockets and the nineteenth-century street crowd
Authors: ANDERSSON PETER K.
Published: July 2013

The history of walking in the city has long been neglected, and the existing scholarship is largely concerned with rioting,flânerieor urban geography. This article aims to detect the behavioural patterns of pedestrian traffic in the late nineteenth century through a close study of the methods of pickpockets in London streets, with information gleaned from trial reports and writings on pickpockets. By analysing the most common ways in which pickpockets operated, as described in numerous accounts, we can see how they adapted to nineteenth-century pedestrian norms, and through this method acquire a rough outline of what pedestrian traffic looked like, and thus how urban dwellers living in a critical historical period adapted and reacted to urban conditions on an everyday level. The evidence shows that pedestrian traffic through the century remained highly interactive, and that the modern aspects of cities identified in theories of civilizing or impoverishment of the public realm had a very limited impact at this time.
The politics of the urban commons in Northern Atlantic Spain in the later Middle Ages
Authors: SOLÓRZANO TELECHEA JESÚS A.
Published: July 2013

This article examines some key issues relating to the emergence of political consciousness and political activity amongst the commons in the towns of Northern Atlantic Spain in the late medieval period. In the fifteenth century, a partnership between the urban business elite and the craft guilds successfully petitioned the monarchy on behalf of the commons, which resulted in municipal reforms. The resolution of issues achieved in the north was radically different from the situation in other cities in the kingdom of Castile, where the commons’ petitions and conflicts with urban oligarchies led to what became known as the ‘Revolt of the Comuneros’ in 1520, which marked the decline of the commons’ assemblies and the end of medieval urban rebellions in the interior of the kingdom.
Hypervalent surface interactions for colloidal stability and doping of silicon nanocrystals
Authors: Wheeler Lance M. , Neale Nathan R. , Chen Ting , Kortshagen Uwe R.
Published: July 2013

Colloidal semiconductor nanocrystals have attracted attention for cost-effective, solution-based deposition of quantum-confined thin films for optoelectronics. However, two significant challenges must be addressed before practical nanocrystal-based devices can be realized. The first is coping with the ligands that terminate the nanocrystal surfaces. Though ligands provide the colloidal stability needed to cast thin films from solution, these ligands dramatically hinder charge carrier transport in the resulting film. Second, after a conductive film is achieved, doping has proven difficult for further control of the optoelectronic properties of the film. Here we report the ability to confront both of these challenges by exploiting the ability of silicon to engage in hypervalent interactions with hard donor molecules. For the first time, we demonstrate the significant potential of applying the interaction to the nanocrystal surface. In this study, hypervalent interactions are shown to provide colloidal stability as well as doping of silicon nanocrystals.
Biological soliton in multicellular movement
Authors: Kuwayama Hidekazu , Ishida Shuji
Published: July 2013

Solitons have been observed in various physical phenomena. Here, we show that the distinct characteristics of solitons are present in the mass cell movement of non-chemotactic mutants of the cellular slime mould Dictyostelium discoideum. During starvation, D. discoideum forms multicellular structures that differentiate into spore or stalk cells and, eventually, a fruiting body. Non-chemotactic mutant cells do not form multicellular structures; however, they do undergo mass cell movement in the form of a pulsatile soliton-like structure (SLS). We also found that SLS induction is mediated by adhesive cell-cell interactions. These observations provide novel insights into the mechanisms of biological solitons in multicellular movement.