bluuebunny/crossref_metadata_2025 huggingface dataset:
C-type natriuretic peptide: a link between hyperandrogenism and anovulation in a mouse model of polycystic ovary syndrome
Authors: Reis Adelina M. , Honorato-Sampaio Kinulpe
Published: May 2018

The polycystic ovary (PCO) syndrome (PCOS) is the most common cause of anovulatory infertility in women and is associated with several clinical disorders. Despite the great amount of research in the area, mechanisms involved in the genesis of this syndrome remain poorly understood. In a recent issue of Clinical Science (vol. 132, issue 7, 759-776), Wang and colleagues, highlight the important role of overactivated C-type natriuretic peptide (CNP) and natriuretic peptide receptor 2 (CNP/NPR2) system in preventing oocyte maturation and ovulation in PCOS mice model induced by androgen. Dehydroepiandrosterone (DHEA) treatment caused anovulation, high levels of androgen and estrogen receptors (AR and ER) in the ovary, high expression of CNP and natriuretic peptide receptor 2 (NPR2) in granulosa cells (GC), and an increase in testosterone and estradiol (E2) levels in sera. The high level of CNP/NPR2 was associated with oocyte meiotic arrest and very low ovulation rate. Treatment with human chorionic gonadotropin (hCG) or inhibitors of AR or ER reduced the level of CNP/NPR2, which resulted in meiotic resumption and ovulation. The article provided important information for understanding the effect of ovarian steroids on control of oocyte maturation and fertility and highlighted CNP/NPR2 as a specific pathway that is potentially involved in the ovulatory disruption in PCOS.
More than a simple biomarker: the role of NGAL in cardiovascular and renal diseases
Authors: Buonafine Mathieu , Martinez-Martinez Ernesto , Jaisser Frédéric
Published: May 2018

Neutrophil gelatinase-associated lipocalin (NGAL) is a small circulating protein that is highly modulated in a wide variety of pathological situations, making it a useful biomarker of various disease states. It is one of the best markers of acute kidney injury, as it is rapidly released after tubular damage. However, a growing body of evidence highlights an important role for NGAL beyond that of a biomarker of renal dysfunction. Indeed, numerous studies have demonstrated a role for NGAL in both cardiovascular and renal diseases. In the present review, we summarize current knowledge concerning the involvement of NGAL in cardiovascular and renal diseases and discuss the various mechanisms underlying its pathological implications.
Non-resonant Alfvénic instability activated by high temperature of ion beams in compensated-current astrophysical plasmas
Authors: Malovichko P. , Voitenko Y. , De Keyser J.
Published: May 2018

Context. Compensated-current systems are established in response to hot ion beams in terrestrial foreshock regions, around supernova remnants, and in other space and astrophysical plasmas.

Aims. We study a non-resonant reactive instability of Alfvén waves propagating quasi-parallel to the background magnetic field B0 in such systems.

Methods. The instability is investigated analytically in the framework of kinetic theory applied to the hydrogen plasmas penetrated by hot proton beams.

Results. The instability arises at parallel wavenumbers kz that are sufficiently large to demagnetize the beam ions, kzVTb/ωBi ≳ 1 (here VTb is the beam thermal speed along B0 and ωBi is the ion-cyclotron frequency). The Alfvén mode is then made unstable by the imbalance of perturbed currents carried by the magnetized background electrons and partially demagnetized beam ions. The destabilizing effects of the beam temperature and the temperature dependence of the instability threshold and growth rate are demonstrated for the first time. The beam temperature, density, and bulk speed are all destabilizing and can be combined in a single destabilizing factor αb triggering the instability at αb > αbthr, where the threshold value varies in a narrow range 2.43 ≤  αbthr ≤ 4.87. New analytical expressions for the instability growth rate and its boundary in the parameter space are obtained and can be directly compared with observations. Two applications to terrestrial foreshocks and foreshocks around supernova remnants are briefly discussed. In particular, our results suggest that the ions reflected by the shocks around supernova remnants can drive stronger instability than the cosmic rays.
The root of a comet tail: Rosetta ion observations at comet 67P/Churyumov–Gerasimenko
Authors: Behar E. , Nilsson H. , Henri P. , Berčič L. , Nicolaou G. , Stenberg Wieser G. , Wieser M. , Tabone B. , Saillenfest M. , Goetz C.
Published: May 2018

Context. The first 1000 km of the ion tail of comet 67P/Churyumov–Gerasimenko were explored by the European Rosetta spacecraft, 2.7 au away from the Sun.

Aims. We characterised the dynamics of both the solar wind and the cometary ions on the night-side of the comet’s atmosphere.

Methods. We analysed in situ ion and magnetic field measurements and compared the data to a semi-analytical model.

Results. The cometary ions are observed flowing close to radially away from the nucleus during the entire excursion. The solar wind is deflected by its interaction with the new-born cometary ions. Two concentric regions appear, an inner region dominated by the expanding cometary ions and an outer region dominated by the solar wind particles.

Conclusions. The single night-side excursion operated by Rosetta revealed that the near radial flow of the cometary ions can be explained by the combined action of three different electric field components, resulting from the ion motion, the electron pressure gradients, and the magnetic field draping. The observed solar wind deflection is governed mostly by the motional electric field −uion×B.
G51.04+0.07 and its environment: Identification of a new Galactic supernova remnant at low radio frequencies
Authors: Supan L. , Castelletti G. , Peters W. M. , Kassim N. E.
Published: May 2018

We have identified a new supernova remnant (SNR), G51.04+0.07, using observations at 74 MHz from the Very Large Array Low-Frequency Sky Survey Redux (VLSSr). Earlier, higher frequency radio continuum, recombination line, and infrared data had correctly inferred the presence of nonthermal radio emission within a larger, complex environment including ionised nebulae and active star formation. However, our observations have allowed us to redefine at least one SNR as a relatively small source (7.′5 × 3′in size) located at the southern periphery of the originally defined SNR candidate G51.21+0.11. The integrated flux density of G51.04+0.07 at 74 MHz is 6.1 ± 0.8 Jy, while its radio continuum spectrum has a slope α = −0.52 ± 0.05 (S v ∝ vα), typical of a shell-type remnant. We also measured spatial variations in the spectral index between 74 and 1400 MHz across the source, ranging from a steeper spectrum (α = −0.50 ± 0.04) coincident with the brightest emission to a flatter component (α = −0.30 ± 0.07) in the surrounding fainter region. To probe the interstellar medium into which the redefined SNR is likely evolving, we have analysed the surrounding atomic and molecular gas using the 21 cm neutral hydrogen (HI) and 13CO(J = 1 − 0) emissions. We found that G51.04+0.07 is confined within an elongated HI cavity and that its radio emission is consistent with the remains of a stellar explosion that occurred ~6300 yr ago at a distance of 7.7 ± 2.3 kpc. Kinematic data suggest that the newly discovered SNR lies in front of HII regions in the complex, consistent with the lack of a turnover in the low frequency continuum spectrum. The CO observations revealed molecular material that traces the central and northern parts of G51.04+0.07. The interaction between the cloud and the radio source is not conclusive and motivates further study. The relatively low flux density (~1.5 Jy at 1400 MHz) of G51.04+0.07 is consistent with this and many similar SNRs lying hidden along complex lines of sight towards inner Galactic emission complexes. It would also not be surprising if the larger complex studied here hosted additional SNRs.
Difference in real-time magnetic image analysis of colonic looping patterns between males and females undergoing diagnostic colonoscopy
Authors: Lam Jacob , Wilkinson James , Brassett Cecilia , Brown Jonathan
Published: May 2018

Background and study aim Magnetic imaging technology is of proven benefit to trainees in colonoscopy, but few studies have examined its benefits in experienced hands. There is evidence that colonoscopy is more difficult in women. We set out to investigate (i) associations between the looping configurations in the proximal and distal colon and (ii) differences in the looping prevalence between the sexes. We have examined their significance in terms of segmental intubation times and position changes required for the completion of colonoscopy.

Patients and methods We analyzed 103 consecutive synchronized luminal and magnetic image videos of diagnostic colonoscopies with normal anatomy undertaken by a single experienced operator.

Results Deep transverse loops and sigmoid N-loops were more common in females. A deep transverse loop was more likely to be present if a sigmoid alpha-loop or N-loop had formed previously. Patients with sigmoid N-loops were turned more frequently from left lateral to supine before the sigmoid-descending junction was reached, but there was no statistical correlation between completion time and looping pattern.

Conclusions This study has reexamined the prevalence of the common looping patterns encountered during colonoscopy and has identified differences between the sexes. This finding may offer an explanation as to why colonoscopy has been shown to be more difficult in females. Although a deep transverse loop following a resolved sigmoid alpha-loop was the most commonly encountered pattern, no statistical correlation between completion time and looping pattern could be shown. It is the first study to examine segmental completion times using a magnetic imager in expert hands.
CuI-Catalyzed [3+2] Cycloaddition of Hindered Vinylidenebisphosphonates (VBP) with Azomethine Imines for Highly Regioselective Access to Dinitrogen-Heterobicycle-Containing Bisphosphonates
Authors: Zhu Zhongxiang , Wang Qinghe , Kong Dulin , Huang Tiao , Wu Mingshu
Published: May 2018

A concise, atom-economic, and highly regioselective synthetic strategy for the construction of several dinitrogen-fused heterocycles bearing bisphosphonates by 1,3-dipolar cycloaddition reaction of azomethine imines with tetraethyl vinylidene-1,1-bisphosphonate in the presence of CuI in toluene media has been developed. The targeted compounds were obtained in good yields and with excellent regioselectivity. This method for the synthesis of gem-bisphosphonates (BPs) is particularly attractive due to features such as low cost, mild conditions, atom economy, high stereoselectivity, and potential biological activity of the product.
[4+3]-Annulation of 3-Cyano-4-aryl-2-iminochromenes with 1,2-Diaminobenzene: An Access to Novel Chromenobenzodiazepines
Authors: Mourya Mohini , Sharma Himanshu , Joshi Yogesh , Basak Ashok
Published: May 2018

3-Cyano-4-aryl-2-iminochromenes undergo [4+3]-annulation with 1,2-diaminobenzene under mild acidic conditions to generate novel chromenobenzodiazepines in good yields. The annulation reaction was also successful with 2-aminophenol and 2-aminothiophenol. The chromenobenzodiazepines could be conveniently reduced to the corresponding 4H-chromenobenzodiazepines under mild acidic conditions.
N-Iodosuccinimide-Mediated Oxidative Coupling of Indoles and Phenols: A Synthetic Study toward the Benzofuroindoline Moiety of Bipleiophylline
Authors: Vincent Guillaume , Denizot Natacha , Guillot Régis , Kouklovsky Cyrille
Published: May 2018

We report our efforts to apply an N-iodosuccinimide-mediated dearomative oxidative coupling of indoles and phenols to benzo­furoindoline-containing polycyclic scaffolds related to the natural product bipleiophylline. Suitable conditions from N-substituted indoles are developed and applied to the synthesis of a hexacyclic model starting from a tetracyclic ABCE precursor.
Dimethylprolinol Versus Diphenylprolinol in CuBr2-Catalyzed
Enantioselective Allenylation of Terminal Alkynols
Authors: Ma Dengke , Duan Xinyu , Fu Chunling , Huang Xin , Ma Shengming
Published: May 2018

The CuBr2-catalyzed enantioselective allenylation of terminal alkynols with carbon chains of different lengths has been developed. Compared with (S)-α,α-diphenylprolinol, the reaction using (S)-α,α-dimethylprolinol as the chiral amine afforded optically active 1,3-disubstuted allenols with higher ee-values. Both aliphatic and aromatic aldehydes could be applied. The naturally occurring phlomic acid was synthesized in four steps from commercially available hex-5-yn-1-ol.
Photoinduced Cross-Coupling of Amines with 1,2-Diiodobenzene and Its Application in the Synthesis of Carbazoles
Authors: Xia Wujiong , Zhao Xinxin , Chen Ming , Huang Binbin , Yang Chao , Gao Yuan
Published: May 2018

A facile and efficient process for the preparation of various tertiary aminobenzenes and carbazole derivatives via photoinduced cross-coupling of amines with 1,2-diiodobenzene is reported. Mechanistic investigations indicate that the transformation proceeds via nucleo­philic addition of an amine to the benzyne intermediate accompanied with a proton transfer process, followed by an oxidative cyclization of the generated diphenylamine to furnish the corresponding carbazole products.
A Mild Multi-Component Reaction for the Synthesis of 4,5-Disubstituted 1H-1,2,3-Triazoles from Phosphonium Salts, Aldehydes, and Sodium Azide
Authors: Wu Qin-Pei , Wu Guang-Long
Published: May 2018

A mild and metal-free multi-component reaction to synthesize 4,5-disubstituted 1H-1,2,3-triazoles from phosphonium salts, aldehydes, and sodium azide is described. The process undergoes an organocatalyzed coupling of formyl group with phosphonium to form a key intermediate, olefinic phosphonium salt, which is followed by the [3+2] cycloaddition of the azide to the activated alkene. A series of representative 4,5-disubstituted 1H-1,2,3-triazoles were prepared.
Prognosis of Transcatheter Closure Compared with Surgical Repair of Paravalvular Leak after Prosthetic Valve Replacement: A Retrospective Comparison
Authors: Yang Chun , Liu Yang , Tang Jiayou , Jin Ping , Li Lanlan , Yu Shiqiang , Yang Jian
Published: May 2018

Objective Paravalvular leak (PVL) after valve replacement remains clinically challenging. Percutaneous closure is an effective therapy for patients with PVLs because reoperation is associated with high rates of morbidity and mortality. The purpose of this study was to retrospectively compare the clinical outcome of transcatheter closure and surgical repair in patients with a PVL.

Methods From January 2000 to May 2016, 131 patients with PVL were treated at three major medical centers in China. Perioperative characteristics and outcomes of the procedure were reviewed.

Results Sixty-eight (51.9%) patients with PVLs were treated with percutaneous transcatheter closure (group I). The procedure was successful in 67 (98%) with no hospital deaths. Sixty-three (48.1%) patients with PVLs had a reoperation (group II). Five of the surgical patients had a third open-heart operation for residual regurgitation, and one underwent successful percutaneous closure. Six patients died in the hospital postoperatively. All patients in group II but only 11 in group I needed perioperative blood transfusions. The procedural time and hospital stay after the procedure were significantly shorter in group I than in group II. At the 1-year follow-up, cardiac function improved by ≥ 1 New York Heart Association functional class in 55 (82%) patients in group I and in 39 (68%) patients in group II.

Conclusions Transcatheter closure was shown to be a safe, effective therapeutic option in patients with PVL. It was associated with a lower hospital mortality rate, shorter procedural time, and fewer blood transfusions than surgical treatment in selected patients.
Efficacy of Miniuniportal Video-Assisted Thoracoscopic Selective Sympathectomy (Ramicotomy) for the Treatment of Severe Palmar and Axillar Hyperhidrosis
Authors: Akil Ali , Semik Michael , Fischer Stefan
Published: May 2018

Background Video-assisted thoracoscopic surgery (VATS) clipping of the sympathetic branch has become the standard approach for the treatment of essential hyperhidrosis when conservative treatment failed. However, this is associated with relevant potential complications such as postoperative compensatory sweating and recurrent sweating. We report the outcome after selective sympathectomy (ramicotomy) through a miniuniportal VATS approach in patients with therapy-refractory palmar and/or axillary hyperhidrosis.

Methods A total of 51 consecutive patients (37 females, mean age: 30 years, range: 12–64 years) who suffered from therapy-refractory palmar and/or axillary severe hyperhidrosis were included. Data were prospectively collected and retrospectively analyzed. All patients underwent bilateral miniuniportal VATS ramicotomy. Duration of surgery, hospital stay, recurrent, and compensatory sweating were documented.

Results All patients had palmar sweating, where 51% had additional axillary sweating and 57% had additional plantar sweating. In all patients, selective division of the rami communicantes of the thoracic sympathetic ganglions Th2 to Th5 was performed. The mean duration of bilateral surgery for both sides was 67 ± 2.5 minutes. The mean postoperative hospital stay was 2 ± 1 days. After surgery and at further follow-up (mean: 12 ± 2.5 months), all patients presented dry and warm hands and axillae, without any evidence of compensatory or recurrent sweating. All patients described a remarkable increase in quality of life.

Conclusion Miniuniportal VATS ramicotomy represents a feasible surgical technique with a very high success and satisfaction rate. Therefore, this approach should be considered as the method of choice for the treatment of patients with severe therapy-refractory palmar and axillary hyperhidrosis.
From Mitten Hand to Five Individual Fingers: One-Stage Coverage Using a Deep Inferior Epigastric Perforator Free Flap for an Extensive Degloving Hand Injury
Authors: Kim Min Ji , Park Bo Young
Published: May 2018

Coverage of hands with degloving injuries is currently being investigated, but it typically involves combinations of free flap operations to cover wide dimensions. In this study, the deep inferior epigastric perforator (DIEP) flap was successfully used to salvage a severely injured hand. After performing an open wound coverage with a flap operation, we did several minimal division operations under local anesthesia, which is a logical surgical option when the patient suffers from general deterioration immediately following significant trauma. We believe that this application of DIEP flap allows for a shorter operation time, decreased rates of infection for one-step coverage, and a higher chance of functional digit division compared with conventional methods.
Between Pachamama and Mother Earth: Gender, Political Ontology and the Rights of Nature in Contemporary Bolivia
Authors: Tola Miriam
Published: May 2018

Focusing on contemporary Bolivia, this article examines promises and pitfalls of political and legal initiatives that have turned Pachamama into a subject of rights. The conferral of rights on the indigenous earth being had the potential to unsettle the Western ontological distinction between active human subjects who engage in politics and passive natural resources. This essay, however, highlights some paradoxical effects of the rights of nature in Bolivia, where Evo Morales’ model of development relies on the intensification of the export-oriented extractive economy. Through the analysis of a range of texts, including paintings, legal documents, political speeches and activist interventions, I consider the equivocation between the normatively gendered Mother Earth that the state recognises as the subject of rights, and the figure of Pachamama evoked by feminist and indigenous activists. Pachamama, I suggest, has been incorporated into the Bolivian state as a being whose generative capacities have been translated into a rigid gender binary. As a gendered subject of rights, Pachamama/Mother Earth is exposed to governmental strategies that ultimately increase its subordination to state power. The concluding remarks foreground the import of feminist perspectives in yielding insights concerning political ontological conflicts.
Mediating the contributions of Facebook to political participation in Italy and the UK: the role of media and political landscapes
Authors: Casteltrione Isidoropaolo , Pieczka Magda
Published: May 2018

Over the last decade, an increasing number of academic studies have examined how digital technologies can contribute to political participation, with numerous publications focusing on social networking websites. This article adds to this strand of research by tackling the scarcity of cross-national comparative studies in the field. Drawing from an original dataset acquired by combining a cross-national comparative approach and a mixed-methods methodology, this paper explores how media and political landscapes mediate the contributions of Facebook to citizens’ political participation in Italy and the United Kingdom. A participatory gap between Italian and British participants, with Italians displaying higher levels of political participation through Facebook, is found and explained with reference to three contextual factors: the greater diffusion and relevance of other online platforms such as Twitter in the UK; Italian participants’ more negative perception of traditional media linked to the high level of political parallelism typical of the Italian media system; and the presence in Italy of a political party such as the Five Stars Movement making full use of the communicative and organizational affordances of Facebook. The findings indicate that the contributions of Facebook, and digital technologies in general, to political participation must be analysed in context, within the larger patterns they fit into, and cannot be examined in isolation. Such contributions are better understood if considered within the hybrid media system in which different digital platforms interact, merge and compete. Similarly, the political scenarios in which citizens and political parties operate need to be accounted for when looking at the links between the Internet and politics.
Complex networks untangle competitive advantage in Australian football
Authors: Braham Calum , Small Michael
Published: May 2018

We construct player-based complex network models of Australian football teams for the 2014 Australian Football League season; modelling the passes between players as weighted, directed edges. We show that analysis of these measures can give an insight into the underlying structure and strategy of Australian football teams, quantitatively distinguishing different playing styles. The relationships observed between network properties and match outcomes suggest that successful teams exhibit well-connected passing networks with the passes distributed between all 22 players as evenly as possible. Linear regression models of team scores and match margins show significant improvements in R2 and Bayesian information criterion when network measures are added to models that use conventional measures, demonstrating that network analysis measures contain useful, extra information. Several measures, particularly the mean betweenness centrality, are shown to be useful in predicting the outcomes of future matches, suggesting they measure some aspect of the intrinsic strength of teams. In addition, several local centrality measures are shown to be useful in analysing individual players' differing contributions to the team's structure.
A multi-objective energy planning considering sustainable development by a TOPSIS-based augmented e-constraint
Authors: Fathipour Fariba , Saidi-Mehrabad Mohammad
Published: May 2018

Due to the importance of conserving resources for future generations in the field of energy planning, this paper examines the concept of sustainable development in this area. The energy planning problem is modeled through incorporating environmental and social concepts into a tri-objective mathematical model. The considered objectives are minimizing energy costs, minimizing greenhouse gas emission, and maximizing the rate of social acceptance. In order to show the applicability of the proposed model, it is implemented over a real case study in Iran. Since the considered problem is a multi-objective one, the Pareto optimal set of solutions for the proposed model is obtained using parametric weighting, e-constraint, and augmented e-constraint methods. The results showed that the best Pareto frontiers are obtained using the augmented e-constraint method. Also, four scenarios are defined to help decision makers in selecting the preferred solution under each scenario using the TOPSIS method. The results of scenario evaluation confirm that the socially oriented scenario is more accepted.
Geometric Lagrangian approach to the physical degree of freedom count in field theory
Authors: Díaz Bogar , Montesinos Merced
Published: May 2018

To circumvent some technical difficulties faced by the geometric Lagrangian approach to the physical degree of freedom count presented in the work of Díaz, Higuita, and Montesinos [J. Math. Phys. 55, 122901 (2014)] that prevent its direct implementation to field theory, in this paper, we slightly modify the geometric Lagrangian approach in such a way that its resulting version works perfectly for field theory (and for particle systems, of course). As in previous work, the current approach also allows us to directly get the Lagrangian constraints, a new Lagrangian formula for the counting of the number of physical degrees of freedom, the gauge transformations, and the number of first- and second-class constraints for any action principle based on a Lagrangian depending on the fields and their first derivatives without performing any Dirac’s canonical analysis. An advantage of this approach over the previous work is that it also allows us to handle the reducibility of the constraints and to get the off-shell gauge transformations. The theoretical framework is illustrated in 3-dimensional generalized general relativity (Palatini and Witten’s exotic actions), Chern-Simons theory, 4-dimensional BF theory, and 4-dimensional general relativity given by Palatini’s action with a cosmological constant.
Temporal-spatial measurement of electron relaxation time in femtosecond laser induced plasma using two-color pump-probe imaging technique
Authors: Pan Changji , Jiang Lan , Wang Qingsong , Sun Jingya , Wang Guoyan , Lu Yongfeng
Published: May 2018

The femtosecond (fs) laser is a powerful tool to study ultrafast plasma dynamics, especially electron relaxation in strong ionization of dielectrics. Herein, temporal-spatial evolution of femtosecond laser induced plasma in fused silica was investigated using a two-color pump-probe technique (i.e., 400 nm and 800 nm, respectively). We demonstrated that when ionized electron density is lower than the critical density, free electron relaxation time is inversely proportional to electron density, which can be explained by the electron-ion scattering regime. In addition, electron density evolution within plasma was analyzed in an early stage (first 800 fs) of the laser-material interaction.
Infrared defect dynamics—Nitrogen-vacancy complexes in float zone grown silicon introduced by electron irradiation
Authors: Inoue Naohisa , Kawamura Yuichi
Published: May 2018

The interaction of nitrogen and intrinsic point defects, vacancy (V) and self-interstitial (I), was examined by infrared absorption spectroscopy on the electron irradiated and post-annealed nitrogen doped float zone (FZ) silicon crystal. Various absorption lines were observed, at 551 cm−1 in as-grown samples, at 726 and 778 cm−1 in as-irradiated samples (Ir group), at 689 cm−1 after post-annealing at 400 °C and above (400 °C group), at 762 and 951 cm−1 after annealing at 600 °C (600 °C group), and at 714 cm−1 up to 800 °C (800 °C group). By irradiation, a part of N2 was changed into the Ir group. VN2 is the candidate for the origin of the Ir group. By the post annealing at 400 and 600 °C, a part of N2 and the Ir group were changed into the 400 °C group, to less extent at 600 °C. V2N2 is the candidate for the origin of the 400 °C group. By annealing at 600 °C, most of the Ir group turned into 400 °C and 600 °C groups. By annealing at 800 °C, N2 recovered almost completely, and most other complexes were not observed. Recently, lifetime degradation has been observed in the nitrogen doped FZ Si annealed at between 450 and 800 °C. The N-V interaction in the same temperature range revealed here will help to understand the lifetime degradation mechanism. The behavior of the 689 cm−1 line corresponded well to the lifetime degradation.
Physics at the SPS
Authors: Gatignon L.
Published: May 2018

The CERN Super Proton Synchrotron (SPS) has delivered a variety of beams to a vigorous fixed target physics program since 1978. In this paper, we restrict ourselves to the description of a few illustrative examples in the ongoing physics program at the SPS. We will outline the physics aims of the COmmon Muon Proton Apparatus for Structure and Spectroscopy (COMPASS), north area 64 (NA64), north area 62 (NA62), north area 61 (NA61), and advanced proton driven plasma wakefield acceleration experiment (AWAKE). COMPASS studies the structure of the proton and more specifically of its spin. NA64 searches for the dark photon A’, which is the messenger for interactions between normal and dark matter. The NA62 experiment aims at a 10% precision measurement of the very rare decay K+ → π+νν. As this decay mode can be calculated very precisely in the Standard Model, it offers a very good opportunity to look for new physics beyond the Standard Model. The NA61/SHINE experiment studies the phase transition to Quark Gluon Plasma, a state in which the quarks and gluons that form the proton and the neutron are de-confined. Finally, AWAKE investigates proton-driven wake field acceleration: a promising technique to accelerate electrons with very high accelerating gradients. The Physics Beyond Colliders study at CERN is paving the way for a significant and diversified continuation of this already rich and compelling physics program that is complementary to the one at the big colliders like the Large Hadron Collider.
Analysis of three-phase equilibrium conditions for methane hydrate by isometric-isothermal molecular dynamics simulations
Authors: Yuhara Daisuke , Brumby Paul E. , Wu David T. , Sum Amadeu K. , Yasuoka Kenji
Published: May 2018

To develop prediction methods of three-phase equilibrium (coexistence) conditions of methane hydrate by molecular simulations, we examined the use of NVT (isometric-isothermal) molecular dynamics (MD) simulations. NVT MD simulations of coexisting solid hydrate, liquid water, and vapor methane phases were performed at four different temperatures, namely, 285, 290, 295, and 300 K. NVT simulations do not require complex pressure control schemes in multi-phase systems, and the growth or dissociation of the hydrate phase can lead to significant pressure changes in the approach toward equilibrium conditions. We found that the calculated equilibrium pressures tended to be higher than those reported by previous NPT (isobaric-isothermal) simulation studies using the same water model. The deviations of equilibrium conditions from previous simulation studies are mainly attributable to the employed calculation methods of pressure and Lennard-Jones interactions. We monitored the pressure in the methane phase, far from the interfaces with other phases, and confirmed that it was higher than the total pressure of the system calculated by previous studies. This fact clearly highlights the difficulties associated with the pressure calculation and control for multi-phase systems. The treatment of Lennard-Jones interactions without tail corrections in MD simulations also contributes to the overestimation of equilibrium pressure. Although improvements are still required to obtain accurate equilibrium conditions, NVT MD simulations exhibit potential for the prediction of equilibrium conditions of multi-phase systems.
Phase separation in the six-vertex model with a variety of boundary conditions
Authors: Lyberg I. , Korepin V. , Ribeiro G. A. P. , Viti J.
Published: May 2018

We present numerical results for the six-vertex model with a variety of boundary conditions. Adapting an algorithm for domain wall boundary conditions, proposed in the work of Allison and Reshetikhin [Ann. Inst. Fourier 55(6), 1847–1869 (2005)], we examine some modifications of these boundary conditions. To be precise, we discuss partial domain wall boundary conditions, reflecting ends, and half turn boundary conditions (domain wall boundary conditions with half turn symmetry). Dedicated to the memory of Ludwig Faddeev
A simple-architecture fibered transmission system for dissemination of high stability 100 MHz signals
Authors: Bakir A. , Rocher C. , Maréchal B. , Bigler E. , Boudot R. , Kersalé Y. , Millo J.
Published: May 2018

We report on the development of a simple-architecture fiber-based frequency distribution system used to transfer high frequency stability 100 MHz signals. This work is focused on the emitter and the receiver performances that allow the transmission of the radio-frequency signal over an optical fiber. The system exhibits a residual fractional frequency stability of 1 × 10−14 at 1 s integration time and in the low 10−16 range after 100 s. These performances are suitable to transfer the signal of frequency references such as those of a state-of-the-art hydrogen maser without any phase noise compensation scheme. As an application, we demonstrate the dissemination of such a signal through a 100 m long optical fiber without any degradation. The proposed setup could be easily extended for operating frequencies in the 10 MHz–1 GHz range.
Almost all quantum channels are equidistant
Authors: Nechita Ion , Puchała Zbigniew , Pawela Łukasz , Życzkowski Karol
Published: May 2018

In this work, we analyze properties of generic quantum channels in the case of large system size. We use random matrix theory and free probability to show that the distance between two independent random channels converges to a constant value as the dimension of the system grows larger. As a measure of the distance we use the diamond norm. In the case of a flat Hilbert-Schmidt distribution on quantum channels, we obtain that the distance converges to 12+2π, giving also an estimate for the maximum success probability for distinguishing the channels. We also consider the problem of distinguishing two random unitary rotations.
The significance of temperature dependence on the piezoelectric energy harvesting by using a phononic crystal
Authors: Aly Arafa H. , Nagaty Ahmed , Khalifa Zaki , Mehaney Ahmed
Published: May 2018

In this study, an acoustic energy harvester based on a two-dimensional phononic crystal has been constructed. The present structure consists of silicon cylinders in the air background with a polyvinylidene fluoride cylinder as a defect to confine the acoustic energy. The presented energy harvester depends on the piezoelectric effect (using the piezoelectric material polyvinylidene fluoride) that converts the confined acoustic energy to electric energy. The maximum output voltage obtained equals 170 mV. Moreover, the results revealed that the output voltage can be increased with increasing temperature. In addition, the effects of the load resistance and the geometry of the piezoelectric material on the output voltage have been studied theoretically. Based on these results, all previous studies about energy harvesting in phononic structures must take temperature effects into account.
Electron paramagnetic resonance g-tensors from state interaction spin-orbit coupling density matrix renormalization group
Authors: Sayfutyarova Elvira R. , Chan Garnet Kin-Lic
Published: May 2018

We present a state interaction spin-orbit coupling method to calculate electron paramagnetic resonance g-tensors from density matrix renormalization group wavefunctions. We apply the technique to compute g-tensors for the TiF3 and CuCl42− complexes, a [2Fe–2S] model of the active center of ferredoxins, and a Mn4CaO5 model of the S2 state of the oxygen evolving complex. These calculations raise the prospects of determining g-tensors in multireference calculations with a large number of open shells.
Diamond family of colloidal supercrystals as phononic metamaterials
Authors: Aryana Kiumars , Zanjani Mehdi B.
Published: May 2018

Colloidal crystals provide a versatile platform for designing phononic metamaterials with exciting applications for sound and heat management. New advances in the synthesis and self-assembly of anisotropic building blocks such as colloidal clusters have expanded the library of available micro- and nano-scale ordered multicomponent structures. Diamond-like supercrystals formed by such clusters and spherical particles are notable examples that include a rich family of crystal symmetries such as diamond, double diamond, zinc-blende, and MgCu2. This work investigates the design of phononic supercrystals by predicting and analyzing phonon transport properties. In addition to size variation and structural diversity, these supercrystals encapsulate different sub-lattice types within one structure. Computational models are used to calculate the effect of various parameters on the phononic spectrum of diamond-like supercrystals. The results show that structures with relatively small or large filling factors (f > 0.65 or f < 0.45) include smaller bandgaps compared to those with medium filling factors (0.65 > f > 0.45). The double diamond and zinc-blende structures render the largest bandgap size compared to the other supercrystals studied in this paper. Additionally, this article discusses the effect of incorporating various configurations of sub-lattices by selecting different material compositions for the building blocks. The results suggest that, for the same structure, there exist multiple phononic variants with drastically different band structures. This study provides a valuable insight for evaluating novel colloidal supercrystals for phononic applications and guides the future experimental work for the synthesis of colloidal structures with desired phononic behavior.
Differential computation method used to calibrate the angle-centroid relationship in coaxial reverse Hartmann test
Authors: Li Xinji , Hui Mei , Zhao Zhu , Liu Ming , Dong Liquan , Kong Lingqin , Zhao Yuejin
Published: May 2018

A differential computation method is presented to improve the precision of calibration for coaxial reverse Hartmann test (RHT). In the calibration, the accuracy of the distance measurement greatly influences the surface shape test, as demonstrated in the mathematical analyses. However, high-precision absolute distance measurement is difficult in the calibration. Thus, a differential computation method that only requires the relative distance was developed. In the proposed method, a liquid crystal display screen successively displayed two regular dot matrix patterns with different dot spacing. In a special case, images on the detector exhibited similar centroid distributions during the reflector translation. Thus, the critical value of the relative displacement distance and the centroid distributions of the dots on the detector were utilized to establish the relationship between the rays at certain angles and the detector coordinates. Experiments revealed the approximately linear behavior of the centroid variation with the relative displacement distance. With the differential computation method, we increased the precision of traditional calibration 10−5 rad root mean square. The precision of the RHT was increased by approximately 100 nm.
Effects of hysteresis and Brayton cycle constraints on magnetocaloric refrigerant performance
Authors: Brown T. D. , Buffington T. , Shamberger P. J.
Published: May 2018

Despite promising proofs of concept, system-level implementation of magnetic refrigeration has been critically limited by history-dependent refrigerant losses that interact with governing thermodynamic cycles to adversely impact refrigeration performance. Future development demands a more detailed understanding of how hysteresis limits performance, and of how different types of cycles can mitigate these limitations, but without the extreme cost of experimental realization. Here, the utility of Brayton cycles for magnetic refrigeration is investigated via direct simulation, using a combined thermodynamic-hysteresis modeling framework to compute the path-dependent magnetization and entropy of a model alloy for a variety of feasible Brayton cycles between 0–1.5 T and 0–5 T. By simultaneously varying the model alloy's hysteresis properties and applying extensions of the thermodynamic laws to non-equilibrium systems, heat transfers and efficiencies are quantified throughout the space of hystereses and Brayton cycles and then compared with a previous investigation using Ericsson cycles. It is found that (1) hysteresis losses remain a critical obstacle to magnetic refrigeration implementation, with efficiencies >80% in the model system requiring hysteresis <0.5 K at 1.5 T; (2) optimal-efficiency Brayton cycles for given field and hysteresis constraints exist and are determined uniquely by the refrigerant transformation temperatures at the relevant fields; (3) for a given hysteresis and field constraint, Brayton and Ericsson-type cycles generate similar efficiencies; for a given temperature span, Ericsson cycles lift more heat per cycle, with the difference decreasing with the refrigerant heat capacity outside the phase transformation region.
Tornado model for a magnetised plasma
Authors: Onishchenko O. G. , Fedun V. , Smolyakov A. , Horton W. , Pokhotelov O. A. , Verth G.
Published: May 2018

A new analytical model of axially-symmetric magnetic vortices with both a twisted fluid flow and a magnetic field is proposed. The exact solution for the three-dimensional structure of the fluid velocity and the magnetic field is obtained within the framework of the ideal magnetohydrodynamic equations for an incompressible fluid in a gravitational field. A quasi-stationary localised vortex arises when the radial flow that tends to concentrate vorticity in a narrow column around the axis of symmetry is balanced by the vertical vortex advection in the axial direction. The explicit expressions for the velocity and magnetic field components are obtained. The proposed analytic model may be used to parameterise the observed solar tornadoes and can provide a new indirect way for estimating magnetic twist from the observed azimuthal velocity profiles.
Peristalticity-driven banded chemical garden
Authors: Pópity-Tóth É. , Schuszter G. , Horváth D. , Tóth Á.
Published: May 2018

Complex structures in nature are often formed by self-assembly. In order to mimic the formation, to enhance the production, or to modify the structures, easy-to-use methods are sought to couple engineering and self-assembly. Chemical-garden-like precipitation reactions are frequently used to study such couplings because of the intrinsic chemical and hydrodynamic interplays. In this work, we present a simple method of applying periodic pressure fluctuations given by a peristaltic pump which can be used to achieve regularly banded precipitate membranes in the copper–phosphate system.
Surface potential extraction from electrostatic and Kelvin-probe force microscopy images
Authors: Xu Jie , Chen Deyuan , Li Wei , Xu Jun
Published: May 2018

A comprehensive comparison study of electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM) is conducted in this manuscript. First, it is theoretically demonstrated that for metallic or semiconductor samples, both the EFM and KPFM signals are a convolution of the sample surface potential with their respective transfer functions. Then, an equivalent point-mass model describing cantilever deflection under distributed loads is developed to reevaluate the cantilever influence on detection signals, and it is shown that the cantilever has no influence on the EFM signal, while it will affect the KPFM signal intensity but not change the resolution. Finally, EFM and KPFM experiments are carried out, and the surface potential is extracted from the EFM and KPFM images by deconvolution processing, respectively. The extracted potential intensity is well consistent with each other and the detection resolution also complies with the theoretical analysis. Our work is helpful to perform a quantitative analysis of EFM and KPFM signals, and the developed point-mass model can also be used for other cantilever beam deflection problems.
Hybrid model based unified scheme for endoscopic Cerenkov and radio-luminescence tomography: Simulation demonstration
Authors: Wang Lin , Cao Xin , Ren Qingyun , Chen Xueli , He Xiaowei
Published: May 2018

Cerenkov luminescence imaging (CLI) is an imaging method that uses an optical imaging scheme to probe a radioactive tracer. Application of CLI with clinically approved radioactive tracers has opened an opportunity for translating optical imaging from preclinical to clinical applications. Such translation was further improved by developing an endoscopic CLI system. However, two-dimensional endoscopic imaging cannot identify accurate depth and obtain quantitative information. Here, we present an imaging scheme to retrieve the depth and quantitative information from endoscopic Cerenkov luminescence tomography, which can also be applied for endoscopic radio-luminescence tomography. In the scheme, we first constructed a physical model for image collection, and then a mathematical model for characterizing the luminescent light propagation from tracer to the endoscopic detector. The mathematical model is a hybrid light transport model combined with the 3rd order simplified spherical harmonics approximation, diffusion, and radiosity equations to warrant accuracy and speed. The mathematical model integrates finite element discretization, regularization, and primal-dual interior-point optimization to retrieve the depth and the quantitative information of the tracer. A heterogeneous-geometry-based numerical simulation was used to explore the feasibility of the unified scheme, which demonstrated that it can provide a satisfactory balance between imaging accuracy and computational burden.
The strengths and limitations of effective centroid force models explored by studying isotopic effects in liquid water
Authors: Yuan Ying , Li Jicun , Li Xin-Zheng , Wang Feng
Published: May 2018

The development of effective centroid potentials (ECPs) is explored with both the constrained-centroid and quasi-adiabatic force matching using liquid water as a test system. A trajectory integrated with the ECP is free of statistical noises that would be introduced when the centroid potential is approximated on the fly with a finite number of beads. With the reduced cost of ECP, challenging experimental properties can be studied in the spirit of centroid molecular dynamics. The experimental number density of H2O is 0.38% higher than that of D2O. With the ECP, the H2O number density is predicted to be 0.42% higher, when the dispersion term is not refit. After correction of finite size effects, the diffusion constant of H2O is found to be 21% higher than that of D2O, which is in good agreement with the 29.9% higher diffusivity for H2O observed experimentally. Although the ECP is also able to capture the redshifts of both the OH and OD stretching modes in liquid water, there are a number of properties that a classical simulation with the ECP will not be able to recover. For example, the heat capacities of H2O and D2O are predicted to be almost identical and higher than the experimental values. Such a failure is simply a result of not properly treating quantized vibrational energy levels when the trajectory is propagated with classical mechanics. Several limitations of the ECP based approach without bead population reconstruction are discussed.