bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling the evection resonance for Trojan satellites: application to the Saturn system
Authors: Giuppone C. A. , Roig F. , Saad-Olivera X.
Published: November 2018

Context. The stability of satellites in the solar system is affected by the so-called evection resonance. The moons of Saturn, in particular, exhibit a complex dynamical architecture in which co-orbital configurations occur, especially close to the planet where this resonance is present.

Aims. We address the dynamics of the evection resonance, with particular focus on the Saturn system, and compare the known behavior of the resonance for a single moon with that of a pair of moons in co-orbital Trojan configuration.

Methods. We developed an analytic expansion of the averaged Hamiltonian of a Trojan pair of bodies, including the perturbation from a distant massive body. The analysis of the corresponding equilibrium points was restricted to the asymmetric apsidal corotation solution of the co-orbital dynamics. We also performed numerical N-body simulations to construct dynamical maps of the stability of the evection resonance in the Saturn system, and to study the effects of this resonance under the migration of Trojan moons caused by tidal dissipation.

Results. The structure of the phase space of the evection resonance for Trojan satellites is similar to that of a single satellite, differing in that the libration centers are displaced from their standard positions by an angle that depends on the periastron difference ϖ2 −ϖ1 and on the mass ratio m2∕m1 of the Trojan pair. In the Saturn system, the inner evection resonance, located at ~8 RS, may capture a pair of Trojan moons by migration; the stability of the captured system depends on the assumed values of the dissipation factor Q of the moons. On the other hand, the outer evection resonance, located at >0.4 RHill, cannot exist at all for Trojan moons, because Trojan configurations are strongly unstable at distances from Saturn longer than ~0.15 RHill.

Conclusions. The interaction with the inner evection resonance may have been relevant during the early evolution of the Saturn moons Tethys, Dione, and Rhea. In particular, Rhea may have had Trojan companions in the past that were lost when it crossed the evection resonance, while Tethys and Dione may either have retained their Trojans or have never crossed the evection. This may help to constrain the dynamical processes that led to the migration of these satellites and to the evection itself.
Faunal diversity of Cladocera (Crustacea: Branchiopoda) with notes on biogeographically important species in the floodplain wetlands of the Subansiri river basin, India
Authors: Gogoi Budhin , Sousa Francisco Diogo R. , Das Debangshu N.
Published: November 2018

The plankton samples collected from the Subansiri floodplain wetlands revealed a rich Cladocera assemblage of 55 species belonging to 30 genera and 7 families. The species richness represents 42% and 75% of the total amount of fresh water species reported from India and Assam, respectively. Chydoridae was the most speciose family, with 31 species, while Ilyocryptidae was represented by a single species. Sididae, Daphniidae, Bosminidae, Moinidae and Macrothricidae were represented by four, five, three, two and four species, respectively. The faunal composition is represented by cosmopolitan, tropical and oriental elements. The documentation ofDiaphanosoma dubium,Latonopsis australis,Simocephalus mixtus,Chydorus sphaericus,Chydorus parvus,Chydorus ovalis,Alonella clathratula,Pleuroxuscf.denticulatus,Picripleuroxus quasidenticulatus,Celsinotummacronyx,Coronatella anodontaandKurzia (Rostrukurzia) brevilabrishas biogeographic importance. We provide brief geographical distributional remarks about these 12 species from the collected samples. This was a preliminary study, as the fauna from the Indian subcontinent is poorly documented, and requires a taxonomic revision as a whole. The faunistic diversity of cladocerans comprises a clear representation of a tropical cladoceran assemblage.
Early clinical cxperience with the SIGN hip construct: a retrospective case series
Authors: Roth Justin , Goldman Brian , Zirkle Lewis , Schlechter John , Ibrahim John , Shearer David
Published: November 2018

Background: As the population ages, the developing world industrializes, and more urban centers emerge, the burden of orthopedic trauma will steadily increase. SIGN Fracture Care International has developed a unique intramedullary device for fixation of hip fractures in low-resource settings lacking fluoroscopy. The purpose of this study is to report the safety profile and complication rate for a consecutive series of hip fracture patients managed using this implant.

Methods: We conducted a retrospective analysis of the first 170 patients treated with the SIGN Hip Construct (SHC) from 2009 to 2014 using the SIGN Online Surgical Database (SOSD). Patients with follow-up greater than 12 weeks and adequate radiographs were included. Data recorded include patient demographics, time-to-surgery, union rate, AO/OTA classification, complications, neck-shaft angle, and clinical outcomes including painless weight bearing and knee flexion greater than 90°.

Results: Of 170 patients, 71 met inclusion criteria with mean follow-up of 39 weeks. Mean age was 49.5 and by WHO, regions were Africa (27), Eastern Mediterranean (21), Western Pacific (17), Americas (3), and Southeast Asia (3). Fractures included intertrochanteric (55), subtrochanteric (7), femoral neck (4), and combined (5). Reduction quality was good in 35 (49%), acceptable in 19 (27%), and poor in 17 (24%). Major complications consisted of varus collapse (6), non- or delayed union (3), intra-articular screw (5), and infection (3). Average postoperative neck-shaft angle was 126° and 119.3° at final follow-up.

Conclusions: This is the first comprehensive report of a novel implant for hip fractures specifically designed for low-resource settings. The early clinical data and outcomes suggest that the SHC can be safely inserted in the absence of fluoroscopy, and facilitates early mobilization while maintaining acceptable reduction until union.
Asymmetric Synthesis of 2,2-Disubstituted Benzofuranones through an Organocatalytic Alkylation with Nitroallylic Acetates
Authors: Enders Dieter , Zhao Long , Raabe Gerhard
Published: November 2018

The asymmetric allylic alkylation of benzofuran-3(2H)-ones with nitroallylic acetates has been achieved employing a bifunctional thiourea organocatalyst via SN2′ substitution. A series of 2,2-disubstituted benzofuranones bearing adjacent tetrasubstituted and tertiary stereocenters have been synthesized with moderate to good yields and very good stereoselectivities.
Coagulation Pathways, Hemostasis, and Thrombosis in Liver Failure
Authors: Davis Jessica , Caldwell Stephen , Intagliata Nicolas
Published: November 2018

Achieving hemostasis, preventing and treating thrombosis, and laboratory measurement of the hemostatic pathways constitute the core elements of managing the critically ill patient with liver failure. Uncontrolled bleeding in acutely decompensated cirrhosis and acute-on-chronic liver failure is probably the most familiar clinical challenge to intensivists. Bleeding in these patients can be broadly divided into pressure-driven (portal hypertension-related) bleeding with only limited dependence on hemostatic pathways and intractable mucosal/wound bleeding, which is much more directly related to a severely disturbed hemostatic system with imbalances in the coagulation cascade and the fibrinolytic system. Both types of bleeding can occur simultaneously and may even coexist with inappropriate thrombosis such as portal vein thrombosis or venous thromboembolism. Due to the fundamental role of the liver in coagulation factor synthesis and its direct and indirect regulation of nearly all aspects of the hemostatic system, laboratory measurements of coagulation pathways also constitute key aspects of all prognostic scores that guide clinical decisions and forecast optimal interventions in both acute and chronic forms of liver failure.
Early Pregnancy Hemoglobin A1C and Pregnancy Outcomes: A Population-Based Study
Authors: Chen Lu , Pocobelli Gaia , Yu Onchee , Shortreed Susan M. , Osmundson Sarah S. , Fuller Sharon , Wartko Paige D. , Mcculloch David , Warwick Susan , Newton Katherine M. , Dublin Sascha
Published: November 2018

Objective Women with prediabetes are identified from screening for overt diabetes in early pregnancy, but the clinical significance of prediabetes in pregnancy is unclear. We examined whether prediabetes in early pregnancy was associated with risks of adverse outcomes.

Study Design We conducted a retrospective cohort study of pregnant women enrolled in Kaiser Permanente Washington from 2011 to 2014. Early pregnancy hemoglobin A1C (A1C) values, covariates, and outcomes were ascertained from electronic medical records and state birth certificates. Women with prediabetes (A1C of 5.7–6.4%) were compared with those with normal A1C levels (<5.7%) for risk of gestational diabetes mellitus (GDM) and other outcomes including preeclampsia, primary cesarean delivery, induction of labor, large/small for gestational age, preterm birth, and macrosomia. We used modified Poisson's regression to calculate adjusted relative risks (RRs) and 95% confidence intervals (CIs).

Results Of 7,020 women, 239 (3.4%) had prediabetes. GDM developed in 48% of prediabetic women compared with 11% of women with normal A1C levels (adjusted RR: 2.8, 95% CI: 2.4–3.3). Prediabetes was not associated with all other adverse maternal and neonatal outcomes.

Conclusion Prediabetes in early pregnancy is a risk factor for GDM. Future research is needed to elucidate whether early intervention may reduce this risk.
Making Politics Visible: Discourses on Gender and Race in the Problematisation of Sex-Selective Abortion
Authors: Anitha Sundari , Gill Aisha K.
Published: November 2018

This paper examines the problematisation of sex-selective abortion (SSA) in UK parliamentary debates on Fiona Bruce's Abortion (Sex-Selection) Bill 2014–15 and on the subsequent proposed amendment to the Serious Crime Bill 2014–15. On the basis of close textual analysis, we argue that a discursive framing of SSA as a form of cultural oppression of minority women in need of protection underpinned Bruce's Bill; in contrast, by highlighting issues more commonly articulated in defence of women's reproductive rights, the second set of debates displaced this framing in favour of a broader understanding, drawing on postcolonial feminist critiques, of how socio-economic factors constrain all women in this regard. We argue that the problematisation of SSA explains the original cross-party support for, and subsequent defeat of, the policies proposed to restrict SSA. Our analysis also highlights the central role of ideology in the policy process, thus making politics visible in policymaking.
‘Neither Pure Love nor Imitating Capitalism’: Euro WILD and the Invention of Women's Music Distribution in Europe, 1980–1982
Authors: Withers D-M
Published: November 2018

Euro Women's Independent Label Distribution (WILD) was a pan-European network of feminist music distributors active in the early 1980s. They were affiliated to WILD, the US-based Women's Music distribution network founded in 1979 to disseminate the growing corpus of Women's Music emerging from the US Women's Liberation Movement (WLM). This article presents an interpretation of archive materials that document Euro WILD's activities from the Women's Revolutions Per Minute archive, housed at the Women's Art Library, London. Constrained and enabled by the archive materials on offer, I revisit some of the practical and political problems the network faced as European distributors of US Women's Music. Key issues explored include the perception of US cultural imperialism by women based in Europe and the affective politics that circulated transnationally between distributors. Finally, this article explores how the concept and practice of the Women's Music industry changed when women beyond the borders of the US engaged with it.
Active Women and Ideal Refugees: Dissecting Gender, Identity and Discourse in the Sahrawi Refugee Camps
Authors: Finden Alice
Published: November 2018

Since the Moroccan invasion in 1975, official reports on visits to Sahrawi refugee camps by international aid agencies and faith-based groups consistently reflect an overwhelming impression of gender equality in Sahrawi society. As a result, the space of the Sahrawi refugee camps in Algeria and, by external association, Sahrawi society and Western Sahara as a nation-in-exile is constructed as ‘ideal’ (Fiddian-Qasmiyeh, 2010, p. 67). I suggest that the ‘feminist nationalism’ of the Sahrawi nation-in-exile is one that is employed strategically by internal representatives of the Popular Front for the Liberation of Saguia el-Hamra and Río de Oro (POLISARIO), the Sahrawi Arab Democratic Republic (SADR) and the National Union of Sahrawi Women (NUSW), and by external actors from international aid agencies and also the colonial Moroccan state. The international attention paid to the active role of certain women in Sahrawi refugee camps makes ‘Other’ Sahrawi invisible, such as children, young women, mothers, men, people of lower socio-economic statuses, (‘liberated’) slave classes and refugees who are not of Sahrawi background. According to Elena Fiddian-Qasmiyeh ( ibid.), it also creates a discourse of ‘good’, ‘ideal’ refugees who are reluctant to complain, in contrast to ‘Other refugees’. This feminisation allows the international community not to take the Sahrawi call for independence seriously and reproduces the myth of Sahrawi refugees as naturally non-violent (read feminine) and therefore ‘ideal’. The myth of non-violence accompanied by claims of Sahrawi secularity is also used to distance Western Sahara from ‘African’, ‘Arab’ and ‘Islamic’, to reaffirm racialised and gendered discourses that associate Islam with terrorism and situate both in the Arab/Muslim East. These binaries make invisible the violence that Sahrawis experience as a result of the gendered constructions of both internal and external actors, and silence voices of dissent and frustration with the more than forty years of waiting to return home.
Using Pain, Living with Pain
Authors: Sheppard Emma
Published: November 2018

This paper presents the early findings of research into the experiences of pain for those who live with chronic pain and engage in BDSM (bondage and discipline, domination and submission, sadism and masochism), explored using a critical crip approach rooted in crip theory and feminist disability studies. The research took the form of a series of interviews with eight disabled people living with chronic pain who experience pain in their BDSM practices, developing a narrative of experiences. The majority of those living with chronic pain, or who have diagnoses of chronic illnesses causing chronic pain, are women. Chronic pain is frequently assumed to be similar to acute pain; however, thinking through pain in terms of normativity and able-bodymindedness reveals the ableist structures that underpin normative attitudes towards pain and those who are in pain. Pain is understood as dehumanising—and thus the person living with chronic pain is understood as not human, abnormal, and disabled. The disabled body, the body in pain, is a horrifying object of abjection, and the non-disabled observer assumes that to be in pain is to suffer; therefore, living with chronic pain is understood as an ontological impossibility and must be stopped. BDSM is a series of practices forming a space in which the people living with chronic pain in this study are able to engage with their somatic experience in ways that do not expect normalcy, while being disabled and living with chronic pain gives them space to explore non-normative sexual practices.
Lonely but avoidant—the unfortunate juxtaposition of loneliness and self-disgust
Authors: Ypsilanti Antonia
Published: November 2018

Loneliness is prevalent worldwide and is a known risk factor for numerous physical and mental health outcomes. The health consequences of chronic loneliness coupled with the cost on public health care has necessitated the development of interventions and campaigns to end loneliness globally. According to a recent meta-analysis, such interventions focus on improving social skills, increasing opportunities for social contact/support (i.e., reducing social isolation) or addressing maladaptive cognition (e.g., irrational thoughts, self-defeating, and self-blame thoughts). The results showed that changing maladaptive thoughts offer “the best chance” for alleviating feelings of loneliness. In accordance with the latter approach, this paper proposes a new paradigm in understanding and treating loneliness that takes into account self-disgust, an aversive self-conscious affective state that reflects disgust directed towards the self. Based on findings from published and unpublished data, it is argued that interventions against loneliness that focus exclusively on improving social skills and increasing opportunities for social contact may be ineffective because lonelier people experience more self-disgust, which makes them more socially inhibited and reluctant to connect with other people. Future interventions should consider self-disgust in the treatment of loneliness and explore ways to counter feelings of self-disgust.
Detecting early-warning signals in periodically forced systems with noise
Authors: Ma Jinzhong , Xu Yong , Kurths Jürgen , Wang Haiyan , Xu Wei
Published: November 2018

Early-warning signals for imminent regime shifts in multi-stable systems are highly desirable because it is often difficult to revert a system to the previous state once a transition has occurred. In this paper, two indicators, the phase lag and amplitude difference of the system's response, are extended to detect early-warning signals of a periodically driven, bistable complex system with noise. Our results show that both indicators can announce a regime shift of a complex system with small noise, namely, the critical point of the regime shift near a bifurcation point of the corresponding deterministic system. However, they fail to early indicate the regime shift in the case of large noise where the shift is far from the original bifurcation point. Based on the moment-expanding scheme, we reduce a large noise to a small one, and then both indicators work well again. We illustrate this approach via a parameterized lake eutrophication model verified by data. The regime shift to eutrophication could be detected in advance by studying the phase lag and amplitude difference of phosphorus concentrations. A basic statistical test is performed for the robustness of the proposed indicators. This approach provides a theoretical basis to prevent ecological environment deteriorations.
Coulomb explosion imaging of CH3I and CH2ClI photodissociation dynamics
Authors: Allum Felix , Burt Michael , Amini Kasra , Boll Rebecca , Köckert Hansjochen , Olshin Pavel K. , Bari Sadia , Bomme Cédric , Brauße Felix , Cunha de Miranda Barbara , Düsterer Stefan , Erk Benjamin , Géléoc Marie , Geneaux Romain , Gentleman Alexander S. , Goldsztejn Gildas , Guillemin Renaud , Holland David M. P. , Ismail Iyas , Johnsson Per , Journel Loïc , Küpper Jochen , Lahl Jan , Lee Jason W. L. , Maclot Sylvain , Mackenzie Stuart R. , Manschwetus Bastian , Mereshchenko Andrey S. , Mason Robert , Palaudoux Jérôme , Piancastelli Maria Novella , Penent Francis , Rompotis Dimitrios , Rouzée Arnaud , Ruchon Thierry , Rudenko Artem , Savelyev Evgeny , Simon Marc , Schirmel Nora , Stapelfeldt Henrik , Techert Simone , Travnikova Oksana , Trippel Sebastian , Underwood Jonathan G. , Vallance Claire , Wiese Joss , Ziaee Farzaneh , Brouard Mark , Marchenko Tatiana , Rolles Daniel
Published: November 2018

The photodissociation dynamics of CH3I and CH2ClI at 272 nm were investigated by time-resolved Coulomb explosion imaging, with an intense non-resonant 815 nm probe pulse. Fragment ion momenta over a wide m/z range were recorded simultaneously by coupling a velocity map imaging spectrometer with a pixel imaging mass spectrometry camera. For both molecules, delay-dependent pump-probe features were assigned to ultraviolet-induced carbon-iodine bond cleavage followed by Coulomb explosion. Multi-mass imaging also allowed the sequential cleavage of both carbon-halogen bonds in CH2ClI to be investigated. Furthermore, delay-dependent relative fragment momenta of a pair of ions were directly determined using recoil-frame covariance analysis. These results are complementary to conventional velocity map imaging experiments and demonstrate the application of time-resolved Coulomb explosion imaging to photoinduced real-time molecular motion.
Effect of time varying transmission rates on the coupled dynamics of epidemic and awareness over a multiplex network
Authors: Sagar Vikram , Zhao Yi , Sen Abhijit
Published: November 2018

A non-linear stochastic model is presented to study the effect of time variation of transmission rates on the co-evolution of epidemics and its corresponding awareness over a two layered multiplex network. In the model, the infection transmission rate of a given node in the epidemic layer depends upon its awareness probability in the awareness layer. Similarly, the infection information transmission rate of a node in the awareness layer depends upon its infection probability in the epidemic layer. The spread of disease resulting from physical contacts is described in terms of a Susceptible Infected Susceptible process over the epidemic layer and the spread of information about the disease outbreak is described in terms of an Unaware Aware Unaware process over the virtual interaction mediated awareness layer. The time variation of the transmission rates and the resulting co-evolution of these mutually competing processes are studied in terms of a network topology dependent parameter (α). Using a second order linear theory, it is shown that in the continuous time limit, the co-evolution of these processes can be described in terms of damped and driven harmonic oscillator equations. From the results of a Monte-Carlo simulation, it is shown that for a suitable choice of the parameter (α), the two processes can either exhibit sustained oscillatory or damped dynamics. The damped dynamics corresponds to the endemic state. Furthermore, for the case of an endemic state, it is shown that the inclusion of the awareness layer significantly lowers the disease transmission rate and reduces the size of the epidemic. The infection probability of the nodes in the endemic state is found to have a dependence on both the transmission rates and on their absolute degrees in each of the network layers and on the relative differences between their degrees in the respective layers.
A videogrammetric system for measuring the full-field blade deformation of a heavy-duty helicopter’s rotating rotor
Authors: Wei Bin , Liang Jin , Hu Hao , Ren Maodong , Yi Hui , Li Jie
Published: November 2018

In this paper, a videogrammetric system, based on three-dimensional digital image processing and industrial close range photogrammetry technology, is proposed to solve the three-dimensional motion and deformation parameters of a rotating blade by identifying a speckle pattern. For the high aspect ratio and flexible rotor blade design often used in heavy-duty helicopters, there are extremely complex aerodynamic, dynamic, and coupling problems that require solutions to measure the full-field deformation of the rotating blade in the test condition of a rotor test tower. The key issues involved include a two-step calibration method using separate internal and external parameters for a large field of view, and a reliable estimation of the seed point method for a large deformation and weak correlation speckle images match. The system was developed and a simulation test was conducted on a rotor test tower. The results show that the proposed system is practicable to measure the surface displacement and motion parameters of a high-speed rotating rotor blade.
Circular photogalvanic effect in Cu/Bi bilayers
Authors: Hirose Hana , Ito Naoto , Kawaguchi Masashi , Lau Yong-Chang , Hayashi Masamitsu
Published: November 2018

We have studied the circular photogalvanic effect (CPGE) in Cu/Bi bilayers. When a circularly polarized light in the visible range is irradiated to the bilayer from an oblique incidence, we find a photocurrent that depends on the helicity of light. Such photocurrent appears in a direction perpendicular to the light plane of incidence but is absent in the parallel configuration. The helicity dependent photocurrent is significantly reduced for a Bi single layer film, and the effect is nearly absent for a Cu single layer film. Conventional interpretation of the CPGE suggests the existence of spin–momentum locked band(s) of Rashba type in the Cu/Bi bilayer. In contrast to previous reports on the CPGE studied in other systems, however, the light energy used here to excite the carriers is much larger than the bandgap of Bi. Moreover, the CPGE of the Cu/Bi bilayer is larger when the energy of the light is larger: the helicity dependent photocurrent excited with a blue light is nearly two times larger than that of a red light. We therefore consider that the CPGE of the Cu/Bi bilayer may have a different origin compared to conventional systems.
Grand-canonical approach to density functional theory of electrocatalytic systems: Thermodynamics of solid-liquid interfaces at constant ion and electrode potentials
Authors: Melander Marko M. , Kuisma Mikael J. , Christensen Thorbjørn Erik Køppen , Honkala Karoliina
Published: November 2018

Properties of solid-liquid interfaces are of immense importance for electrocatalytic and electrochemical systems, but modeling such interfaces at the atomic level presents a serious challenge and approaches beyond standard methodologies are needed. An atomistic computational scheme needs to treat at least part of the system quantum mechanically to describe adsorption and reactions, while the entire system is in thermal equilibrium. The experimentally relevant macroscopic control variables are temperature, electrode potential, and the choice of the solvent and ions, and these need to be explicitly included in the computational model as well; this calls for a thermodynamic ensemble with fixed ion and electrode potentials. In this work, a general framework within density functional theory (DFT) with fixed electron and ion chemical potentials in the grand canonical (GC) ensemble is established for modeling electrocatalytic and electrochemical interfaces. Starting from a fully quantum mechanical description of multi-component GC-DFT for nuclei and electrons, a systematic coarse-graining is employed to establish various computational schemes including (i) the combination of classical and electronic DFTs within the GC ensemble and (ii) on the simplest level a chemically and physically sound way to obtain various (modified) Poisson-Boltzmann (mPB) implicit solvent models. The detailed and rigorous derivation clearly establishes which approximations are needed for coarse-graining as well as highlights which details and interactions are omitted in vein of computational feasibility. The transparent approximations also allow removing some of the constraints and coarse-graining if needed. We implement various mPB models within a linear dielectric continuum in the GPAW code and test their capabilities to model capacitance of electrochemical interfaces as well as study different approaches for modeling partly periodic charged systems. Our rigorous and well-defined DFT coarse-graining scheme to continuum electrolytes highlights the inadequacy of current linear dielectric models for treating properties of the electrochemical interface.
A fast scanning ion conductance microscopy imaging method using compressive sensing and low-discrepancy sequences
Authors: Wang Zhiwu , Zhuang Jian , Gao Zijun , Liao Xiaobo
Published: November 2018

A scanning ion conductance microscope (SICM) is a multifunctional, high-resolution imaging technique whose non-contact nature makes it very suitable for imaging of biological samples such as living cells in a physiological environment. However, a drawback of hopping/backstep mode of SICM is its relatively slow imaging speed, which seriously restricts the study on the dynamic process of biological samples. This paper presents a new undersampled scanning method based on Compressed Sensing (CS-based scanning mode) theory to solve extended acquisition time issues in the hopping/backstep mode. Compressive sensing can break through the limit of the Nyquist sampling theorem and sample the original sparse/compressible signal at a rate lower than the Nyquist frequency. In the CS-based scanning mode, three sampling patterns, including the random sampling pattern and two kinds of sampling patterns produced by low-discrepancy sequences, were employed as the measurement locations to obtain the undersampled data with different undersampling ratios. Also TVAL3 (Total Variation Augmented Lagrangian ALternating-direction ALgorithm) was then utilized as a reconstruction algorithm to reconstruct the undersampled data. Compared with the nonuniform sampling points of random patterns at a low undersampling ratio, low-discrepancy sequences can produce a more uniform distribution point. Three types of samples with different complexity of topography were scanned by SICM using the conventional hopping/backstep mode and CS-based undersampled scanning mode. The comparisons of the imaging speed and quality with two scanning modes illustrate that the CS-based scanning mode can effectively speed up SICM imaging speed while not sacrificing the image quality. Also low-discrepancy sampling patterns can achieve a better reconstruction performance than that of the random sampling pattern under the same undersampling ratio.
Experimental study of low inertia vortex rings in shear-thinning fluids
Authors: Bentata O. , Anne-Archard D. , Brancher P.
Published: November 2018

The present work investigates experimentally the dynamics of vortex rings in shear-thinning fluids at low generalized Reynolds numbers, with a focus on the range from 300 down to 30. The experimental apparatus consists of a vertical cylinder-piston system with the lower part immersed in a tank filled with the liquid. Particle image velocimetry is used to analyze the influence of the non-Newtonian nature of the fluid on the generation, propagation, and eventual dissipation of vortex rings. The results show that shear-thinning controls the generation phase, whereas the vortex ring subsequent evolution is independent of the power-law index. In particular, it is found that the final dissipation stage is characterized by a flow dynamics which tends ultimately to a regime at a constant viscosity corresponding to the Newtonian plateau. This reveals the role of the Carreau number and of the Reynolds number based on this specific viscosity as relevant control parameters for this last stage.
Particle-in-cell/Monte Carlo collisional simulation of negative streamer formation and branching between planar electrodes
Authors: Wang Dan , Wang Lijun , Zheng Yashuang
Published: November 2018

In this paper, the mechanism of negative streamer formation and branching between planar electrodes is studied using a two dimensional particle-in-cell/Monte Carlo collisional model. Super-particles, each one of which represents many physical particles, are used in our model to reduce the calculation and memory usage. The electric field applied to the gap between electrodes is constant and is above the breakdown value already before the streamer formation. For nitrogen at standard temperature and pressure, the simulation is first performed in the background field of 10 MV/m. The results show that prior to branching, the streamer head is flattened, and the non-uniform distribution of electrons accelerated to energies above 50 eV is obtained at the flat streamer head, which then leads to streamer branching. Then, additional simulations in the background fields of 9 MV/m, 11 MV/m, and 12 MV/m are performed to investigate the effects of background field. The results show that the streamer propagates faster, has larger plasma density, and branches more rapidly in a stronger field. The simulation results of argon are also given at a standard temperature and pressure in the background field of 10 MV/m. The results show that more branches can be obtained in argon compared with nitrogen, which agrees well with the experimental results.
Numerical study of an electrowetting liquid microlens
Authors: Lv Shuyuan , Liu Chongqi , Luo WenFeng
Published: November 2018

We construct a numerical model for a liquid microlens formed by filling a microwell with two immiscible liquids, namely oil and water. The water–oil interface can be actuated as a tunable liquid lens because its curvature is well controlled by applying an external electric field. The contact angle of the oil droplet has the opposite tendency to that of a traditional water-filled microwell because of the repulsion force from the water phase. We study the dynamic interface deformation as functions of time and applied voltage, which typically within 10 ms is good enough as an imaging system for human eyes. In addition, using two different filling liquids provides more possibilities for tuning the focal length.
Deviations of dynamic parameters characterizing enthalpic and dielectric relaxations in glass forming alkyl phosphates
Authors: Saini Manoj K. , Guo Yuxing , Wu Tao , Ngai K. L. , Wang Li-Min
Published: November 2018

In our recent study [T. Wu et al., J. Chem. Phys. 147, 134501 (2017)], an alkyl phosphate glass former was studied and it suggested that the enthalpy relaxation involving the motions of all parts of the molecule is global, while the dielectric relaxation detects the local rotation of the polar core. In this work, we study a series of trialkyl phosphates using calorimetric and dielectric measurements over a wide temperature range. The results indicate a departure of the dielectric fragility indexes from the enthalpic ones as the length of the branch chain increases in the trialkyl phosphates. The Kirkwood correlation factor (gk) is found to coincide at ∼0.6 at glass transition temperature (Tg) from triethyl phosphate to tributyl phosphate, indicating a similar structural alignment. The enthalpic relaxation serving as the more fundamental relaxation relevant to the structural relaxation is confirmed. Strikingly, we observed the relation of Tg to the chain length in alkyl phosphates, revealing a minimum Tg behavior, and its explanation assists in the understanding of the glass transition in relation to the structure of the glass-formers.
Targeted synchronization in an externally driven population of mechanical oscillators
Authors: Chhabria Sumit , Blaha Karen A. , Della Rossa Fabio , Sorrentino Francesco
Published: November 2018

We experimentally investigate the synchronization of driven metronomes using a servo motor to impose external control. We show that a driven metronome will only synchronize in a narrow range near its own frequency; when we introduce coupling between metronomes, we can widen the range of frequencies over which a metronome will synchronize to the external input. Using these features, we design a signal to synchronize a population of dissimilar metronomes; separately we design a signal to selectively synchronize a subpopulation of metronomes within a heterogeneous population.
Measuring monopole and dipole polarizability of acoustic meta-atoms
Authors: Jordaan Joshua , Punzet Stefan , Melnikov Anton , Sanches Alexandre , Oberst Sebastian , Marburg Steffen , Powell David A.
Published: November 2018

We present a method to extract monopole and dipole polarizability from experimental measurements of two-dimensional acoustic meta-atoms. In contrast to extraction from numerical results, this enables all second-order effects and uncertainties in material properties to be accounted for. We apply the technique to 3D-printed labyrinthine meta-atoms of a variety of geometries. We show that the polarizability of structures with a shorter acoustic path length agrees well with numerical results. However, those with longer path lengths suffer strong additional damping, which we attribute to the strong viscous and thermal losses in narrow channels.
Inhomogeneous barrier heights at dipole-controlled SrRuO3/Nb:SrTiO3 Schottky junctions
Authors: Yajima T. , Minohara M. , Bell C. , Hwang H. Y. , Hikita Y.
Published: November 2018

It has recently been shown that the Schottky barrier height (SBH) formed at metal-semiconductor perovskite oxide heterojunctions can be dramatically tuned by the insertion of atomic-scale dipole layers at the interface. However, in idealized form, this would only allow for specific values of the SBH, discretized by the dipole layer thickness. Here, we examine the effect of fractional unit cell LaAlO3 dipoles inserted between SrRuO3 and Nb:SrTiO3 in (001) Schottky junctions, as a function of their in-plane lateral distribution. When the LaAlO3 dipoles are finely dispersed, we observe uniformly rectifying junctions, with SBHs reflecting the fractional LaAlO3 coverage. For larger length-scale distributions, the junction characteristics reflect the inhomogeneous combination of regions with and without the interface dipole. The characteristic length scale dividing the two regimes corresponds to the semiconductor depletion width scaled by the dipole potential, determining the effective scale for which the SBH can be continuously tuned.
Bloch-Siegert effects in two-photon excitations: Fixed laser-molecule configurations versus orientational averaging
Authors: Meath William J.
Published: November 2018

The two-level rotating wave approximation for two-photon excitations in dipolar molecules is modified to include the effects of the Bloch-Siegert shift in the two-photon resonance energy. The resulting analytical results are used to establish a criterion for when Bloch-Siegert effects are important and the relevance of these effects are compared for fixed laser-molecule configurations versus orientationally averaged results. Two-level model molecules, with parallel permanent and transition dipoles, are used in this work and the effects of Bloch-Siegert shifts are discussed for resonance profiles, time-dependent populations of the excited state, and time-averaged excitation rates. Bloch-Siegert shifts can have pronounced effects on resonance energies and the shape of resonance profiles and, for example, on the magnitudes and the temporal locations of the maxima in the temporal evolution of the time-dependent properties of the system.
Circular dichroism in photoionization of degenerate orbitals: Spin-polarized photoelectrons and spontaneous separation of oriented photoions
Authors: Suzuki Yoshi-Ichi
Published: November 2018

This work investigated the circular dichroic effect on the photoionization integral cross section of molecules in conjunction with irreducible tensor theory and effective operator formalism. The results show that the dichroic effect can be non-zero for complex orbitals, but becomes zero for all real orbitals due to time-reversal symmetry, within the electric dipole and Born-Oppenheimer approximations. Calculations were performed for carbon monoxide, boric acid, and fullerene, and implications of the first-order coefficient for the spin polarization of photoelectrons and the molecular axis orientation of photoions are discussed herein. The results of this work demonstrate that the photoionization of complex orbitals can cause photoions to become oriented such that photoions originating from complex conjugate orbitals are oriented opposite to one another. Due to electron-ion recoil, the spontaneous separation of these two kinds of photoions is expected for the point groups Cn, Cnv, C∞v, Cnh, and Sn with n ≥ 3.
Letter: Similarity model for corner roll in turbulent Rayleigh-Bénard convection
Authors: Zhou Wen-Feng , Chen Jun
Published: November 2018

The corner roll (CR) in the Rayleigh-Bénard convection accounts for the behaviors of convection flow and heat transport in the corner. The three-dimensional direct numerical simulations for 108 < Ra < 5 × 109 show that CR presents a well-defined similarity and multi-layer structure. The CR can be described by a stream function derived from the homotopy and the structure ensemble dynamics. The scale of CR has a negative scaling r = 0.770Ra−0.085. A new scaling theory for CR suggests the scalings for Recr ∼ Ra0.248 and Nucr ∼ Ra1/3 very close to the simulated ones.
Density functional theory from spherically symmetric densities
Authors: Nagy Á.
Published: November 2018

In a recent paper, Theophilou [J. Chem. Phys 149, 074104 (2018)] proved that in molecules and solids, a set of spherically symmetric densities determines uniquely the external potential. Here an alternative derivation of Theophilou’s new theorem is presented. A somewhat more general version is also proved via constrained search. Euler equations and Kohn-Sham equations are derived for spherically symmetric densities.
First principles study on ferromagnetism of diluted magnetic semiconductor Li(Zn, Mn)N
Authors: Cui Y. , Zhu J. G. , Tao H. L. , Liu S. M. , Lv Y. Z. , He M. , Song B. , Zhang Z. H.
Published: November 2018

Based on the first-principles calculations, the ferromagnetic origin and magnetic mechanisms of the Li(Zn, Mn)N system were investigated. The systems with different concentrations of magnetic moments and carriers were established. Compared with the Li16+y(Zn15Mn)N16 systems, the Li16+y(Zn14Mn2)N16 systems are more stable. Different from the Li15(Zn14Mn2)N16 system, Li16(Zn14Mn2)N16 and Li18(Zn14Mn2)N16 systems are anti-ferromagnetic semiconductors; the ferromagnetic state of the Li17(Zn14Mn2)N16 system is the preferred state. The spin magnetic moments mostly originated from Mn-3d states strongly hybridized with the N-2p and Li-2s states around the Fermi level. The ferromagnetic mechanism can be explained by the Mn-N-Mn chain with the p-d hybridization.
Sensitivity enhancement of a resonant mass sensor based on internal resonance
Authors: Zhang Tianyi , Wei Xueyong , Jiang Zhuangde , Cui Tianhong
Published: November 2018

There exist numerous vibration modes in a resonant structure, and these modes can interact with each other. Here, the internal resonance between the fundamental mode and higher order modes is observed in a polyvinylidene fluoride piezoelectric membrane as a resonant mass sensor. Higher order modes draw energy from the fundamental one and vibrate at integer times of the fundamental mode's frequency. The resonance frequency shift of the fundamental mode can thus be magnified integer times through internal resonance. The sensitivity of the resonant mass sensor, defined by the resonance frequency shift caused by mass change, is enhanced based on this mechanism. The sensing characteristics are experimentally studied with a concentrated mass load attached to the sensor. The sensitivity improvement of directly using higher order modes and detecting the internal resonance response is tested and compared in our experiment. An 11 times sensitivity magnification is achieved with the internal resonance method, which has an obvious advantage over the higher order method.
Electrically controllable plasmon induced reflectance in hybrid metamaterials
Authors: Habib Mohsin , Gokbayrak Murat , Ozbay Ekmel , Caglayan Humeyra
Published: November 2018

The tunable plasmon induced reflectance (PIR) effect has been numerically investigated and experimentally realized by hybrid metal-graphene metamaterials. The PIR effect is produced by two parallel strips of gold (Au) and controlled electrically by applying the gate voltage to the graphene layer. The PIR response is generated by the weak hybridization of two bright modes of the gold strips and tuned by changing the Fermi level (Ef) of the graphene. The total shift of 211.7 nm was achieved in the reflection peak by applying only 3 V. This concept of real time electrical tuning of PIR, with a modulation depth of ∼49% and a spectral contrast ratio of 66.6%, can be used for designing optical switches, optical modulators, and tunable sensors.
Effect of bimodal surface modification of graphyne on enhanced H2 storage: Density functional theory study
Authors: Kwon Yongju , Kim Jeongho , Kim Taeyoon , Shin Hyun Suk , Kwon Soonchul
Published: November 2018

Studies on hydrogen storage materials are proceeding worldwide to enhance adsorptive capacity with a proper adsorption energy between physisorption and chemisorption. Graphyne is the carbon allotropes having sp- and sp2-hybridized carbon atoms. It has not been synthesized yet, but have taken the center stage for decades owing to its promising electronic properties and applicability. Therefore, we performed geometry optimization using density functional theory calculation to determine the adsorptive behaviors of graphyne with decoration and doping approaches for improving hydrogen storage. Graphyne decorated with alkali metal cations showed highly adsorptive properties owing to the enhanced basicity by cations, whereas doped graphyne showed a lower adsorption energy within the desirable hydrogen storage range (−0.20 eV to −0.70 eV). Therefore, we applied bimodal surface modification using doped/co-doped graphyne in the presence of alkali decoration. We found that both decoration and doping approaches compensated each other, yielding an energy suitable for hydrogen storage (min: −0.24 eV, max: −0.32 eV), which elucidates the promising properties of a hydrogen storage material.
Measuring singularities of cylindrically structured light beams using a radial grating
Authors: Zhang Yi , Li Peng , Zhong Jinzhan , Qi Shuxia , Guo Xuyue , Wu Dongjing , Liu Sheng , Zhao Jianlin
Published: November 2018

Optical singularities, including phase and polarization singularities that are prevalent in vortex beams, cylindrical vector beams, and cylindrical vector vortex beams, were widely investigated in the past few decades because of their physical and application interest. Here, we propose a method for measuring the singularities within these cylindrically structured light beams by using a radial grating (RG), which is fabricated by etching patterns on the chrome plated soda-lime glass and exhibits a broadband performance. We demonstrate the versatility and compatibility of the measuring method by obtaining the topological charge and polarization order that characterize the phase and polarization singularity, respectively. The reliability of the RG was also inspected by analyzing the grating period and the illumination location of the input field on it.
Graphene − quantum dot hybrid nanostructures with controlled optical and photoelectric properties for solar cell applications
Authors: Sokolov Pavel M. , Zvaigzne Maria A. , Krivenkov Victor A. , Litvin Alexander P. , Baranov Alexander V. , Fedorov Anatoly V. , Samokhvalov Pavel S. , Nabiev Igor R.
Published: November 2018

State-of-the-art research related to increasing the efficiency and reducing the cost of solar energy converters is analyzed. An approach to solving these issues is to introduce graphene and its derivatives into the photoactive layer of solar cells. These materials have record high charge carrier mobility at normal temperatures and low absorption cross-sections of solar radiation. The review considers chemical materials science methods and nanotechnology approaches to the design of 2D hybrid structures based on graphene and quantum dots. Examples of their most successful use in solar cells are given and promising areas of research and development in this field are formulated.

The bibliography includes 173 references.