bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical study of collisionless q = 1 double tearing instability in a cylindrical plasma
Authors: WEI LAI , YANG XUEFENG , ZHENG SHU , LIU YUE 
Published: July 2012

AbstractThe double tearing mode (DTM) instability with two qs = 1 rational surfaces is investigated by taking into account the collisionless effects, including electron inertia and electron viscosity in a cylindrical geometry. The calculations show that for q-profile with a small distance between two rational surfaces, Δrs, there exists a broad linear spectrum of collisionless DTMs. The collisionless effects not only can significantly increase the linear growth rate of DTMs but can also enlarge the width of spectrum of unstable modes. For the q-profile with fixed Δrs and fixed magnetic shears at two rational surfaces, the high-order harmonics with smaller wavelength, such as the m/n = 2/2, 3/3 and 4/4 modes, can be easily excited to have larger growth rates than the m/n = 1/1 mode by ‘lifting’ the safety factor value between two rational surfaces. The characteristics of eigenmode structures of the most unstable and secondly unstable DTMs with various mode numbers are analyzed in detail and the corresponding collisionless scalings are numerically obtained and verified theoretically based on the previous relevant analytical theories. In addition, the synergetic effects of plasma resistivity, electron inertia and electron viscosity on the linear growth rates of DTMs are analyzed.
Swarm robotics reviewed
Authors: Barca Jan Carlo , Sekercioglu Y. Ahmet 
Published: July 2012

SUMMARYWe present a review of recent activities in swarm robotic research, and analyse existing literature in the field to determine how to get closer to a practical swarm robotic system for real world applications. We begin with a discussion of the importance of swarm robotics by illustrating the wide applicability of robot swarms in various tasks. Then a brief overview of various robotic devices that can be incorporated into swarm robotic systems is presented. We identify and describe the challenges that should be resolved when designing swarm robotic systems for real world applications. Finally, we provide a summary of a series of issues that should be addressed to overcome these challenges, and propose directions for future swarm robotic research based on our extensive analysis of the reviewed literature.
The probability that x and y commute in a compact group
Authors: HOFMANN KARL H. , RUSSO FRANCESCO G. 
Published: July 2012

AbstractWe show that a compact group G has finite conjugacy classes, i.e., is an FC-group if and only if its center Z(G) is open if and only if its commutator subgroup G′ is finite. Let d(G) denote the Haar measure of the set of all pairs (x,y) in G×G for which [x,y]=1; this, formally, is the probability that two randomly picked elements commute. We prove that d(G) is always rational and that it is positive if and only if G is an extension of an FC-group by a finite group. This entails that G is abelian by finite. The proofs involve measure theory, transformation groups, Lie theory of arbitrary compact groups, and representation theory of compact groups. Examples and references to the history of the discussion are given at the end of the paper.
Human metapneumovirus infection among family members
Authors: MATSUZAKI Y. , ITAGAKI T. , IKEDA T. , AOKI Y. , ABIKO C. , MIZUTA K. 
Published: July 2012

SUMMARYThe transmission of human metapneumovirus (hMPV) among family members is not well understood. We identified 15 families in which multiple members were diagnosed with hMPV infection by real-time PCR in 2008 and 2010. Index patients ranged in age from 2 years to 11 years (median 5 years), and all 15 index cases were children who attended primary school, kindergarten, or nursery school. Contact patients ranged in age from 2 months to 46 years (median 6 years). Excluding five adult cases, contact patients were significantly younger than index patients (P = 0·0389). Of the 12 contact children, seven (58%) were infants who were taken care of at home. The serial interval between the onset of symptoms in an index patient and the onset of symptoms in a contact patient was estimated to be 5 days. These results suggest that the control of school-based outbreaks is important for preventing hMPV infection in infants.
Discrimination against older people
Authors: van den Heuvel Wim JA 
Published: July 2012

SummaryThe increasing number of old people is becoming a growing policy concern. Negative attitudes towards old people raise questions about the extent to which discrimination against old people exists and elder abuse occurs. This paper describes the occurrence of discrimination against old people and elder abuse, as well as the factors related to it, based on a review of (scientific) literature, official documents and the actions of legal bodies.Frequent or regular age discrimination, as experienced by old people themselves, is reported by a quarter of European citizens. Data on elder abuse vary and are often not representative; the same goes for data on inequality. Nevertheless, the analysis shows that discrimination against old age and elder abuse occurs regularly in the ‘western world’. Vulnerable old people are especially at risk. National and regional, multi-component action plans are recommended to combat discrimination against old people.
The effects of exercise on strength and physical performance in frail older people: a systematic review
Authors: Nash Katharine CM 
Published: July 2012

SummaryThe proportion of older people becoming frail will increase with the expanding older population. Apart from poor health, frailty is associated with loss of strength and functional dependency. Building on previous work in this area, this review investigates the effectiveness, sustainability and adverse effects of exercise interventions on muscle strength and physical performance in frail older people. Randomized controlled trials reporting physical outcomes in frail older people were identified from seven electronic databases. Thirteen trials involving 1652 participants met the inclusion criteria. There was wide heterogeneity in degree of frailty, types of intervention, outcome measures and results. However, evidence from this review suggests that exercise and some physical activity programmes, particularly moderate intensity and multi-component programmes, are safe and can improve strength and function in the majority of frail older people except highly frail individuals with multiple co-morbidities. There was limited evidence on transferability of improvements into everyday life, and sustainability could not be determined.
Boundary behaviour of special cohomology classes arising from the Weil representation
Authors: Funke Jens , Millson John 
Published: July 2012

AbstractIn our previous paper [J. Funke and J. Millson, Cycles with local coefficients for orthogonal groups and vector-valued Siegel modular forms,American J. Math.128 (2006), 899–948], we established a correspondence between vector-valued holomorphic Siegel modular forms and cohomology with local coefficients for local symmetric spaces$X$attached to real orthogonal groups of type$(p, q)$. This correspondence is realized using theta functions associated with explicitly constructed ‘special’ Schwartz forms. Furthermore, the theta functions give rise to generating series of certain ‘special cycles’ in$X$with coefficients.In this paper, we study the boundary behaviour of these theta functions in the non-compact case and show that the theta functions extend to the Borel–Sere compactification$ \overline{X} $of$X$. However, for the$ \mathbb{Q} $-split case for signature$(p, p)$, we have to construct and consider a slightly larger compactification, the ‘big’ Borel–Serre compactification. The restriction to each face of$ \overline{X} $is again a theta series as in [J. Funke and J. Millson, loc. cit.], now for a smaller orthogonal group and a larger coefficient system.As an application we establish in certain cases the cohomological non-vanishing of the special (co)cycles when passing to an appropriate finite cover of$X$. In particular, the (co)homology groups in question do not vanish. We deduce as a consequence a sharp non-vanishing theorem for${L}^{2} $-cohomology.
Double sodium layers observation over Beijing, China
Authors: Wang Jihong , Yang Yong , Cheng Xuewu , Yang Guotao , Song Shalei , Gong Shunsheng 
Published: July 2012

The altitude of the sodium layer in the mesosphere and lower thermosphere is usually from 80 km to 105 km. In this paper, we report a set of double sodium layer (DSL) events observed by sodium lidar over Beijing, China. In these DSL events, the normal sodium layer and secondary sodium layer (SeSL) present separately. There were about 17 DSL events occurred in 319 observation nights during 2009∼2011. All DSL events were observed in spring and summer. The SeSL appeared independently within the altitude range from 105 km to 130 km. The density of the SeSL is very high. The maximum ratio of peak density and the ratio of column density for the SeSL to the normal sodium layer are up to ∼60% and ∼47%, respectively. The SeSL lasted several hours, and then merged into the normal sodium layer. After the SeSL, a sporadic sodium layer occurred in the normal sodium layer.
First daytime thermospheric wind observation from a balloon‐borne Fabry‐Perot interferometer over Kiruna (68N)
Authors: Wu Qian , Wang W. , Roble R. G. , Häggström Ingemar , Strømme Anja 
Published: July 2012

HIWIND (High altitude Interferometer WIND Observation) is the first balloon Fabry‐Perot interferometer (FPI) to achieve successful thermospheric wind measurement for both day and night. By flying at ∼40 km altitude, HIWIND avoids the high solar scattering background and enables daytime remote sensing of Doppler shift in airglow for thermospheric wind observation. During its first flight in June 2011 from Kiruna, (68N, 65 MLAT), HIWIND observed persistent equatorward winds, while the NCAR TIEGCM model predicted poleward winds on the dayside. Combined with simultaneous EISCAT incoherent scatter radar observation, HIWIND yielded a daytime Burnside factor value of 0.85. HIWIND data appear to suggest that upward vertical winds near the auroral oval may be the cause for large differences between the FPI measured and radar derived winds near midnight.
A physical model for electron radiation belts of Saturn
Authors: Lorenzato Lise , Sicard Angélica , Bourdarie Sébastien 
Published: July 2012

Radiation belts cause irreversible damages to on‐board instrument materials. Studies about radiation belts can provide precious information for future interplanetary missions. Pioneer 11, Voyager 2 and nowadays Cassini missions give the characteristics of Saturn's inner magnetosphere: Saturn's famous rings, various moons, neutral particles ejected from Enceladus and waves. Thanks to its experience with the Earth's and Jupiter's radiation belt studies, ONERA is now able to develop an electron radiation belt model for Saturn's environment, i.e., a new version of Salammbô. The study of Saturn's inner magnetosphere emphasizes the most important physical processes governing radiation belt dynamics: electrons losses due to dense rings are the dominant physical process near the planet (L < 2.3). For high energies (E > ∼50 keV), radial diffusion and local losses due to the moons are predominant from L = 2.3 to the boundary condition (L = 6). The analysis of spacecraft in situ data (Pioneer 11, Voyager 2, and Cassini) allows a boundary condition to be built for the model and the Salammbô results to be validated. The Salammbô Kronian model has also been compared to the empirical radiation belt model SATRAD (for SATurn RADiation model) based on Pioneer 11 and Voyager 2 data. Comparisons of Salammbô results with in situ data and SATRAD confirm that Salammbô is a good mean model for Saturn electron radiation belts, for energies from about a hundred keV to a few MeV.
Regulation of S100A2 expression by TGF-β-induced MEK/ERK signalling and its role in cell migration/invasion
Authors: Naz Sarwat , Ranganathan Prathibha , Bodapati Priyanka , Shastry Arun H. , Mishra Laxmi N. , Kondaiah Paturu 
Published: July 2012

S100A2, an EF hand calcium-binding protein, is a potential biomarker in several cancers and is also a TGF-β (transforming growth factor-β)-regulated gene in melanoma and lung cancer cells. However, the mechanism of S100A2 regulation by TGF-β and its significance in cancer progression remains largely unknown. In the present study we report the mechanism of S100A2 regulation by TGF-β and its possible role in TGF-β-mediated tumour promotion. Characterization of the S100A2 promoter revealed an AP-1 (activator protein-1) element at positions −1161 to −1151 as being the most critical factor for the TGF-β1 response. Chromatin immunoprecipitation and electrophoretic mobility-shift assays confirmed the functional binding of the AP-1 complex, predominantly JunB, to the S100A2 promoter in response to TGF-β1 in HaCaT keratinocytes. JunB overexpression markedly stimulated the S100A2 promoter which was blocked by the dominant–negative JunB and MEK1 [MAPK (mitogen-activated protein kinase)/ERK (extracellular-signal-regulated kinase) kinase 1] inhibitor, PD98059. Intriguingly, despite the presence of a putative SMAD-binding element, S100A2 regulation by TGF-β1 was found to be SMAD3 independent. Interestingly, p53 protein and TGF-β1 show synergistic regulation of the S100A2 promoter. Finally, knockdown of S100A2 expression compromised TGF-β1-induced cell migration and invasion of Hep3B cells. Together our findings highlight an important link between the TGF-β1-induced MAPK and p53 signalling pathways in the regulation of S100A2 expression and pro-tumorigenic actions.
Highly efficient and robust molecular ruthenium catalysts for water oxidation
Authors: Duan Lele , Araujo Carlos Moyses , Ahlquist Mårten S.G. , Sun Licheng 
Published: July 2012

Water oxidation catalysts are essential components of light-driven water splitting systems, which could convert water to H
2
driven by solar radiation (H
2
O +
h
ν → 1/2O
2
+ H
2
). The oxidation of water (H
2
O → 1/2O
2
+ 2H
+
+ 2e
-
) provides protons and electrons for the production of dihydrogen (2H
+
+ 2e
-
→ H
2
), a clean-burning and high-capacity energy carrier. One of the obstacles now is the lack of effective and robust water oxidation catalysts. Aiming at developing robust molecular Ru-bda (H
2
bda = 2,2
′
-bipyridine-6,6′-dicarboxylic acid) water oxidation catalysts, we carried out density functional theory studies, correlated the robustness of catalysts against hydration with the highest occupied molecular orbital levels of a set of ligands, and successfully directed the synthesis of robust Ru-bda water oxidation catalysts. A series of mononuclear ruthenium complexes [Ru(bda)L
2
] (L = pyridazine, pyrimidine, and phthalazine) were subsequently synthesized and shown to effectively catalyze Ce
IV
-driven [Ce
IV
= Ce(NH
4
)
2
(NO
3
)
6
] water oxidation with high oxygen production rates up to 286 s
-1
and high turnover numbers up to 55,400.
1,500 year quantitative reconstruction of winter precipitation in the Pacific Northwest
Authors: Steinman Byron A. , Abbott Mark B. , Mann Michael E. , Stansell Nathan D. , Finney Bruce P. 
Published: July 2012

Multiple paleoclimate proxies are required for robust assessment of past hydroclimatic conditions. Currently, estimates of drought variability over the past several thousand years are based largely on tree-ring records. We produced a 1,500-y record of winter precipitation in the Pacific Northwest using a physical model-based analysis of lake sediment oxygen isotope data. Our results indicate that during the Medieval Climate Anomaly (MCA) (900–1300 AD) the Pacific Northwest experienced exceptional wetness in winter and that during the Little Ice Age (LIA) (1450–1850 AD) conditions were drier, contrasting with hydroclimatic anomalies in the desert Southwest and consistent with climate dynamics related to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). These findings are somewhat discordant with drought records from tree rings, suggesting that differences in seasonal sensitivity between the two proxies allow a more compete understanding of the climate system and likely explain disparities in inferred climate trends over centennial timescales.
Photochemical oxidation of water and reduction of polyoxometalate anions at interfaces of water with ionic liquids or diethylether
Authors: Bernardini Gianluca , Wedd Anthony G. , Zhao Chuan , Bond Alan M. 
Published: July 2012

Photoreduction of [P2W18O62]6-, [S2Mo18O62]4-, and [S2W18O62]4-polyoxometalate anions (POMs) and oxidation of water occurs when water–ionic liquid and water–diethylether interfaces are irradiated with white light (275–750 nm) or sunlight. The ionic liquids (ILs) employed were aprotic ([Bmim]X; Bmim = (1-butyl-3-methylimidazolium,X = BF4,PF6) and protic (DEAS = diethanolamine hydrogen sulphate; DEAP = diethanolamine hydrogen phosphate). Photochemical formation of reduced POMs at both thermodynamically stable and unstable water–IL interfaces led to their initial diffusion into the aqueous phase and subsequent extraction into the IL phase. The mass transport was monitored visually by color change and by steady-state voltammetry at microelectrodes placed near the interface and in the bulk solution phases. However, no diffusion into the organic phase was observed when [P2W18O62]6-was photo-reduced at the water–diethylether interface. In all cases, water acted as the electron donor to give the overall process: 4POM + 2H2O + hν → 4POM- + 4H+ + O2. However, more highly reduced POM species are likely to be generated as intermediates. The rate of diffusion of photo-generated POM-was dependent on the initial concentration of oxidized POM and the viscosity of the IL (or mixed phase system produced in cases in which the interface is thermodynamically unstable). In the water-DEAS system, the evolution of dioxygen was monitored in situ in the aqueous phase by using a Clark-type oxygen sensor. Differences in the structures of bulk and interfacial water are implicated in the activation of water. An analogous series of reactions occurred upon irradiation of solid POM salts in the presence of water vapor.
High-frequency self-aligned graphene transistors with transferred gate stacks
Authors: Cheng Rui , Bai Jingwei , Liao Lei , Zhou Hailong , Chen Yu , Liu Lixin , Lin Yung-Chen , Jiang Shan , Huang Yu , Duan Xiangfeng 
Published: July 2012

Graphene has attracted enormous attention for radio-frequency transistor applications because of its exceptional high carrier mobility, high carrier saturation velocity, and large critical current density. Herein we report a new approach for the scalable fabrication of high-performance graphene transistors with transferred gate stacks. Specifically, arrays of gate stacks are first patterned on a sacrificial substrate, and then transferred onto arbitrary substrates with graphene on top. A self-aligned process, enabled by the unique structure of the transferred gate stacks, is then used to position precisely the source and drain electrodes with minimized access resistance or parasitic capacitance. This process has therefore enabled scalable fabrication of self-aligned graphene transistors with unprecedented performance including a record-high cutoff frequency up to 427 GHz. Our study defines a unique pathway to large-scale fabrication of high-performance graphene transistors, and holds significant potential for future application of graphene-based devices in ultra–high-frequency circuits.
Dynamics, transition states, and timing of bond formation in Diels–Alder reactions
Authors: Black Kersey , Liu Peng , Xu Lai , Doubleday Charles , Houk Kendall N. 
Published: July 2012

The time-resolved mechanisms for eight Diels–Alder reactions have been studied by quasiclassical trajectories at 298 K, with energies and derivatives computed by UB3LYP/6-31G(d). Three of these reactions were also simulated at high temperature to compare with experimental results. The reaction trajectories require 50–150 fs on average to transverse the region near the saddle point where bonding changes occur. Even with symmetrical reactants, the trajectories invariably involve unequal bond formation in the transition state. Nevertheless, the time gap between formation of the two new bonds is shorter than a C─C vibrational period. At 298 K, most Diels–Alder reactions are concerted and stereospecific, but at high temperatures (approximately 1,000 K) a small fraction of trajectories lead to diradicals. The simulations illustrate and affirm the bottleneck property of the transition state and the close connection between dynamics and the conventional analysis based on saddle point structure.
Nasal Swab Screening for Methicillin-Resistant Staphylococcus aureus—How Well Does It Perform? A Cross-Sectional Study
Authors: Matheson Ann , Christie Peter , Stari Traiani , Kavanagh Kim , Gould Ian M. , Masterton Robert , Reilly Jacqui S. 
Published: July 2012

Objective.To determine the proportion of methicillin-resistant Staphylococcus aureus (MRSA) detections identified by nasal swabbing using agar culture in comparison with multiple body site testing using agar and nutrient broth culture.Design.Cross-sectional study.Patients.Adult patients admitted to 36 general specialty wards of 2 large hospitals in Scotland.Methods.Patients were screened for MRSA via multiple body site swabs (nasal, throat, axillary, perineal, and wound/invasive device sites) cultured individually on chromogenic agar and pooled in nutrient broth. Combined results from all sites and cultures provided a gold-standard estimate of true MRSA prevalence.Results.This study found that nasal screening performed better than throat, axillary, or perineal screening but at best identified only 66% of true MRSA carriers against the gold standard at an overall prevalence of 2.9%. Axillary screening performed least well. Combining nasal and perineal swabs gave the best 2-site combination (82%). When combined with realistic screening compliance rates of 80%–90%, nasal swabbing alone probably detects just over half of true colonization in practice. Swabbing of clinically relevant sites (wounds, indwelling devices, etc) is important for a small but high-prevalence group.Conclusions.Nasal swabbing is the standard method in many locations for MRSA screening. Its diagnostic efficiency in practice appears to be limited, however, and the resource implications of multiple body site screening have to be balanced against a potential clinical benefit whose magnitude and nature remains unclear.