bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro differentiation of human umbilical cord mesenchymal stem cells (hUCMSCs), derived from Wharton's jelly, into choline acetyltransferase (ChAT)‐positive cells
Authors: Zhang Lei , Tan Xuefeng , Dong Chuanming , Zou Linqing , Zhao Heyan , Zhang Xinhua , Tian Meiling , Jin Guohua
Published: June 2012

We isolated and expanded fibroblast‐like cells from the Wharton's jelly of human umbilical cord successfully. Immunocytochemistry showed that they were positive for several markers of mesenchymal stem cells (CD73, CD90, and CD105) and integrin markers (CD29 and CD44), but negative for a hematopoietic cell maker (CD45) and an endothelial cell marker (CD31). Their differentiation into osteocytes and adipocytes under specific conditions indicated that they had multi‐lineage differentiation potential. Therefore these results proved that the cells we obtained from Wharton's jelly were human umbilical cord mensenchymal stem cells (hUCMSCs). Using immunocytochemistry and Western blotting analysis, we found that after treatment with neuronal induction medium [NIM; consisting of brain‐derived neurotrophic factor (BDNF) and low‐serum media] for 14 days, hUCMSCs expressed a neuronal specific marker, microtubule associated protein 2 (MAP2), and extended neurite‐like processes. After treatment with NIM, supplemented with hippocampal cholinergic neurostimulating peptide (HCNP) or rat denervated hippocampal extract [rDHE; derived from rat fimbria fornix (FF) transected hippocampus], hUCMSCs expressed choline acetytransferase (ChAT) and this action could be enhanced when cells were cultured with NIM, supplemented with HCNP and rDHE in combination. ELISA showed that these ChAT‐positive cells could secrete acetylcholine (ACh). These findings indicate that hUCMSCs possess the potential of differentiation into functional ChAT‐positive cells in vitro and provide a new candidate of cells for the cell transplantation to treat Alzheimer's disease (AD).
Revised 14C dating of ice wedge growth in interior Alaska (USA) to MIS 2 reveals cold paleoclimate and carbon recycling in ancient permafrost terrain
Authors: Lachniet Matthew S. , Lawson Daniel E. , Sloat Alison R.
Published: June 2012

Establishing firm radiocarbon chronologies for Quaternary permafrost sequences remains a challenge because of the persistence of old carbon in younger deposits. To investigate carbon dynamics and establish ice wedge formation ages in Interior Alaska, we dated a late Pleistocene ice wedge, formerly assigned to Marine Isotope Stage (MIS) 3, and host sediments near Fairbanks, Alaska, with 24 radiocarbon analyses on wood, particulate organic carbon (POC), air-bubble CO2, and dissolved organic carbon (DOC). Our new CO2 and DOC ages are up to 11,170 yr younger than ice wedge POC ages, indicating that POC is detrital in origin. We conclude an ice wedge formation age between 28 and 22 cal ka BP during cold stadial conditions of MIS 2 and solar insolation minimum, possibly associated with Heinrich event 2 or the last glacial maximum. A DOC age for an ice lens in a thaw unconformity above the ice wedge returned a maximum age of 21,470 ± 200 cal yr BP. Our variable 14C data indicate recycling of older carbon in ancient permafrost terrain, resulting in radiocarbon ages significantly older than the period of ice-wedge activity. Release of ancient carbon with climatic warming will therefore affect the global 14C budget.
Current subsidiary peak in triggered lightning strokes
Authors: Wang Caixia , Jiang Rubin , Yang Jing , Liu Mingyuan
Published: June 2012

Mainly based on the channel base current of the 0803 and 0902 flashes detected in the Shandong Artificial Triggering Lightning Experiment (SHATLE) from 2005 to 2010, the current waveforms of six return strokes and an RM process (a process characterized by both a return stroke and an M‐component) containing subsidiary peaks were analyzed. The percentage of strokes with subsidiary peak is approximately 17%. The amplitudes of the stroke primary and subsidiary peaks varied from 8.53 to 16.34 kA and 5.40 to 15.86 kA, respectively. The time intervals between the primary and the secondary peak varied from 6.3 to 12.0 μs. The strokes of the 0803 and 0902 flashes have different current waveform characteristics, indicating that the mechanisms generating the subsidiary peaks in the two lightning may be different. To learn more about the causes of forming the subsidiary peaks based on the assumption that channel branches and every peak corresponds to a physical process, a Heidler function model was used to simulate the current waveforms of four strokes and an RM in flash 0902. The simulated results indicated that the Heidler function component could reflect the physical characteristics of the peaks to some extent. Based on simulated results and comparison of waveforms, four possibilities of forming subsidiary peaks were proposed: channel branching, flashover along a triggering wire from a previous unsuccessful launch, the corona current or reflection of the current. Branching and flashover may be the main causes of generating the subsidiary peaks in 0902 and 0803 flashes, respectively.
Senate hearing considers Law of the Sea treaty
Authors: Showstack Randy
Published: June 2012

The U.S. Senate Committee on Foreign Relations is once again discussing the Law of the Sea Convention (LOS). The treaty, which was adopted in 1982 by parties to a United Nations Conference as a framework for governing uses of the world's oceans, has been ratified by more than 160 countries, but the United States is a notable exception. The treaty has been approved twice by the Foreign Relations Committee but has not made it to a full Senate vote because of opponents' concerns about potential loss of U.S. sovereignty and U.S. access to the deep seabed, among other reasons. During a 23 May hearing of the committee, chairman John Kerry (D‐Mass.), a strong supporter of the treaty, said U.S. ratification “is now more urgent than ever” and that to remain outside of the treaty “is fundamentally, directly counter to the best interests” of the United States.
Strategies to deliver information on regional climate changes to communities
Authors: von Storch Hans , Zwiers Francis
Published: June 2012

Regional Climate Services Workshop 2011; Victoria, British Columbia, Canada, 21–23 November 2011 Recognizing that adaptation to both current and projected climate variability and change is best undertaken locally and regionally, a recent workshop was convened to analyze how regional climate services are delivered. Regional climate service organizations facilitate efficient adaptation by interacting with local and regional stakeholders. Regional and local contextualization of observed and projected climate change is an important issue in large federally organized countries like Canada and Germany (as opposed to centralized countries). Exchanging knowledge and knowledge needs on changing climate regimes takes place in societal context within which scientific knowledge is challenged by various interest‐ led knowledge claims about climate change and its societal significance.
Keir receives 2011 Jason Morgan Early Career Award
Authors: Green Harry W.
Published: June 2012

Derek Keir received the 2011 Jason Morgan Early Career Award at the 2011 AGU Fall Meeting, held 5–9 December in San Francisco, Calif. The award is for significant early‐career contributions in tectonophysics.
Properties of solitary waves in Lake Constance
Authors: Balcerak Ernie
Published: June 2012

Solitary waves—large individual waves that can travel long distances holding their shape, unlike normal waves that would tend to flatten out—occur in oceans and in lakes, both on the surface and as internal waves below the surface. In lakes, these waves can affect circulation and mixing and influence aquatic ecosystems, but many studies of the properties and effects of internal solitary waves in lakes are based on limited observations. From observations recorded over 6 years in Lake Constance, in Germany,Preusse et al. studied seasonal changes in the properties of internal solitary waves. Their study, which included 219 wave trains with a range of numbers of waves per train, amplitude, propagation depth, and other properties, shows that internal solitary waves are a regular occurrence. They found that a substantial number of the solitary waves were strongly nonlinear and that solitary wave properties varied with the stratification of the lake, which changes with season. (Journal of Geophysical Research‐Oceans, doi:10.1029/2011JC007403, 2012)
Vertical heat transfer in the Arctic Ocean: The role of double‐diffusive mixing
Authors: Sirevaag Anders , Fer Ilker
Published: June 2012

Microstructure profiles collected in the central Amundsen Basin are analyzed in order to quantify the role of double‐diffusive mixing for vertical heat transfer from the Atlantic layer. In the profiles, a persistent, but laterally incoherent thermohaline staircase structure is identified in the 200–260 m depth range. The staircase contains homogeneous layers with average height of 1.3 m and thin, high‐gradient interfaces with average temperature and salinity jumps of about 0.065°C and 0.015, respectively. When inferred from a commonly used diffusive convection parameterization, the average vertical heat flux within the staircase is 0.6 W m−2. This is one order of magnitude larger than the molecular diffusion alone and of the same order as the overall heat loss from the Atlantic layer in the deep basins of the Arctic Ocean. The parameterization is evaluated using observed turbulent heat fluxes and is found to overestimate diffusive convective fluxes with up to an order of magnitude, especially for weak thermal forcing (small temperature jumps in staircase). Staircases coexist with thermohaline intrusions in the vertical temperature and salinity profiles. Lomonosov Ridge is identified as a potential region for formation of intrusions. It is found that salt fingering is the dominant process during intrusion growth whereas diffusive convection is the dominant process in maintaining the intrusions at steady state in the deep basins.
Scaling relationships for event water contributions and transit times in small‐forested catchments in Eastern Quebec
Authors: Segura C. , James A. L. , Lazzati D. , Roulet N. T.
Published: June 2012

Recent studies of catchment hydrologic response are incorporating increasingly complex datasets to investigate model representation of spatial and temporal variability. In this paper, catchment rainfall‐runoff and stable isotope tracer response were modeled using a lumped conceptual model that integrates the unit hydrograph and isotope hydrograph separation methodologies. The model was applied across eight nested catchments (7 to 147 ha) for four rainstorms collected between summer and fall in 2001–2002, generating a usable 23 rainstorm datasets ranging from 1.2 to 10.3 h in length and spanning variability in environmental conditions related to storm characteristics (size and intensity) and antecedent moisture. Monte Carlo simulations were run for four model structures of varying complexity and evaluated using a Generalized Likelihood Uncertainty Estimation (GLUE) approach. We found that a model of intermediate complexity was adequate to model all catchment‐storm pairs. Relationships between the parameters of the best model and catchment and storm characteristics were sought. We found that the fraction of effective rainfall routed as event water was correlated to rainstorm size but insensitive to catchment size, indicating that it is controlled by environmental conditions such as storm intensity and size. The mean transit time of event water decreased with increasing rainstorm size, indicating increased connectivity during larger rainstorms. Finally, a linear relation was found between the mean transit time of event water and catchment size suggesting that the time it takes for event water to be transferred to the stream is directly related to catchment size, particularly for catchments greater than 30 ha.
Mindfully Resisting the Bandwagon: Reconceptualising IT Innovation Assimilation in Highly Turbulent Environments
Authors: Wolf Martin , Beck Roman , Pahlke Immanuel
Published: June 2012

Environmental turbulence (ET), as exemplified by the recent financial crisis between 2007 and 2009, leads to a high degree of uncertainty, and fosters mimicry and resulting bandwagon phenomena in information technology (IT) innovation assimilation processes. In these highly turbulent environments, ‘mindless’ IT innovation assimilation by participating organizations plays a major role in the manifestation and facilitation of mimetic influences. Even in less turbulent economic cycles, highly turbulent industries such as the financial services industry have to deal with demanding IT innovation assimilation processes, and are exposed to varying levels of ET and mimicry. Drawing upon the theory of dynamic capabilities, organizational mindfulness (OM) is one viable means to mitigate the potentially negative consequences of mimetic behaviour. Here, mindful organizations are more successful in overcoming situations of high dynamism, and sometimes are even able to exploit them. So far, little empirical research has been conducted to quantify the influence of OM in scenarios of high dynamism and mimicry. On the basis of 302 complete responses from senior IT managers in the financial services industry from the Anglo-Saxon countries (the United States, Canada and the United Kingdom), this research contributes to a deeper understanding of the interaction of OM with institutional pressures against the background of ET.
Hard x-ray or gamma ray laser by a dense electron beam
Authors: Son S. , Joon Moon Sung
Published: June 2012

A dense electron beam propagating through a laser undulator can radiate a coherent x-ray or gamma ray. This lasing scheme is studied with the Landau damping theory. The analysis suggests that, with currently available physical parameters, coherent gamma rays of up to 50 keV can be generated. The electron quantum diffraction suppresses the free electron laser action, which limits the maximum radiation.
Ab initio spin-orbit calculations on the lowest states of the nickel dimer
Authors: Cheskidov Alexander V. , Buchachenko Alexei A. , Bezrukov Dmitry S.
Published: June 2012

Potential energy curves of the lowest electronic states of the Ni2 dimer are calculated near the equilibrium using the multireference ab initio methods including the spin-orbit interaction. Scalar-relativistic results fully confirm previous qualitative interpretations based on the correlation with atomic limits and the symmetry of vacancies in the atomic 3d9 shells. Spin-orbit calculations firmly establish the symmetry of the ground state as 0+g and give the excitation energies 70 ± 30 cm−1 and 200 ± 80 cm−1 for the lowest 0−u and 5u states, respectively. The model electronic spectrum of the Ni2 shows some trends that might be observed in matrix isolation far-infrared and electron spin resonance spectra.
Charging efficiency improvement by structuring lithium battery electrodes
Authors: Liu Xiaojing , Zhou Youhe , Zheng Xiaojing , Wang Jizeng
Published: June 2012

For atomic intercalation into an infinite long solid electrode, Haftbaradaran et al. [Appl. Phys. Lett. 96, 091909 (2010)] have pointed out that a coupling between internal stresses and activation energy for diffusion may result in surface locking instability accompanied by very large stresses near the electrode surface, significantly limiting the overall charging rate for high energy density lithium batteries. In the present study, we applied this model to the cylindrical electrode with finite length and found that free ends of the electrode may help to release surface stress within certain extent to each of them and postpone the surface locking of diffusion to occur. Following this finding, we further created parallel grooves on the electrode surface and quantitatively investigated the influences of the groove size and interval to the stress distribution and critical charging current density under galvanostatic charging and discharging conditions. It shows that such treatment of surface slotting to electrodes can significantly decrease the mechanical stresses during atomic intercalation and extraction, and improve the electrode charging efficiency, providing some beneficial inspirations to the Lithium battery technology.
Accurate relativistic energy-consistent pseudopotentials for the superheavy elements 111 to 118 including quantum electrodynamic effects
Authors: Hangele Tim , Dolg Michael , Hanrath Michael , Cao Xiaoyan , Schwerdtfeger Peter
Published: June 2012

Energy-consistent two-component semi-local pseudopotentials for the superheavy elements with atomic numbers 111–118 have been adjusted to fully relativistic multi-configuration Dirac–Hartree–Fock calculations based on the Dirac–Coulomb Hamiltonian, including perturbative corrections for the frequency-dependent Breit interaction in the Coulomb gauge and lowest-order quantum electrodynamic effects. The pseudopotential core includes 92 electrons corresponding to the configuration [Xe]4f 145d105f 14. The parameters for the elements 111–118 were fitted by two-component multi-configuration Hartree–Fock calculations in the intermediate coupling scheme to the total energies of 267 up to 797 J levels arising from 31 up to 62 nonrelativistic configurations, including also anionic and highly ionized states, with mean absolute errors clearly below 0.02 eV for averages corresponding to nonrelativistic configurations. Primitive basis sets for one- and two-component pseudopotential calculations have been optimized for the ground and excited states and exhibit finite basis set errors with respect to the finite-difference Hartree–Fock limit below 0.01 and 0.02 eV, respectively. General contraction schemes have been applied to obtain valence basis sets of polarized valence double- to quadruple-zeta quality. Results of atomic test calculations in the intermediate coupling scheme at the Fock-space coupled-cluster level are in good agreement with those of corresponding fully relativistic all-electron calculations based on the Dirac–Coulomb–Breit Hamiltonian. The results demonstrate besides the well-known need of a relativistic treatment at the Dirac–Coulomb level also the necessity to include higher-order corrections for the superheavy elements.
Field sensing in MgO double barrier magnetic tunnel junctions with a superparamagnetic Co50Fe50 free layer
Authors: Yu G. Q. , Feng J. F. , Kurt H. , Liu H. F. , Han X. F. , Coey J. M. D.
Published: June 2012

Linear response and low frequency noise have been investigated in MgO double barrier magnetic tunnel junctions with a superparamagnetic Co50Fe50 free layer. Linear and hysteresis-free switching was observed for the Co50Fe50 thickness t ≤ 1 nm. A tunneling magnetoresistance ratio of up to 108% and large magnetic field sensitivity value of 61%/mT were obtained at room temperature when t = 1.0 nm. The angular dependence of magnetoresistance suggests that weak coupling between superparamagnetic islands in a 1.0 nm free layer permits continuous rotation of magnetization, whereas the islands in a 0.8 nm layer switch rather independently. The frequency dependence of noise power spectrum density and field dependence of Hooge parameter (α) also behave differently for junctions with 0.8 and 1.0 nm free layers. The noise sensitivity of 1.0 nm free layer junctions is independent of bias, and it is estimated to reach 400 pT/Hz0.5 at 500 kHz.
A high-resolution spectrometer based on a compact planar two dimensional photonic crystal cavity array
Authors: Gan Xuetao , Pervez Nadia , Kymissis Ioannis , Hatami Fariba , Englund Dirk
Published: June 2012

We demonstrate a compact spectrometer based on an array of high-quality-factor photonic crystal nanocavities, coupled via a planar two-dimensional waveguide. This architecture enables spectral analysis of incident light with resolution as high as the bandwidth of the cavity mode–0.3 nm at 840 nm for our device. The design is easily extended to the visible and deep-infrared spectral ranges. The two-dimensional cavity array can be mated to commercial two-dimensional optical detector arrays, creating a compact and high-resolution spectrometer suitable for a range of applications including materials and chemical analysis.
The controllable synthesis, structural, and ferromagnetic properties of Co doped GaN nanowires
Authors: Li Yanan , Chen Zhuo , Cao Chuanbao , Usman Zahid , Feng Yajuan , Pan Zhiyun , Wu Ziyu
Published: June 2012

The controllable synthesis route of Co doped GaN nanowires was developed and the structural and magnetic properties of Co doped GaN nanowires were studied. The results indicate that Co atoms substitute Ga sites in GaN lattice, suggesting the intrinsic nature of ferromagentism at room temperature.
Structural transition in II-VI nanofilms: Effect of molar ratio on structural, morphological, and optical properties
Authors: Kumar Suresh , Sharma Pankaj , Sharma Vineet
Published: June 2012

Cadmium sulphide nanofilms have been deposited by chemical bath deposition technique on glass substrates. The effect of S/Cd molar ratio on the structural, morphological, and optical properties of CdS nanofilms has been investigated. Structural parameters have been analyzed using x-ray diffractometer. Scanning electron microscope and energy dispersive x-ray analyzer have been used to study surface morphology and elemental composition of nanofilms, respectively. The optical properties of the nanofilms have been studied for varying S/Cd molar ratio. The variation in S/Cd molar ratio induces reorientation in lattice structure of the nanofilms and a phase transition has been observed with changing molar ratios. The modification in properties with varying S/Cd ratio has been discussed in terms of quantum confinement and compared with theoretical results based on effective mass approximation and tight binding model.
A coarse-grained kinetic equation for neutral particles in turbulent fusion plasmas
Authors: Mekkaoui A. , Marandet Y. , Reiter D. , Boerner P. , Catoire F. , Genesio P. , Rosato J. , Stamm R. , Capes H. , Koubiti M. , Godbert-Mouret L.
Published: June 2012

A coarse-grained kinetic equation for neutral particles (atoms, molecules) in magnetized fusion plasmas, valid on time scales large compared to the turbulence correlation time, is presented. This equation includes the effects of plasma density fluctuations, described by gamma statistics, on the transport of neutral particles. These effects have so far been neglected in plasma edge modeling, in spite of the fact that the amplitude of fluctuations can be of order unity. Density fluctuations are shown to have a marked effect on the screening of neutrals and on the spatial localization of the ionization source, in particular at high density. The coarse-grained equations obtained in this work are readily implemented in edge code suites currently used for fusion plasma analysis and future divertor design (ITER, DEMO).
Correlation between filament distribution and resistive switching properties in resistive random access memory consisting of binary transition-metal oxides
Authors: Tanaka Hayato , Kinoshita Kentaro , Yoshihara Masataka , Kishida Satoru
Published: June 2012

Large variation in basic memory properties is a serious issue that hinders the practical use of ReRAMs. This study revealed that one of the main factors causing variation is the presence of multiple filaments in each memory cell. An operating filament switches to another filament having the smallest set voltage at each instant of switching. We propose a resistive switching model that takes the presence of multiple filaments into consideration. A Monte Carlo simulation based on the resistive switching model reproduces the Vset distribution. The dependence of  on the number of switching cycles was predicted by the model and confirmed experimentally.
Zero-birefringence pressure-sensitive adhesives
Authors: Ito Hiroto , Yanai Satoshi , Oda Sumihisa , Tagaya Akihiro , Koike Yasuhiro
Published: June 2012

We have developed zero-birefringence pressure-sensitive adhesives (PSAs) that exhibit almost no birefringence at any orientation of polymer chains. To evaluate the birefringence of PSAs quantitatively, we report a novel birefringence-measurement method utilizing zero–zero-birefringence polymers that exhibit no birefringence at any orientation of polymer chains and in elastic deformation. By employing this method, we designed and synthesized poly(butyl acrylate/phenoxyethyl acrylate/acrylic acid/hydroxyethyl acrylate) = 80.0:20.0:1.5:1.0 (by weight) that contains 1.8 wt% isocyanate-type crosslinker that exhibited almost zero birefringence. Furthermore, we demonstrated that after the accelerated aging test by applying heat, this zero-birefringence PSA almost completely prevented light leakage through crossed polarizers.
Dense regeneration of floodplain Eucalyptus coolabah: invasive scrub or passive restoration of an endangered woodland community?
Authors: Good Megan K. , Price Jodi N. , Clarke Peter J. , Reid Nick
Published: June 2012

Clearing of native vegetation and changes to disturbance regimes have resulted in dense regeneration of native trees and shrubs in parts of Australia. The conversion of open vegetation to dense woodlands may result in changes to the composition of plant communities and ecosystem function if structure, composition and function are tightly linked. Widespread clearing of the floodplain tree Eucalyptus coolabah subsp. coolabah (coolibah), in New South Wales, Australia, has led to state and federal listings of coolibah woodland as an endangered ecological community. Dense regeneration of coolibah in the mid 1970s, however, also resulted in its listing as an ‘invasive native species’ in NSW, meaning it can be legally cleared under certain conditions. Dense regeneration could be a novel state dissimilar to the threatened community or it could represent the next generation of coolibah woodlands and may contribute to passive restoration of heavily cleared landscapes. This study investigated if dense stands are distinct from remnant woodland by comparing floristic composition of the ground-storey community and top-soil properties of four coolibah vegetation states: derived grassland, derived degraded grassland, dense regeneration and remnant woodland. Ground-storey composition was found to overlap broadly among states regardless of tree density. Most species were common to all states, although dense regeneration contained characteristic woodland species that were absent from grasslands. The carbon : nitrogen ratio of the soil was significantly higher in dense regeneration and remnant woodland than in either of the grassland states, indicating that the woody states are broadly similar in terms of nutrient cycling. The study demonstrates that structurally different vegetation states (grasslands, woodlands and dense regeneration) are not associated with distinct plant communities. The results also suggest that grazing management has a more pronounced effect on ground-storey composition of plant communities than tree density and that well managed derived grasslands and dense regeneration are floristically similar to remnant woodlands. Since dense regeneration and remnant woodlands are not floristically distinct from one another, dense regeneration could contribute to the conservation of endangered coolibah woodlands in cleared agricultural landscapes.
Morphological and molecular data reveal three rather than one species of Sicyos (Cucurbitaceae) in Australia, New Zealand and Islands of the South West Pacific
Authors: Telford Ian R. H. , Sebastian Patrizia , de Lange Peter J. , Bruhl Jeremy J. , Renner Susanne S.
Published: June 2012

Morphometric data have long suggested the existence of three species of Sicyos in Australia and New Zealand. Molecular data now corroborate this and place the three species in the context of the remaining 72 species of Sicyos, most of them in the New World. We here describe and illustrate Sicyos undara I.Telford & P.Sebastian from northern Queensland and S. mawhai I.Telford & P.Sebastian from New Zealand, and emend the circumscription of S. australis to account for the removal of these two extraneous elements. We also provide a key to the three species, map their ranges, and note their habitat and conservation status.
Religion as a means to assure paternity
Authors: Strassmann Beverly I. , Kurapati Nikhil T. , Hug Brendan F. , Burke Erin E. , Gillespie Brenda W. , Karafet Tatiana M. , Hammer Michael F.
Published: June 2012

The sacred texts of five world religions (Buddhism, Christianity, Hinduism, Islam, and Judaism) use similar belief systems to set limits on sexual behavior. We propose that this similarity is a shared cultural solution to a biological problem: namely male uncertainty over the paternity of offspring. Furthermore, we propose the hypothesis that religious practices that more strongly regulate female sexuality should be more successful at promoting paternity certainty. Using genetic data on 1,706 father–son pairs, we tested this hypothesis in a traditional African population in which multiple religions (Islam, Christianity, and indigenous) coexist in the same families and villages. We show that the indigenous religion enables males to achieve a significantly (
P
= 0.019) lower probability of cuckoldry (1.3% versus 2.9%) by enforcing the honest signaling of menstruation, but that all three religions share tenets aimed at the avoidance of extrapair copulation. Our findings provide evidence for high paternity certainty in a traditional African population, and they shed light on the reproductive agendas that underlie religious patriarchy.
Discovery of antimicrobial ribonucleotide reductase inhibitors by screening in microwell format
Authors: Tholander Fredrik , Sjöberg Britt-Marie
Published: June 2012

Ribonucleotide reductase (RNR) catalyzes reduction of the four different ribonucleotides to their corresponding deoxyribonucleotides and is the rate-limiting enzyme in DNA synthesis. RNR is a well-established target for the antiproliferative drugs Gemzar and Hydrea, for antisense therapy, and in combination chemotherapies. Surprisingly, few novel drugs that target RNR have emerged, partly because RNR activity assays are laboratory-intense and exclude high-throughput methodologies. Here, we present a previously undescribed PCR-based assay for RNR activity measurements in microplate format. We validated the approach by screening a diverse library of 1,364 compounds for inhibitors of class I RNR from the opportunistic pathogen
Pseudomonas aeruginosa
, and we identified 27 inhibitors with IC
50
values from ∼200 nM to 30 μM. Interestingly, a majority of the identified inhibitors have been found inactive in human cell lines as well as in anticancer and in vivo tumor tests as reported by the PubChem BioAssay database. Four of the RNR inhibitors inhibited growth of
P. aeruginosa
, and two were also found to affect the transcription of RNR genes and to decrease the cellular deoxyribonucleotide pools. This unique PCR-based assay works with any RNR enzyme and any substrate nucleotide, and thus opens the door to high-throughput screening for RNR inhibitors in drug discovery.
RecQ helicase translocates along single-stranded DNA with a moderate processivity and tight mechanochemical coupling
Authors: Sarlós Kata , Gyimesi Máté , Kovács Mihály
Published: June 2012

Maintenance of genome integrity is the major biological role of RecQ-family helicases via their participation in homologous recombination (HR)-mediated DNA repair processes. RecQ helicases exert their functions by using the free energy of ATP hydrolysis for mechanical movement along DNA tracks (translocation). In addition to the importance of translocation per se in recombination processes, knowledge of its mechanism is necessary for the understanding of more complex translocation-based activities, including nucleoprotein displacement, strand separation (unwinding), and branch migration. Here, we report the key properties of the ssDNA translocation mechanism of
Escherichia coli
RecQ helicase, the prototype of the RecQ family. We monitored the pre–steady-state kinetics of ATP hydrolysis by RecQ and the dissociation of the enzyme from ssDNA during single-round translocation. We also gained information on the translocation mechanism from the ssDNA length dependence of the steady-state ssDNA-activated ATPase activity. We show that RecQ occludes 18 ± 2 nt on ssDNA during translocation. The hydrolysis of ATP is noncooperative in the presence of ssDNA, indicating that RecQ active sites work independently during translocation. In the applied conditions, the enzyme hydrolyzes 35 ± 4 ATP molecules per second during ssDNA translocation. RecQ translocates at a moderate processivity, with a mean run length of 100–320 nt on ssDNA. The determined tight mechanochemical coupling of 1.1 ± 0.2 ATP consumed per nucleotide traveled indicates an inchworm-type mechanism.
Force of infection is key to understanding the epidemiology ofPlasmodium falciparummalaria in Papua New Guinean children
Authors: Mueller Ivo , Schoepflin Sonja , Smith Thomas A. , Benton Kathryn L. , Bretscher Michael T. , Lin Enmoore , Kiniboro Benson , Zimmerman Peter A. , Speed Terence P. , Siba Peter , Felger Ingrid
Published: June 2012

GenotypingPlasmodium falciparumparasites in longitudinal studies provides a robust approach to estimating force of infection (FOI) in the presence of superinfections. The molecular parametermolFOI, defined as the number of newP. falciparumclones acquired over time, describes basic malaria epidemiology and is suitable for measuring outcomes of interventions. This study was designed to test whethermolFOI influenced the risk of clinical malaria episodes and how farmolFOI reflected environmental determinants of transmission, such as seasonality and small-scale geographical variation or effects of insecticide-treated nets (ITNs). Two hundred sixty-four children 1–3 y of age from Papua New Guinea were followed over 16 mo. Individual parasite clones were tracked longitudinally by genotyping. On average, children acquired 5.9 (SD 9.6) newP. falciparuminfections per child per y.molFOI showed a pronounced seasonality, was strongly reduced in children using ITNs (incidence rate ratio, 0.49; 95% confidence interval, [0.38, 0.61]), increased with age, and significantly varied within villages (P= 0.001). The acquisition of new parasite clones was the major factor determining the risk of clinical illness (incidence rate ratio, 2.12; 95% confidence interval, [1.93, 2.31]). Adjusting for individual differences inmolFOI completely explained spatial variation, age trends, and the effect of ITN use. This study highlights the suitability ofmolFOI as a measure of individual exposure and its central role in malaria epidemiology. It has substantial advantages over entomological measures in studies of transmission patterns, and could be used in analyses of host variation in susceptibility, in field efficacy trials of novel interventions or vaccines, and for evaluating intervention effects.
Stochastic branching-diffusion models for gene expression
Authors: Cottrell David , Swain Peter S. , Tupper Paul F.
Published: June 2012

A challenge to both understanding and modeling biochemical networks is integrating the effects of diffusion and stochasticity. Here, we use the theory of branching processes to give exact analytical expressions for the mean and variance of protein numbers as a function of time and position in a spatial version of an established model of gene expression. We show that both the mean and the magnitude of fluctuations are determined by the protein’s Kuramoto length—the typical distance a protein diffuses over its lifetime—and find that the covariance between local concentrations of proteins often increases if there are substantial bursts of synthesis during translation. Using high-throughput data, we estimate that the Kuramoto length of cytoplasmic proteins in budding yeast to be an order of magnitude larger than the cell diameter, implying that many such proteins should have an approximately uniform concentration. For constitutively expressed proteins that live substantially longer than their mRNA, we give an exact expression for the deviation of their local fluctuations from Poisson fluctuations. If the Kuramoto length of mRNA is sufficiently small, we predict that such local fluctuations become approximately Poisson in bacteria in much of the cell, unless translational bursting is exceptionally strong. Our results therefore demonstrate that diffusion can act to both increase and decrease the complexity of fluctuations in biochemical networks.
Critical features for biosynthesis, stability, and functionality of a G protein-coupled receptor uncovered by all-versus-all mutations
Authors: Schlinkmann Karola M. , Honegger Annemarie , Türeci Esin , Robison Keith E. , Lipovšek Daša , Plückthun Andreas
Published: June 2012

The structural features determining efficient biosynthesis, stability in the membrane and, after solubilization, in detergents are not well understood for integral membrane proteins such as G protein-coupled receptors (GPCRs). Starting from the rat neurotensin receptor 1, a class A GPCR, we generated a separate library comprising all 64 codons for each amino acid position. By combining a previously developed FACS-based selection system for functional expression [Sarkar C, et al. (2009)
Proc Natl Acad Sci USA
105:14808–14813] with ultradeep 454 sequencing, we determined the amino acid preference in every position and identified several positions in the natural sequence that restrict functional expression. A strong accumulation of shifts, i.e., a residue preference different from wild type, is detected for helix 1, suggesting a key role in receptor biosynthesis. Furthermore, under selective pressure we observe a shift of the most conserved residues of the N-terminal helices. This unique data set allows us to compare the in vitro evolution of a GPCR to the natural evolution of the GPCR family and to observe how selective pressure shapes the sequence space covered by functional molecules. Under the applied selective pressure, several positions shift away from the wild-type sequence, and these improve the biophysical properties. We discuss possible structural reasons for conserved and shifted residues.
Perforin-dependent CD4+T-cell cytotoxicity contributes to control a murine poxvirus infection
Authors: Fang Min , Siciliano Nicholas A. , Hersperger Adam R. , Roscoe Felicia , Hu Angela , Ma Xueying , Shamsedeen Ahamed R. , Eisenlohr Laurence C. , Sigal Luis J.
Published: June 2012

CD4+T cells are generally regarded as helpers and regulators of the immune response. Although cytolytic CD4+T cells have been described, whether those generated during the course of a viral infection play a role in virus control remains unknown. Here we show that during acute infection with ectromelia virus, the mouse homolog of the human virus of smallpox, large numbers of CD4+T cells in the draining lymph node and liver of resistant mice have a cytotoxic phenotype. We also show that these cells kill targets in vivo in a perforin-dependent manner and that mice with specific deficiency of perforin in CD4+T cells have impaired virus control. Thus, perforin-dependent CD4+T-cell killing of infected cells is an important mechanism of antiviral defense.
Digital atom interferometer with single particle control on a discretized space-time geometry
Authors: Steffen Andreas , Alberti Andrea , Alt Wolfgang , Belmechri Noomen , Hild Sebastian , Karski Michał , Widera Artur , Meschede Dieter
Published: June 2012

Engineering quantum particle systems, such as quantum simulators and quantum cellular automata, relies on full coherent control of quantum paths at the single particle level. Here we present an atom interferometer operating with single trapped atoms, where single particle wave packets are controlled through spin-dependent potentials. The interferometer is constructed from a sequence of discrete operations based on a set of elementary building blocks, which permit composing arbitrary interferometer geometries in a digital manner. We use this modularity to devise a space-time analogue of the well-known spin echo technique, yielding insight into decoherence mechanisms. We also demonstrate mesoscopic delocalization of single atoms with a separation-to-localization ratio exceeding 500; this result suggests their utilization beyond quantum logic applications as nano-resolution quantum probes in precision measurements, being able to measure potential gradients with precision 5 × 10
-4
in units of gravitational acceleration
g
.
Roles of cell confluency and fluid shear in 3-dimensional intracellular forces in endothelial cells
Authors: Hur Sung Sik , del Álamo Juan C. , Park Joon Seok , Li Yi-Shuan , Nguyen Hong A. , Teng Dayu , Wang Kuei-Chun , Flores Leona , Alonso-Latorre Baldomero , Lasheras Juan C. , Chien Shu
Published: June 2012

We use a novel 3D inter-/intracellular force microscopy technique based on 3D traction force microscopy to measure the cell–cell junctional and intracellular tensions in subconfluent and confluent vascular endothelial cell (EC) monolayers under static and shear flow conditions. We found that z-direction cell–cell junctional tensions are higher in confluent EC monolayers than those in subconfluent ECs, which cannot be revealed in the previous 2D methods. Under static conditions, subconfluent cells are under spatially non-uniform tensions, whereas cells in confluent monolayers are under uniform tensions. The shear modulations of EC cytoskeletal remodeling, extracellular matrix (ECM) adhesions, and cell–cell junctions lead to significant changes in intracellular tensions. When a confluent monolayer is subjected to flow shear stresses with a high forward component comparable to that seen in the straight part of the arterial system, the intracellular and junction tensions preferentially increase along the flow direction over time, which may be related to the relocation of adherens junction proteins. The increases in intracellular tensions are shown to be a result of chemo-mechanical responses of the ECs under flow shear rather than a direct result of mechanical loading. In contrast, the intracellular tensions do not show a preferential orientation under oscillatory flow with a very low mean shear. These differences in the directionality and magnitude of intracellular tensions may modulate translation and transcription of ECs under different flow patterns, thus affecting their susceptibility for atherogenesis.
ἰδέα τοῦ ἀγαϑοῦ – ἀγαϑὸν ἐπέκεινα τῆς οὐσίας
Authors: Lavecchia Salvatore
Published: June 2012

In Plato’s Republic the prime cause of all things, the Good, is presented both as transcending every form of being (509b9 f.) and as the supreme Idea, that is to say as the supreme being. The inconsistency between these two characterizations seems to point to the paradoxical relation subsisting between the absolutely transcendent Good and its supreme self-revelation (the Idea of the Good): by revealing itself, the ἀγαϑὸν ἐπέκεινα τῆς οὐσίας constitutes the highest being and therefore has to be considered to be identical with the ἰδέα τοῦ ἀγαϑοῦ; on the other hand its absolute transcendence implies a clear supereminence in regard to the Idea of the Good. This article tries to highlight and illustrate these antinomic aspects of Plato’s notion of the Good with the help of both the so-called ἄγραφα δόγματα and the representation of the Demiurge in Plato’s work.
Selbstrealisierung
Authors: Leinkauf Thomas
Published: June 2012

This article tries to give a survey of anthropological thinking in early modern philosophy, taking ‘anthropology’ not in its modern sense and not even sensu strictu as for example Otto Casman did it in his work from the late 16th century, i.e.: as the physiology of the human being, but sensu lato as a philosophical reflection on the condition of man as an ‘animal rationale’. The arguments focus on three ‘directions’ of the inner movement of the mental and psychological activity of mankind (towards God, towards the mind itself, towards the world), which, taken all together, form the total concept of “Selbstrealisierung” (realisation of the self).
Bild-Symbol, Geometrie und Methode: Philosophische Implikationen der frühneuzeitlichen Textillustration
Authors: Leinkauf Thomas
Published: June 2012

This article tries to point out that in the early modern period, including the Renaissance, philosophy increasingly developed a certain kind of thinking and arguing that needed to be sustained by ›icons‹, ›pictures‹ or ›signs‹. Following a suggestion made by Stephen Clucas in inviting a group of scholars to discuss the topos of ›silent languages‹ at Birbeck College (University of London), this paper discusses 1. a general possible meaning of ›silent language‹, divided into three modes of symbolic and geometric representation, and introducing 2. three ›stages‹ in the historical development of philosophical systems representing these three modes: Plotinus, Cusanus, the philosophy of the 16th and 17th century.
Dic cur hic?
Authors: Salatowsky Sascha
Published: June 2012

In order to attain a deeper understanding of Aristotelian philosophy in the Renaissance, it is necessary to consider the theological implications of given facts. This article discusses a basic problem centring on the reception of Aristotle’s Ethics. The Nicomachean Ethics was widely regarded as the basis for a virtuous ethical life, yet how could a pagan philosophy, with its concepts of happiness, virtue, justice, etc., be the basis of a Christian society? The aim of the present article is to show how Lutheran scholars solved this problem in confrontation with Catholic and Calvinist scholars of the time. The first part deals with the two basic components of Aristotle’s Ethics, namely the doctrines of happiness (Eudaimonologia) and virtue (Aretologia), and attempts to show that Aristotle’s Ethics should not be understood as a system of rules, but rather as a handbook for the cultivation of practical habits in the free human being who strives to live a good life. The second part examines two key ideological confrontations in relation to Aristotle’s philosophy: between Lutherans and Calvinists in respect of definition of theology and philosophical and theological virtues on the one hand, and between Lutherans and ›the Enthusiasts‹ in respect of the concept of virtues on the other.
Comparing English and Chinese persuasive strategies in Trade Fair invitations
Authors: Zhu Yunxia
Published: June 2012

This paper aims to compare the persuasive strategies used by English and Chinese letters of invitation to trade fairs, from a sociocognitive perspective mainly based on genre study (Swales, 1990) and schema theory (Rumelhart, 1980). Cross-cultural persuasive strategies involving ethos, logos, and pathos are compared in a top-down process. In this approach, a corpus of forty letters of invitation (twenty in Chinese and twenty in English) was examined. It was found that although the English and Chinese letters share the ultimate goal of inviting the reader to the trade fair, they exhibit di¬erent preferences as to whether they appeal to emotion or to logic. The English invitations were found to appeal strongly to logic. The Chinese invitations, by contrast, tended to emphasize an appeal both to logic and to the emotions; the latter is characterized by a formal and respectful register.