bluuebunny/crossref_metadata_2025 huggingface dataset:
Regional and environmental impacts of expanding the heavy duty vehicle charge to the secondary road network in Austria
Authors: Steininger Karl W. , Schmid Christoph , Tobin Alexandra
Published: February 2012

In road freight transport a particularly large share of the total social costs generated is not borne by road users. To correct for this, many European countries use pricing instruments specifically targeted at heavy duty vehicles, so far targeted almost exclusively at the primary road network. In line with the overall EU objective of greening the transport sector, we discuss the possibility of expanding the road charging system to a more comprehensive, area-wide one. The degree to which peripheral or disadvantaged regions are hit over-proportionally by such a measure remains an open question in the literature on heavy duty vehicle road pricing. We combine an input–output and a computable general equilibrium approach to analyse the case for Austria. We find that while it is not the sectors of highest economic importance in the periphery regions that are hit by the charge, those sectors that are hit are those which are relatively more important in peripheral regions (with up to a twofold share in value added) and for whom production price impacts tend to be relatively strong. The short term consumer price effect of extending the current primary road network charges to the secondary network is found not to exceed 0.15%. In terms of the principles of sustainable transport we find that extending charge coverage is compatible with most core principles, the exception being the principle of regional need. In terms of environmental impact, for example, expanding heavy duty vehicle charges to the secondary road network reduces heavy duty vehicle kilometres in the overall network (and related emissions) by roughly 2%. However, in order to comply with the needs principle, suitable complementary transfer policies need to be designed and implemented for peripheral regions.
Trehalose‐Induced Changes in Seed Oil Composition and Antioxidant Potential of Maize Grown Under Drought Stress
Authors: Ali Qasim , Ashraf Muhammad , Anwar Farooq , Al‐Qurainy Fahad
Published: February 2012

The present investigation was conducted to determine if foliar‐applied trehalose (an osmoprotectant) could ameliorate the adverse effects of water shortage on maize seed oil composition and oil antioxidant potential. Drought stress significantly reduced the seed oil but increased oleic acid and linolenic acid contents of the oil with a concomitant decrease in linoleic acid content, which resulted in an increased oil oleic/linoleic ratio in both maize cultivars. Water stress also increased the seed oil α‐ γ‐ δ‐ and total tocopherols and flavonoids of both maize cultivars, however, oil phenolic content and oil antioxidant activity decreased. Exogenously applied trehalose positively influenced seed composition of both maize cultivars under non‐stress and water stress conditions. Exogenous application of trehalose further increased the oil oleic and linolenic acid contents with a subsequent decrease in linoleic acid. Furthermore, exogenous application of trehalose increased the oil antioxidant activity in terms of oil DPPH (2,2‐diphenyl‐1‐picrylhydrazyl) free radical scavenging activity with an increase in oil tocopherols, total flavonoids and total phenolics contents.
Propagation of solitary waves and shock wavelength in the pair plasma
Authors: MALEKOLKALAMI BEHROOZ , MOHAMMADI TAIMUR
Published: February 2012

The propagation of electrostatic waves is studied in plasma system consisting of pair-ions and stationary additional ions in presence of the Sagdeev potential (pseudopotential) as function of electrostatic potential (pseudoparticle). It is remarked that both compressive and rarefective solitary waves can be propagated in this plasma system. These electrostatic solitary waves, however, cannot be propagated if the density of stationary ions increases from one critical value or decreases from another when the temperature and the Mach number are fixed. Also, when pseudoparticle is affected with a little dissipation of energy, it is trapped in potential well and can oscillate. Oscillations generate shock wave in the media, and in the negative minimal point of the well it is possible to compute numerically the shock wavelength for the allowed values of the plasma parameters.
Generic maps of the projective plane with a single triple point
Authors: HOWARD GREG , GOODMAN SUE
Published: February 2012

Cromwell and Marar present an analysis of semi-regular (generic) surfaces with a single triple point and connected self-intersection set. Six of their surfaces are the projective plane, including Boy's surface and Steiner's surface. We build on their work by incorporating twists similar to that of Apery's immersion of the projective plane and show that with a few additional surfaces, all such generic maps of the projective plane are now identified.
Verification of ADS-B positioning by direction of arrival estimation
Authors: Reck Christoph , Reuther Max S. , Jasch Alexander , Schmidt Lorenz-Peter
Published: February 2012

ADS-B provides convenient means of air traffic control (ATC) for its low cost and simple ground station hardware. In a low percentage of cases, aircraft positions transmitted via ADS-B are error prone due to e.g. faulty wiring with onboard navigation systems. In the proposed approach, direction of arrival (DOA) estimation is used to verify ADS-B airborne positions. The potential positioning error of ADS-B is thereby evaluated by comparing DOA estimates to DOA values calculated from ADS-B references and the sensor position and orientation. To prove the accuracy of the applied DOA estimation sensor, an additional measurement campaign using a dedicated measurement aircraft has been conducted.
Improvement of daytime land surface skin temperature over arid regions in the NCEP GFS model and its impact on satellite data assimilation
Authors: Zheng Weizhong , Wei Helin , Wang Zhuo , Zeng Xubin , Meng Jesse , Ek Michael , Mitchell Ken , Derber John
Published: February 2012

Comparison of the land surface skin temperature (LST) from the National Centers for Environmental Prediction (NCEP) operational Global Forecast System (GFS) against satellite and in situ data in summer 2007 indicates that the GFS has a large and cold bias in LST over the arid western continental United States (CONUS) during daytime. This LST bias contributes to large errors in simulated satellite brightness temperatures over land by the Community Radiative Transfer Model (CRTM) and hence the rejection of satellite data in the NCEP Gridpoint Statistical Interpolation (GSI) system, especially for surface‐sensitive satellite channels. The new vegetation‐dependent formulations of momentum and thermal roughness lengths are tested in the GFS. They substantially reduce the large cold bias of daytime LST over the arid western CONUS in the warm season. This, in turn, significantly reduces the large biases of calculated satellite brightness temperatures found for infrared and microwave sensors in window or near‐window channels, so that many more satellite data can be assimilated in the GSI system. In the arid western CONUS, the calculation of surface emissivity for microwave sensors in the CRTM can be further improved, and the new microwave land emissivity model together with increased LST via changes in surface roughness length formulations reduces biases and root‐mean‐square errors in the calculated brightness temperature.
Frozen and active seismic anisotropy beneath southern Africa
Authors: Vinnik L. , Kiselev S. , Weber M. , Oreshin S. , Makeyeva L.
Published: February 2012

P receiver functions from 23 stations of the SASE experiment in southern Africa are inverted simultaneously with SKS waveforms for azimuthal anisotropy in the upper mantle. Our analysis resolves the long‐standing issue of depth dependence and origins of anisotropy beneath southern Africa. In the uppermost mantle we observe anisotropy with a nearly E‐W fast direction, parallel to the trend of the Limpopo belt. This anisotropy may be frozen since the Archean. At a depth of 160 km the fast direction of anisotropy changes to 40° and becomes close to the recent plate motion direction. This transition is nearly coincident in depth with activation of dominant glide systems in olivine and with a pronounced change in other properties of the upper mantle. Another large change in the fast direction of anisotropy corresponds to the previously found low‐S‐velocity layer atop the 410‐km discontinuity.
Ferromagnetic resonance of micro- and nano-sized hexagonal ferrite powders at millimeter waves
Authors: Korolev Konstantin A. , McCloy John S. , Afsar Mohammed N.
Published: February 2012

Complex magnetic permeability and dielectric permittivity of micro- and nano-sized powdered barium (BaFe12O19) and strontium (SrFe12O19) hexaferrites have been studied in a broadband millimeter wave frequency range (30–120 GHz). Transmittance measurements have been performed using a free-space quasi-optical millimeter wave spectrometer, equipped with a set of high-power backward wave oscillators. Real and imaginary parts of dielectric permittivity for both types of micro- and nanoferrites have been calculated using analysis of recorded high-precision transmittance spectra. Frequency dependences of the magnetic permeability have been obtained from Schlömann’s equation for partially magnetized ferrites. These materials show promise as tunable millimeter wave absorbers, based on their size-dependent absorption.
Laser ion source with solenoid for Brookhaven National Laboratory-electron beam ion source
Authors: Kondo K. , Yamamoto T. , Sekine M. , Okamura M.
Published: February 2012

The electron beam ion source (EBIS) preinjector at Brookhaven National Laboratory (BNL) is a new heavy ion-preinjector for relativistic heavy ion collider (RHIC) and NASA Space Radiation Laboratory (NSRL). Laser ion source (LIS) is a primary ion source provider for the BNL-EBIS. LIS with solenoid at the plasma drift section can realize the low peak current (∼100 μA) with high charge (∼10 nC) which is the BNL-EBIS requirement. The gap between two solenoids does not cause serious plasma current decay, which helps us to make up the BNL-EBIS beamline.
Recent developments of the ion sources at Tri University Meson Factory/Isotope Separator and ACcelerator Facility
Authors: Bricault P. G. , Ames F. , Dombsky M. , Labrecque F. , Lassen J. , Mjos A. , Minor G. , Tigelhoefer A.
Published: February 2012

This paper describes the recent progresses concerning the on-line ion source at the Tri University Meson Factory/Isotope Separator and ACcelerator (TRIUMF/ISAC) Radioactive Ion-Beam Facility; description of the new design of the surface-ion-source for improved stability of the beam intensity, description of the transport path to the east target station at ISAC, description of the new brazing techniques that solved recurrent problems with water leaks on the target/ion source assembly in the vacuum system, finally, recent developments concerning the Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source are reported. In particular, a study on the effect of the plasma chamber volume on the ionization efficiency was completed.
Tuning the cation distribution and magnetic properties of single phase nanocrystalline Dy3Fe5O12 garnet
Authors: Guillot M. , Chinnasamy C. N. , Greneche J. M. , Harris V. G.
Published: February 2012

Synthesizing single phase nanocrystalline rare earth iron garnet is difficult owing due to its complex crystal structure. In this report, single phase Dy3Fe5O12 nanoparticles with different grain sizes (50, 32, and 22 nm) were prepared using the ball milling technique in a controlled atmosphere. The average grain size decreases with milling time, and reaches 22 nm after 30 h of milling. The magnetization for the as-prepared micron sized Dy3Fe5O12 is in quasi-perfect agreement with the single crystal values, and all the Fe and Dy ions are in trivalent state. When the grain size is reduced below 50 nm (10 h), the magnetization strongly depends upon the applied field, and no saturation is observed even at an applied field of 280 kOe. The compensation temperature (Tcomp) for the nanocrystalline Dy3Fe5O12 samples are a few degrees higher than that of the bulk. There is no evidence for the presence of Fe2+ charge state in the as-prepared garnets. However, Mössbauer spectroscopy studies show that about 14–15 at. % Fe2+ content was found in the 30 h (22 nm) milled sample at 77 K. Oxygen vacancies created during milling induces the presence of Fe2+ ions in the nanocrystalline Dy3Fe5O12 particles.
Soft M-type hexaferrite for very high frequency miniature antenna applications
Authors: Lee Jaejin , Hong Yang-Ki , Lee Woncheol , Abo Gavin S. , Park Jihoon , Neveu Nicholas , Seong Won-Mo , Park Sang-Hoon , Ahn Won-Ki
Published: February 2012

We have studied soft M-type BaFe9.6Co1.2Ti1.2O19 hexaferrite for T-DMB (terrestrial digital media broadcasting) antenna applications. The effect of magneto-dynamic properties on antenna size, bandwidth, and radiation efficiency was investigated. The soft M-type BaFe9.6Co1.2Ti1.2O19 hexaferrite (Co/Ti-substituted BaM) was synthesized by a combination of ball-milling and two-step sintering processes. Permeability and loss tan δµ of the Co/Ti-substituted BaM were measured to be 4.5 and 0.039 at 200 MHz, respectively. The Wheeler cap method and network analyzer were used to evaluate antenna radiation efficiency and measure return losses, respectively. Our experimental results show that the low-loss Co/Ti-substituted BaM is an excellent soft magnetic material for VHF (very high frequency: 30–300 MHz) miniature antenna applications.
Formation of fullerene superlattices by interlayer bonding in twisted bilayer graphene
Authors: Muniz Andre R. , Maroudas Dimitrios
Published: February 2012

Based on first-principles density functional theory calculations, we report a novel class of carbon nanostructures consisting of superlattice arrangements of caged fullerene configurations of various sizes embedded within planes of twisted bilayer graphene. Formation of these structures is the outcome of interlayer C-C bonding between pairs of graphene planes chemically modified with certain patterns of chemisorbed hydrogen and rotated with respect to each other by angles around 30°. A specific subclass of these nanostructures preserves the main features of the electronic structure of pristine single-layer graphene. Our study proposes possible functionalization strategies to systematically tailor the electronic properties of bilayer graphene.
Influence of Cu column under-bump-metallizations on current crowding and Joule heating effects of electromigration in flip-chip solder joints
Authors: Liang Y. C. , Tsao W. A. , Chen Chih , Yao Da-Jeng , Huang Annie T. , Lai Yi-Shao
Published: February 2012

The electromigration behavior of SnAg solder bumps with and without Cu column under-bump-metallizations (UBMs) has been investigated under a current density of 2.16 × 104 A/cm2 at 150 °C. Different failure modes were observed for the two types of samples. In those without Cu column UBMs, when SnAg solder bumps that had implemented 2 μm Ni UBMs were current stressed at 2.16 × 104 A/cm2, open failure occurred in the bump that had an electron flow direction from the chip side to the substrate side. However, in those with Cu column UBMs, cracks formed along the interface of Cu6Sn5 intermetallic compounds and the solder on the substrate side in the Sn-3.0Ag–0.5Cu solder bump that had an electron flow direction from the substrate side to the chip side. A three-dimensional simulation of the current density distribution was performed in order to obtain a better understanding of the current crowding behavior in solder bumps. The current crowding effect was found to account for the void formation on both the chip and the substrate side for the two kinds of solder bumps. One more important finding, as confirmed by infrared microscopy, is that the alleviation of current crowding by Cu column UBMs also helped decrease the Joule heating effect in solder bumps during current stressing. Therefore, the measured failure time for the solder joints with Cu column UBMs appears to be much longer than that of the ones with the 2 μm Ni UBMs.
The study of negative thermal expansion and magnetic evolution in antiperovskite compounds Cu0.8-xSnxMn0.2NMn3(0 ≤ x ≤ 0.3)
Authors: Lin J. C. , Wang B. S. , Lin S. , Tong P. , Lu W. J. , Zhang L. , Song W. H. , Sun Y. P.
Published: February 2012

With increasing the substitution of Sn for Cu in Cu0.8-xSnxMn0.2NMn3, the initial cubic-tetragonal structural phase transition disappears for the samples x ≥ 0.10 and is replaced by a discontinuous lattice expansion with a cubic structure which has been confirmed by the measurements of variable temperature x-ray diffractions and specific heat. The discontinuous lattice expansion broadens with increasing the doping level x and the negative thermal expansion coefficient up to −64.54 ppm/K between 190 K and 235 K is found for the sample x = 0.3. Detailed magnetic measurements indicate that the magnetic ground state is meta-stable for the lower-doping level and transforms into spin-glass-like state owing to the enhancement of antiferromagnetic interaction when x is up to 0.3. Furthermore, the magnetization curves M(T) display abnormal behaviors for lower-x. For the samples x = 0.1 and 0.2, the jump of field-cooled magnetization curve MFC (defined as ΔMFC/MFC) around the lower-temperature magnetic transition is suppressed with increasing the magnetic field. These abnormalities of magnetizations are also discussed based on a simple model.
Balloon-borne disposable radiometer for cloud detection
Authors: Nicoll K. A. , Harrison R. G.
Published: February 2012

A low cost, disposable instrument for measuring solar radiation during meteorological balloon flights through cloud layers is described. Using a photodiode detector and low thermal drift signal conditioning circuitry, the device showed less than 1% drift for temperatures varied from +20 °C to −35 °C. The angular response to radiation, which declined less rapidly than the cosine of the angle between the incident radiation and normal incidence, is used for cloud detection exploiting the motion of the platform. Oriented upwards, the natural motion imposed by the balloon allows cloud and clear air to be distinguished by the absence of radiation variability within cloud, where the diffuse radiation present is isotropic. The optical method employed by the solar radiation instrument has also been demonstrated to provide higher resolution measurements of cloud boundaries than relative humidity measurements alone.
Interaction of a supersonic, radiatively cooled plasma jet with an ambient medium
Authors: Suzuki-Vidal F. , Bocchi M. , Lebedev S. V. , Swadling G. F. , Burdiak G. , Bland S. N. , de Grouchy P. , Hall G. N. , Harvey-Thompson A. J. , Khoory E. , Patankar S. , Pickworth L. , Skidmore J. , Smith R. , Chittenden J. P. , Krishnan M. , Madden R. E. , Wilson-Elliot K. , Ciardi A. , Frank A.
Published: February 2012

An experimental investigation into the interaction of a supersonic, radiatively cooled plasma jet with argon gas is presented. The jet is formed by ablation of an aluminum foil driven by a 1.4 MA, 250 ns current pulse in a radial foil Z-pinch configuration. The outflow consists of a supersonic (Mach number ∼3–5), dense (ion density ni ∼ 1018 cm−3), highly collimated (half-opening angle ∼2°−5°) jet surrounded by a lower density halo plasma moving with the same axial velocity as the jet. The addition of argon above the foil leads to the formation of a shock driven by the ablation of halo plasma, together with a bow-shock driven by the dense jet. Experimental data with and without the presence of argon are compared with three-dimensional, magneto-hydrodynamic simulations using the GORGON code.
Particle-in-cell simulations of hollow cathode enhanced capacitively coupled radio frequency discharges
Authors: Lafleur T. , Boswell R. W.
Published: February 2012

A two-dimensional particle-in-cell simulation has been developed to study density enhancement of capacitively coupled rf discharges with multi-slit electrodes. The observed density increase is shown to result from a hollow cathode effect that takes place within the multi-slit electrode configuration, which forms as a result of secondary electron emission due to ion bombardment. By investigating the ionization and power deposition profiles, it is found that rf sheath heating is too weak to sustain the discharge, and that secondary electron acceleration within the sheath is the primary heating mechanism. Due to a capacitive voltage divider formed by the rf sheaths at each electrode, the area ratio of the powered and ground electrodes is observed to have a strong effect on the resulting discharge, and if the ground electrode area is too small, the voltage drop at the powered electrode is too low to sustain a hollow cathode discharge.
Vibration analysis of circular double-layered graphene sheets
Authors: Natsuki Toshiaki , Shi Jin-Xing , Ni Qing-Qing
Published: February 2012

This paper presents a study on the natural vibration of circular double-layer graphene sheets (DLGSs) using circular plate theory. The circular DLGSs are assumed to be coupled together through the carbon–carbon van der Waals (vdW) force between their two layers. An analytical solution of coupled governing equations is proposed to predict the natural frequencies of circular DLGSs. The vibration behaviors in circular DLGSs are found to have an in-phase mode (IPM) associated with the classical natural frequency, and an anti-phase mode (APM) owing to the influence of the vdW interaction. The natural frequencies of the IPM are independent of vdW interactions between adjacent layers, while those of the APM depend on the vdW interaction, and are larger. Based on the exact solution, the influences of wavenumbers (m, n) on the natural frequencies of simply supported circular DLGSs are also investigated in detail.
Silicon intercalation at the interface of graphene and Ir(111)
Authors: Meng Lei , Wu Rongting , Zhou Haitao , Li Geng , Zhang Yi , Li Linfei , Wang Yeliang , Gao H.-J.
Published: February 2012

We report on the structural and electronic properties in the heterostructure of graphene/silicon/Ir(111). A (√19 × √19)R23.41° superstructure is confirmed by low energy electron diffraction and scanning tunneling microscopy and its formation is ascribed to silicon intercalation at the interface between the graphene and the Ir(111) substrate. The dI/dV measurements indicate that the interaction between graphene and Ir is effectively decoupled after silicon intercalation. Raman spectroscopy also reveals the vibrational states of graphene, G peak and 2D peak, which further demonstrates that the silicon-buffered graphene behaves more like intrinsic graphene.
Note: Ultrasonic liquid flow meter for small pipes
Authors: Yu Yang , Zong Guanghua
Published: February 2012

An ultrasonic flow meter for small pipes is presented. For metal pipe diameter smaller than 10 mm, clamp-on ultrasonic contrapropagation flow meters may encounter difficulties if cross talk or the short acoustic path contributes to large uncertainty in transit time measurement. Axial inline flow meters can avoid these problems, but they may introduce other problems if the transducer port is not properly positioned. Three types of pipe connecting tees are compared using the computational fluid dynamics (CFD) method. CFD shows the 45° tee has more uniform velocity distribution over the measuring section. A prototype flow meter using the 45° tee was designed and tested. The zero flow experiment shows the flow meter has a maximum of 0.002 m/s shift over 24 h. The flow meter is calibrated by only 1 meter factor. After calibration, inaccuracy lower than 0.1% of reading was achieved in the laboratory, for a measuring range from 15 to 150 g/s (0.29 to 2.99 m/s; Re = 2688 to 26 876).
Note: The role of external electric fields in enhancing ion mobility, drift velocity, and drift-diffusion rates in aqueous electrolyte solutions [J. Chem. Phys. 134, 114504 (2011)]
Authors: Murad Sohail
Published: February 2012

The effect of external electric fields on enhancing ion mobility, drift velocity, and drift diffusion as a function of solution concentration has been investigated using molecular dynamics simulations. Our results show that the unusual nonlinear behavior observed when the solution concentration matches seawater is also observed when the concentration is reduced to half of that value. These results are of significance in designing processes for desalinating seawater using electro-deionization in which the concentration would decrease during salt removal, and for purification of brackish waters which also have lower salt content.
Structural insights into the biogenesis and biofilm formation by the
Escherichia coli
common pilus
Authors: Garnett James A. , Martínez-Santos Verónica I. , Saldaña Zeus , Pape Tillmann , Hawthorne William , Chan Jennifer , Simpson Peter J. , Cota Ernesto , Puente José L. , Girón Jorge A. , Matthews Steve
Published: February 2012

Bacteria have evolved a variety of mechanisms for developing community-based biofilms. These bacterial aggregates are of clinical importance, as they are a major source of recurrent disease. Bacterial surface fibers (pili) permit adherence to biotic and abiotic substrates, often in a highly specific manner. The
Escherichia coli
common pilus (ECP) represents a remarkable family of extracellular fibers that are associated with both disease-causing and commensal strains. ECP plays a dual role in early-stage biofilm development and host cell recognition. Despite being the most common fimbrial structure, relatively little is known regarding its biogenesis, architecture, and function. Here we report atomic-resolution insight into the biogenesis and architecture of ECP. We also derive a structural model for entwined ECP fibers that not only illuminates interbacteria communication during biofilm formation but also provides a useful foundation for the design of novel nanofibers.
The molten globule state is unusually deformable under mechanical force
Authors: Elms Phillip J. , Chodera John D. , Bustamante Carlos , Marqusee Susan
Published: February 2012

Recently, the role of force in cellular processes has become more evident, and now with advances in force spectroscopy, the response of proteins to force can be directly studied. Such studies have found that native proteins are brittle, and thus not very deformable. Here, we examine the mechanical properties of a class of intermediates referred to as the molten globule state. Using optical trap force spectroscopy, we investigated the response to force of the native and molten globule states of apomyoglobin along different pulling axes. Unlike natively folded proteins, the molten globule state of apomyoglobin is compliant (large distance to the transition state); this large compliance means that the molten globule is more deformable and the unfolding rate is more sensitive to force (the application of force or tension will have a more dramatic effect on the unfolding rate). Our studies suggest that these are general properties of molten globules and could have important implications for mechanical processes in the cell.
Low-Reynolds-number swimming at pycnoclines
Authors: Doostmohammadi Amin , Stocker Roman , Ardekani Arezoo M.
Published: February 2012

Microorganisms play pivotal functions in the trophic dynamics and biogeochemistry of aquatic ecosystems. Their concentrations and activities often peak at localized hotspots, an important example of which are pycnoclines, where water density increases sharply with depth due to gradients in temperature or salinity. At pycnoclines organisms are exposed to different environmental conditions compared to the bulk water column, including reduced turbulence, slow mass transfer, and high particle and predator concentrations. Here we show that, at an even more fundamental level, the density stratification itself can affect microbial ecology at pycnoclines, by quenching the flow signature, increasing the energetic expenditure, and stifling the nutrient uptake of motile organisms. We demonstrate this through numerical simulations of an archetypal low-Reynolds-number swimmer, the “squirmer.” We identify the Richardson number—the ratio of buoyancy forces to viscous forces—as the fundamental parameter that quantifies the effects of stratification. These results demonstrate an unexpected effect of buoyancy on low-Reynolds-number swimming, potentially affecting a broad range of abundant organisms living at pycnoclines in oceans and lakes.
Drought is a recurring challenge in the Middle East
Authors: Kaniewski David , Van Campo Elise , Weiss Harvey
Published: February 2012

Climate change and water availability in the Middle East are important in understanding human adaptive capacities in the face of long-term environmental changes. The key role of water availability for sedentary and nomad populations in these arid to semiarid landscapes is understood, but the millennium-scale influence of hydrologic instability on vegetation dynamics, human occupation, and historic land use are unknown, which has led to a stochastic view of population responses and adaptive capacities to precipitation anomalies. Within the time-frame of the last two global climate events, the Medieval Climate Anomaly and the Little Ice Age, we report hydrologic instability reconstructed from pollen-derived climate proxies recovered near Tell Leilan, at the Wadi Jarrah in the Khabur Plains of northeastern Syria, at the heart of ancient northern Mesopotamia. By coupling climate proxies with archaeological-historical data and a pollen-based record of agriculture, this integrative study suggests that variability in precipitation is a key factor on crop yields, productivity, and economic systems. It may also have been one of the main parameters controlling human settlement and population migrations at the century to millennial timescales in the arid to semiarid areas of the Middle East. An abrupt shift to drier conditions at ca. AD 1400 is contemporaneous with a change from sedentary village life to regional desertion and nomadization (sheep/camel pastoralists) during the preindustrial era in formerly Ottoman realms, and thereby adds climate change to the multiple causes for Ottoman Empire “decline.”
Absence of hematopoietic tissue factor pathway inhibitor mitigates bleeding in mice with hemophilia
Authors: Maroney Susan A. , Cooley Brian C. , Ferrel Josephine P. , Bonesho Catherine E. , Nielsen Lone V. , Johansen Peter B. , Hermit Mette B. , Petersen Lars C. , Mast Alan E.
Published: February 2012

Tissue factor pathway inhibitor (TFPI) blocks thrombin generation via the extrinsic blood coagulation pathway. Because the severe bleeding in patients with hemophilia occurs from deficiency of intrinsic blood coagulation pathway factor VIII or IX, pharmacological agents that inactivate TFPI and, therefore, restore thrombin generation via the extrinsic pathway, are being developed for treatment of hemophilia. Murine models of combined TFPI and factor VIII deficiency were used to examine the impact of TFPI deficiency on bleeding and clotting in hemophilia. In breeding studies, Factor VIII null (F8
−/−
) did not rescue the embryonic death of TFPI null (Tfpi
−/−
) mice. Tfpi
+/−
did not alter the bleeding phenotype of F8
−/−
mice. However, total inhibition of intravascular TFPI through injection of anti-TFPI antibody mitigated tail vein bleeding. Interestingly, tail blood loss progressively decreased at doses greater than needed to totally inhibit plasma TFPI, suggesting that inhibition of a sequestered pool of TFPI released at the injury site mitigates bleeding. Because TFPI is sequestered within platelets and released following their activation, the function of platelet TFPI was examined in F8
−/−
mice lacking hematopoietic cell TFPI that was generated by fetal liver transplantation. Blood loss after tail transection significantly decreased in Tfpi
+/−
;F8
−/−
mice with hematopoietic Tfpi
−/−
cells compared with Tfpi
+/−
;F8
−/−
mice with Tfpi
+/+
hematopoietic cells. Additionally, following femoral vein injury, Tfpi
+/−
;F8
−/−
mice with Tfpi
−/−
hematopoietic cells had increased fibrin deposition compared with identical-genotype mice with Tfpi
+/+
hematopoietic cells. These findings implicate platelet TFPI as a primary physiological regulator of bleeding in hemophilia.
Aerobic kinetoplastid flagellate
Phytomonas
does not require heme for viability
Authors: Kořený Luděk , Sobotka Roman , Kovářová Julie , Gnipová Anna , Flegontov Pavel , Horváth Anton , Oborník Miroslav , Ayala Francisco J. , Lukeš Julius
Published: February 2012

Heme is an iron-coordinated porphyrin that is universally essential as a protein cofactor for fundamental cellular processes, such as electron transport in the respiratory chain, oxidative stress response, or redox reactions in various metabolic pathways. Parasitic kinetoplastid flagellates represent a rare example of organisms that depend on oxidative metabolism but are heme auxotrophs. Here, we show that heme is fully dispensable for the survival of
Phytomonas serpens
, a plant parasite. Seeking to understand the metabolism of this heme-free eukaryote, we searched for heme-containing proteins in its de novo sequenced genome and examined several cellular processes for which heme has so far been considered indispensable. We found that
P. serpens
lacks most of the known hemoproteins and does not require heme for electron transport in the respiratory chain, protection against oxidative stress, or desaturation of fatty acids. Although heme is still required for the synthesis of ergosterol, its precursor, lanosterol, is instead incorporated into the membranes of
P. serpens
grown in the absence of heme. In conclusion,
P. serpens
is a flagellate with unique metabolic adaptations that allow it to bypass all requirements for heme.
On the centrality and uniqueness of species from the network perspective
Authors: Lai Shu-Mei , Liu Wei-Chung , Jordán Ferenc
Published: February 2012

Identifying important species for maintaining ecosystem functions is a challenge in ecology. Since species are components of food webs, one way to conceptualize and quantify species importance is from a network perspective. The importance of a species can be quantified by measuring the centrality of its position in a food web, because a central node may have greater influence on others in the network. A species may also be important because it has a unique network position, such that its loss cannot be easily compensated. Therefore, for a food web to be robust, we hypothesize that central species must be functionally redundant in terms of their network position. In this paper, we test our hypothesis by analysing the Prince William Sound ecosystem. We found that species centrality and uniqueness are negatively correlated, and such an observation is also carried over to other food webs.
Leaf surface structures enable the endemic Namib desert grass
Stipagrostis sabulicola
to irrigate itself with fog water
Authors: Roth-Nebelsick A. , Ebner M. , Miranda T. , Gottschalk V. , Voigt D. , Gorb S. , Stegmaier T. , Sarsour J. , Linke M. , Konrad W.
Published: February 2012

The Namib grass
Stipagrostis sabulicola
relies, to a large degree, upon fog for its water supply and is able to guide collected water towards the plant base. This directed irrigation of the plant base allows an efficient and rapid uptake of the fog water by the shallow roots. In this contribution, the mechanisms for this directed water flow are analysed.
Stipagrostis sabulicola
has a highly irregular surface. Advancing contact angle is 98° ± 5° and the receding angle is 56° ± 9°, with a mean of both values of approximately 77°. The surface is thus not hydrophobic, shows a substantial contact angle hysteresis and therefore, allows the development of pinned drops of a substantial size. The key factor for the water conduction is the presence of grooves within the leaf surface that run parallel to the long axis of the plant. These grooves provide a guided downslide of drops that have exceeded the maximum size for attachment. It also leads to a minimum of inefficient drop scattering around the plant. The combination of these surface traits together with the tall and upright stature of
S. sabulicola
contributes to a highly efficient natural fog-collecting system that enables this species to thrive in a hyperarid environment.
How host heterogeneity governs tuberculosis reinfection?
Authors: Gomes M. Gabriela M. , Águas Ricardo , Lopes João S. , Nunes Marta C. , Rebelo Carlota , Rodrigues Paula , Struchiner Claudio J.
Published: February 2012

Recurrent episodes of tuberculosis (TB) can be due to relapse of latent infection or exogenous reinfection, and discrimination is crucial for control planning. Molecular genotyping of
Mycobacterium tuberculosis
isolates offers concrete opportunities to measure the relative contribution of reinfection in recurrent disease. Here, a mathematical model of TB transmission is fitted to data from 14 molecular epidemiology studies, enabling the estimation of relevant epidemiological parameters. Meta-analysis reveals that rates of reinfection after successful treatment are higher than rates of new TB, raising an important question about the underlying mechanism. We formulate two alternative mechanisms within our model framework: (i) infection increases susceptibility to reinfection or (ii) infection affects individuals differentially, thereby recruiting high-risk individuals to the group at risk for reinfection. The second mechanism is better supported by the fittings to the data, suggesting that reinfection rates are inflated through a population phenomenon that occurs in the presence of heterogeneity in individual risk of infection. As a result, rates of reinfection are higher when measured at the population level even though they might be lower at the individual level. Finally, differential host recruitment is modulated by transmission intensity, being less pronounced when incidence is high.
Tricarbonyl(η5-formylcyclopentadienyl)manganese(I) and tricarbonyl(η5-formylcyclopentadienyl)rhenium(I) containing short π(CO)...π(CO) and π(CO)...π interactions
Authors: Romanov Alexander S. , Angles Gary F. , Antipin Mikhail Yu. , Timofeeva Tatiana V.
Published: February 2012

The structures of tricarbonyl(formylcyclopentadienyl)manganese(I), [Mn(C6H5O)(CO)3], (I), and tricarbonyl(formylcyclopentadienyl)rhenium(I), [Re(C6H5O)(CO)3], (II), were determined at 100 K. Compounds (I) and (II) both possess a carbonyl group in atransposition relative to the substituted C atom of the cyclopentadienyl ring, while the other two carbonyl groups are in almost eclipsed positions relative to their attached C atoms. Analysis of the intermolecular contacts reveals that the molecules in both compounds form stacks due to short attractive π(CO)...π(CO) and π(CO)...π interactions, along the crystallographiccaxis for (I) and along the [201] direction for (II). Symmetry-related stacks are bound to each other by weak intermolecular C—H...O hydrogen bonds, leading to the formation of the three-dimensional network.
Antimicrobial peptides in the pathogenesis of psoriasis
Authors: MORIZANE Shin , GALLO Richard L.
Published: February 2012

One characteristic abnormality of lesional skin in psoriasis is the excessive production of antimicrobial peptides and proteins (AMPs). AMPs typically are small (12–50 amino acids), have positive charge and amphipathic structure, and are found in all living organisms including mammals, insects, plants and invertebrates. These peptides are best known for their integral role in killing pathogenic microorganisms; however, in vertebrates, they are also capable of modifying host inflammatory responses by a variety of mechanisms. In psoriatic lesions, many AMPs are highly expressed, and especially the associations between psoriasis and cathelicidin, β‐defensins or S100 proteins have been well studied. Among them, a cathelicidin peptide, LL‐37, has been highlighted as a modulator of psoriasis development in recent years. AMPs had been thought to worsen psoriatic lesions but recent evidence has also suggested the possibility that the induction of AMPs expression might improve aspects of the disease. Further investigations are needed to uncover a previously underappreciated role for AMPs in modulating the immune response in psoriasis, and to improve disease without the risks of systemic immunosuppressive approaches.
Shape, variance and integration during craniogenesis: contrasting marsupial and placental mammals
Authors: GOSWAMI A. , POLLY P. D. , MOCK O. B. , SÁNCHEZ‐VILLAGRA M. R.
Published: February 2012

Studies of morphological integration can provide insight into developmental patterns, even in extinct taxa known only from skeletal remains, thus making them an important tool for studies of evolutionary development. However, interpreting patterns of integration and assessing their significance for organismal evolution requires detailed understanding of the developmental interactions that shape integration and how those interactions change through ontogeny. Thus far, relatively little comparative data have been produced for this important topic, and the data that do exist are overwhelmingly from humans and their close relatives or from laboratory models such as mice. Here, we compare data on shape, variance and integration through postnatal ontogeny for a placental mammal, the least shrew,Cryptotis parva, and a marsupial mammal, the gray short‐tailed opossum,Monodelphis domestica. Cranial variance decreased dramatically from early to late ontogeny inCryptotis, but remained stable through ontogeny inMonodelphis, potentially reflecting functional constraints related to the short gestation and early ossification of oral bones in marsupials. BothCryptotisandMonodelphisshowed significant changes in cranial integration through ontogeny, with a mixture of increased, decreased and stable levels of integration in different cranial regions. Of particular note is thatMonodelphisshowed an unambiguous decrease in integration of the oral region through ontogeny, potentially relating to their early ossification. Selection at different stages of development may have markedly different effects if patterns of integration change substantially through ontogeny. Our results suggest that high integration of the oral region combined with functional constraints for suckling during early postnatal ontogeny may drive the stagnant variance observed inMonodelphisand potentially other marsupials.
Charipinae fauna from New Zealand with descriptions of two new species of Alloxysta Förster (Hymenoptera: Cynipoidea: Figitidae: Charipinae)
Authors: Ferrer‐Suay Mar , Paretas‐Martínez Jordi , Selfa Jesús , Pujade‐Villar Juli
Published: February 2012

Biologically, New Zealand is an important country for its high levels of endemism. However, the recorded fauna of Charipinae in this country included only three cosmopolitan species: Alloxysta fuscicornis (Hartig), Alloxysta victrix (Westwood) and Phaenoglyphis villosa (Hartig). Here, we describe the first endemic charipines for New Zealand: Alloxysta rubidus n. sp. and Alloxysta thorpei n. sp. This significantly increases the knowledge of cynipoid diversity in Australasia, where this hymenopteran group is very poorly known. The new species are diagnosed, described, illustrated and information about their hosts and distribution is given. Characters useful to distinguish these species are discussed. A key and distribution map to all species of New Zealand Charipinae is provided.
Motivating and demotivating technical visionaries in large corporations: a comparison of perspectives
Authors: Hebda John M. , Vojak Bruce A. , Griffin Abbie , Price Raymond L.
Published: February 2012

A substantial body of literature addresses the motivation of technical professionals in large corporations. Included are considerations of the motivation of subgroups, such as contrasting the motivation of scientists and engineers. Notably absent, however, is an in‐depth, multiple‐perspective consideration of both the motivation and demotivation of the small number of individuals in nearly every corporation who contribute significantly and disproportionately to the growth and profitability of the corporation. These exceptional, high‐performing technologists, whom we refer to as technical visionaries (TVs), are the drivers of breakthrough, radical innovation. Through 64 in‐depth interviews with TVs, their direct technical managers (TMs) and their human resource managers (HRMs), this research explores the similarities and differences in perception between these three groups concerning TV motivation and demotivation. TMs predominantly apply informal, personalized, and relational management motivating techniques. HRMs predominantly perceive value in the formalized, standard corporate structures and reward systems that serve the ‘typical employee’ for motivating TVs. By comparing the perspectives of TVs, TMs, and HRMs, we observe that the TMs are in strong alignment with TV perspectives on motivation and demotivation, while the HRMs are not in alignment with TV perspectives. Interestingly, both TMs and HRMs emphasize techniques most readily available to them. Most notable relative to demotivating TVs, the HRMs are least able to articulate an understanding consistent with that of the TVs. Based on these and other observations, we offer recommendations for those who manage these critical and unique technical visionaries.
Early procedure‐related complications of fetal blood sampling and intrauterine transfusion for fetal anemia
Authors: JOHNSTONE‐AYLIFFE CARINA , PRIOR TOMAS , ONG CHARAS , REGAN FIONA , KUMAR SAILESH
Published: February 2012

Objective. To review the procedure‐related complication rates following fetal blood sampling and intrauterine red cell transfusion for anaemic fetuses at a single tertiary center. Design. A retrospective study of 114 intrauterine transfusions. Setting. A single tertiary referral fetal medicine center at Queen Charlotte's and Chelsea Hospital, Imperial College London, London, UK. Sample. All cases (114) undergoing fetal blood sampling and intrauterine transfusion between January 2003 and May 2010. Methods. Early procedure‐related complications (severe fetal bradycardia requiring either abandonment of the procedure or emergency delivery, fetal death, preterm labor or rupture of membranes) were investigated by review of computerized records and individual chart review. Main outcome measures. Live birth rate, perinatal mortality, procedure‐related fetal bradycardia, preterm labor and procedure‐related spontaneous rupture of membranes. Results. The majority of cases (77.8%) were due to red cell alloimmunization, with anti‐D being the commonest cause. The live birth rate was 93.5%, with a procedure‐related fetal death rate of 0.9%. The preterm labor rate (<37 weeks’ gestation) was 3.5% only occurring in patients undergoing multiple (>3) fetal transfusions. Complications in this series did not appear to be increased the earlier the gestation at which the first transfusion took place. Conclusions. Despite a reduction in the number of cases requiring intrauterine therapy for fetal anemia, contemporary outcomes appear to be good if not improving. It is important that the experience required to manage these cases should be concentrated in fewer centers to maximize good perinatal outcome.
Institutional shrinkage: The deviant case of Swiss banking secrecy
Authors: Steinlin Simon , Trampusch Christine
Published: February 2012

Using the Mahoney–Thelen causal model one would expect “layering” to be the dominant kind of institutional change affecting Swiss banking secrecy. Our research into governance in Swiss banking shows that it does not fit this theoretical model. Applying deviant case analysis we have refined our understanding of institutional change. We argue that the removal of rules and the momentum of pressure should be acknowledged when explaining variations of institutional change and we suggest that the processes of shrinkage should not be ignored.