bluuebunny/crossref_metadata_2025 huggingface dataset:
Infinite networks and variation of conductance functions in discrete Laplacians
Authors: Jorgensen Palle , Tian Feng
Published: April 2015

For a given infinite connected graph G = (V, E) and an arbitrary but fixed conductance function c, we study an associated graph Laplacian Δc; it is a generalized difference operator where the differences are measured across the edges E in G; and the conductance function c represents the corresponding coefficients. The graph Laplacian (a key tool in the study of infinite networks) acts in an energy Hilbert space ℋE computed from c. Using a certain Parseval frame, we study the spectral theoretic properties of graph Laplacians. In fact, for fixed c, there are two versions of the graph Laplacian, one defined naturally in the l2 space of V and the other in ℋE. The first is automatically selfadjoint, but the second involves a Krein extension. We prove that, as sets, the two spectra are the same, aside from the point 0. The point zero may be in the spectrum of the second, but not the first. We further study the fine structure of the respective spectra as the conductance function varies, showing now how the spectrum changes subject to variations in the function c. Specifically, we study an order on the spectra of the family of operators Δc, and we compare it to the ordering of pairs of conductance functions. We show how point-wise estimates for two conductance functions translate into spectral comparisons for the two corresponding graph Laplacians, involving a certain similarity: We prove that point-wise ordering of two conductance functions c on E induces a certain similarity of the corresponding (Krein extensions computed from the) two graph Laplacians Δc. The spectra are typically continuous, and precise notions of fine-structure of spectrum must be defined in terms of equivalence classes of positive Borel measures (on the real line). Our detailed comparison of spectra is analyzed this way.
An anti-ferroelectric gated Landau transistor to achieve sub-60 mV/dec switching at low voltage and high speed
Authors: Karda Kamal , Jain Ankit , Mouli Chandra , Alam Muhammad Ashraful
Published: April 2015

Landau field effect transistors promise to lower the power-dissipation of integrated circuits (ICs) by reducing the subthreshold swing (S) below the Boltzmann limit of 60 mV/dec. The key idea is to replace the classical gate insulator with dielectrics that exhibit negative capacitance (NC) associated with double-well energy landscape, for example, ferroelectrics (FE), air-gap capacitors, or a combination thereof. Indeed, S is dramatically reduced, constrained only by the limits of hysteresis-free operation. Unfortunately, the following limitations apply (i) the need for capacitance matching constrains steep S only to the small subthreshold region for FE based negative capacitance field effect transistor (NCFET) and requires an insulator too thick for sub-20 nm scaling; (ii) the kinetics of mechanical switching for airgap based NCFET obviate high-speed operation; and (iii) the lattice mismatch between the substrate and the dielectric makes defect-free integration difficult. In this article, we demonstrate that a FET integrated with 10 nm HfO2-based anti-ferroelectric and FE hetero stack would achieve ultralow S with ON-current (Ion) at par with classical transistors at significantly lower voltage and would simplify integration. Our results address the well-known challenges/criticisms of classical Landau transistors, thereby, making them technology relevant for modern ICs.
Demonstration of the stabilization technique for nonplanar optical resonant cavities utilizing polarization
Authors: Akagi T. , Araki S. , Funahashi Y. , Honda Y. , Miyoshi S. , Okugi T. , Omori T. , Shimizu H. , Sakaue K. , Takahashi T. , Tanaka R. , Terunuma N. , Uesugi Y. , Urakawa J. , Washio M. , Yoshitama H.
Published: April 2015

Based on our previously developed scheme to stabilize nonplanar optical resonant cavities utilizing polarization caused by a geometric phase in electromagnetic waves traveling along a twisted path, we report an application of the technique for a cavity installed in the Accelerator Test Facility, a 1.3-GeV electron beam accelerator at KEK, in which photons are generated by laser-Compton scattering. We successfully achieved a power enhancement of 1200 with 1.4% fluctuation, which means that the optical path length of the cavity has been controlled with a precision of 14 pm under an accelerator environment. In addition, polarization switching utilizing a geometric phase of the nonplanar cavity was demonstrated.
Resonance behavior of a charged particle in presence of a time dependent magnetic field
Authors: Ray Somrita , Rano Madhumita , Bag Bidhan Chandra
Published: April 2015

In this article, we have explored the resonance behavior of a particle in the presence of a time dependent magnetic field (TDMF). The particle is bound in a harmonic potential well. Based on the Hamiltonian description of the system in terms of action and angle variables, we have derived the resonance condition for the applied TDMF along z-direction which is valid for arbitrary frequencies along x and y directions of the two dimensional harmonic oscillator. We have also derived resonance condition for the applied magnetic field which is lying in a plane. Finally, we have explored resonance condition for the isotropic magnetic field. To check the validity of the theoretical calculation, we have solved equations of motion numerically for the parameter sets which satisfy the derived resonance condition. The numerical experiment fully agrees with the theoretically derived resonance conditions.
The transverse magnetic field effect on steady-state solutions of the Bursian diode
Authors: Pramanik Sourav , Ender A. Ya. , Kuznetsov V. I. , Chakrabarti Nikhil
Published: April 2015

A study of steady-states of a planar vacuum diode driven by a cold electron beam (the Bursian diode) under an external transverse magnetic field is presented. The regime of no electrons turned around by a magnetic field only is under the consideration. The emitter electric field is evaluated as a characteristic function for the existence of solutions depending on the diode length, the applied voltage, and the magnetic field strength. At certain conditions, it is shown that a region of non-unique solutions exists in the Bursian diode when the magnetic field is absent. An expression for the maximum current transmitted through the diode is derived. The external magnetic field is put forth to control fast electronic switches based on the Bursian diode.
On the self-excitation mechanisms of plasma series resonance oscillations in single- and multi-frequency capacitive discharges
Authors: Schüngel Edmund , Brandt Steven , Korolov Ihor , Derzsi Aranka , Donkó Zoltán , Schulze Julian
Published: April 2015

The self-excitation of plasma series resonance (PSR) oscillations is a prominent feature in the current of low pressure capacitive radio frequency discharges. This resonance leads to high frequency oscillations of the charge in the sheaths and enhances electron heating. Up to now, the phenomenon has only been observed in asymmetric discharges. There, the nonlinearity in the voltage balance, which is necessary for the self-excitation of resonance oscillations with frequencies above the applied frequencies, is caused predominantly by the quadratic contribution to the charge-voltage relation of the plasma sheaths. Using Particle In Cell/Monte Carlo collision simulations of single- and multi-frequency capacitive discharges and an equivalent circuit model, we demonstrate that other mechanisms, such as a cubic contribution to the charge-voltage relation of the plasma sheaths and the time dependent bulk electron plasma frequency, can cause the self-excitation of PSR oscillations, as well. These mechanisms have been neglected in previous models, but are important for the theoretical description of the current in symmetric or weakly asymmetric discharges.
Note: A silicon-on-insulator microelectromechanical systems probe scanner for on-chip atomic force microscopy
Authors: Fowler Anthony G. , Maroufi Mohammad , Moheimani S. O. Reza
Published: April 2015

A new microelectromechanical systems-based 2-degree-of-freedom (DoF) scanner with an integrated cantilever for on-chip atomic force microscopy (AFM) is presented. The silicon cantilever features a layer of piezoelectric material to facilitate its use for tapping mode AFM and enable simultaneous deflection sensing. Electrostatic actuators and electrothermal sensors are used to accurately position the cantilever within the x-y plane. Experimental testing shows that the cantilever is able to be scanned over a 10 μm × 10 μm window and that the cantilever achieves a peak-to-peak deflection greater than 400 nm when excited at its resonance frequency of approximately 62 kHz.
On the interplay between the slowdown of dynamics and the kinetics of aggregation: The case study of a reactive binary mixture
Authors: Mereu Isabella , Liotta Andrea , Comez Lucia , Corezzi Silvia
Published: April 2015

Modeling the kinetics of aggregation requires a proper strategy to take into account not only the reactivity of reagents but also the ability they have to diffuse. The lack of direct information about diffusion represents the most serious experimental obstacle to the use of diffusion-corrected mean-field equations, which is usually overcome by using information on the structural relaxation dynamics. A very accurate description of the entire kinetics of aggregation can be made by introducing a single time scale of diffusion, set by the structural relaxation time τ of the system according to ∼τξ, with ξ a fractional exponent. Here, we apply this modeling to the case of a reactive binary mixture made of diglycidyl ether of bisphenol-A and 1,3-phenylenediamine, where the reaction proceeds along an autocatalyic (hydroxyl catalyzed) and a non-catalytic (impurity catalyzed) pathway and find that a very small value of the exponent ξ = 0.27 ± 0.03 is needed to reproduce all the data. Our results help revise some preconceived ideas: contrary to widely held assumptions, we find that (i) the time scale of diffusion neither increases proportionally to the structural relaxation time nor is related to τ by a power law with the same fractional exponent as that relating τ to conductivity; (ii) no direct connection exists between the transition to diffusion-control and the development of a gel network or formation of a glassy phase; and (iii) there is no significant difference in the enthalpy barrier for bond formation in the presence of hydroxyl or other than hydroxyl catalyst groups.
A design and optimization method for matching the torque of the wind turbines
Authors: Al-Abadi Ali , Ertunç Özgür , Weber Horst , Delgado Antonio
Published: April 2015

An aerodynamic shape optimization method for a horizontal axis wind turbine is developed and verified through experimentation with a laboratory-scale wind turbine. Our method is based on matching the rotor's and the coupled generator's torque. Prior to shape optimization, an initial rotor design is established with a hybrid use of Schmitz and blade element momentum theories. The experimental verification of the developed method is conducted with a small-scale wind turbine; thus, the operating Reynolds number is one order of magnitude lower than large-scale wind turbines. Therefore, a high-lift low-Re airfoil, namely, SG6043, is selected for the blade along the whole span. The shape is optimized by determining the optimum chord and cumulative pitch angle distributions by manipulating the tapering and twisting of the blade. The objective of the optimization is to maximize the turbine's power coefficient Cp, while maintaining the torque equal to that of the generator. The generator's characteristics are found through experimentations which are conducted apart from the wind tunnel experiments. During the optimization process, the local aerodynamic forces on the blade are calculated by interfacing the optimization program with XFOIL; thus, the torque and power can be calculated for the rotor at each iteration step. The optimized turbine performance is evaluated under a design and off-design operating condition. The performance verification experiments are carried out in the wind tunnel with a specially designed setup. A comparison of the measured and computed performance shows good agreement.
Disappearance of electron-hole asymmetry in nanoparticles of Nd1−xCaxMnO3(x=0.6,0.4): magnetization and electron paramagnetic resonance evidence
Authors: Bhagyashree K. S. , Bhat S. V.
Published: April 2015

We study and compare magnetic and electron paramagnetic resonance behaviors of bulk and nanoparticles of Nd1−xCaxMnO3 in hole doped (x=0.4;NCMOH) and electron doped (x=0.6;NCMOE) samples. NCMOH in bulk form shows a complex temperature dependence of magnetization M(T), with a charge ordering transition at ∼250 K, an antiferromagnetic (AFM) transition at ∼150 K, and a transition to a canted AFM phase/mixed phase at ∼80 K. Bulk NCMOE behaves quite differently with just a charge ordering transition at ∼280 K, thus providing a striking example of the so called electron-hole asymmetry. While our magnetization data on bulk samples are consistent with the earlier reports, the new results on the nanoparticles bring out drastic effects of size reduction. They show that M(T) behaviors of the two nanosamples are essentially similar in addition to the absence of the charge order in them thus providing strong evidence for vanishing of the electron-hole asymmetry in nanomanganites. This conclusion is further corroborated by electron paramagnetic resonance studies which show that the large difference in the “g” values and their temperature dependences found for the two bulk samples disappears as they approach a common behavior in the corresponding nanosamples.
Towards direct realisation of the SI unit of sound pressure in the audible hearing range based on optical free-field acoustic particle measurements
Authors: Koukoulas Triantafillos , Piper Ben
Published: April 2015

Since the introduction of the International System of Units (the SI system) in 1960, weights, measures, standardised approaches, procedures, and protocols have been introduced, adapted, and extensively used. A major international effort and activity concentrate on the definition and traceability of the seven base SI units in terms of fundamental constants, and consequently those units that are derived from the base units. In airborne acoustical metrology and for the audible range of frequencies up to 20 kHz, the SI unit of sound pressure, the pascal, is realised indirectly and without any knowledge or measurement of the sound field. Though the principle of reciprocity was originally formulated by Lord Rayleigh nearly two centuries ago, it was devised in the 1940s and eventually became a calibration standard in the 1960s; however, it can only accommodate a limited number of acoustic sensors of specific types and dimensions. International standards determine the device sensitivity either through coupler or through free-field reciprocity but rely on the continuous availability of specific acoustical artefacts. Here, we show an optical method based on gated photon correlation spectroscopy that can measure sound pressures directly and absolutely in fully anechoic conditions, remotely, and without disturbing the propagating sound field. It neither relies on the availability or performance of any measurement artefact nor makes any assumptions of the device geometry and sound field characteristics. Most importantly, the required units of sound pressure and microphone sensitivity may now be experimentally realised, thus providing direct traceability to SI base units.
High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum
Authors: Amendt Peter , Ho Darwin D. , Jones Ogden S.
Published: April 2015

A recent low gas-fill density (0.6 mg/cc 4He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc 4He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.
Communication: SHG-detected circular dichroism imaging using orthogonal phase-locked laser pulses
Authors: Jarrett Jeremy W. , Liu Xiaoying , Nealey Paul F. , Vaia Richard A. , Cerullo Giulio , Knappenberger Kenneth L.
Published: April 2015

We demonstrate a novel method for second harmonic generation-detected circular dichroism (CD) imaging based on the use of phase-locked, temporally delayed femtosecond laser pulses. The polarization state of the fundamental wave was controllably changed over 2π rad by using a birefringent delay line, which provided attosecond inter-pulse delays for orthogonal phase-locked replicas; the achievable phase stability was 14 as. By introducing either a positive or negative delay of ∼667 as, we induced a ±π/2 phase shift between the orthogonally polarized pulses, resulting in left circularly polarized or right circularly polarized light. CD imaging performance using the pulse sequence was compared to results obtained for plasmonic nanoantennas using a rotating quarter-wave plate. The pulse sequence is expected to simplify polarization-resolved optical imaging by reducing experimental artifacts and decreasing image acquisition times. This method can be easily extended to other CD spectroscopy measurements.
Surface strain mediated dipole alignment of ClAlPc on Au(111)
Authors: Niu Tianchao
Published: April 2015

In this letter, we demonstrate the control of dipole alignment of monolayer chloroaluminum phthalocyanine (ClAlPc) molecules via the strain in Au(111) substrates. Local ordering of ClAlPc dipole comprising alternate Cl-up and Cl-down configurations is found on the tensile-strained Au(111)/mica as a result of strain-enhanced absorption of Cl-down ClAlPc's and the dipole-dipole interaction. In contrast, the strain-released single crystal Au(111) substrate shows negligible coupling to Cl-down ClAlPc, therefore, facilitating the formation of unidirectionally aligned Cl-up ClAlPc dipole array. The dipole-dipole interaction becomes less prominent at low ClAlPc coverage where ClAlPc molecules can find their favorable absorption sites more easily according to their inherent dipole orientation. Our results emphasize the superior role of molecule-substrate interaction in functional molecular engineering on metal surface hence provide fundamental insight into the potential applications in molecular nanodevices with tunable and controllable properties.
Idealism and Materialism in Perception
Authors: Rose David , Brown Dora
Published: April 2015

Koenderink (2014, Perception, 43, 1–6) has said most Perception readers are deluded, because they believe an ‘All Seeing Eye’ observes an objective reality. We trace the source of Koenderink's assertion to his metaphysical idealism, and point to two major weaknesses in his position—namely, its dualism and foundationalism. We counter with arguments from modern philosophy of science for the existence of an objective material reality, contrast Koenderink's enactivism to his idealism, and point to ways in which phenomenology and cognitive science are complementary and not mutually exclusive.
Testing the Mechanisms Underlying Improved Distance Judgments in Virtual Environments
Authors: Kunz Benjamin R , Creem-Regehr Sarah H , Thompson William B
Published: April 2015

Virtual environments (VEs) presented via head-mounted displays are typically perceived as smaller in scale than intended. Visual–motor experience in VEs can reduce this underestimation of distance, though the mechanisms underlying this improved accuracy of distance estimates are unknown. To address this question, we created a mismatch between biomechanical and visual indicators of self-movement within the VE, and assessed the effect on distance and size judgments. Our results suggest that visual–motor feedback influences subsequent distance judgments by recalibrating perceptual–motor relationships, but we found no evidence that perceived size, which was substantially underestimated, changed as a function of this feedback. In contrast to recent studies that suggest that feedback in VEs causes a broad rescaling of virtual space, our results are consistent with a visual–motor recalibration account for much of the improvement in distance judgments following VE experience.
Synthesis and Properties of Novel Borondipyrromethene (BODIPY)-Tethered Triphenylamine Conjugates
Authors: Wang Yucai , Liao Junxu , Wang Bangying , Chen Hongbiao , Zhao Hongbin , Peng Min , Fan Sujuan
Published: April 2015

A series of novel donor–acceptor type borondipyrromethene (BODIPY)-tethered triphenylamine conjugates (BDP4–8) containing one or two BODIPY cores attached to a triphenylamine scaffold at the 4- or 4,4′- positions were successfully synthesised via a mild and effective protocol. Their photophysical and electrochemical properties were investigated. The absorption spectra indicated that the meso-substituted BODIPY with triphenylamine did not give rise to an intense intramolecular charge transfer (ICT) and did not effectively extend the conjugated length compared with substitution at the 2,6- and 3,5-positions as previously reported. It is worth noticing that the asymmetric mono-BODIPY-tethered triphenylamine conjugates (BDP5, BDP7) showed an electronic distribution imbalance due to the special 3D propeller shape of triphenylamine resulting in twisted molecular space configurations. In contrast, the symmetric bis-BODIPY-tethered triphenylamine conjugates (BDP4, BDP6, and BDP8) exhibited a balanced electronic distribution. The photoluminescence spectra of these conjugates exhibited significant Stokes shifts (5300–6700 cm–1), which caused fluorescence emission spectra in near-infrared regions. Cyclic voltammograms reveal that the asymmetric mono-BODIPY-tethered triphenylamine conjugates (BDP5, BDP7) have higher LUMO energy levels and lower HOMO energy levels, thus resulting in larger bandgaps than the bis-BODIPY-tethered triphenylamine ones.
Formation of polyaromatic hydrocarbon (PAH)-quinones during the gas phase reactions of PAHs with the OH radical in the atmosphere
Authors: Lee Ji Yi , Lane Douglas A. , Kim Yong Pyo
Published: April 2015

Environmental context
Atmospheric quinones present a potential toxic risk to human health because of their involvement in the generation of reactive oxygen species. Gas phase reactions of naphthalene and phenanthrene with the OH radical are investigated in a laboratory reaction chamber to provide a preliminary assessment of the importance of the atmospheric formation of quinones.

Abstract
In light of the potential toxicity of quinones (QNs) to human health, previous studies carried out measurement of QNs in ambient air samples and from motor vehicle emissions to understand the characteristics and the sources of QNs in the atmosphere. The major compounds observed in the ambient air samples comprised two and three benzene rings and included polyaromatic hydrocarbon (PAH)-quinones (PAH-QNs) such as 1,2-naphthoquinone (1,2-NQ), 1,4-naphthoquinone (1,4-NQ), 9,10-phenanthrenequinone (9,10-PQ) and 9,10-anthraquinone (9,10-AQ). Although these PAH-QNs are found in vehicular emissions, they may also be formed by the photochemical reactions of gas phase PAHs with atmospheric oxidants. In this study, to allow an assessment of the importance of the atmospheric formation of PAH-QNs and to understand more clearly the sources of PAH-QNs in the atmosphere, the formation yields of PAH-QNs from the gas phase reactions of naphthalene and phenanthrene with the OH radical were observed in a laboratory reaction chamber. In addition, the phase distribution of the PAH-QNs was determined. For naphthoquinones (NQs), the formation yields of 1,4-NQ and 1,2-NQ were 1.5±0.4 and 5.1±2.7% respectively. The measured yields of PQs were 3.6±0.8% for 9,10-PQ and 2.7±1.1% for 1,4-PQ. From the measured yield data, the atmospheric formation of PAH-QNs was estimated and the importance of the atmospheric formation of PAH-QNs from the gas phase reaction of PAHs with the OH radical is discussed.
Cold-blooded indifference: a case study of the worsening status of threatened reptiles from Victoria, Australia
Authors: Clemann Nick
Published: April 2015

For the first time in the history of life, a biodiversity extinction crisis is being driven by a single species – humans. Humans also have unprecedented control over both the threats and conservation actions that influence this crisis. When prioritising conservation actions, innate human bias often favours endothermic vertebrates over other fauna. Reptiles are the least popular terrestrial vertebrate class, and consequently are particularly disadvantaged in terms of being listed as threatened and receiving conservation management. Despite 30 years of formally evaluating and listing threatened vertebrates in the Australian State of Victoria, there is a strong worsening trend in the conservation status of all faunal groups. The deteriorating status of Victorian reptiles mirrors worrying documented trends in reptile conservation status around the world. I review the history of listing threatened reptiles in Victoria, detail worsening trends in their conservation status, and suggest that, as in other parts of the world, the threats common to most listed taxa are climate change, habitat loss and degradation, and elevated rates of predation by exotic predators. I also identify poor advice and planning as a considerable threat to Victorian reptiles; this threat is rarely reported, but may be more pervasive than currently recognised. I argue that what is needed for most reptiles to have the greatest chance of persisting in the long term is prevention of habitat loss and degradation, research to underpin listing and management, improved policy so that unproven management strategies are not sanctioned, and vetting of consultant’s reports so that unproven ‘mitigation’ strategies and inadequate preimpact surveys do not mask the true cost of loss and degradation of habitat.
Determinants of bird assemblage composition in riparian vegetation on sugarcane farms in the Queensland Wet Tropics
Authors: Keir Anita F. , Pearson Richard G. , Congdon Robert A.
Published: April 2015

Remnant habitat patches in agricultural landscapes can contribute substantially to wildlife conservation. Understanding the main habitat variables that influence wildlife is important if these remnants are to be appropriately managed. We investigated relationships between the bird assemblages and characteristics of remnant riparian forest at 27 sites among sugarcane fields in the Queensland Wet Tropics bioregion. Sites within the remnant riparian zone had distinctly different bird assemblages from those of the forest, but provided habitat for many forest and generalist species. Width of the riparian vegetation and distance from source forest were the most important factors in explaining the bird assemblages in these remnant ribbons of vegetation. Gradual changes in assemblage composition occurred with increasing distance from source forest, with species of rainforest and dense vegetation being replaced by species of more open habitats, although increasing distance was confounded by decreasing riparian width. Species richness increased with width of the riparian zone, with high richness at the wide sites due to a mixture of open-habitat species typical of narrower sites and rainforest species typical of sites within intact forest, as a result of the greater similarity in vegetation characteristics between wide sites and the forest proper. The results demonstrate the habitat value for birds of remnant riparian vegetation in an agricultural landscape, supporting edge and open vegetation species with even narrow widths, but requiring substantial width (>90 m) to support specialists of the closed forest, the dominant original vegetation of the area.
Changes in lysosomal enzymes and mannose-6-phosphate receptors related to sexual maturation in bull epididymis
Authors: Aguilera Andrea C. , Carvelli Lorena , Boschin Verónica , Mohamed Fabián , Zyla Leila , Sosa Miguel A.
Published: April 2015

One of the most striking features of the mammalian epididymis is the secretion of lysosomal enzymes (LE). These LE may play a role in sperm maturation. In the present study we investigated the activity and distribution of four LE (β-galactosidase (β-Gal), N-acetyl-β-D-glucosaminidase (β-NAG), α-mannosidase (α-Man) and β-glucuronidase (β-Glu)) in bull epididymis at two different ages (6 months and 4 years) to determine whether these enzymes vary with sexual maturity. In young, sexually immature (SI) bulls we found high LE activity in the epididymal tissue that accounts for a developed and active lysosomal apparatus. In contrast, low LE activity was measured in sexually mature (SM) bulls, and β-NAG and β-Gal were mostly secreted into the lumen. We also attempted to correlate LE distribution with the expression and functionality of mannose-6-phosphate receptors (MPRs), which are thought to be involved in proper delivery of LE to lysosomes. The cation-dependent MPR was highly expressed in SI bulls, with expression decreasing during adulthood, whereas the expression of the cation-independent MPR was higher in SM than SI bulls. In addition, the four enzymes recovered from the epididymal lumen interact with both MPRs at each age. We conclude that the activity and distribution of LE in bull epididymis varies with sexual maturity and that the distribution is regulated differently by the two types of MPR. These findings could provide some molecular basis for male infertility.
MicroSort® sperm sorting causes no increase in major malformation rate
Authors: Marazzo Donald P. , Karabinus David , Johnson Lawrence A. , Schulman Joseph D.
Published: April 2015

The purpose of the present study was to evaluate the safety of MicroSort (MicroSort Division, GIVF, Fairfax, VA, USA) sperm sorting by monitoring major malformations in infants and fetuses conceived using sorted spermatozoa. Data were collected in a prospective protocol with monitoring that began from conception through birth until 1 year of life. Comprehensive ascertainment identified fetuses and stillbirths with malformations after 16 weeks gestation, pregnancies terminated for malformations and babies with major malformations. Outcomes in MicroSort pregnancies were compared with outcomes in published studies that used active and comprehensive ascertainment of malformations in the general population and in pregnancies established after assisted reproduction. Using comprehensive outcomes from all pregnancies, the rate of major malformations in MicroSort pregnancies conceived after IVF with or without intracytoplasmic sperm injection was 7.8%; this did not differ significantly from the rates reported in the three assisted reproductive technology control studies not associated with MicroSort (8.6%, 9.2% and 8.3%). Similarly, the rate of major malformations in MicroSort pregnancies initiated with intrauterine insemination was 6.0%, not significantly different from that reported in non-assisted reproductive technology pregnancies not associated with MicroSort (6.9%, 4.6% and 5.7%). Prospective record review of pregnancy outcomes and paediatric evaluation to 1 year indicate no association between MicroSort sperm sorting and major malformations.
Maternal and congenital syphilis in selected Latin America and Caribbean countries: a multi-country analysis using data from the Perinatal Information System
Authors: Serruya Suzanne J. , Duran Pablo , Martinez Gerardo , Romero Mario , Caffe Sonja , Alonso Monica , Silveira Mariangela F.
Published: April 2015

Background
Maternal syphilis has an important impact on reproductive health. In 2010, World Health Organization (WHO)/Pan American Health Organization (PAHO) member countries approved the Strategy and Plan of Action for Elimination of Mother-to-Child Transmission of HIV and Congenital Syphilis in the Americas by 2015. This paper aims to describe epidemiological and programmatic characteristics related to maternal and congenital syphilis in selected countries of Latin America and Caribbean for the period 2010–12. Methods: The report is based on a multi-country, quantitative and qualitative analysis from data collected from several sources, representing a compilation of country reports from nine countries as part of the 2012 mid-term evaluation of the Strategy. Data was collected based on standardised procedures at country level. Results: Results are variable among countries. All countries have a strategic national plan to eliminate congenital syphilis, with some distinct characteristics for each country. Protocols and guidelines for the management and treatment of maternal and congenital syphilis in all countries were updated between 2011 and 2013. A high rate of missing information for all countries for some indicators was noticed. Conclusions: The main limitation of the analyses is the huge amount of missing data. Countries must continue to be supported to build capacity for collecting high-quality data on intervention coverage and inequities, and to use it as a basis for decisions about how best to reach women and children with interventions. A high level political commitment is necessary to put into practice the Regional Initiative to Eliminate Congenital Syphilis, with the support of Health Ministries.
Biology in the Anthropocene: Challenges and insights from young fossil records
Authors: Kidwell Susan M.
Published: April 2015

With overwhelming evidence of change in habitats, biologists today must assume that few, if any, study areas are natural and that biological variability is superimposed on trends rather than stationary means. Paleobiological data from the youngest sedimentary record, including death assemblages actively accumulating on modern land surfaces and seabeds, provide unique information on the status of present-day species, communities, and biomes over the last few decades to millennia and on their responses to natural and anthropogenic environmental change. Key advances have established the accuracy and resolving power of paleobiological information derived from naturally preserved remains and of proxy evidence for environmental conditions and sample age so that fossil data can both implicate and exonerate human stressors as the drivers of biotic change and permit the effects of multiple stressors to be disentangled. Legacy effects from Industrial and even pre-Industrial anthropogenic extirpations, introductions, (de)nutrification, and habitat conversion commonly emerge as the primary factors underlying the present-day status of populations and communities; within the last 2 million years, climate change has rarely been sufficient to drive major extinction pulses absent other human pressures, which are now manifold. Young fossil records also provide rigorous access to the baseline composition and dynamics of modern-day biota under pre-Industrial conditions, where insights include the millennial-scale persistence of community structures, the dominant role of physical environmental conditions rather than biotic interactions in determining community composition and disassembly, and the existence of naturally alternating states.
Simple versus complex models of trait evolution and stasis as a response to environmental change
Authors: Hunt Gene , Hopkins Melanie J. , Lidgard Scott
Published: April 2015

Significance

Paleontologists have long argued about what the fossil record call tell us about how species evolve over long periods. Simple models such as stasis and random walks have been used to explore evolutionary patterns, but these have not always adequately captured the ways in which traits change over time in fossil species. Here we find that models with complex evolutionary dynamics are often favored, especially for fossil series that sample many populations, suggesting that the underlying evolutionary reality is likely more complex than represented by simplified—though still useful—models of trait change.
Organogenesis in deep time: A problem in genomics, development, and paleontology
Authors: Pieretti Joyce , Gehrke Andrew R. , Schneider Igor , Adachi Noritaka , Nakamura Tetsuya , Shubin Neil H.
Published: April 2015

Significance

Phylogenetic data inclusive of rich paleontological records can be used to inform hypotheses on evolutionary transformations. These data, when combined with developmental studies and functional genomic assays in model and nonmodel organisms, expand our understanding of the evolutionary processes that build and pattern the vertebrate body plan. Here, we highlight a direction of the fossil record, one of “experimental paleontology,” where morphological transformations inferred from the fossil record can be experimentally assayed in the lab. With the addition of genomic techniques to test hypotheses, researchers can now begin to explore genomic states that have influenced both past and present morphological diversity.
Syringyl lignin production in conifers: Proof of concept in a Pine tracheary element system
Authors: Wagner Armin , Tobimatsu Yuki , Phillips Lorelle , Flint Heather , Geddes Barbara , Lu Fachuang , Ralph John
Published: April 2015

Significance

This study shows that metabolic engineering can be used to imbue pine tracheary elements with an ability to synthesize sinapyl alcohol, a lignin monomer not normally used for lignification in conifers such as pine. The dynamic nature of the lignification process enables pines to incorporate this monolignol, allowing them to produce hardwood-like lignins that are known to facilitate refining processes such as biofuel production and chemical pulping. The potential to improve the refining of conifer-derived biomass through lignin manipulations is important, as even small improvements in yield can lead to significant environmental and economic benefits in such processes.
Highly polarized C-terminal transition state of the leucine-rich repeat domain of PP32 is governed by local stability
Authors: Dao Thuy Phuong , Majumdar Ananya , Barrick Doug
Published: April 2015

Significance

Proteins fold to their native structure in significantly shorter timescales than expected for a random search mechanism. Rapid folding, which is likely to be important to optimize yield and avoid misfolded, aggregated states, has been proposed to result from specific folding pathways. However, mapping such pathways and understanding the principles by which they are selected remain central problems in protein science. Repeat proteins, containing tandem repeated structural units, greatly simplify folding studies. Here, we exploit the linear architecture of a β-strand-containing leucine-rich repeat protein and discover that folding is highly polarized toward the C terminus. By measuring the energy distribution, we observe that polarization is guided by local stability.
Geologic carbon storage is unlikely to trigger large earthquakes and reactivate faults through which CO2could leak
Authors: Vilarrasa Victor , Carrera Jesus
Published: April 2015

Significance

Geologic carbon storage remains a safe option to mitigate anthropogenic climate change. Properly sited and managed storage sites are unlikely to induce felt seismicity because (i) sedimentary formations, which are softer than the crystalline basement, are rarely critically stressed; (ii) the least stable situation occurs at the beginning of injection, which makes it easy to control; (iii) CO2will dissolve into brine at a significant rate, reducing overpressure; and (iv) CO2will not flow across the caprock because of capillarity, but brine will, which will reduce overpressure further. Furthermore, CO2leakage through fault reactivation is unlikely because the high clay content of caprocks ensures a reduced permeability and increased entry pressure along localized deformation zones.
Declining vulnerability to river floods and the global benefits of adaptation
Authors: Jongman Brenden , Winsemius Hessel C. , Aerts Jeroen C. J. H. , Coughlan de Perez Erin , van Aalst Maarten K. , Kron Wolfgang , Ward Philip J.
Published: April 2015

Significance

Understanding the vulnerability of societies around the world is crucial for understanding historical trends in flood risk and for producing accurate projections of fatalities and losses. We reproduced historical river flood occurrence using daily climate data for the period 1980–2010 and quantified the natural and socioeconomic contributions to flood risk trends. We show that the fatalities and losses as a share of the exposed population and gross domestic product are decreasing with rising income. We also show that there is a tendency of convergence in vulnerability levels between low- and high-income countries. Projections based on a wide range of climate change and socioeconomic development scenarios demonstrate that amplified adaptation efforts have the potential to largely contain losses from future floods.
Buried ionizable networks are an ancient hallmark of G protein-coupled receptor activation
Authors: Isom Daniel G. , Dohlman Henrik G.
Published: April 2015

Significance

In the early 1980s, scientists began searching for cell-surface receptors that bind to hormones and neurotransmitters. Among the first was the β-adrenergic receptor, a G protein-coupled receptor (GPCR) that is activated by norepinephrine and epinephrine. Recent breakthroughs have provided more than 100 new GPCR structures, including several in activated conformations. This new structural information presents an opportunity to identify features that distinguish unactivated and activated receptors. Here we use a computational approach to identify structural signatures unique to activated GPCRs. Remarkably, we find that these signatures also are present in distantly related receptors from archaea and bacteria. We propose that these new structural indicators are central to GPCR function and are indicative of GPCR activation.
On the factors that promote the diversity of herbivorous insects and plants in tropical forests
Authors: Becerra Judith X.
Published: April 2015

Significance

A central mission in ecology has been to explain differences in biodiversity across the world and across groups of organisms. This knowledge is not only fundamental as a scientific objective but also for practical issues of major concern to humankind. Plants and phytophagous insects comprise the highest macroscopic diversity on Earth, making it particularly important to know the mechanisms that allow their species to coexist. This study suggests that without insect specialization the maintenance of tropical plant diversity might not be possible. Also, without high divergence of defenses among plants, insect tropical diversity may not persist either.
Enhancing the antitumor efficacy of a cell-surface death ligand by covalent membrane display
Authors: Nair Pradeep M. , Flores Heather , Gogineni Alvin , Marsters Scot , Lawrence David A. , Kelley Robert F. , Ngu Hai , Sagolla Meredith , Komuves Laszlo , Bourgon Richard , Settleman Jeffrey , Ashkenazi Avi
Published: April 2015

Significance

A recombinant soluble version of the transmembrane death ligand Apo2L/TRAIL has shown compelling preclinical results as a potential cancer therapeutic, but studies in cancer patients have demonstrated little efficacy. Supported membrane display of Apo2L/TRAIL, to mimic the endogenous ligand more faithfully, markedly augments receptor clustering and apoptosis stimulation in cancer cells. Covalent attachment of Apo2L/TRAIL to the surface of liposomes offers a therapeutically tractable approach to membrane display that substantially increases tumor exposure, caspase activation, and antitumor potency. These findings open new avenues for clinical investigation of Apo2L/TRAIL as a cancer therapeutic and may apply to other members of the TNF superfamily, such as FasL and CD70, which are expressed on immune-cell surfaces and are important candidates for cancer immunotherapy.
Large-area formation of self-aligned crystalline domains of organic semiconductors on transistor channels using CONNECT
Authors: Park Steve , Giri Gaurav , Shaw Leo , Pitner Gregory , Ha Jewook , Koo Ja Hoon , Gu Xiaodan , Park Joonsuk , Lee Tae Hoon , Nam Ji Hyun , Hong Yongtaek , Bao Zhenan
Published: April 2015

Significance

Solution-processed organic electronics are expected to pave the way for low-cost large-area electronics with new and exciting applications. However, realizing solution-processed organic electronics requires densely packed transistors with patterned and precisely registered organic semiconductors (OSCs) within the transistor channel with uniform electrical properties over a large area, a task that remains a significant challenge. To address such a challenge, we have developed an innovative technique that generates self-patterned and self-registered OSC film with low variability in electrical properties over a large area. We have fabricated highest density of transistors with a yield of 99%, along with various logic circuits. This work significantly advances organic electronics field to enable large-scale circuit fabrication in a facile and economical manner.
Continental-scale distributions of dust-associated bacteria and fungi
Authors: Barberán Albert , Ladau Joshua , Leff Jonathan W. , Pollard Katherine S. , Menninger Holly L. , Dunn Robert R. , Fierer Noah
Published: April 2015

Significance

We inhale thousands of microbial cells when we breathe in outdoor air, and some of these airborne microbes can serve as pathogens or triggers of allergic disorders. Using settled dust samples from ∼1,200 locations, we generated the first atlas, to our knowledge, of airborne bacterial and fungal distributions across the continental United States. We found that airborne microbial communities, such as terrestrial plants and animals, exhibit nonrandom geographic patterns, and we identified the factors that shape the continental-scale distributions of microbial taxa. Furthermore, we found that the airborne microbes found in urban and more rural areas are not distinct in composition, but the dust-associated communities found in more urbanized areas are more homogeneous across the United States.
Genomic perspectives on the birth and spread of plastids
Authors: Archibald John M.
Published: April 2015

The endosymbiotic origin of plastids from cyanobacteria was a landmark event in the history of eukaryotic life. Subsequent to the evolution of primary plastids, photosynthesis spread from red and green algae to unrelated eukaryotes by secondary and tertiary endosymbiosis. Although the movement of cyanobacterial genes from endosymbiont to host is well studied, less is known about the migration of eukaryotic genes from one nucleus to the other in the context of serial endosymbiosis. Here I explore the magnitude and potential impact of nucleus-to-nucleus endosymbiotic gene transfer in the evolution of complex algae, and the extent to which such transfers compromise our ability to infer the deep structure of the eukaryotic tree of life. In addition to endosymbiotic gene transfer, horizontal gene transfer events occurring before, during, and after endosymbioses further confound our efforts to reconstruct the ancient mergers that forged multiple lines of photosynthetic microbial eukaryotes.