bluuebunny/crossref_metadata_2025 huggingface dataset:
Salicylic and jasmonic acid pathways are necessary for defence against Dickeya solani as revealed by a novel method for Blackleg disease screening of in vitro grown potato
Authors: Burra D. D. , Mühlenbock P. , Andreasson E.
Published: April 2015

Potato is major crop ensuring food security in Europe, and blackleg disease is increasingly causing losses in yield and during storage. Recently, one blackleg pathogen, Dickeya solani has been shown to be spreading in Northern Europe that causes aggressive disease development. Currently, identification of tolerant commercial potato varieties has been unsuccessful; this is confounded by the complicated etiology of the disease and a strong environmental influence on disease development. There is currently a lack of efficient testing systems. Here, we describe a system for quantification of blackleg symptoms on shoots of sterile in vitro potato plants, which saves time and space compared to greenhouse and existing field assays. We found no evidence for differences in infection between the described in vitro‐based screening method and existing greenhouse assays. This system facilitates efficient screening of blackleg disease response of potato plants independent of other microorganisms and variable environmental conditions. We therefore used the in vitro screening method to increase understanding of plant mechanisms involved in blackleg disease development by analysing disease response of hormone‐ related (salicylic and jasmonic acid) transgenic potato plants. We show that both jasmonic (JA) and salicylic (SA) acid pathways regulate tolerance to blackleg disease in potato, a result unlike previous findings in Arabidopsis defence response to necrotrophic bacteria. We confirm this by showing induction of a SA marker, pathogenesis‐related protein 1 (StPR1), and a JA marker, lipoxygenase (StLOX), in Dickeya solani infected in vitro potato plants. We also observed that tubers of transgenic potato plants were more susceptible to soft rot compared to wild type, suggesting a role for SA and JA pathways in general tolerance to Dickeya.
Stress memory induced transcriptional and metabolic changes of perennial ryegrass (Lolium perenne) in response to salt stress
Authors: Hu Tao , Jin Yupei , Li Huiying , Amombo Erick , Fu Jinmin
Published: April 2015

Preexposure to a stress could induce stable signals and reactions on plant physiology and gene expression during future encounters as a ‘stress memory’. In this study, we found that two trainable genes, BPSP encoding putative brown plant hopper susceptibility protein and sucs encoding sucrose synthase displayed transcriptional memory for their considerably higher transcript levels during two or more subsequent stresses (S3, S4) relative to the initial stress (S0), and their expression returning to basal transcript levels (non‐stressed) during the recovery states (R1, R2 and R3). Removing the repetitive stress/recovery exercise, activated transcriptional memory from two trainable genes persisted for at least 4 days in perennial ryegrass. The pretrainable genes with stress memory effort had higher response to the subsequent elevated NaCl concentration treatment than the non‐trainable plants, which was confirmed by lower electrolyte leakage and minimum H2O2 and O2− accumulation. Salt stress elevated the content of 41 metabolites in perennial ryegrass leaves, and sugars and sugar alcohol accounted for more than 74.1% of the total metabolite content. The salt stress memory was associated with higher contents of 11 sugars and 1 sugar alcohol in the pretrainable grass leaves. Similarly, six sugars showed greater content in the pretrainable grass roots. These novel phenomena associated with transcriptional memory and metabolite profiles could lead to new insights into improving plant salinity acclimation process.
Is Leadership in the Eye of the Beholder? A Study of Intended and Perceived Leadership Practices and Organizational Performance
Authors: Jacobsen Christian Bøtcher , Bøgh Andersen Lotte
Published: April 2015

Leadership is a matter of both intentions and perceptions, which do not necessarily always match. Because employees’ motivation and commitment are only affected by leadership if they notice it, employee‐perceived leadership is expected to have a stronger correlation with organizational performance than leader‐intended leadership. This expectation is tested for transformational and transactional leadership, as both types of practices are expected to increase performance. Using a sample of 1,621 teachers and 79 Danish high school principals, the authors find that leader‐intended and employee‐perceived transformational and transactional leadership are only weakly correlated and that only employee‐perceived leadership practices (both transformational and transactional) are significantly related to objectively measured school performance. The results show that it is important to distinguish between intended and perceived leadership and that leaders should be aware of how their practices are perceived.
Connecting Social Psychology and the Sociology of Sport: Using Goffman as a Framework for Sociological Sports Research
Authors: Peterson Gretchen
Published: April 2015

Research on the sociology of sports has much to contribute to public discourse on sports and is well positioned to do so through the connection between sociology of sports and social psychology. This article uses the work of Erving Goffman () as a framework for situating research in the sociology of sports into the themes of courage and gameness, integrity, and composure. This framework provides a way of organizing research in the field and also highlights areas where further research is needed.
Government Spending, Shocks, and the Role of Legislature Size: Evidence from the American States*
Authors: Hankins William B.
Published: April 2015

Objective

I examine the relationship between legislature size and several components of government spending using a methodology that allows me to estimate how legislature size influences the fiscal response to shocks that are common to all states.

Method

I use nonlinear least squares on a panel of 48 of the 50 American states over the period 1978–2008.

Results

I find little evidence that states with larger than average lower or upper chambers experience a larger change in spending per capita in the presence of a shock. I do find a positive relationship between lower chamber size and the first difference of welfare spending per capita, but this increase is partially offset by a negative relationship between upper chamber size and welfare spending.

Conclusion

These results are consistent with the interest groups theory of government, which states that larger legislatures can be associated with lobbying and bargaining costs that may have offsetting effects.
Marr's Levels Revisited: Understanding How Brains Break
Authors: Hardcastle Valerie G. , Hardcastle Kiah
Published: April 2015

While the research programs in early cognitive science and artificial intelligence aimed to articulate what cognition was in ideal terms, much research in contemporary computational neuroscience looks at how and why brains fail to function as they should ideally. This focus on impairment affects how we understand David Marr's hypothesized three levels of understanding. In this essay, we suggest some refinements to Marr's distinctions using a population activity model of cortico‐striatal circuitry exploring impulsivity and behavioral inhibition as a case study. In particular, we urge that Marr's computational level should be redefined to include a description of how systems break down. We also underscore that feed‐forward processing, cognition disconnected from behavioral context, and representations do not always drive cognition in the way that Marr originally assumed.
Use of 16S rRNA sequencing and quantitative PCR to correlate venous leg ulcer bacterial bioburden dynamics with wound expansion, antibiotic therapy, and healing
Authors: Sprockett Daniel D. , Ammons Christine G. , Tuttle Marie S.
Published: April 2015

Clinical diagnosis of infection in chronic wounds is currently limited to subjective clinical signs and culture‐based methods that underestimate the complexity of wound microbial bioburden as revealed by DNA‐based microbial identification methods. Here, we use 16S rRNA next generation sequencing and quantitative polymerase chain reaction to characterize weekly changes in bacterial load, community structure, and diversity associated with a chronic venous leg ulcer over the 15‐week course of treatment and healing. Our DNA‐based methods and detailed sampling scheme reveal that the bacterial bioburden of the wound is unexpectedly dynamic, including changes in the bacterial load and community structure that correlate with wound expansion, antibiotic therapy, and healing. We demonstrate that these multidimensional changes in bacterial bioburden can be summarized using swabs taken prior to debridement, and therefore, can be more easily collected serially than debridement or biopsy samples. Overall, this case illustrates the importance of detailed clinical indicators and longitudinal sampling to determine the pathogenic significance of chronic wound microbial dynamics and guide best use of antimicrobials for improvement of healing outcomes.
Exercise‐induced changes in tumour LDH‐B and MCT1 expression are modulated by oestrogen‐related receptor alpha in breast cancer‐bearing BALB/c mice
Authors: Aveseh Malihe , Nikooie Rohollah , Aminaie Mohsen
Published: April 2015

Key points

Monocarboxylate transporters (MCTs) and lactate dehydrogenase A (LDH‐A) play important roles in sustaining the glycolytic phenotype seen in cancer.

Endurance training improves aerobic capacity; however, whether endurance training alters the metabolic phenotype of a solid tumour, from the perspective of lactate metabolism, is yet to be proven.

This study showed that endurance training decreases expression of the MCT1 basigin (CD147) and LDH‐A , and also increases LDH‐B expression in solid tumours and attenuates tumour lactate metabolism.

Similar results for MCT1 and LDH‐B were found with inhibition of the oestrogen‐related receptor alpha (ERRα). The training effects were not additive to the ERRα effects on MCT1 and LDH‐B expression in the tumour, which indicated that exercise‐induced alterations in MCT1 and LDH‐B expression were modulated by ERRα.

These results suggest that endurance training could be a useful tool in cancer therapy, especially in basal‐like and luminal‐like breast carcinomas.

Several factors, including overexpression of lactate dehydrogenase (LDH) and monocarboxylate transporters (MCTs), promote an aerobic lactate production that allows some cancer cells to sustain higher proliferation rates in hostile environments outside the cell. To elucidate the effect of endurance training on the metabolic phenotype of solid tumours, we focused on the tumour expression of LDH‐A, LDH‐B, MCT1, MCT4, oestrogen‐related receptor alpha (ERRα) and LDH isozymes in control (C), trained (T), control+XCT790 (CX) and trained+XCT790 (TX) mice. First, we found that the metabolically altered tumours from the trained animals exhibited lower values for lactate concentration than the control group. The decreased lactate concentration was associated with a shift in the tumour LDH isozyme profile towards LDH‐1. These exercise‐induced changes were also associated with decreases in the expression of the tumour MCT1, ERRα and CD147 in the trained animals. Secondly, the inhibition of ERRα by treatment of MC4‐L2 human breast cancer cells with XCT790 (inverse agonist ligand of ERRα) before injection into the animals not only increased LDH‐B expression in the tumour, but also decreased MCT1 expression in the CX group in comparison to the C group. The effects of ERRα inhibition were not additive to the training effects on the expressions of MCT1 and LDH‐B in the solid tumours. In conclusion, our results suggest that exercise‐induced suppression of ERRα expression modulates alterations in solid tumour expression of LDH‐B and MCT1 and contributes towards the prevention of tumour development.
Exergy Performance Analysis and Optimization of a Desiccant Wheel System
Authors: Ali Mandegari Mohsen , Farzad Somayeh , Pahlavanzadeh Hassan
Published: April 2015

This paper focused on the exergy analysis and optimization of a dehumidification desiccant wheel (DW) system. A two-dimensional unsteady state numerical model was developed for simulation of the heat and mass transfer phenomena in a representative channel of a DW matrix. The DW mathematical model was validated using a series of experimental data and parametric studies were conducted to investigate the effects of operating parameters on the DW system performance. Exergy parameters were also studied and adopted to predict the total inlet–outlet exergy and exergy destruction, as well as exergy effectivenesses. Furthermore, a new exergy effectiveness parameter was introduced based on the concept of dehumidification. Parametric studies were carried out to characterize the optimal performance of the overall system regarding exergy destruction and exergy dehumidification effectivenesses. The results demonstrate that electrical power consumption, regeneration heat, and heat and mass transfer between air and desiccant are the main sources of exergy destruction. The optimization calculation shows that at the lowest process air velocity (up = 0.2 m/s), lowest DW rotational speed (NDW = 4 Rph), highest regeneration air temperature (Ta,r,in = 140 °C), and moderate regeneration air velocity (ur = 1.7 m/s), minimum exergy destruction occurs. The optimal value of the parameters proves that, when exergy destruction effectiveness is selected as the objective function, the only regeneration air velocity is decision variable of optimization and operational limits impose on the other parameters.
Feasibility Study of a Radial Inflow Compressor
Authors: Boyce M. P. , Bale Y. S.
Published: April 2015

This paper is a feasibility study of the radial inflow compressor. The goal was to study theoretically the flow in such a compressor. The blade loadings have been computed for various pressure ratios and the optimum loading is presented. The rotor efficiency of such a compressor is lower than that encountered in a similar pressure ratio radial outflow impeller. The efficiency in the diffuser is slightly higher for the radial inflow compressor, with an axial relative flow discharge. This combination leads to an efficiency between 70 to 75 percent for a 3:1 pressure ratio compressor stage. This agrees favorably with two-stage radial outlfow compressor in which the two compressors are close together for axial compactness. Thus the radial inflow configuration could give comparable efficiencies when paired with a radial outlfow compressor and more axial compactness. This makes the radial inflow compressor worth considering for use in small auxiliary power units.
Turbine Engine Icing and Ice Detection
Authors: Lacey J. J.
Published: April 2015

A review of conditions necessary for turbine engine icing is presented along with the potential problems caused by engine icing. Methods of protecting the engine against icing are briefly presented and a method of automatic anti-ice operation is proposed.
Nine Years With Jet-Engined Generators
Authors: North R. L.
Published: April 2015

This paper covers the operating and maintenance experiences with aircraft type light gas turbine driven generators and the use to which they have been put on a New England System over the past nine years.
A Turbojet Simulator for Mach Numbers up to 2.0
Authors: Steffen F. W. , Satmary E. A. , Vanco M. R. , Nosek S. M.
Published: April 2015

A turbojet simulator has been designed and fabricated for use in wind tunnel models. The simulator contains a six-stage, axial-flow compressor powered by a three-stage, axial-flow turbine. High pressure heated air was used to drive the turbine. At design conditions, compressor axial flow, turbine exit flow, and a third supplementary flow all entered the exhaust nozzle at equal values of pressure and temperature. Overall aerodynamic design, instrumentation, and calibration procedure is presented. Performance of the device when used to simulate a J-85 turbojet engine at transonic speeds is reported. The installed nozzle performance obtained with the simulator is also discussed and compared with flight data.
A Gas Turbine Powered LNG Tanker
Authors: Svensen N. A.
Published: April 2015

The author discusses some of the design features of the power plant for the world’s first gas turbine LNG carrier. The basic features of the dual fuel system are examined with respect to the use of LNG boil-off gas fuel, and marine operating and automation requirements. Marine classification society design criteria and operating constraints are briefly studied with respect to plant safety and functional interfaces with ship control systems. The concept of locked-shaft flaring of boil-off gas in port is discussed with emphasis on land-based system experience. The conclusion emphasizes safety and reliability features of this new marine application of the Heavy Duty Gas Turbine.
Preliminary Staging Selection for Gas Turbine Driven Centrifugal Gas Compressors
Authors: Sapiro Leon
Published: April 2015

A procedure for optimizing the preliminary design of a gas turbine driven multistage centrifugal compressor package is discussed. The optimization procedure is based on the variation of single-stage centrifugal compressor adiabatic efficiency as a function of specific speed and Mach number. It permits the selection of optimum impeller diameter and the number of stages to cover a prescribed compressor market zone, indicating regions of maximum efficiency. Flow limitations resulting from decreasing efficiency at off-optimum specific speeds, as well as the mechanical design limitations following excessive seal temperatures and axial thrust, are delineated. The procedure has been successfully used at the author’s company for the preliminary selection of stage geometries for a family of multistage gas compressors.
Evaluation of Gas Turbines for Pipelines
Authors: Heard T. C. , Lang R. P. , Mayer C. B.
Published: April 2015

The wide range of sizes and types of gas turbine offered today present the gas pipeline system designer with a formidable task in determining the best equipment for a particular gas pipeline application. It is suggested that an analytical approach to account for the statistical or expected availability of various considered compressor-driver units will not only assist in making these decisions but provide a more accurate overall economic comparison. This paper reviews some concepts of accounting for differences in equipment availability in terms of resulting overall system compression costs.
Total Energy Applications for Ships Service Power
Authors: Greene G. T. , Warner C. E.
Published: April 2015

With the advent of high-speed, gas-turbine-powered naval vessels, new lighter weight concepts are required for service power. This paper demonstrates how a gas-turbine-driven ship service generator set can be used to supply multiple functions, including electrical power, thermal power, pneumatic power, and direct shaft-driven equipment. The thermal power can be used to perform heating, distillation plant operation, galley services, and air conditioning functions. The Canadian DDH 280 Class destroyer system is presented as an example of a total energy system. Heat recovery boiler and gas turbine characteristics are presented for 600-hp and 5000-hp marine gas turbines. A gas turbine total energy system is compared to a conventional diesel system without heat recovery.
Lift Engine Bleed Flow Management for a V/STOL Fighter Reaction Control System
Authors: Webster C. N.
Published: April 2015

In a lift-plus-lift/cruise V/STOL fighter, reaction control may be used to provide pitch, roll and yaw control power during hover and low speed flight when aerodynamic control surfaces are ineffective. This power is provided by reaction jets in the pitch, roll and yaw axes. Reaction thrust is derived from lift engine bleed air. This paper discusses the trade studies leading to the selection of a reaction control system arrangement and a bleed air management concept. The selected system, its performance characteristics, and flow management are discussed.
V/STOL Airframe/Propulsion Integration Problem Areas
Authors: Sutliff Dale
Published: April 2015

The integration of V/STOL airframe and propulsion systems requires consideration of problems not experienced in conventional aircraft. These problems are discussed in terms of several propulsion arrangements of lift jets and vectored cruise engines. Thrust requirements are compared for the propulsion arrangements and the exhaust flow pattern, and its interference and reingestion effects developed in ground proximity, are reviewed. Selected design problems involving store and landing gear location and the use of lift jets for emergency cruise are discussed. Finally, a comparison is made of the weight and costs of the aircraft, each using a different propulsion arrangement.
Pressure Measurements on the Rotating Blades of an Axial-Flow Compressor
Authors: Sexton M. R. , O’Brien W. F. , Moses H. L.
Published: April 2015

A rotor-mounted radio telemetry instrument system for measuring surface pressures on the rotating blades of an axial-flow compressor was developed and tested. The paper describes the design of the instrument system and several tests to establish its accuracy. Measurements of average and fluctuating surface pressures were reported. Measured pressure levels were found to agree with theory and available experimental data.
Gas Turbines in the Arctic Environment
Authors: Kindl F. H.
Published: April 2015

The operation of gas turbines in regions where the atmospheric temperature may go below freezing introduces some special kinds of application problems which must be accounted for in the design if the units are to perform satisfactorily. These conditions are aggravated as the temperatures go down and gas turbines applied in Arctic regions can be severely limited in their operation if proper design precautions are not taken. The purpose of this paper is to list the various characteristics about arctic applications which are different from those in more southerly parts of the world and the design changes that must be made in order to cope with these problems. In addition, the paper outlines some characteristics of the gas turbine which are enhanced by the low temperature application and how it is possible to take advantage of these features. The subjects of Inlet Icing, Low Temperature Effects on Materials, and the Impact of Low Inlet Air Temperatures on Total Machine Capability are all discussed. In addition, the results of a number of years operating experience in arctic applications are covered and test data from a few installations is reported.
Gas Turbine Maintenance Support
Authors: Cornell D. E.
Published: April 2015

The intent of this paper is to identify and describe the functions required from supporting groups to the Maintenance Department. Further, it will show how proper documentation and interpretation from this support can and will reduce maintenance costs. This is the tangible advantage. However, the intangible advantages show increased production because of reduced planned and unplanned shutdowns and is likewise included in this presentation.
Gas Turbine Driven Vapor Compressor for Desalination Purpose: Design Considerations and Test Results
Authors: Olsson E. K. A. , Egnell R. J. E. , Paulsson L. O.
Published: April 2015

A gas turbine driven vapor compressor has been designed for a desalination plant incorporating vertical tube evaporators (VTE) as complement to conventional multistage flash (MSF) evaporators. The plant will produce a water quantity of 31,600 m3/day (8 mgd) at an estimated water cost of 0.014 $/m3. This paper describes the design philosophy of the turbine-compressor train and report the test results of the unit using air as flow-medium.
The Inverted Brayton Cycle for Waste-Heat Utilization
Authors: Wilson D. G. , Dunteman N. R.
Published: April 2015

The inverted Brayton cycle, which can be simply defined as one in which hot gas is first expanded through a turbine to low pressure, is then cooled at constant pressure, and lastly, is recompressed to the initial pressure, has been shown to give attractive incremental gains in thermal efficiency, and large returns on investment, when added to a conventional shaft-power gas turbine exhausting into a waste-heat boiler. When the inverted Brayton cycle is applied by itself as a method of obtaining shaft power from the hot waste gas stream, there appears to be range of temperature and pressure ratios at which the cycle is competitive with other methods of waste-heat utilization.
Effect of Rotor Tip Clearance and Configuration on Overall Performance of a 12.77-Centimeter Tip Diameter Axial-Flow Turbine
Authors: Haas J. E. , Kofskey M. G.
Published: April 2015

An extensive experimental investigation was made to determine the effect of varying the rotor tip clearance of a 12.77-cm-tip diameter, single-stage, axial-flow reaction turbine. In this investigation, the rotor tip clearance was obtained by use of a recess in the casing above the rotor blades and also by use of a reduced blade height. For the recessed casing configuration, the optimum rotor blade height was found to be the one where the rotor tip diameter was equal to the stator tip diameter. The tip clearance loss associated with this optimum recessed casing configuration was less than that for the reduced blade height configuration.
Internal Aerodynamics and Heat Transfer Problems Associated to Film Cooling of Gas Turbines
Authors: Le Grivès Emile , Nicolas J.-J. , Génot Jeanne
Published: April 2015

Heat transfer and aerodynamic processes within coolant ducts and film emission holes of high temperature gas turbine components have been investigated at ONERA by means of specially devised test rigs affording an adequate similitude of geometrical or aerothermal parameters. Results obtained in tests at steady or transient thermal regime are reported for several points of interest concerning internal coolant circuits:

• Heat transfer through multihole parts of turbine airfoils

• Aerodynamics of flows within perforated ducts, with special attention to coolant mass flow distribution, to pressure losses and heat transfer coefficients in small or scaled up turbine blade models

• Heat transfer over a perforated wall, with mass transfer of the coolant flow through holes of various patterns and pitch-to-diameter ratio.

Experimental data are discussed in regard to desired accuracy for the analysis of heat transfer in air-cooled gas turbines, except for the effects of rotation.
Marine Reversing Gear Incorporating Single Reversing Hydraulic Coupling and Direct-Drive Clutch for Each Turbine
Authors: Fortunato E. , Clements H. A.
Published: April 2015

The paper introduces a new design of Reversing Hydraulic Coupling which is used in combination with a Direct-Drive Clutch to provide an extremely compact marine reversing gearbox, suitable for high power marine propulsion drives. The resulting unit needs a very simple control system and is highly flexible in operation.
Design and Test of an Extremely Wide Flow Range Compressor
Authors: Flynn P. F. , Weber H. G.
Published: April 2015

A fundamental theoretical study of the flow within a compressor wheel suggests that: (a) a necessary (but not sufficient) criterion for the prevention of surge can be obtained from the inviscid solution of the internal compressor flow problem, (b) the use of backward leaning blades is not the only blade passage modification which has the potential to increase the usable flow range of the compressor, and (c) a usable flow range much broader than previously thought to exist can be obtained. One alternative approach suggested by this study has been experimentally tested up to compressor pressure ratios in excess of 3.0. The new approach allowed a 50 percent reduction in the surge mass flow at design impeller speed while maintaining the inducer geometry of the machine identical to that of a conventional radial-bladed impeller used as a comparison standard. This new approach indicates the potential for a-priori prediction of surge flow characteristics of radial turbomachinery. Conversely, the design of hardware to a prespecified surge to choke flow ratio may be able to be accomplished by predefined blade geometry. It appears that the usable flow range for centrifugal compressors could extend down to 15 to 20 percent of the choke flow capability without sacrificing maximum component efficiencies.
On the design and characterization of a new cold atmospheric pressure plasma jet and its applications on cancer cells treatment
Authors: Akhlaghi Morteza , Rajayi Hajar , Mashayekh Amir Shahriar , Khani Mohammadreza , Hassan Zuhair Mohammad , Shokri Babak
Published: April 2015

In this paper, a new configuration of a cold atmospheric pressure plasma jet has been designed and constructed. Poly-methyl-methacrylate was used as a new dielectric in this configuration which in comparison to other dielectrics is inexpensive, more resistant against break, and also more shapeable. Then, the plasma jet parameters such as plume temperature, rotational and vibrational temperatures, power, electrical behavior (voltage and current profile), electron density, and the produced reactive species were characterized. In order to determine the jet temperature and the amount of reactive species, effects of applied voltage, gas flow rate, and distance from the nozzle were studied. The power of the jet was specified using Lissajous curve approach. The plume temperature of the plasma jet was about the room temperature. Optical emission spectroscopy determined the type of reactive species, and also electron density and its corresponding plasma frequency (∼6.4 × 1013 cm−3 and 4.52 × 1011 Hz). Because of producing different reactive species, the device can be used in different applications, especially in plasma medicine. Thus, 4T1 cancer cells were treated using this plasma jet. The results showed that this plasma jet has a great potential to kill one of the most aggressive and resistant cancerous cell lines.
Linear rheology and structure of molecular bottlebrushes with short side chains
Authors: López-Barrón Carlos R. , Brant Patrick , Eberle Aaron P. R. , Crowther Donna J.
Published: April 2015

We investigate the microstructure and linear viscoelasticity of model molecular bottlebrushes (BBs) using rheological and small-angle X-ray and neutron scattering measurements. Our polymers have short atactic polypropylene (aPP) side chains of molecular weight ranging from 119 g/mol to 259 g/mol and narrow molecular weight distribution (Mw/Mn 1.02–1.05). The side chain molecular weights are a small fraction of the entanglement molecular weight of the corresponding linear polymer (Me,aPP= 7.05 kg/mol), and as such, they are unentangled. The morphology of the aPP BBs is characterized as semiflexible thick chains with small side chain interdigitation. Their dynamic master curves, obtained by time-temperature superposition, reveal two sequential relaxation processes corresponding to the segmental relaxation and the relaxation of the BB backbone. Due to the short length of the side chains, their fast relaxation could not be distinguished from the glassy relaxation. The fractional free volume is an increasing function of the side chain length (NSC). Therefore, the glassy behavior of these polymers as well as their molecular friction and dynamic properties are influenced by their NSC values. The apparent flow activation energies are a decreasing function of NSC, and their values explain the differences in zero-shear viscosity measured at different temperatures.
SARM1 activation triggers axon degeneration locally via NAD
+
destruction
Authors: Gerdts Josiah , Brace E.J. , Sasaki Yo , DiAntonio Aaron , Milbrandt Jeffrey
Published: April 2015

SARM1-driven axon degeneration

Axons, the long protrusions of nerve cells, are programmed to self-destruct under certain conditions that occur during development, stress, or disease states. Gerdts
et al.
outline a biochemical mechanism that controls such axon degeneration. The authors designed versions of SARM1 (sterile alpha and TIR motif—constraining 1) that could be activated or inhibited in cells. Their experiments showed that the activation of SARM1 was necessary and sufficient to cause axon destruction in cultured mouse neurons. SARM1-mediated destruction was associated with depletion of the metabolic cofactor NAD
+
from cells.

Science
, this issue p. 453
Inbred wolf population on Isle Royale collapses
Authors: Mlot Christine
Published: April 2015

But other wolves adopt a new Lake Superior island.
A space icon turns 25
Authors: Clery Daniel
Published: April 2015

As the Hubble Space Telescope enters the last few years of its mission, researchers charged with creating an orbiting observatory to take its place are discovering that Hubble is a tough act to follow.
Hubble on steroids
Authors: Schilling Govert
Published: April 2015

As the Hubble Space Telescope's decades-long mission winds down, astronomers are worried about the future of optical and ultraviolet astronomy from space.
Selective assemblies of giant tetrahedra via precisely controlled positional interactions
Authors: Huang Mingjun , Hsu Chih-Hao , Wang Jing , Mei Shan , Dong Xuehui , Li Yiwen , Li Mingxuan , Liu Hao , Zhang Wei , Aida Takuzo , Zhang Wen-Bin , Yue Kan , Cheng Stephen Z. D.
Published: April 2015

Creating unusual nanostructures

Self-assembly often occurs when dissimilar molecular fragments are forced together by covalent bonding. Surfactants or block copolymers are two common examples. Huang
et al.
grafted four different nanoparticles, based on polyhedral oligomeric silsesquioxanes with slightly different compositions, onto a single tetrahedal core (see the Perspective by Yang). Depending on the type of nanoparticle, they assembled into a range of defined, ordered supramolecular lattices similar to a range of metal alloys. These include phases that have higher coordination numbers than usually found in the packing of spherical objects.

Science
, this issue p. 424; see also p. 396
Biological signatures in clumped isotopes of O
2
Authors: Yeung Laurence Y. , Ash Jeanine L. , Young Edward D.
Published: April 2015

What controls clumped isotopes?

Stable isotopes of a molecule can clump together in several combinations, depending on their mass. Even for simple molecules such as O
2
, which can contain
16
O,
17
O, and
18
O in various combinations, clumped isotopes can potentially reveal the temperatures at which molecules form. Away from equilibrium, however, the pattern of clumped isotopes may reflect a complex array of processes. Using high-resolution gas-phase mass spectrometry, Yeung
et al.
found that biological factors influence the clumped isotope signature of oxygen produced during photosynthesis (see the Perspective by Passey). Similarly, Wang
et al.
showed that away from equilibrium, kinetic effects causing isotope clumping can lead to overestimation of the temperature at which microbially produced methane forms.

Science
, this issue p. 431; p. 428; see also p. 394
Migration, interrupted
The Narrow Edge A Tiny Bird, an Ancient Crab, and an Epic Journey
Deborah Cramer
Yale University Press, 2015. 303 pp.
Authors: Clark Nigel A.
Published: April 2015

The imperiled existence of the rufa red knot.
Human Invasive Muscular Sarcocystosis Induces Th2 Cytokine Polarization and Biphasic Cytokine Changes, Based on an Investigation among Travelers Returning from Tioman Island, Malaysia
Authors: Tappe Dennis , Slesak Günther , Pérez-Girón José Vicente , Schäfer Johannes , Langeheinecke Andreas , Just-Nübling Gudrun , Muñoz-Fontela César , Püllmann Kerstin
Published: April 2015

Sarcocystis nesbitti
is a parasite responsible for a biphasic eosinophilic febrile myositis syndrome in two recent outbreaks in Malaysia. We demonstrate Th2 cytokine polarization in infected travelers, an overall cytokine production decrease in the early phase of the disease suggestive of initial immunosuppression, and elevated levels of proinflammatory and chemotactic cytokines in the later myositic phase.
Detection of Group A Streptococcus from Pharyngeal Swab Samples by Bacterial Culture Is Challenged by a Novel mariPOC Point-of-Care Test
Authors: Vakkila Jukka , Koskinen Janne O. , Brandt Annika , Muotiala Anna , Liukko Viivi , Soittu Sari , Meriluoto Siiri , Vesalainen Marika , Huovinen Pentti , Irjala Kerttu
Published: April 2015

mariPOC is a novel point-of-care test system for rapid detection of respiratory tract infections. We compared the performance of the mariPOC test to that of bacterial culture for detecting group A streptococcus (GAS) in 219 pharyngitis patients (ages 1–64 years) and 109 healthy asymptomatic controls (ages 19–69 years). In addition, 42 patient samples were analyzed by quantitative PCR (qPCR). Of the 219 pharyngeal patient samples, 32 were positive in a GAS bacterial culture (prevalence 15%) and 65 (30%) in the mariPOC test. The amount of GAS in samples reported positive by the mariPOC test and negative by culture was, on average, 10-fold less than that of those positive in both methods. This indicated that the negative results in bacterial cultures were due to lower sensitivity. The qPCR results were positive and in line with the mariPOC results in 43% of the discordant samples studied. Two GAS culture-positive samples were negative by the mariPOC test. The prevalences of GAS in the control subjects were 2% and 6% by culture and mariPOC results, respectively. We conclude that the mariPOC antigen detection test is more sensitive than the conventional bacterial culture for the detection of GAS among symptomatic pharyngitis patients. The higher prevalence of GAS by the mariPOC test among symptomatic patients was probably not due to carriership, since among the control patients, the difference in the prevalence of GAS by the mariPOC test and culture was not nearly as high, 15% versus 4%, respectively. Clinical trials are needed to show the clinical importance of our findings.
Aspergillus-Specific Lateral-Flow Device and Real-Time PCR Testing of Bronchoalveolar Lavage Fluid: a Combination Biomarker Approach for Clinical Diagnosis of Invasive Pulmonary Aspergillosis
Authors: Johnson Gemma L. , Sarker Shah-Jalal , Nannini Francesco , Ferrini Arianna , Taylor Emma , Lass-Flörl Cornelia , Mutschlechner Wolfgang , Bustin Stephen A. , Agrawal Samir G.
Published: April 2015

Clinical experience with the impact of serum biomarkers for invasive fungal disease (IFD) varies markedly in hemato-oncology. Invasive pulmonary aspergillosis (IPA) is the most common manifestation, so we evaluated biomarkers in bronchoalveolar lavage (BAL) fluid. An
Aspergillus-
specific lateral-flow device (LFD), quantitative real-time PCR (qPCR), and the galactomannan (GM) test were used with 32 BAL fluid samples from 32 patients at risk of IPA. Eight patients had proven IPA, 3 had probable IPA, 6 had possible IPA, and 15 patients had no IPA by European Organization for Research and Treatment of Cancer Invasive Fungal Infections Cooperative Group/Mycoses Study Group of the National Institute of Allergy and Infectious Diseases (EORTC/MSG) criteria. The diagnostic accuracies of the tests were evaluated, and pairwise agreement between biomarkers was calculated. The diagnostic performance of the EORTC/MSG criteria was evaluated against the test(s) identified to be the most useful for IPA diagnosis. Using the EORTC/MSG criteria, the sensitivities of qPCR and LFD were 100% and the sensitivity of the GM test was 87.5% (GM test index cutoff, >0.8), with the tests having specificities of between 66.7 and 86.7%. The agreement between the results of qPCR and LFD was almost perfect (Cohen's kappa coefficient = 0.93, 95% confidence interval, 0.81 to 1.00). LFD and qPCR combined had a sensitivity of 100% and a specificity of 85.7%. Calcofluor staining and culture of all BAL fluid samples were negative for fungal infection. The median time from the start of mold-active antifungal therapy to the time of collection of BAL fluid was 6 days. Reversing roles and using dual testing by LFD and qPCR to classify cases, the EORTC/MSG criteria had a sensitivity of 83.3%. All three tests are useful for the diagnosis of IPA in BAL fluid samples. Despite the significant delays between the start of antifungal therapy and bronchoscopy, unlike microscopy and culture, the biomarkers remained informative. In particular, the combination of LFD and qPCR allows the sensitive and specific detection of IPA.
Rapid Detection of Acquired and Inducible Clarithromycin Resistance in Mycobacterium abscessus Group by a Simple Real-Time PCR Assay
Authors: Luo Robert F. , Curry Cheyenne , Taylor Nathan , Budvytiene Indre , Banaei Niaz
Published: April 2015

By targeting the
erm
(41) and
rrl
genes in the
Mycobacterium abscessus
group, a multiplex real-time PCR assay for clarithromycin resistance showed 95% (38/40) concordance with nucleic acid testing and 95% (37/39) concordance with phenotypic testing. This assay provides a simple and rapid alternative to extended incubation or
erm
(41) sequencing.
Comparison of Onclarity Human Papillomavirus (HPV) Assay with Hybrid Capture II HPV DNA Assay for Detection of Cervical Intraepithelial Neoplasia Grade 2 and 3 Lesions
Authors: Bottari F. , Sideri M. , Gulmini C. , Igidbashian S. , Tricca A. , Casadio C. , Carinelli S. , Boveri S. , Ejegod D. , Bonde J. , Sandri M. T.
Published: April 2015

Analytical and clinical performance validation is essential before introduction of a new human papillomavirus (HPV) assay into clinical practice. This study compares the new BD Onclarity HPV assay, which detects E6/E7 DNA from 14 high-risk HPV types, to the Hybrid Capture II (HC2) HPV DNA test, to concurrent cytology and histology results, in order to evaluate its performance in detecting high-grade cervical lesions. A population of 567 women, including 325 with ≥ASCUS (where ASCUS stands for atypical cells of undetermined significance) and any HC2 result and 242 with both negative cytology and negative HC2 results, were prospectively enrolled for the study. The overall agreement between Onclarity and HC2 was 94.6% (95% confidence intervals [CI], 92.3% to 96.2%). In this population with a high prevalence of disease, the relative sensitivities (versus adjudicated cervical intraepithelial neoplasia grades 2 and 3 [CIN2+] histology endpoints) of the Onclarity and HC2 tests were 95.2% (95% CI, 90.7% to 97.5%) and 96.9% (95% CI, 92.9% to 98.7%), respectively, and the relative specificities were 50.3% (95% CI, 43.2% to 57.4%) for BD and 40.8% (95% CI, 33.9%, 48.1%) for HC2. These results indicate that the BD Onclarity HPV assay has sensitivity comparable to that of the HC2 assay, with a trend to an increased specificity. Moreover, as Onclarity gives the chance to discriminate between the different genotypes, we calculated the genotype prevalence and the absolute risk of CIN2+: HPV 16 was the most prevalent genotype (19.8%) with an absolute risk of CIN2+ of 77.1%.
Dual Invasive Infection with Phaeoacremonium parasiticum and Paraconiothyrium cyclothyrioides in a Renal Transplant Recipient: Case Report and Comprehensive Review of the Literature of Phaeoacremonium Phaeohyphomycosis
Authors: Colombier Marie-Alice , Alanio Alexandre , Denis Blandine , Melica Giovanna , Garcia-Hermoso Dea , Levy Bénédicte , Peraldi Marie-Noëlle , Glotz Denis , Bretagne Stéphane , Gallien Sébastien
Published: April 2015

Despite increasing reports of human infection, data about the optimal care of
Phaeoacremonium
infections are missing. We report a case of an infection due to
Phaeoacremonium parasiticum
and
Paraconiothyrium cyclothyrioides
, initially localized to skin and soft tissue, in a kidney transplant patient. Despite surgical drainage and excision of the lesion and combination antifungal therapy with voriconazole and liposomal amphotericin B, a disseminated infection involving the lungs and brain developed and led to death. We performed a systematic literature review to assess the general features and outcome of human infections due to
Phaeoacremonium
species. Thirty-six articles were selected, and 42 patients, including ours, were reviewed. Thirty-one patients (74%) were immunocompromised because of organ or bone marrow transplantation (
n
= 17), diabetes or glucose intolerance (
n
= 10), rheumatoid arthritis or Still's disease (
n
= 4), chronic hematological diseases (
n
= 3), or chronic granulomatous disease (
n
= 3). Ten patients (24%) reported initial cutaneous trauma. Skin and soft tissue infections represented 57% of infections (
n
= 24), and disseminated infections, all occurring in immunocompromised patients, represented 14% of infections (
n
= 6). The main antifungal drugs used were azoles (
n
= 41) and amphotericin B (
n
= 16). Surgical excision or drainage was performed in 64% of cases (
n
= 27). The cure rate was 67% (
n
= 28). There were 10% cases of treatment failure or partial response (
n
= 4), 19% relapses (
n
= 8), and 7% losses to follow-up (
n
= 3). The death rate was 19% (
n
= 8). Management of
Phaeoacremonium
infections is complex because of slow laboratory identification and limited clinical data, and treatment relies on a combination of surgery and systemic antifungal therapy.
The Serum Very-Low-Density Lipoprotein Serves as a Restriction Factor against Hepatitis C Virus Infection
Authors: Tao Jian , Kang Kyung-Don , Hall Stacy D. , Laube Audra H. , Liu Jia , Renfrow Matthew B. , Novak Jan , Luo Guangxiang
Published: April 2015

Recent studies demonstrated that transgenic mice expressing key human hepatitis C virus (HCV) receptors are susceptible to HCV infection, albeit at very low efficiency. Robust mouse models of HCV infection and replication are needed to determine the importance of host factors in HCV replication, pathogenesis, and carcinogenesis as well as to facilitate the development of antiviral agents and vaccines. The low efficiency of HCV replication in the humanized mouse models is likely due to either the lack of essential host factors or the presence of restriction factors for HCV infection and/or replication in mouse hepatocytes. To determine whether HCV infection is affected by restriction factors present in serum, we examined the effects of mouse and human sera on HCV infectivity. Strikingly, we found that mouse and human sera potently inhibited HCV infection. Mechanistic studies demonstrated that mouse serum blocked HCV cell attachment without significant effect on HCV replication. Fractionation analysis of mouse serum in conjunction with targeted mass spectrometric analysis suggested that serum very-low-density lipoprotein (VLDL) was responsible for the blockade of HCV cell attachment, as VLDL-depleted mouse serum lost HCV-inhibitory activity. Both purified mouse and human VLDL could efficiently inhibit HCV infection. Collectively, these findings suggest that serum VLDL serves as a major restriction factor of HCV infection
in vivo
. The results also imply that reduction or elimination of VLDL production will likely enhance HCV infection in the humanized mouse model of HCV infection and replication.

IMPORTANCE
HCV is a major cause of liver diseases, such as chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Recently, several studies suggested that humanized mouse or transgenic mouse expressing key HCV human receptors became susceptible to HCV infection. However, HCV infection and replication in the humanized animals were very inefficient, suggesting either the lack of cellular genes important for HCV replication or the presence of restriction factors inhibiting HCV infection and replication in the mouse. In this study, we found that both mouse and human sera effectively inhibited HCV infection. Mechanistic studies demonstrated that VLDL is the major restriction factor that blocks HCV infection. These findings suggest that VLDL is beneficial to patients by restricting HCV infection. More importantly, our findings suggest that elimination of VLDL will lead to the development of more robust mouse models for the study of HCV pathogenesis, host response to HCV infection, and evaluation of HCV vaccines.