bluuebunny/crossref_metadata_2025 huggingface dataset:
A review of the potential for competitive cereal cultivars as a tool in integrated weed management
Authors: Andrew I K S , Storkey J , Sparkes D L
Published: January 2015

Competitive crop cultivars offer a potentially cheap option to include in integrated weed management strategies (IWM). Although cultivars with high competitive potential have been identified amongst cereal crops, competitiveness has not traditionally been considered a priority for breeding or farmer cultivar choice. The challenge of managing herbicide‐resistant weed populations has, however, renewed interest in cultural weed control options, including competitive cultivars. We evaluated the current understanding of the traits that explain variability in competitive ability between cultivars, the relationship between suppression of weed neighbours and tolerance of their presence and the existence of trade‐offs between competitive ability and yield in weed‐free scenarios. A large number of relationships between competitive ability and plant traits have been reported in the literature, including plant height, speed of development, canopy architecture and partitioning of resources. There is uncertainty over the relationship between suppressive ability and tolerance, although tolerance is a less stable trait over seasons and locations. To realise the potential of competitive crop cultivars as a tool in IWM, a quick and simple‐to‐use protocol for assessing the competitive potential of new cultivars is required; it is likely that this will not be based on a single trait, but will need to capture the combined effect of multiple traits. A way needs to be found to make this information accessible to farmers, so that competitive cultivars can be better integrated into their weed control programmes.
Is Foreign Aid Working? The Impact of Foreign Aid on Savings, Investment, and Economic Growth in Haiti
Authors: Jean Arché
Published: January 2015

Despite increases in foreign aid inflow to Haiti, the country remains one of the poorest in the world. Findings regarding the benefits of foreign aid have been inconsistent. The purpose of this quantitative, archival study was to examine the extent to which total foreign aid explained gross domestic savings, gross domestic investment, and GDP growth rates in Haiti from 1975 to 2010 after 3-year, 4-year, and 5-year time lags. Foreign aid was disaggregated into grants and concessional loans. Data were drawn from the World Bank, the International Monetary Fund, and the Organization for Economic Cooperation and Development from 1970 to 2010. To analyze the extent to which total foreign aid predicted gross domestic savings and gross domestic investment, weighted least squares regression analyses were conducted, with per capita income, interest rates, and inflation rates as covariates. To examine the degree to which total foreign aid predicted GDP growth rates, multiple linear regression analyses were conducted, with consumption, government spending, gross domestic investment, and net trade balance as covariates. Foreign aid did not predict gross domestic savings for 3-year time lag, F (5, 30) = 1.32, p =.28; 4-year time lag, F (5, 30) = 1.24, p =.32, or 5-year time lag, F(5,30) = 1.30, p =.15. Foreign aid did not predict gross domestic investment for 3-year time lag, F(5, 30) = 1.49, p =.22; 4-year time lag, F(5,30)= 1.73, p =.16, or 5-year time lag, F(5, 30) = 2.29, p =.07. Foreign aid did not predict GDP growth rates for 3-year time lag, F(6, 29), p =.44; 4-year time lag, F(6, 29) = 1.11, p =.38, or 5-year time lag F(6, 29) = 0.83, p =.56. Findings showed that foreign aid inflows to Haiti have not predicted improved economic development. Future research should focus on determining the relationship between foreign aid and government investment in infrastructure, education, health, and social projects. The discussion should shift from whether foreign aid flows to developing countries are effective to how to make the allocation of foreign aid inflows more effective. The result would be improved use of the inflow of foreign aid and improved economic and social progress in developing nations.
Estimation of Storm Peak and Intrastorm Directional–Seasonal Design Conditions in the North Sea
Authors: Feld Graham , Randell David , Wu Yanyun , Ewans Kevin , Jonathan Philip
Published: January 2015

Specification of realistic environmental design conditions for marine structures is of fundamental importance to their reliability over time. Design conditions for extreme waves and storm severities are typically estimated by extreme value analysis of time series of measured or hindcast significant wave height, HS. This analysis is complicated by two effects. First, HS exhibits temporal dependence. Second, the characteristics of HSsp are nonstationary with respect to multiple covariates, particularly wave direction, and season. We develop directional–seasonal design values for storm peak significant wave height (HSsp) by estimation of, and simulation under a nonstationary extreme value model for HSsp. Design values for significant wave height (HS) are estimated by simulating storm trajectories of HS consistent with the simulated storm peak events. Design distributions for individual maximum wave height (Hmax) are estimated by marginalization using the known conditional distribution for Hmax given HS. Particular attention is paid to the assessment of model bias and quantification of model parameter and design value uncertainty using bootstrap resampling. We also outline existing work on extension to estimation of maximum crest elevation and total extreme water level.
Flow Boiling Heat Transfer and Two-Phase Flow Instability of Nanofluids in a Minichannel
Authors: Yu Leyuan , Sur Aritra , Liu Dong
Published: January 2015

Single-phase convective heat transfer of nanofluids has been studied extensively, and different degrees of enhancement were observed over the base fluids, whereas there is still debate on the improvement in overall thermal performance when both heat transfer and hydrodynamic characteristics are considered. Meanwhile, very few studies have been devoted to investigating two-phase heat transfer of nanofluids, and it remains inconclusive whether the same pessimistic outlook should be expected. In this work, an experimental study of forced convective flow boiling and two-phase flow was conducted for Al2O3–water nanofluids through a minichannel. General flow boiling heat transfer characteristics were measured, and the effects of nanofluids on the onset of nucleate boiling (ONB) were studied. Two-phase flow instabilities were also explored with an emphasis on the transition boundaries of onset of flow instabilities (OFI). It was found that the presence of nanoparticles delays ONB and suppresses OFI, and the extent is correlated to the nanoparticle volume concentration. These effects were attributed to the changes in available nucleation sites and surface wettability as well as thinning of thermal boundary layers in nanofluid flow. Additionally, it was observed that the pressure-drop type flow instability prevails in two-phase flow of nanofluids, but with reduced amplitude in pressure, temperature, and mass flux oscillations.
Correlation of the Volumetric Tool Wear Rate of Carbide Milling Inserts With the Material Removal Rate of Ti–6Al–4V
Authors: Kuttolamadom Mathew , Mehta Parikshit , Mears Laine , Kurfess Thomas
Published: January 2015

The objective of this paper is to assess the correlation of volumetric tool wear (VTW) and wear rate of carbide tools on the material removal rate (MRR) of titanium alloys. A previously developed methodology for assessing the worn tool material volume is utilized for quantifying the VTW of carbide tools when machining Ti–6Al–4V. To capture the tool response, controlled milling experiments are conducted at suitable corner points of the recommended feed-speed design space, for constant stock material removal volumes. For each case, the tool material volume worn away, as well as the corresponding volumetric wear profile evolution in terms of a set of geometric coefficients, is quantified—these are then related to the MRR. Further, the volumetric wear rate and the M-ratio (volume of stock removed to VTW) which is a measure of the cutting tool efficiency, are related to the MRR—these provide a tool-life based optimal MRR for profitability. This work not only elevates tool wear from a 1D to 3D concept, but helps in assessing machining economics from a stock material-removal-efficiency perspective as well.
Analysis of Fiber Optic Sensor to Measure Velocities During High Deformation Rate Material Forming Processes
Authors: Thibaudeau E. , Turner B. , Gross T. , Kinsey B. L.
Published: January 2015

Previous methods of measuring high velocities, e.g., during electromagnetic forming (EMF) and magnetic pulse welding processes where the workpiece is deforming, include photon Doppler velocimetry (PDV), laser micrometers, and high speed photography. In this paper, an alternative method is presented, implementing a fiber optic, reflectance dependent sensor. The sensor is shown to be an attractive, low purchase cost solution to measure high velocities. Data are shown with respect to sensor characterization including various surface reflectivity values, curvatures, and misalignments; implementation in two EMF/welding processes; and verification with high velocity PDV measurements. The sensor system is one twentieth the purchase cost of a PDV system, and yet measures velocities accurately (using PDV measurements as the reference) to at least 150 m/s provided that local curvature is not extreme and the displacement is less than approximately 27 mm. Sensor performance is also enhanced by the use of retroreflective tape, which is shown to increase the displacement range by 9×, decrease sensitivity to misalignment, and increase repeatability and ease of implementation.
Wear of Form Taps in Threading of Steel Cold Forged Parts
Authors: Fernández Landeta Javier , Fernández Valdivielso Asier , López de Lacalle L. N. , Girot Franck , Pérez Pérez J. M.
Published: January 2015

Tapping of blind or through holes is a common operation in several applications in the automotive, windmill towers, general machinery, and other industrial sectors. On the other hand, tapping is usually performed at the final manufacturing stage of components, so operation errors can lead to very expensive scraps. This article focuses on the performance of different forming taps since there are no standardized procedures for evaluating form tapping, beyond the mere visual assessment or go/no-go tests. Tool behavior was studied according to four aspects: (a) wear analysis of tap forming lobes, (b) measurement of thrust force and torque during tapping, (c) metallographic study of threads, and finally (d) evaluation of coating and tap geometry. In the work presented here, tap wear and thread quality are correlated with processes monitoring parameters. A useful conclusion for tap manufacturers is that taps with hexagonal section and 5 pitches in the chamfer zone led to lower thrust forces and torques than pentagonal section ones, along with a lower wear. Hexagonal/5-pitch taps led to better results due to a more gradual deformation process for producing a thread. A larger number of pitches before reaching the nominal diameter resulted in a reduction of strain between successive lobes, generating lower force and torque values.
Effect of Impact Pressure on Reducing the Weld Residual Stress by Water Jet Peening in Repair Weld to 304 Stainless Steel Clad Plate
Authors: Jiang Wenchun , Luo Yun , Wang Huai , Wang B. Y.
Published: January 2015

Stainless steel clad plate manufactured by explosive bonding is widely used in the chemical industry, but cracks are often initiated in the clad layer. Repair welding is a popular method to repair the cracked zone. But residual stresses are generated inevitably, which can lead to further cracking. How to decrease the residual stress is critical to ensure the structure integrity. This paper studies a method to reduce weld residual stresses by water jet peening (WJP) in 304 stainless steel clad plate. The effect of impact pressure is discussed. A sequential coupling finite element method is developed to simulate the as-welded residual stresses, which is validated by impact indentation measurement. Then, a user subroutine is developed to model the moving load generated by WJP. The results show that the WJP can introduce compressive stresses on the metal surface and thus decrease the as-welded tensile stresses. As the maximum impact pressure at the center of impact (P0) increases, the residual stresses are decreased greatly and even change to compressive stresses. There is a critical value P0, which changes the tensile stresses to compressive stresses. As P0 increases to 1.4 times the yield strength of 304 stainless steel, the initial tensile stresses on the surface have been decreased to compressive stresses.
Hydrostatic Implosion of GFRP Composite Tubes Studied by Digital Image Correlation
Authors: Pinto Michael , Gupta Sachin , Shukla Arun
Published: January 2015

The mechanisms and pressure fields associated with the hydrostatic implosion of glass fiber reinforced polymer (GFRP) tubes with varying reinforcement are investigated using high-speed photography. Experiments are conducted in a large pressure vessel, designed to provide constant hydrostatic pressure throughout collapse. Three-dimensional (3D) digital image correlation (DIC) is used to capture full-field displacements, and dynamic pressure transducers measure the pressure pulse generated by the collapse. Results show that braided GFRP tubes release pressure waves with significantly greater impulse upon collapse as compared to filament-wound tubes, increasing their damage potential.
Aeroacoustic Response of a Single Cylinder With Straight Circular Fins in Cross-Flow
Authors: Arafa Nadim , Mohany Atef
Published: January 2015

The phenomenon of sound generation has been investigated in some detail for the case of bare cylinders; however, the effect of adding fins to the cylinder on the flow–sound interaction mechanism is not yet fully understood. Thus, the aeroacoustic response of a cylinder with straight circular fins in cross-flow is investigated experimentally in this work. During the experiments, the acoustic modes of the duct housing the cylinder are self-excited due to the vortex shedding that emerges from the cylinder's surface. In order to determine the effect of different fin parameters on the onset and intensity of acoustic resonance, 14 different finned cylinders with fin thickness ranging from 0.35 to 1.5 mm and fin density ranging from 4 to 13.7 fin/in. are investigated. It is observed that the finned cylinders experience an earlier acoustic resonance and higher levels of acoustic pressure compared to their equivalent bare cylinders. Moreover, it is observed that, for constant fin spacing, the acoustic pressure amplitude increases and the acoustic resonance occurs at earlier velocities as the fin thickness increases. On the other hand, for constant fin thickness, as the fin spacing increases the amplitude of the acoustic pressure decreases while the onset of the resonance is delayed. Finally, the effect of the cylinder's aspect ratio on the acoustic resonance excitation is presented. It is shown that as the finned cylinders' aspect ratio increases from 4.85 to 11.3, the normalized acoustic pressure during resonance increases drastically. However, for bare cylinders the normalized acoustic pressure during resonance is not highly dependent on the cylinders' aspect ratio. These results indicate that adding fins to the cylinder alters the flow field downstream of the cylinder in a manner that makes it more susceptible to acoustic excitation.
Crude Oil Corrosion Fatigue of L485MB Pipeline Steel
Authors: Gajdoš Ľ. , Šperl M. , Bystrianský J.
Published: January 2015

An investigation was made into the fatigue properties of L485MB (X70) pipeline steel after 13 yr of exploitation as a crude oil pipeline material. Fatigue tests in zero-to-tension loading were carried out (i) in air, (ii) in crude oil, (iii) in a mixture of crude oil with rainwater, and (iv) in water separated from the crude oil phase. The aim of the investigation was to assess the degree of degradation of the fatigue properties of this steel due to the action of environments typical for crude oil processing and transport. The results are not directly comparable to any corrosion fatigue experienced by the crude oil pipeline, since the strain rate for the tests was higher by an order of five than the strain rate observed in typical loading cycles. The results showed that crude oil and a mixture of crude oil with rainwater had no aggressive effect on the steel in the sense of reducing its fatigue characteristics, while the separated water had an aggressive effect.
Piezoelectric oscillation sensor based noncontact atomic force microscope for imaging in both ambient and liquid environments
Authors: Froning Jens P. , Xia Dan , Zhang Shuai , Lægsgaard Erik , Besenbacher Flemming , Dong Mingdong
Published: January 2015

A new design of a noncontact atomic force microscope (AFM) is introduced in this paper, based on a piezoelectric oscillator sensor (PEOS) for ambient and liquid environments. Because of the recent development of quartz technology, the PEOS sensor operates independently from conventional laser alignments. The sensor is based on the length extension resonator, which has high force sensitivity and can deliver high resolution AFM images in ultrahigh vacuum. The oscillator design was tested in different gas compositions and liquids to determine its oscillation stability. The scan performance was investigated in both air and liquid on the topography of an inorganic hard material, graphite. The usability of PEOS for soft organic materials was further proven by imaging biological samples of DNA origami.
Monte Carlo simulation of the dose response of a novel 2D silicon diode array for use in hybrid MRI–LINAC systems
Authors: Gargett Maegan , Oborn Brad , Metcalfe Peter , Rosenfeld Anatoly
Published: January 2015

Purpose:

MRI‐guided radiation therapy systems (MRIgRT) are being developed to improve online imaging during treatment delivery. At present, the operation of single point dosimeters and an ionization chamber array have been characterized in such systems. This work investigates a novel 2D diode array, named “magic plate,” for both single point calibration and 2D positional performance, the latter being a key element of modern radiotherapy techniques that will be delivered by these systems.

Methods:

geant4 Monte Carlo methods have been employed to study the dose response of a silicon diode array to 6 MV photon beams, in the presence of in‐line and perpendicularly aligned uniform magnetic fields. The array consists of 121 silicon diodes (dimensions 1.5 × 1.5 × 0.38 mm3) embedded in kapton substrate with 1 cm pitch, spanning a 10 × 10 cm2 area in total. A geometrically identical, water equivalent volume was simulated concurrently for comparison. The dose response of the silicon diode array was assessed for various photon beam field shapes and sizes, including an IMRT field, at 1 T. The dose response was further investigated at larger magnetic field strengths (1.5 and 3 T) for a 4 × 4 cm2 photon field size.

Results:

The magic plate diode array shows excellent correspondence (< ± 1%) to water dose in the in‐line orientation, for all beam arrangements and magnetic field strengths investigated. The perpendicular orientation, however, exhibits a dose shift with respect to water at the high‐dose‐gradient beam edge of jaw‐defined fields [maximum (4.3 ± 0.8)% over‐response, maximum (1.8 ± 0.8)% under‐response on opposing side for 1 T, uncertainty 1σ]. The trend is not evident in areas with in‐field dose gradients typical of IMRT dose maps.

Conclusions:

A novel 121 pixel silicon diode array detector has been characterized by Monte Carlo simulation for its performance inside magnetic fields representative of current prototype and proposed MRI–linear accelerator systems. In the in‐line orientation, the silicon dose is directly proportional to the water dose. In the perpendicular orientation, there is a shift in dose response relative to water in the highest dose gradient regions, at the edge of jaw‐defined and single‐segment MLC fields. The trend was not observed in‐field for an IMRT beam. The array is expected to be a valuable tool in MRIgRT dosimetry.
Rotationally resliced 3D prostate TRUS segmentation using convex optimization with shape priors
Authors: Qiu Wu , Yuan Jing , Ukwatta Eranga , Fenster Aaron
Published: January 2015

Purpose:

Efficient and accurate segmentations of 3D end‐firing transrectal ultrasound (TRUS) images play an important role in planning of 3D TRUS guided prostate biopsy. However, poor image quality of the input 3D TRUS images, such as strong imaging artifacts and speckles, often makes it a challenging task to extract the prostate boundaries accurately and efficiently.

Methods:

In this paper, the authors propose a novel convex optimization‐based approach to delineate the prostate surface from a given 3D TRUS image, which reduces the original 3D segmentation problem to a sequence of simple 2D segmentation subproblems over the rotational reslices of the 3D TRUS volume. Essentially, the authors introduce a novel convex relaxation‐based contour evolution approach to each 2D slicewise image segmentation with the joint optimization of shape information, where the learned 2D nonlinear statistical shape prior is incorporated to segment the initial slice, its result is propagated as a shape constraint to the segmentation of the following slices. In practice, the proposed segmentation algorithm is implemented on a GPU to achieve the high computational performance.

Results:

Experimental results using 30 patient 3D TRUS images show that the proposed method can achieve a mean Dice similarity coefficient of 93.4% ± 2.2% in 20 s for one 3D image, outperforming the existing local‐optimization‐based methods, e.g., level‐set and active‐contour, in terms of accuracy and efficiency. In addition, inter‐ and intraobserver variability experiments show its good reproducibility.

Conclusions:

A semiautomatic segmentation approach is proposed and evaluated to extract the prostate boundary from 3D TRUS images acquired by a 3D end‐firing TRUS guided prostate biopsy system. Experimental results suggest that it may be suitable for the clinical use involving the image guided prostate biopsy procedures.
The current health of the signing Deaf community in the UK compared with the general population: a cross-sectional study
Authors: Emond Alan , Ridd Matthew , Sutherland Hilary , Allsop Lorna , Alexander Andrew , Kyle Jim
Published: January 2015

Objectives

To assess the current health of the Deaf community in the UK and compare with the general population.

Design

A quota sample of adult Deaf British Sign Language (BSL) users underwent a health assessment and interview in 2012–2013. Comparative data were obtained from the Health Survey for England (HSE) 2011 and the Quality Outcomes Framework (QOF) 2012.

Setting

Participants completed a structured interview and health assessment at seven Bupa centres across the UK, supported in BSL by Deaf advisers and interpreters.

Participants

298 Deaf people, 20–82 years old, 47% male, with 12% from ethnic minorities.

Main outcome measures

Self–reported health conditions, medication usage, tobacco and alcohol consumption; measured blood pressure (BP), body mass index, fasting blood sugar and lipid profile.

Results

Rates of obesity in the Deaf sample were high, especially in those over 65 years, and 48% were in a high risk group for serious illness. High BP readings were obtained in 37% of Deaf people (21% in HSE): 29% were unaware of this (6% in HSE). Only 42% of Deaf people being treated for hypertension had adequate control, compared with 62% of the general population. Deaf people with self-reported cardiovascular disease (CVD) were significantly less than the general population. One-third of Deaf participants had total cholesterol >5 mmol/L but although control rates were high compared with HSE, treatment rates for self-reported CVD were half the general population rate. Eleven per cent of Deaf participants had blood sugar at prediabetic or diabetic levels, and 77% of those at prediabetic levels were unaware of it. Deaf respondents self-reported more depression (31% of women, 14% of men), but less smoking (8%) and alcohol intake (2–8 units/week).

Conclusions

Deaf people's health is poorer than that of the general population, with probable underdiagnosis and undertreatment of chronic conditions putting them at risk of preventable ill health.
Production rates of walleye and their relationship to exploitation in Escanaba Lake, Wisconsin, 1965–2009
Authors: Rypel Andrew L. , Goto Daisuke , Sass Greg G. , Vander Zanden M. Jake
Published: January 2015

Understanding variability in fish production, biomass, production/biomass (P/B) ratios, and their relationship to exploitation is central to fisheries sustainability. At Escanaba Lake, Wisconsin, USA, data from a compulsory creel census (1965–2009) were combined with survey data on fish populations to test for empirical relationships between annual production and exploitation rates of walleye (Sander vitreus). Empirical estimates of walleye production were relatively high and temporally variable in Escanaba Lake. Annual production, biomass, and P/B ratios ranges were 2.4–11.3 kg·ha−1·year−1, 9.1–49.4 kg·ha−1, and 0.15–0.30 year−1, respectively. Walleye production rates were significantly and positively correlated with adult (i.e., age 3+) walleye density — the core metric used to manage walleye populations in the Ceded Territory of Wisconsin. However, adult walleye density correlated best with ages 4–6 production. Annual exploitation based on the percentage of individuals removed from the population was linearly related to annual exploitation based on the percentage of production removed. On average, 100% of annual production was harvested at ∼20% annual exploitation of individuals; thus, higher sustained exploitation rates would deplete walleye biomass in Escanaba Lake over time. A sustainable annual exploitation rate of 20% annually is lower than the 35% limit reference point currently used for walleye management in the Ceded Territory of Wisconsin. Nevertheless, our estimate is strongly concordant with two recent and independent modeling efforts addressing this same topic. We suggest empirical estimates of fish production are a vastly underutilized tool for better understanding sustainable exploitation rates in walleye populations and, likely, fisheries in general.
Observation of nonuniversal scaling exponent in a novel erosion model
Authors: Nath Palash , Jana Debnarayan
Published: January 2015

In this present numerical work, we report a discrete erosion kind of model in (1 + 1)-dimension. Erosion and re-deposition phenomena with probabilities p and q(= 1 - p) are considered as two tunable parameters, which control the overall kinetic roughening behavior of the interface. Redeposition or diffusion dominated erosion like kinetic roughening model gives rise to nonuniversal growth exponent, which varies continuously with respect to erosion probability. However, universal character is restored for the roughness exponent with the value of 0.5 in (1 + 1)-dimension with respect to p. Due to nonuniversal nature of growth exponent, we observe a significant modification to the scaling behavior of surface width with respect to erosion probability. For low erosion probability (≲ 0.1) a power law like divergence has been observed of the correlation growth time. This can be argued as limiting behavior of a generalized functional behavior of crossover time with erosion probability.
Stochastic Bose superfluid
Authors: Maćkowiak Jan
Published: January 2015

The ideas of Mitus et al. are exploited to define the liquid state as a state of matter, in which particles perform locally ordered motion. The presence of the liquid phase is accounted for by a stochastic term in the Hamiltonian, which simulates this property of a liquid. The Bogoliubov–Lee–Huang theory of He II, recently modified by use of effective temperature scale and more stringent reduction procedure (DHSET theory) is extended, by incorporating this term into the 4 He Hamiltonian. The resulting thermodynamics accounts for effects, which are beyond the scope of other He I and He II theories, e.g., the atomic momentum distribution and excitation spectrum have the form of diffused bands, similarly as in He II; the He I, theoretical heat capacity CV(T) is a convex function, with a minimum at T min > Tλ, which qualitatively simulates experimental He I heat capacity. Other thermodynamic functions are similar to those of DHSET theory.
Resonant tunneling dynamics and the related tunneling time
Authors: Xiao Zhi , Huang Hai , Lu Xiang-Xiang
Published: January 2015

In close analogy with optical Fabry–Pérot (FP) interferometer, we rederive the transmission and reflection coefficients of tunneling through a rectangular double barrier (RDB). Based on the same analogy, we also get an analytic finesse formula for its filtering capability of matter waves, and with this formula, we reproduce the RDB transmission rate in exactly the same form as that of FP interferometer. Compared with the numerical results obtained from the original finesse definition, we find the formula works well. Next, we turn to the elusive time issue in tunneling, and show that the "generalized Hartman effect" can be regarded as an artifact of the opaque limit βl → ∞. In the thin barrier approximation, phase (or dwell) time does depend on the free inter-barrier distance d asymptotically. Further, the analysis of transmission rate in the neighborhood of resonance shows that, phase (or dwell) time could be a good estimate of the resonance lifetime. The numerical results from the uncertainty principle support this statement. This fact can be viewed as a support to the idea that, phase (or dwell) time is a measure of lifetime of energy stored beneath the barrier. To confirm this result, we shrink RDB to a double Dirac δ-barrier. The landscape of the phase (or dwell) time in k and d axes fits excellently well with the lifetime estimates near the resonance. As a supplementary check, we also apply phase (or dwell) time formula to the rectangular well, where no obstacle exists to the propagation of particle. However, due to the self-interference induced by the common cavity-like structure, phase (or dwell) time calculation leads to a counterintuitive "slowing down" effect, which can be explained appropriately by the lifetime assumptions.
High Speed Min/Max Architecture Based on a Novel Comparator in 0.18-μm CMOS Process
Authors: Fathi Amir , Khoei Abdollah , Hadidi Khayrollah
Published: January 2015

This paper describes the design of a high speed min/max architecture based on a new current comparator. The main advantage of the proposed circuit which employs a novel preamplifier-latch comparator is the higher operating frequency feature in comparison with previous works. Because the comparator can work in voltage mode, the min/max structure can be redesigned either in voltage or current mode. The designed comparator is refreshed without any external clock. Therefore, it does not degrade the speed performance of proposed min/max structure. These features along with low power consumption qualify the proposed architecture to be widely used in high speed fuzzy logic controllers (FLCs). Post-layout simulation results confirm 3.4 GS/s comparison rate with 9-bit resolution for a 0.9 V peak-to-peak input signal range for the comparator and 800 MHz operating frequency for min/max circuit. The power consumption of whole structure is 912 μW from a 1.8 V power supply using TSMC 0.18-μm CMOS technology.
Analysis of Phase Noise in 28 nm CMOS LC Oscillator Differential Topologies: Armstrong, Colpitts, Hartley and Common-Source Cross-Coupled Pair
Authors: Chlis Ilias , Pepe Domenico , Zito Domenico
Published: January 2015

Comparative Phase Noise analyses of common-source cross-coupled pair, Colpitts, Hartley and Armstrong differential oscillator circuit topologies, designed in 28 nm bulk CMOS technology in a set of common conditions for operating frequencies in the range from 1 GHz to 100 GHz, are carried out in order to identify their relative performance. The impulse sensitivity function (ISF) is used to carry out qualitative and quantitative analyses of the noise contributions exhibited by each circuit component in each topology, allowing an understanding of their impact on phase noise. The comparative analyses show the existence of five distinct frequency regions in which the four topologies rank unevenly in terms of best phase noise performance. Moreover, the results obtained from the ISF show the impact of flicker noise contribution as the major effect leading to phase noise degradation in nanoscale CMOS LC oscillators.
Infrared Oscillators in Conventional Carbon Nanotube FET Technology
Authors: I'msaddak Lobna , Ben Issa Dalenda , Kachouri Abdennaceur , Samet Mounir , Samet Hekmet
Published: January 2015

This paper presents the design of C-CNTFET oscillator's arrays for infrared 'IR' technology. These arrays are contained by both of the LC-tank and the voltage control 'coupled N- and P-type C-CNTFET LC-tank' oscillators. In this paper, the analysis of the impact of CNT diameter variations and the nonlinear capacitances (C GD and C GS ) were introduced, especially on propagation time, oscillation frequency and power consumption. The C-CNTFET inverter, ring oscillator, LC-tank and coupled N- and P-type C-CNTFET LC-tank oscillator structures were designed and their speeding and performances have been investigated with the proposed n-type of C-CNTFET model supplied by a 0.5 V power voltage. Simulation results show that the n- and p-types LC-tank oscillator circuit designs achieved an approximately equal oscillation frequency, response time and power consumption. Whereas the coupled N- and P-type C-CNTFET LC-tank oscillator has the lowest power consumption equal to 0.13 μW, the highest oscillation frequency (10.08 THz) and the fastest response time (1.81 ps).
Improved dynamics and gravitational collapse of tachyon field coupled with a barotropic fluid
Authors: Marto João , Tavakoli Yaser , Moniz Paulo Vargas
Published: January 2015

We consider a spherically symmetric gravitational collapse of a tachyon field with an inverse square potential, which is coupled with a barotropic fluid. By employing an holonomy correction imported from loop quantum cosmology (LQC), we analyze the dynamics of the collapse within a semiclassical description. Using a dynamical system approach, we find that the stable fixed points given by the standard general relativistic setting turn into saddle points in the present context. This provides a new dynamics in contrast to the black hole and naked singularities solutions appearing in the classical model. Our results suggest that classical singularities can be avoided by quantum gravity effects and are replaced by a bounce. By a thorough numerical studies we show that, depending on the barotropic parameter γ, there exists a class of solutions corresponding to either a fluid or a tachyon dominated regimes. Furthermore, for the case γ ~ 1, we find an interesting tracking behavior between the tachyon and the fluid leading to a dust-like collapse. In addition, we show that, there exists a threshold scale which determines when an outward energy flux emerges, as a nonsingular black hole is forming, at the corresponding collapse final stages.
OPTIMUM COMPROMISE BETWEEN OPTICAL ABSORPTION AND ELECTRICAL PROPERTY OF THE PLANAR MULTI-HETEROJUNCTION ORGANIC SOLAR CELLS BASED WITH NEW THIAZOL DERIVATIVE, THE (2-THIOXO-3-N-(2-METHOXYPHENYL) THIAZOLIDIN-4-ONE), AS ELECTRON DONOR
Authors: TOUMI A. LAKHDAR , KHELIL A. , BERNÈDE J. C. , MOUCHAAL Y. , DJAFRI A. , TOUBAL K. , HELLAL N. , CATTIN L.
Published: January 2015

The synthesis of a new thiazol derivative, the (2-thioxo-3-N-(2-methoxyphenyl) thiazolidin-4-one) (called TH-2) is described. After characterization of the TH-2, the cyclic voltammetry study coupled with optical absorbance measurements show that its LUMO and HOMO are −3.5 and −5.5 respectively. Then the TH-2 is used as electron donor (ED) in organic solar cells (OSCs). The anode buffer layer being CuI the devices are based on the planar heterojunction TH-2/fullerene. Homogeneous amorphous films of TH-2 are obtained when it is deposited onto CuI. For an optimum TH-2 thickness of 20 nm, a power conversion efficiency of 0.42% is obtained. Then, in order to broaden the absorption range of the OSCs, it is coupled with the tetraphenyl-dibenzoperiflanthene, whose band structure matches the band structure of TH-2. Such new multilayer structure allows achieving a power conversion efficiency of 0.49%.
Helmholtz non-paraxial beam propagation method: An assessment
Authors: Chamorro-Posada Pedro , McDonald Graham S.
Published: January 2015

We present a performance evaluation of a non-paraxial beam propagation method suitable for the study of Helmholtz solitons. The analysis aims to determine the accuracy limits of the numerical scheme in terms of the maximum propagation angle addressable. Our investigation is based on the spectral representation of the exact soliton solutions and the study of their evolution at extreme propagation angles, together with the analysis of the propagation invariants. Based on these results, a simple heuristic criterion for the boundaries of the validity domain of the algorithm is provided.
𝒫𝒯-symmetric nonlocal gap solitons in optical lattices
Authors: Jisha Chandroth P. , Alberucci Alessandro , Assanto Gaetano
Published: January 2015

The existence and stability of 𝒫𝒯-symmetric gap solitons in a periodic structure with defocusing nonlocal nonlinearity are studied. It is found that solitons are in general unstable, their instability rate depending on the magnitude of the imaginary potential. For low values of the imaginary potential solitons survive over distances many times the Rayleigh distance, whereas for high values of the imaginary potential solitons develop an oscillatory instability, eventually leading to a transverse drift towards the gain region.
Removal of Methylene Blue and Orange-G from Waste Water Using Magnetic Biochar
Authors: Mubarak N. M. , Fo Y. T. , Al-Salim Hikmat Said , Sahu J. N. , Abdullah E. C. , Nizamuddin S. , Jayakumar N. S. , Ganesan P.
Published: January 2015

The study on the removal of methylene blue (MB) and orange-G dyes using magnetic biochar derived from the empty fruit bunch (EFB) was carried out. Process parameters such as pH, adsorbent dosage, agitation speed and contact time were optimized using Design-Expert Software v.6.0.8. The statistical analysis reveals that the optimum conditions for the maximum adsorption of MB are at pH 2 and pH 10, dosage 1.0 g, and agitation speed and contact time of 125 rpm and 120 min respectively. While for orange-G, at pH 2, dosage 1.0 g, and agitation speed and contact time of 125 rpm and 120 min respectively. The maximum adsorption capacity of 31.25 mg/g and 32.36 mg/g for MB and orange-G respectively. The adsorption kinetic for both dyes obeyed pseudo-second order.
Local contact homology and applications
Authors: Hryniewicz Umberto L. , Macarini Leonardo
Published: January 2015

We introduce a local version of contact homology for an isolated periodic orbit of the Reeb flow and prove that its rank is uniformly bounded for isolated iterations. Several applications are obtained, including a generalization of Gromoll–Meyer's theorem on the existence of infinitely many simple periodic orbits, resonance relations and conditions for the existence of non-hyperbolic periodic orbits. Most of the results of this paper remain conjectural until the foundational issues of Symplectic Field Theory are resolved.
Brachypodium distachyon and Setaria viridis: Model Genetic Systems for the Grasses
Authors: Brutnell Thomas P. , Bennetzen Jeffrey L. , Vogel John P.
Published: January 2015

The family of grasses encompasses the world's most important food, feed, and bioenergy crops, yet we are only now beginning to develop the genetic resources to explore the diversity of form and function that underlies economically important traits. Two emerging model systems, Brachypodium distachyon and Setaria viridis, promise to greatly accelerate the process of gene discovery in the grasses and to serve as bridges in the exploration of panicoid and pooid grasses, arguably two of the most important clades of plants from a food security perspective. We provide both a historical view of the development of plant model systems and highlight several recent reports that are providing these developing communities with the tools for gene discovery and pathway engineering.
The Polycomb Group Protein Regulatory Network
Authors: Mozgova Iva , Hennig Lars
Published: January 2015

Correct expression of specific sets of genes in time and space ensures the establishment and maintenance of cell identity, which is required for proper development of multicellular organisms. Polycomb and Trithorax group proteins form multisubunit complexes that antagonistically act in epigenetic gene repression and activation, respectively. The traditional view of Polycomb repressive complexes (PRCs) as executors of long-lasting and stable gene repression is being extended by evidence of flexible repression in response to developmental and environmental cues, increasing the complexity of mechanisms that ensure selective and properly timed PRC targeting and release of Polycomb repression. Here, we review advances in understanding of the composition, mechanisms of targeting, and function of plant PRCs and discuss the parallels and differences between plant and animal models.
Protein Export into Malaria Parasite–Infected Erythrocytes: Mechanisms and Functional Consequences
Authors: Spillman Natalie J. , Beck Josh R. , Goldberg Daniel E.
Published: January 2015

Phylum Apicomplexa comprises a large group of obligate intracellular parasites of high medical and veterinary importance. These organisms succeed intracellularly by effecting remarkable changes in a broad range of diverse host cells. The transformation of the host erythrocyte is particularly striking in the case of the malaria parasite Plasmodium falciparum. P. falciparum exports hundreds of proteins that mediate a complex cellular renovation marked by changes in the permeability, rigidity, and cytoadherence properties of the host erythrocyte. The past decade has seen enormous progress in understanding the identity and function of these exported effectors, as well as the mechanisms by which they are trafficked into the host cell. Here we review these advances, place them in the context of host manipulation by related apicomplexans, and propose key directions for future research.
Topological Crystalline Insulators and Topological Superconductors: From Concepts to Materials
Authors: Ando Yoichi , Fu Liang
Published: January 2015

In this review, we discuss recent progress in the explorations of topological materials beyond topological insulators; specifically, we focus on topological crystalline insulators and bulk topological superconductors. The basic concepts, model Hamiltonians, and novel electronic properties of these new topological materials are explained. The key role of the symmetries that underlie their topological properties is elucidated. Key issues in their materials realizations are also discussed.
Natural Antibody Repertoires: Development and Functional Role in Inhibiting Allergic Airway Disease
Authors: Kearney John F. , Patel Preeyam , Stefanov Emily K. , King R. Glenn
Published: January 2015

In this review we discuss the effects of microbial exposure on the B cell repertoire. Neonatal exposure to conserved bacterial carbohydrates and phospholipids permanently reprograms the natural antibody repertoire directed toward these antigens by clonal expansion, alterations in clonal dominance, and increased serum antibody levels. These epitopes are present not only in bacterial cell walls, but also in common environmental allergens. Neonatal immunization with bacterial polysaccharide vaccines results in attenuated allergic airway responses to fungi-, house dust mite-, and cockroach-associated allergens in mouse models. The similarities between mouse and human natural antibody repertoires suggest that reduced microbial exposure in children may have the opposite effect, providing a potential mechanistic explanation for the hygiene hypothesis. We propose that understanding the effects of childhood infections on the natural antibody repertoire and the mechanisms of antibody-mediated immunoregulation observed in allergy models will lead to the development of prevention/interventional strategies for treatment of allergic asthma.
Genetics and Epigenetics of Human Retinoblastoma
Authors: Benavente Claudia A. , Dyer Michael A.
Published: January 2015

Retinoblastoma is a pediatric tumor of the developing retina from which the genetic basis for cancer development was first described. Inactivation of both copies of the RB1 gene is the predominant initiating genetic lesion in retinoblastoma and is rate limiting for tumorigenesis. Recent whole-genome sequencing of retinoblastoma uncovered a tumor that had no coding-region mutations or focal chromosomal lesions other than in the RB1 gene, shifting the paradigm in the field. The retinoblastoma genome can be very stable; therefore, epigenetic deregulation of tumor-promoting pathways is required for tumorigenesis. This review highlights the genetic and epigenetic changes in retinoblastoma that have been reported, with special emphasis on recent whole-genome sequencing and epigenetic analyses that have identified novel candidate genes as potential therapeutic targets.
Pathobiology of Transfusion Reactions
Authors: Zimring James C. , Spitalnik Steven L.
Published: January 2015

Antibody-induced hemolytic transfusion reactions were first described over 300 years ago. Indeed, during its early evolution, transfusion medicine focused almost exclusively on issues in immunohematology to prevent such events. However, despite the best of efforts to avoid them, incompatible transfusions still occur, through both error and an inability to obtain compatible red blood cells for patients who are alloimmunized against multiple antigens. Because transfusing units of incompatible blood is potentially lethal, studies on human volunteers are not ethical. Thus, understanding of hemolytic transfusion reactions is generated through clinical cases, animal models, inference from related human pathologies, or studies using small volumes of transfused red blood cells. Over the past several decades, substantial new knowledge has been accumulated regarding the mechanisms of hemolysis, the metabolism of products of hemolysis, and the effects of both on recipient biology. Using these data sources, this article traces the historical generation of this knowledge and describes recent advances.
Protein Glycosylation in Cancer
Authors: Stowell Sean R. , Ju Tongzhong , Cummings Richard D.
Published: January 2015

Neoplastic transformation results in a wide variety of cellular alterations that impact the growth, survival, and general behavior of affected tissue. Although genetic alterations underpin the development of neoplastic disease, epigenetic changes can exert an equally significant effect on neoplastic transformation. Among neoplasia-associated epigenetic alterations, changes in cellular glycosylation have recently received attention as a key component of neoplastic progression. Alterations in glycosylation appear to not only directly impact cell growth and survival but also facilitate tumor-induced immunomodulation and eventual metastasis. Many of these changes may support neoplastic progression, and unique alterations in tumor-associated glycosylation may also serve as a distinct feature of cancer cells and therefore provide novel diagnostic and even therapeutic targets.