bluuebunny/crossref_metadata_2025 huggingface dataset:
High resolution imaging of few-layer graphene
Authors: Albrektsen O. , Eriksen R. L. , Novikov S. M. , Schall D. , Karl M. , Bozhevolnyi S. I. , Simonsen A. C.
Published: March 2012

In this work, we successfully demonstrate how imaging ellipsometry can be applied to obtain high-resolution thickness maps of few-layer graphene (FLG) samples, with the results being thoroughly validated in a comparative study using several complementary techniques: Optical reflection microscopy (ORM), atomic force microscopy (AFM), and scanning confocal Raman microscopy. The thickness map, revealing distinct terraces separated by steps corresponding to mono- and bilayers of graphene, is extracted from a pixel-to-pixel fitting of ellipsometric spectra using optical constants (n = 2.7 and k = 1.2) derived by fitting slab model calculations to averaged Ψ and Δ spectra collected in large homogenous sample areas. An analysis of reflection spectra and contrast images acquired by ORM confirm the results by quantifying the number of graphene layers and retrieving the FLG optical constants using a simple Fresnel-law-based slab model. The morphology results are further corroborated with AFM and Raman images, the latter unambiguously verifying that the thinnest part of the FLG consists of a graphene bilayer and providing additional information of electronic origin that might help identifying subtle FLG features, such as the presence of impurities, variations in stacking order, or rolling and folding at the FLG edges.
Reversible bistability of conductance on graphene/CuOx/Cu nanojunction
Authors: Kwon Sangku , Seo Hyungtak , Lee Hyunsoo , Jeon Ki-Joon , Young Park Jeong
Published: March 2012

We report that a nanojunction composed of graphene, copper oxide, and Cu substrate exhibits resistive switching behavior, revealed with conductive probe atomic force microscopy at ultrahigh vacuum. The current-voltage curve measured between the titanium nitride-coated tip and the nanojunction exhibited reversible bistable resistance states. We propose that the switching behavior is controlled by the migration of oxygen ions in the copper oxide layer, leading to the reversible formation/disruption of a CuOx-associated charge tunneling barrier, which is consistent with glancing-angle x-ray photoelectron spectroscopy analysis.
Linear stability analysis of a sub-to-supercritical jet
Authors: Roy Arnab , Segal Corin
Published: March 2012

A linear stability analysis was performed on a viscous jet injected into subcritical and supercritical atmospheres. The analysis complements previous experiments. The system is binary, so that effects of the second species on jet disintegration could be inspected in the analysis. The subcritical cases showed good correlation with previously solved cases of stability in viscous jets. The supercritical solutions, which have not yet been solved using a similar analysis, are found here through an asymptotic solution of the dispersion equation for exceedingly high Weber numbers.
Ti10Sb60Te30 for phase change memory with high-temperature data retention and rapid crystallization speed
Authors: Zhu Min , Wu Liangcai , Song Zhitang , Rao Feng , Cai Daolin , Peng Cheng , Zhou Xilin , Ren Kun , Song Sannian , liu Bo , Feng Songlin
Published: March 2012

With a high crystallization temperature of 211 °C, Ti10Sb60Te30 phase change material exhibits a data retention of 10-yr at 137 °C, which is much better than that of usual Ge2Sb2Te5. No other phase is formed in Ti10Sb60Te30 film except hexagonal Sb2Te phase. For Ti10Sb60Te30-based phase change memory cell, as short as 6 ns electric pulse can fulfill the Set operation, demonstrating an extremely rapid crystallization speed of Ti10Sb60Te30. The programming cycles can reach 2.2 × 104 with very short Set/Reset pulses of 100 ns/50 ns.
Plasmon resonant excitation in grating-gated AlN barrier transistors at terahertz frequency
Authors: Wang Lin , Hu Weida , Wang Jun , Wang Xiaodong , Wang Shaowei , Chen Xiaoshuang , Lu Wei
Published: March 2012

This paper describes the plasmon resonances in AlN/GaN high electron mobility transistors. It is shown that wide tunable resonances with the frequency located at terahertz band can be obtained in this material system. The results originate from the ultra-high electron density induced by the polarization effect and higher order plasmon excitation. At room temperature, the dielectric response caused by phonon-polariton interactions obliterates the higher order plasmon resonances at frequency higher than 10 THz. However, the viscosity contribution to the damping of plasmons is very small in these devices. Our results also show the potential of this device for terahertz applications.
A switch for epitaxial graphene electronics: Utilizing the silicon carbide substrate as transistor channel
Authors: Krach F. , Hertel S. , Waldmann D. , Jobst J. , Krieger M. , Reshanov S. , Schöner A. , Weber H. B.
Published: March 2012

Due to the lack of graphene transistors with large on/off ratio, we propose a concept employing both epitaxial graphene and its underlying substrate silicon carbide (SiC) as electronic materials. We demonstrate a simple, robust, and scalable transistor, in which graphene serves as electrodes and SiC as a semiconducting channel. The common interface has to be chosen such that it provides favorable charge injection. The insulator and gate functionality is realized by an ionic liquid gate for convenience but could be taken over by a solid gate stack. On/off ratios exceeding 44000 at room temperature are found.
Generalized conductivity model for polar semiconductors at terahertz frequencies
Authors: Lloyd-Hughes J.
Published: March 2012

A theoretical framework is presented that calculates the conductivity of polar semiconductors at terahertz frequencies without resorting to phenomenological fit parameters, using an expression derived from the Boltzmann transport equation. The time-dependent photoconductivity of InAs and the temperature dependent conductivity of n-doped GaAs are found experimentally by terahertz time-domain spectroscopy. The observed deviation from the Drude-Lorentz conductivity in these model systems is accounted for by this approach, which calculates the energy-dependent electron scattering time.
High Si and Ge n-type doping of GaN doping - Limits and impact on stress
Authors: Fritze S. , Dadgar A. , Witte H. , Bügler M. , Rohrbeck A. , Bläsing J. , Hoffmann A. , Krost A.
Published: March 2012

We report on GaN n-type doping using silane, germane, and isobutylgermane as Si and Ge dopants, respectively. A significant increase in tensile stress during growth is observed for Si doped samples while this is not the case for Ge doping. In addition, Ge can be doped up to 2.9 × 1020 cm−3, while Si doping leads to 3-D growth already at concentrations around 1.9 × 1019 cm−3. The free carrier concentration was determined by Hall-effect measurements, crystal quality, and structural properties by x-ray diffraction measurements. Additionally, secondary ion mass spectroscopy and Raman measurements were performed demonstrating the high material quality of Ge doped samples.
Adjustable nitrogen-vacancy induced magnetism in AlN
Authors: Liu Yu , Jiang Liangbao , Wang Gang , Zuo Sibin , Wang Wenjun , Chen Xiaolong
Published: March 2012

Nitrogen-vacancy-induced magnetism in AlN is investigated both theoretically and experimentally. First-principles calculations reveal that magnetic coupling between the vacancy-induced moments varies with the vacancy concentration. A sizable ferromagnetic coupling for nitrogen vacancies is found. Experimentally, the magnetism manipulation is realized accordingly by introducing vacancies through varying the nitrogen atmosphere in AlN whiskers. The vacancy control may be applicable to other III-V nitride semiconductors in tuning their magnetism.
Low magnetic field reversal of electric polarization in a Y-type hexaferrite
Authors: Wang Fen , Zou Tao , Yan Li-Qin , Liu Yi , Sun Young
Published: March 2012

We report on the magnetically tunable ferroelectricity and giant magnetoelectric sensitivity up to 250 K in a Y-type hexaferrite, BaSrCoZnFe11AlO22. Not only the magnitude but also the sign of electric polarization can be effectively controlled by applying low magnetic fields (a few hundreds of Oe) that modifies the spiral magnetic structures. The magnetically induced ferroelectricity is stabilized even in zero magnetic field. Decayless reproducible flipping of electric polarization by oscillating low magnetic fields is shown. The maximum linear magnetoelectric coefficient reaches a high value of ∼3.0 × 103 ps/m at 200 K.
An experimental and theoretical approach to the study of the photoacoustic signal produced by cancer cells
Authors: Solano Rafael Pérez , Ramirez-Perez Francisco I. , Castorena-Gonzalez Jorge A. , Anell Edgar Alvarado , Gutiérrez-Juárez Gerardo , Polo-Parada Luis
Published: March 2012

The distinctive spectral absorption characteristics of cancer cells make photoacoustic techniques useful for detection in vitro and in vivo. Here we report on our evaluation of the photoacoustic signal produced by a series of monolayers of different cell lines in vitro. Only the melanoma cell line HS936 produced a detectable photoacoustic signal in which amplitude was dependent on the number of cells. This finding appears to be related to the amount of melanin available in these cells. Other cell lines (i.e. HL60, SK-Mel-1, T47D, Hela, HT29 and PC12) exhibited values similar to a precursor of melanin (tyrosinase), but failed to produce sufficient melanin to generate a photoacoustic signal that could be distinguished from background noise. To better understand this phenomenon, we determined a formula for the time-domain photoacoustic wave equation for a monolayer of cells in a non-viscous fluid on the thermoelastic regime. The theoretical results showed that the amplitude and profile of the photoacoustic signal generated by a cell monolayer depended upon the number and distribution of the cells and the location of the point of detection. These findings help to provide a better understanding of the factors involved in the generation of a photoacoustic signal produced by different cells in vitro and in vivo.
Oral necrobacillosis ('lumpy jaw') in a free-ranging population of eastern grey kangaroos (Macropus giganteus) in Victoria
Authors: Borland D. , Coulson G. , Beveridge I.
Published: March 2012

A high prevalence (54%) of oral necrobacillosis, commonly referred to as ‘lumpy jaw’ based primarily on the presence of cranial osteological lesions, is reported from a free-living population of Macropus giganteus in Victoria. Lesions were found primarily in the maxillary bone and the mandible, in association with the rostral region of the dental arcade. Autopsy data provided additional evidence that the osteological lesions observed were due to oral necrobacillosis. Lesions were more common in older kangaroos. The study was carried out during a drought with limited pasture availability and heavy faecal contamination of pasture, conditions that may have contributed to the high prevalence of the disease.
Nitrogen metabolism and recycling in yaks (Bos grunniens) offered a forage - concentrate diet differing in N concentration
Authors: Guo X. S. , Zhang Y. , Zhou J. W. , Long R. J. , Xin G. S. , Qi B. , Ding L. M. , Wang H. C.
Published: March 2012

An experiment was conducted to characterise N use efficiency and quantify urea fluxes in yaks offered four levels of dietary N (1.43%, 1.97%, 2.45% and 2.90% of diet DM) in a 4 × 4 Latin square design. The incremental increase in N intake linearly increased N retention (P = 0.003) and the excretion of urinary N (P < 0.001), but no difference (P > 0.05) in faecal N excretion was observed in growing yaks fed any of the four diets. Microbial N production had quadratic (P < 0.001) responses to dietary N, characterised by the highest microbial N production occurring in the 1.97% N diet (P < 0.05). As the N content of the diet increased, the urinary excretion of urea increased from 13% to 27% of urea entry rate (quadratic, P < 0.001), whereas gastrointestinal entry urea returned to ornithine cycling decreased from 46% to 40% (linear, P < 0.001), and the gastrointestinal entry urea used for anabolism increased from 50% to 56% (linear, P < 0.001). Gastrointestinal entry urea incorporated into bacterial N decreased linearly (P < 0.001) with incremental increase in N intake, and the greatest concentration (23.5%) of bacterial N originating from plasma urea N was in yaks fed the 1.43% N diet. As much as 87% of the urea synthesised in the liver was returned to the gastrointestinal tract when the yaks were fed a diet with 1.43% N (1.1 times the maintenance N level). Moreover, constantly greater urea production than the intake of digestible N, and the gastrointestinal-urea clearance than the kidney-urea clearance were observed, respectively, in the growing yaks, regardless of the level of N intake. These results suggest that yaks might be more efficient at utilising N under harsh environment than are cattle.
An initial investigation on rumen fermentation pattern and methane emission of sheep offered diets containing urea or nitrate as the nitrogen source
Authors: Li L. , Davis J. , Nolan J. , Hegarty R.
Published: March 2012

The effects of dietary nitrate and of urea on rumen fermentation pattern and enteric methane production were investigated using 4-month-old ewe lambs. Ten lambs were allocated into two groups (n = 5) and each group was offered one of two isonitrogenous and isoenergetic diets containing either 1.5% urea (T1) or 3% calcium nitrate (T2). Methane production was estimated using open-circuit respiration chambers after 6 weeks of feeding. No difference in nitrogen (N) balance, apparent digestibility of N or microbial N outflow existed between treatments (P > 0.05). Animals offered the T2 diet lost less energy through methane than did those fed the T1 diet (P < 0.05). Total volatile fatty acid concentration, molar proportion of propionate, and the molar ratio of acetate to propionate in rumen fluid were not affected by dietary N source. Compared with urea inclusion, nitrate inclusion caused a significantly higher acetate and lower butyrate percentage in rumen volatile fatty acid. Nitrate supplementation tended to lower methane production by ~7.7 L/day relative to urea supplementation (P = 0.06). Methane yield (L/kg DM intake) was reduced (P < 0.05) by 35.4% when 1.5% urea was replaced by 3% calcium nitrate in the diet. Emission intensity (L methane/kg liveweight gain) was ~17.3% lower in the nitrate-supplemented sheep when compared with urea-fed sheep; however, the reduction was not statistically significant (P > 0.05). This study confirms that the presence of nitrate in the diet inhibits enteric methane production. As no clinical symptoms of nitrite toxicity were observed and sheep receiving nitrate-supplemented diet had similar growth to those consuming urea-supplemented diet, it is concluded that 3% calcium nitrate can replace 1.5% urea as a means of meeting ruminal N requirements and of reducing enteric methane emissions from sheep, provided animals are acclimated to nitrate gradually.
Effects of afforestation with Eucalyptus grandis on soil physicochemical and microbiological properties
Authors: Zhang Danju , Zhang Jian , Yang Wanqin , Wu Fuzhong
Published: March 2012

It is generally believed that plantations of Eucalyptus bring about a decrease in soil fertility. Soil physicochemical and microbiological properties were measured across a range of E. grandis plantation ages (1–10 years) in south-western China to determine whether and how eucalypt afforestation of agricultural land affected the soil fertility. The results indicate that afforestation with E. grandis caused changes in soil properties with soil depth, and the changes were dependent on the stand age. Soil bulk density decreased significantly, but water-holding capacity increased significantly with time. Soil organic matter content, C : N ratio, and soil microbial biomass C and N concentrations showed an initial phase of decline and then increased significantly over time in the upper soil layers of E. grandis plantations aged from 1 to 4 or 5 years. Soil pH in E. grandis plantations did not change significantly with stand age or soil layer. Cation exchange capacity in the upper soil layer of E. grandis plantations increased significantly over time. Total exchangeable bases and base saturation in the soil decreased significantly with depth and with increasing plantation age. Furthermore, E. grandis afforestation of arable soils had no significant effects on total N, total P, and available P contents. The requirements of the trees, understory microenvironmental conditions, and allelopathic effects might play important roles in the dynamic changes of soil physicochemical and microbiological properties. The results demonstrate the progressive development of processes that lead to the restoration of soil fertility following E. grandis afforestation of arable soils. However, most of the properties measured for the afforested soils resembled the properties of arable soils and did not resemble those of the soil of control forests. Thus, reversion of soil properties in the study plantations is likely to require a considerable period of time. Long-term research is needed to understand changes in the soil properties resulting from afforestation with Eucalyptus and to predict future trends.
Effects of rainfall harvesting and mulching technologies on soil water, temperature, and maize yield in Loess Plateau region of China
Authors: Li Rong , Hou Xianqing , Jia Zhikuan , Han Qingfang , Yang Baoping
Published: March 2012

Precipitation is the major factor limiting crop growth in the semi-arid Loess Plateau region of China. Ridge-and-furrow rainfall harvesting systems (RFRHS) with mulches are used to increase water availability to crops, thereby improving and stabilising agricultural production in the semi-arid region of China. We conducted a field experiment from 2007 to 2010 in the Weibei Highlands of China, to determine the influence of RFRHS with different mulching patterns on soil water content, temperature, water-use efficiency, and maize yield (Zea mays L.). Ridges were covered with standard plastic film in all RFRHS treatments, while different furrow treatments were mulched with standard plastic film (PP), biodegradable film (PB), maize straw (PS), or liquid film (PL), or left uncovered (P). A conventional flat treatment without mulching was used as the control. In the early stage of maize growth, the topsoil temperature (5–20 cm) under PP and PB was significantly (P < 0.05) higher than under the control, whereas the soil temperature under PS was significantly (P < 0.05) lower than under the control. Treatments PP, PB, and PS also significantly improved soil water content during early growth stages. There was no significant difference in soil water content between PS and the control during middle and late growth stages. However, the soil water content in the deep soil layers with PP and PB was less than that of the control. Soil temperature and soil water content of PL and P were slightly higher than the control during the whole growing season. Higher maize yield and water-use efficiency was found with PP, PB, and PS. Compared with the control, the 4-year average maize yield with PP, PB, and PS was significantly (P < 0.05) increased, by 35, 35, and 34%, while the average water-use efficiency increased by 30, 31, and 29%, respectively. Net income was highest with PS, followed by PB, where the 4-year average net income increased by 2779 and 2752 Chinese yuan (CNY) ha–1, respectively, compared with the control. Soil water and temperature conditions were improved, while the maize yield and net income were increased, when ridges were covered with standard plastic film and the furrows were mulched with either biodegradable film or straw. Therefore, these two treatments are considered most efficient for maize production in the drought-prone, semi-humid region of the Loess Plateau, China.
Re-examining the ‘origins’ of the prenominal periphrastic possessive construction Jan z’n boek in Dutch
Authors: Hendriks Jennifer
Published: March 2012

The dative reanalysis ‘origins’ explanation for prenominal periphrastic possessive constructions (PPPCs) in Dutch has been maintained for well over a century. This paper brings new evidence to bear on this hypothesis, arguing that while genitive relational case marking on the possessor NP in earlier Dutch PPPCs is clearly attested, we lack evidence that the dative was used in this way. Instead, two types of case marking strategies are in use in earlier Dutch PPPCs — one relational and one concordial — as a solution to case conflict in instances which would otherwise give rise to double case marking. Historical and present-day dialect data from German is also examined to address the common assumption that developments in Dutch PPPCs mirrored those in German. Similar to Dutch, clear evidence attests to genitive relational case marking in earlier German PPPCs.
On the development of the Romance demonstrative systems
Authors: Stavinschi Alexandra
Published: March 2012

The paper provides a structured account of the evolution of the Romance pronominal/adnominal demonstrative systems, using both the analysis of medieval corpora and recent fieldwork. It identifies the mechanisms involved, building on a detailed analysis of the textual and extra-textual usage of demonstratives, which gives new insight into the nature of deixis and anaphora. The evidence shows that the genetic relation between deictics and anaphorics is not unidirectional: not only can anaphors originate from deictics, the reverse can also be shown to hold true, with pure anaphorics appearing to be a viable source for second-person deictics. The main driving force in the process is subjectification, which conditions the development at every stage. The evolution follows predictable pathways and turns out to be cyclic: three main recurrent patterns are clearly identifiable for all the varieties investigated.
Agreement processes in English and Spanish
Authors: Outeiral Sara María Riveiro , Acuña-Fariña Juan Carlos
Published: March 2012

The nature of agreement has been the topic of extensive debate in the recent literature of both linguistics and psycholinguistics. In contrast to either fully syntactic or fully semantic accounts, so-called ‘constraint-satisfaction models’ (Haskell et al. 2010, among others) posit that all grammatical encoding is subject to a number of influences (syntax, semantics, pragmatics, frequency, etc.) which compete to dominate every computation, including agreement processes. After briefly considering psycholinguistic work on attraction (Wagers et al. 2009 and references therein), we try to shed light on this debate by observing how agreement operates in certain structures which were previously tested by Berg (1998) in a comparison of German and English. Here, we establish the same type of comparison between Spanish and English, and conclude that: 1. agreement is resolved after a constant tug-of-war between the syntactic and the semantic, a process in which semantics is likely to interfere in formal operations when these are performed in the context of a weak morphology; 2. agreement resolution is effectively subject to various linguistic influences, including the morphological characteristics of each language, but also the domain in which agreement is realised; and 3. agreement is responsible for shaping overall linguistic systems in the sense that, as noted by Berg, it may motivate left–orientation (as in English) or not (as in Spanish) as a general default strategy for locating subjects.
‘Con il volere di Dio’: Bernardo Provenzano and religious symbolic ritual
Authors: Merlino Rossella
Published: March 2012

This article adopts an interdisciplinary approach to analyse the symbolic religious language utilised by mafia boss Bernardo Provenzano in his social interactions with the lower echelons of the Sicilian mafia. When Provenzano assumed control of Cosa Nostra in the 1990s, he inherited an organisation severely diminished by a decade of internal conflicts, violence and the arrest of numerous leaders. The article argues that religious performative behaviour and language were used by the mafia boss to establish his leadership over Cosa Nostra, reshape its internal structure, and thereby revitalise an organisation in apparent terminal decline.
Patterns of teaching style and active teaching: do they differ across subjects in low and high performing primary schools in Kenya?
Authors: Ngware Moses W. , Mutisya Maurice , Oketch Moses
Published: March 2012

This paper focuses on the patterns of teaching styles and active teaching across subjects and between low and high performing schools in an attempt to examine what accounts for differences in performance between schools which are within the same locality. It uses data collected in 72
primary schools spread across six districts in Kenya. Video recordings of 213 lessons in maths (72), science (71) and English (70), and interviews with subject teachers in primary schools, were used to generate evidence on patterns of teaching styles and active teaching. Results show that
teaching practice across subjects is inclined towards the command and task styles that do not promote critical thinking among learners. The dominant teaching activity was individual seat work in maths lessons; recitation in English lessons; and whole class chorus in science lessons. Overall,
active teaching accounted for 62% of the lesson time. The one way ANOVA results show insignificant variation between subjects and school category on active teaching, and therefore this may not be the source of differential performance between low and high performing schools.
What explains gender gaps in maths achievement in primary schools in Kenya?
Authors: Ngware Moses W. , Ciera James , Abuya Benta A. , Oketch Moses , Mutisya Maurice
Published: March 2012

This paper aims to improve the understanding of classroom-based gender differences that may lead to differential opportunities to learn provided to girls and boys in low and high performing primary schools in Kenya. The paper uses an opportunity to learn framework and tests the hypothesis
that teaching practices and classroom interactions explain gender gaps in maths achievement in Kenya. The data used is obtained from a cross sectional study involving video recordings of 70 lessons in mathematics, students' scores in a maths test and interviews with subject teachers in Kenyan
primary schools randomly selected from six districts. Results show that gender gaps in maths achievement are more evidenced in the area of measurement. The gaps are more pronounced among low achievers in favour of boys. The most revealing finding is that entry achievement level is the main
source of gender gaps in maths learning outcomes, implying that girls start at lower levels than boys and this gap is not closed by school. The policy implication to education is that boys have better chances of transition to secondary school and tertiary levels than girls, and consequently,
there are broader gender disparities than can be closed by pro-gender education policies.
Heat acclimation responses of an ultra‐endurance running group preparing for hot desert‐based competition
Authors: Costa Ricardo J. S. , Crockford Michael J. , Moore Jonathan P. , Walsh Neil P.
Published: March 2012

Heat acclimation induces adaptations that improve exercise tolerance in hot conditions. Here we report novel findings into the effects of ultra‐marathon specific exercise load in increasing hot ambient conditions on indices of heat acclimation. Six male ultra‐endurance runners completed a standard pre‐acclimation protocol at 20°C ambient temperature (T amb), followed by a heat acclimation protocol consisting of six 2 h running exercise‐heat exposures (EH) at 60% O2max on a motorised treadmill in an environmental chamber. Three EH were performed at 30°C T amb, followed by another three EH at 35°C T amb. EH were separated by 48 h within T amb and 72 h between T amb. Nude body mass (NBM), blood and urine samples were collected pre‐exercise; while NBM and urine were collected post‐exercise. Rectal temperature (T re), heart rate (HR), thermal comfort rating (TCR) and rating of perceived exertion were measured pre‐exercise and monitored every 5 min during exercise. Water was provided ad libitum during exercise. Data were analysed using a repeated measures and one‐way analysis of variance (ANOVA), with post hoc Tukey's HSD. Significance was accepted as P< 0.05. Overall mean T re was significantly lower during 30°C EH3 and 35°C EH3 compared with their respective EH1 (−0.20 and−0.23°C, respectively; P<0.05). Similarly, overall mean HR was significantly lower during 30°C EH3 and 35°C EH3 compared with their respective EH1 (8 and 7 bpm respectively; P<0.05). A significant decrease in overall mean TCR was observed during 35°C EH3, compared with 35°C EH1 (P< 0.05). Significant increases in resting pre‐exercise plasma volume (estimated from Hb and Hct) were observed by 30°C EH3 (7.9%; P< 0.05). Thereafter, plasma volume remained above baseline throughout the experimental protocol. Two EH of 2 h at 60% O2max at 30°C T amb was sufficient to initiate heat acclimation in all ultra‐endurance runners. Further, heat acclimation responses occurred with increasing EH to 35°C T amb. Preventing exertional heat illnesses and optimising performance outcomes in ultra‐endurance runners may occur with exposure to at least 2 h of exercise‐heat stress on at least two occasions in the days leading up to multi‐stage ultra‐marathon competition in the heat.
Investigating reaction times and stopping performance of skiers and snowboarders
Authors: Schmitt Kai‐Uwe , Muser Markus
Published: March 2012

On‐slope experiments were performed to determine the reaction time of recreational skiers and snowboarders. Volunteers riding a slope were instructed to brake to a complete stop after a visual and acoustic signal. Reaction time and parameters such as the duration of the braking manoeuvre and the corresponding stopping distance were recorded. A total of 70 runs were evaluated, including 37 runs with snowboarders and 33 runs with skiers. The average time until the first observable reaction (reaction time) for all athletes was 420 ms; there was no statistically significant difference between skiers and snowboarders. Participants needed on average an additional 470 ms until they actually started braking. Snowboarders needed significantly more time to prepare for braking than skiers and it took snowboarders significantly longer to stop (p<0.05). In line with these findings, snowboarders also exhibited significantly less deceleration during braking compared to skiers. This study quantifies the reaction times of skiers and snowboarders and provides data related to braking of skiers and snowboarders. This data is useful for the development of injury prevention measures and can be used to ensure reasonable slope design.
Anthropometric variables and their relationship to performance and ability in male surfers
Authors: Barlow Matthew John , Findlay Malcolm , Gresty Karen , Cooke Carlton
Published: March 2012

The aim of this study was to evaluate the anthropometric profiles of male surfers and to investigate the relationship of these measures with performance and ability. Following institutional ethical approval, 79 male surfers underwent anthropometric assessment. These surfers composed of three sub‐groups of professional (n=17; age: 34.12, s =3.81 years, stature: 177.28, s =6.29 cm; body mass: 78.57, s =7.17 kg), junior national level (n=15; age: 15.61, s =1.06 years, stature: 173.86, s =5.72 cm; body mass: 63.27, s =7.17 kg) and intermediate level surfers (n=47; age: 22.47, s =2.80 years, stature: 179.90, s =5.41; body mass: 77.83, s =9.43 kg). The mean somatotype values for the different groups of surfers were found to be 2.48, 5.00 and 1.03 for the professional surfers; 2.18, 3.72 and 3.24 for the junior national surfers and 2.79, 3.57 and 2.42 for the intermediate surfers. Professional surfers were significantly (P < 0.01) more mesomorphic and less ectomorphic than intermediate level surfers. Significant correlations were observed between endomorphy (r = −0.399, P < 0.01), sum of six skinfolds (r = −0.341, P < 0.05), and body fat percentage (r = −0.380, P < 0.01) and the rating of ability among the intermediate group of surfers. Across all participants, the rating of surfer ability was significantly correlated with endomorphy (r = −0.366, P≤0.01), mesomorphy (r = 0.442, P < 0.01), sum of six skinfolds (r = −0.274, P < 0.05) and body fat percentage (r = −0.268, P < 0.05). Findings suggest that the levels of adiposity and muscularity may influence the potential for progression between intermediate and professional‐level surfing performance.
Punished: Policing the Lives of Black and Latino Boys by Victor M. Rios
Authors: Kindle Peter
Published: March 2012

The societal consequences of the War on Drugs may already be clear to the majority who read this review: mass incarceration, escalating correctional and other criminal justice costs, neighborhood deterioration, and the erosion of basic American civil liberties. In contrast with this societal perspective, Victor Rios has provided a powerful microscopic perspective from shadowing the lives of 40 African American and Latino adolescents for three years (2002 to 2005) in Oakland, California. Participants were recruited through snowball techniques and the inclusion criteria required previous identification as an at-risk delinquent. Thirty had been arrested but all lived in highcrime neighborhoods and had siblings or friends who had been involved with crime. Nineteen reported gang membership. In addition to the 40 participants he shadowed, Rios interviewed an additional 78 youths of which two-thirds reported gang membership. Their stories and Rios’s conclusions contain much that can inform social workers, law enforcement and probation officers, school personnel, and others concerned about addressing the social problems anchored in poor, urban communities.
Hectd1 regulates intracellular localization and secretion of Hsp90 to control cellular behavior of the cranial mesenchyme
Authors: Sarkar Anjali A. , Zohn Irene E.
Published: March 2012

Hectd1 mutant mouse embryos exhibit the neural tube defect exencephaly associated with abnormal cranial mesenchyme. Cellular rearrangements in cranial mesenchyme are essential during neurulation for elevation of the neural folds. Here we investigate the molecular basis of the abnormal behavior of Hectd1 mutant cranial mesenchyme. We demonstrate that Hectd1 is a functional ubiquitin ligase and that one of its substrates is Hsp90, a chaperone protein with both intra- and extracellular clients. Extracellular Hsp90 enhances migration of multiple cell types. In mutant cranial mesenchyme cells, both secretion of Hsp90 and emigration of cells from cranial mesenchyme explants were enhanced. Importantly, we show that this enhanced emigration was highly dependent on the excess Hsp90 secreted from mutant cells. Together, our data set forth a model whereby increased secretion of Hsp90 in the cranial mesenchyme of Hectd1 mutants is responsible, at least in part, for the altered organization and behavior of these cells and provides a potential molecular mechanism underlying the neural tube defect.
‘Reading’ in the digital environment
Authors: NICHOLAS David , CLARK David
Published: March 2012

For ten years CIBER has been studying the logs of scholarly publishers, and what was clear from the very beginning was that scholars conducted very brief visits to websites and spent very little time reading when there, yet publishers envisaged they would dwell; and if not dwell, then at least deep read the PDF later. Yet CIBER's research points to the fact that ‘lite’ reading is in fact endemic: younger people prefer it anyway and older people are getting used to it for the speed and convenience it brings. PDFs are largely a means of archiving and collecting and are not the gold standard reading metric people think. User satisfaction comes not from a PDF but from the ability to deep dive into a site and snatch what you are interested as quickly as possible. Publishers are still not comfortable with that and this article helps explain why they have to be.
Pricing principles used by scholarly open access publishers
Authors: BJÖRK Bo‐Christer , SOLOMON David
Published: March 2012

The article processing charge (APC) is currently the primary method of funding professionally published open access (OA) peer‐reviewed journals. The pricing principles of 77 OA publishers publishing over 1,000 journals using APCs were studied and classified. The most commonly used pricing method is a single fixed fee, which can either be the same for all of a publisher's journals or individually determined for each journal. Fees are usually only levied for publication of accepted papers, but there are some journals that also charge submission fees. Instead of fixed prices, many publishers charge by the page or have multi‐tiered fees depending on the length of articles. The country of origin of the author can also influence the pricing, in order to facilitate publishing for authors from developing countries.
Book Reviews
Authors: ESPOSITO Joseph J.
Published: March 2012

Patron‐driven Acquisitions: History and Best Practices David A. Swords (editor) Boston, De Gruyter Saur, 2011, 205pp. ISBN 978‐3‐11‐025301‐6, $102 US, £66.50 UK, hbk
Book Reviews
Authors: SAUNDERS Joss
Published: March 2012

Moral Rights: Principles, Practice and New Technology Mira T. Sundara Rajan Oxford, Oxford University Press, 2011, 549 pp. ISBN 978‐0‐19‐539031‐5, £95, $150 pbk
Observation of global Alfvén eigenmode avalanche events on the National Spherical Torus Experiment
Authors: Fredrickson E.D. , Gorelenkov N.N. , Belova E. , Crocker N.A. , Kubota S. , Kramer G.J. , LeBlanc B. , Bell R.E. , Podesta M. , Yuh H. , Levinton F.
Published: March 2012

Instabilities excited by the fast-ion population on NSTX (Ono et al
2000 Nucl. Fusion
40 557) extend from low-frequency energetic particle modes (EPMs) at tens of kHz through toroidal Alfvén eigenmodes (TAEs) in the range 50–150 kHz to global and compressional Alfvén eigenmodes (GAE and CAE) in the frequency range 0.3–2.5 MHz, or roughly 0.1ωci to 0.7ωci. The GAE instabilities exhibit complex non-linear behaviour, including onset of strong growth above an amplitude threshold. This is conjectured to occur when resonance regions in phase space start to overlap, resulting in enhanced rapid growth and redistribution of energetic particles, a process referred to as an ‘avalanche’ (Berk et al
1995 Nucl. Fusion
35 1661). The GAE are suppressed following the avalanche, suggesting depletion of the fast-ion population resonantly driving the modes, and in some instances the GAE bursts appear to trigger lower frequency TAE avalanches or EPMs, suggesting some significant redistribution of fast ions in phase space has occurred. These are the first reported observations of avalanching behaviour for an instability driven through the Doppler-shifted cyclotron resonance. This paper also provides internal measurements of GAE structure showing that the mode amplitude peaks towards the plasma core.
Determination of electron thermal diffusivity at the WEGA stellarator
Authors: Zhang D. , Glaubitz M. , Laqua H.P. , Marsen S. , Otte M. , Stange T.
Published: March 2012

For determining the thermal diffusivity in WEGA the electron cyclotron resonance heating power from a 28 GHz gyrotron is square-wave modulated to provide a periodically varying energy source at the plasma centre causing a modulation mainly of the electron temperature T
e. A fast Si-diode bolometer system, whose 16 channel view the entire plasma cross-section, is employed to monitor the heat propagation process. A fast Fourier transform analysis shows clear coherency of the line-integrated signals among different channels and monotonic radial increment of the phase delays of the fundamental components in the central channel signals, allowing the determination of the electron thermal diffusivity coefficient D. A purely diffusive heat transport is assumed and is simulated using a Monte Carlo method. The thermal diffusivity is determined by matching the simulated results to the measured ones. A typical value of D = 1.9 m2 s−1 is obtained. This value is then compared with the result based on a local power balance analysis. Within the error bars the local power balance calculation yields a similar diffusivity value. The limitations and conditions of using bolometric diagnostic for this purpose are discussed.
Cognitive function in patients with decompensated heart failure: the Cognitive Impairment in Heart Failure (CogImpair‐HF) study
Authors: Kindermann Ingrid , Fischer Denise , Karbach Julia , Link Andreas , Walenta Katrin , Barth Christine , Ukena Christian , Mahfoud Felix , Köllner Volker , Kindermann Michael , Böhm Michael
Published: March 2012

Aims

The objective of this study was to examine cognitive and psychological processes systematically in patients with decompensated chronic heart failure (CHF) and to document changes in cognitive function after compensation. Executive functions, episodic memory, and attention are impaired in patients with stable CHF, influencing health behaviour and disease management. Cognitive function and psychological co‐morbidities are associated with hospitalization, disability, and mortality.

Methods and results

Cognitive performance, self‐perceived quality of life, and depression were compared in 20 patients with decompensated CHF [ejection fraction (EF) 27 ± 8%, N‐terminal pro brain natriuretic peptide (NT‐proBNP) 10 880 pg/mL, interquartile range (4495–13 683)] before and after compensation, 20 age‐ and gender‐matched stable CHF patients [New York Heart Assocation (NYHA) III–IV, EF 32 ± 10%, NT‐proBNP 1881 pg/mL (323–1502)], and 20 healthy controls (EF 70 ± 5%). Patients with decompensated CHF showed significantly poorer performance in terms of short‐term memory, working memory, executive control, and processing speed (P < 0.05) compared with stable CHF patients. Compensation improved the cognitive performance of decompensated CHF patients up to the level of patients with stable CHF. Compared with healthy controls, both patient groups were affected with respect to episodic memory (P < 0.0001) and fluid intelligence (P < 0.01).

Conclusion

Decompensated heart failure patients are highly impaired in cognitive functioning, which improves but does not normalize after compensation. Neuropsychological diagnostics delivers important details for daily life activities and might identify individuals deserving special care.
Compressive strength of delaminated aerospace composites
Authors: Butler Richard , Rhead Andrew T. , Liu Wenli , Kontis Nikolaos
Published: March 2012

An efficient analytical model is described which predicts the value of compressive strain below which buckle-driven propagation of delaminations in aerospace composites will not occur. An extension of this efficient strip model which accounts for propagation transverse to the direction of applied compression is derived. In order to provide validation for the strip model a number of laminates were artificially delaminated producing a range of thin anisotropic sub-laminates made up of 0°, ±45° and 90° plies that displayed varied buckling and delamination propagation phenomena. These laminates were subsequently subject to experimental compression testing and nonlinear finite element analysis (FEA) using cohesive elements. Comparison of strip model results with those from experiments indicates that the model can conservatively predict the strain at which propagation occurs to within 10 per cent of experimental values provided (i) the thin-film assumption made in the modelling methodology holds and (ii) full elastic coupling effects do not play a significant role in the post-buckling of the sub-laminate. With such provision, the model was more accurate and produced fewer non-conservative results than FEA. The accuracy and efficiency of the model make it well suited to application in optimum ply-stacking algorithms to maximize laminate strength.
Compliant shell mechanisms
Authors: Seffen K. A.
Published: March 2012

This paper describes a class of lightweight structures known as compliant shell mechanisms. These are novel reconfigurable solutions for advanced structures, such as morphing shells and deployable membranes. They have local, discrete corrugations, which articulate and deform to achieve dramatic changes in the overall shape of the shell. The unique kinematics are considered by highlighting examples and by performing analysis using established and novel concepts, and favourable predictions of shape compared with laboratory models are demonstrated.
Geometric modelling of kink banding in laminated structures
Authors: Wadee M. Ahmer , Völlmecke Christina , Haley Joseph F. , Yiatros Stylianos
Published: March 2012

An analytical model founded on geometric and potential energy principles for kink band deformation in laminated composite struts is presented. It is adapted from an earlier successful study on confined layered structures that was formulated to model kink band formation in the folding of geological layers. This study's principal aim was to explore the underlying mechanisms governing the kinking response of flat, laminated components comprising unidirectional composite laminae. A pilot parametric study indicates that the key features of the mechanical response are captured well and that quantitative comparisons with experiments presented in the literature are highly encouraging.
Numerical optimization approach to modelling delamination and buckling of geometrically constrained structures
Authors: Mullineux G. , Hicks B. J. , Berry C.
Published: March 2012

Understanding what happens in terms of delamination during buckling of laminate materials is of importance across a range of engineering sectors. Normally concern is that the strength of the material is not significantly impaired. Carton-board is a material with a laminate structure and, in the initial creation of carton nets, the board is creased in order to weaken the structure. This means that when the carton is eventually folded into its three-dimensional form, correct folding occurs along the weakened crease lines. Understanding what happens during creasing and folding is made difficult by the nonlinear nature of the material properties. This paper considers a simplified approach which extends the idea of minimizing internal energy so that the effects of delamination can be handled. This allows a simulation which reproduces the form of buckling–delamination observed in practice and the form of the torque–rotation relation.
Stripe patterns and a projection-valued formulation of the eikonal equation
Authors: Peletier Mark A. , Veneroni Marco
Published: March 2012

We describe recent work on striped patterns in a system of block copolymers. A by-product of the characterization of such patterns is a new formulation of the eikonal equation. In this formulation, the unknown is a field of projection matrices of the form
P
=
e
⊗
e
, where
e
is a unit vector field. We describe how this formulation is better adapted to the description of striped patterns than the classical eikonal equation, and illustrate this with examples.