bluuebunny/crossref_metadata_2025 huggingface dataset:
A new scenario framework for climate change research: background, process, and future directions
Authors: Ebi Kristie L. , Hallegatte Stephane , Kram Tom , Arnell Nigel W. , Carter Timothy R. , Edmonds Jae , Kriegler Elmar , Mathur Ritu , O’Neill Brian C. , Riahi Keywan , Winkler Harald , Van Vuuren Detlef P. , Zwickel Timm
Published: September 2013

The scientific community is developing new global, regional, and sectoral scenarios to facilitate interdisciplinary research and assessment to explore the range of possible future climates and related physical changes that could pose risks to human and natural systems; how these changes could interact with social, economic, and environmental development pathways; the degree to which mitigation and adaptation policies can avoid and reduce risks; the costs and benefits of various policy mixes; and the relationship of future climate change adaptation and mitigation policy responses with sustainable development. This paper provides the background to and process of developing the conceptual framework for these scenarios, as described in the three subsequent papers in this Special Issue (Van Vuuren et al., 2013; O’Neill et al., 2013; Kriegler et al., Submitted for publication in this special issue). The paper also discusses research needs to further develop, apply, and revise this framework in an iterative and open-ended process. A key goal of the framework design and its future development is to facilitate the collaboration of climate change researchers from a broad range of perspectives and disciplines to develop policy- and decision-relevant scenarios and explore the challenges and opportunities human and natural systems could face with additional climate change.
Testing the Antioxidant Effect of Essential Oils and BHT on Corn Oil at Frying Temperatures: a Response Surface Methodology
Authors: İnanç Tuğba , Maskan Medeni
Published: September 2013

Food habits worldwide have increased the demand for oxidative‐resistant oils that can be used for deep‐frying. Oxidative stability in oils can be improved by changing the fatty acid composition of the oil or by adding natural antioxidants to the oil. In this study, the effect of essential oils of seven plants; cinnamon, rosemary, sage, turmeric, clove, thyme and oregano enriched with carvacrol on the oxidative stability of corn oil at frying temperatures were studied. Experiments were conducted by using a PetroOxy device, a rapid small scale oxidation stability test. A central composite design was used to evaluate the effects of concentration of essential oil (X1: 1,500–5,000 ppm) and temperature (X2: 150–180 °C), on the induction time of corn oil. In order to compare the results with the synthetic antioxidant, butylated hydroxy toluene (BHT), another design was made with a concentration range (60–350 ppm) containing the legal upper limit of BHT, 200 ppm. Induction periods obtained from the accelerated oxidation test revealed that increasing temperature decreased the induction time of all the samples. However, the essential oils except for oregano oil had no significant antioxidative effect on corn oil, probably due to a lower content of their active components. The antioxidative effect of oregano oil was also found to be higher compared to BHT. At very high temperatures (e.g., 180 °C), the concentration of antioxidants had no effect on the induction periods.
Increasing Tree Cover in Degrading Landscapes: ‘Integration’ and ‘Intensification’ of Smallholder Forest Culture in the Alutilla Valley, Matiranga, Bangladesh
Authors: Rahman Syed Ajijur , Rahman Md Faizar , Sunderland Terry
Published: September 2013

Research was conducted in Alutilla Valley in eastern Bangladesh to identify the nature of existing agroforestry systems and to identify potential agroforestry models that could ameliorate currently degrading forest resources Data were collected through farmer participatory research and a structured quarterly survey in two villages. Qualitative and supplementary quantitative analysis methods were used to assess the financial potential of agroforestry systems. Various patterns of agroforestry exist in the study site, but all have two common principles, namely ‘integration with agriculture’ and ‘multi-functionality’. Two agroforestry models suitable for adoption by farmers have been identified. Multi-strata agroforestry, based on a fruit and timber tree canopy with vegetables and tuber species in the understorey, can be practiced in the shifting cultivation fields near settlements. Fruit and timber tree-based conservation agroforestry is well suited to manage large-scale biologically depleted landscapes. Both systems yield early financial returns, facilitating the change from shifting cultivation to multi-strata agroforestry or fruit and tree-based conservation agroforestry.
The Educational Consequences of Teen Childbearing
Authors: Kane Jennifer B. , Morgan S. Philip , Harris Kathleen Mullan , Guilkey David K.
Published: September 2013

A huge literature shows that teen mothers face a variety of detriments across the life course, including truncated educational attainment. To what extent is this association causal? The estimated effects of teen motherhood on schooling vary widely, ranging from no discernible difference to 2.6 fewer years among teen mothers. The magnitude of educational consequences is therefore uncertain, despite voluminous policy and prevention efforts that rest on the assumption of a negative and presumably causal effect. This study adjudicates between two potential sources of inconsistency in the literature—methodological differences or cohort differences—by using a single, high-quality data source: namely, The National Longitudinal Study of Adolescent Health. We replicate analyses across four different statistical strategies: ordinary least squares regression; propensity score matching; and parametric and semiparametric maximum likelihood estimation. Results demonstrate educational consequences of teen childbearing, with estimated effects between 0.7 and 1.9 fewer years of schooling among teen mothers. We select our preferred estimate (0.7), derived from semiparametric maximum likelihood estimation, on the basis of weighing the strengths and limitations of each approach. Based on the range of estimated effects observed in our study, we speculate that variable statistical methods are the likely source of inconsistency in the past. We conclude by discussing implications for future research and policy, and recommend that future studies employ a similar multimethod approach to evaluate findings.
Interactive E-learning module in pharmacology: a pilot project at a rural medical
college in India
Authors: Gaikwad Nitin , Tankhiwale Suresh
Published: September 2013

Many medical educators are experimenting with innovative ways of E-learning.
E-learning provides opportunities to students for self-directed learning in addition to
other advantages. In this study, we designed and evaluated an interactive E-learning
module in pharmacology for effectiveness, acceptability and feasibility, with the aim of
promoting active learning in this fact-filled subject. A quasi-experimental single-group
pre-test/post-test study was conducted with fourth-semester students of the second
professionals course (II MBBS), selected using non-probability convenience sampling
method. An E-learning module in endocrine pharmacology was designed to comprise three
units of interactive PowerPoint presentations. The pre-validated presentations were
uploaded on the website according to a predefined schedule and the 42 registered
students were encouraged to self-learning using these interactive presentations.
Cognitive gain was assessed using an online pre- and post-test for each unit. Students’
perceptions were recorded using an online feedback questionnaire on a 5-point Likert
scale. Finally, focused group discussion was conducted to further explore students’
views on E-learning activity. Significant attrition was observed during the E-learning
activity. Of the 42 registered students, only 16 students completed the entire
E-learning module. The summed average score of all three units (entire module) was
increased significantly from 38.42 % (summed average pre-test score: 11.56/30 ± 2.90) to
66.46 % (summed average post-test score: 19.94/30 ± 6.13). The class-average normalized
gain for the entire module was 0.4542 (45.42).
Problem-based learning and undergraduate research: another student’s
perspective
Authors: Li Joule J.
Published: September 2013

None
Effect of glutamate transporter EAAT2 gene variants and gray matter deficits on working memory in schizophrenia
Authors: Poletti S. , Radaelli D. , Bosia M. , Buonocore M. , Pirovano A. , Lorenzi C. , Cavallaro R. , Smeraldi E. , Benedetti F.
Published: September 2013

Glutamate is the major excitatory neurotransmitter in the brain, with up to 40% of all synapses being glutamatergic. An altered glutamatergic transmission could play a critical role in working memory deficts observed in schizophrenia and could underline progressive changes such as grey matter loss throughout the brain. The aim of the study was to investigate if gray matter volume and working memory could be modulated by a genetic polymorphism related to glutamatergic function. Fifty schizophrenia patients underwent magnetic resonance and working memory testing outside of the scanner and were genotyped for rs4354668 EAAT2 polymorphism. Carriers of the G allele had lower gray matter volumes than T/T homozygote and worse working memory performance. Poor working memory performance was associated with gray matter reduction. Differences between the three genotypes are more relevant among patients showing poor performance at the 2-back task. Since glutamate abnormalities are known to be involved in excitotoxic processes, the decrease in cortical thickness observed in schizophrenia patients could be linked to an excess of extracellular glutamate. The differential effect of EAAT2 observed between good and poor performers suggests that the effect of EEAT2 on gray matter might reveal in the presence of a pathological process affecting gray matter.
Thyroid hormone‐dependent development of the GABAergic pre‐ and post‐synaptic components in the rat hippocampus
Authors: Sawano Erika , Takahashi Masaki , Negishi Takayuki , Tashiro Tomoko
Published: September 2013

Thyroid hormone (TH) plays essential roles in normal brain development mainly by regulating gene expression through binding to specific nuclear receptors which serve as transcription factors. Previous studies showed that perinatal deficiency of TH or impairment of its signaling severely affect brain development, especially the development of the γ‐aminobutyric acid (GABA) system, but cellular and molecular targets of the hormone are only partly uncovered. In the present study, we focused on the developing rat hippocampus which was confirmed to be one of the regions highly sensitive to TH status, and found two new targets of the hormone among the pre‐ and post‐synaptic components of the GABAergic system. One was glutamic acid decarboxylase 65 (GAD65), the protein level of which was reduced to less than 50% of control in the hippocampus of hypothyroid rats (obtained by administering 0.025% methimazole in drinking water to pregnant dams from gestational day 15 until 4 weeks postpartum) and recovered to control levels by daily thyroxine‐replacement after birth. Reduction in GAD65 protein was correlated immunohistochemically with a 37% reduction in the number of GAD65‐positive cells as well as a reduction in GAD65‐positive processes. In contrast, the other GAD isotype, GAD67, was not affected by TH status. A subpopulation of GABAergic neurons containing parvalbumin was also confirmed to be highly dependent on TH status. The second target of thyroid hormone was neuron‐specific K+/Cl−co‐transporter, KCC2, which is responsible for switching of GABA action from excitatory to inhibitory. In the euthyroid hippocampus, a sharp rise ofkcc2expression was observed at postnatal day (PND)10 which was followed by a large increase in KCC2 protein at PND15. This transient rise inkcc2expression was completely suppressed by hypothyroidism, resulting in nearly 80% reduction in KCC2 protein at PND15. These results indicate that the development of GABAergic terminals and the excitatory to inhibitory maturation of GABA signaling are strongly dependent on TH.
Late Precambrian terrigenous rocks of the Anamakit–Muya zone of the Baikal–Muya belt: geochemistry and results of LA-ICP-MS dating of detrital zircons
Authors: Dmitrieva N.V. , Letnikova E.F. , Buslov M.M. , Proshenkin A.I. , Geng H.
Published: September 2013

A comparative geochemical characteristics of Late Precambrian sedimentary rocks (Ust’-Kelyana and Tuluya rock units) in the Anamakit–Muya zone of the Baikal–Muya belt is given, and the conditions of their sedimentation are considered. The first results of U–Pb (LA-ICP-MS) dating of detrital zircons and Sm–Nd isotope data on the Tuluya unit deposits are presented. Petrogeochemical study showed that the studied sediments are first-cycle rocks similar in composition to terrigenous island-arc sediments. The low contents of Th, Rb, Zr, Hf, and LREE and high contents of Co, Ni, Sc, V, Cr, and Fe2O3* in the sandstones of the Ust’-Kelyana unit evidence that these rocks are similar to oceanic-arc deposits. In contrast, the enrichment of the Tuluya unit rocks in Zr, LREE, Th, Rb, and Nb indicates their similarity to deposits of continental island arcs or active continental margin. Isotope-geochronological studies of the Tuluya rock unit showed the mixing of detrital material resulted from the erosion of Neoproterozoic island-arc igneous rock associations (625–700 Ma), like those in the Karalon–Mamakan zone (Yakor’ and Karalon Formations), and more ancient associations, like the Kelyana (812–824 Ma) and/or Dzhaltuk Groups. Judging from the minimum age of detrital zircon, the lower time bound of sedimentation corresponds to 0.6 Ga.
Restitic ultramafic rocks in the Early Caledonian collisional system of western Cisbaikalia
Authors: Mekhonoshin A.S. , Vladimirov A.G. , Vladimirov V.G. , Volkova N.I. , Kolotilina T.B. , Mikheev E.I. , Travin A.V. , Yudin D.S. , Khlestov V.V. , Khromykh S.V.
Published: September 2013

Early Caledonides in the Olkhon region of western Cisbaikalia, being part of the folded framing of the Siberian craton, are a unique geologic object for studying processes of mantle–crust interaction at deep levels of the Earth’s crust. This paper describes restitic ultramafic bodies and boudins spatially confined to faults (blastomylonite sutures), as well as synkinematic granites related to amphibolite facies of metamorphism. Estimates are given for the PT-conditions of metamorphic rocks from the folded framing of the ultramafic bodies, the chemical and mineral compositions of ultramafic rocks, blastomylonites and synkinematic granites, and the results of U–Pb and Ar–Ar isotopic dating. Particular attention is paid to the thermal history of tectonic exposure of the ultramafic bodies as relics of the paleo-oceanic crust in the Early Caledonian collisional system of western Cisbaikalia.
Petrology and geochemistry of gabbro and picrites from the Altai collisional system of Hercynides: evidence for the activity of the Tarim plume
Authors: Khromykh S.V. , Vladimirov A.G. , Izokh A.E. , Travin A.V. , Prokop’ev I.R. , Azimbaev E. , Lobanov S.S.
Published: September 2013

We present petrological, isotopic, and geochronological data on gabbro-picrite plutons from the Altai collisional system of Hercynides (eastern Kazakhstan). The geological, geochemical, and geochronological data suggest that these rocks are indicators of the activity of the Tarim plume. The gabbro and picrites formed in two stages (~293 and 280 Ma) in an acid-to-basic succession, explained by a model for the interaction of thermochemical plumes with the lithosphere. Early igneous activity, which gave rise to subalkalic gabbro plutons, reflects the first interaction between the ascending plume and the lithosphere, with low-melting sublithospheric protoliths. Further interaction was characterized by the sublithospheric spread of the plume head with intense heating of the lithospheric base and possible intrusion of deep melts, which resulted in the formation of Cu–Ni–PGE gabbro-picrite plutons in the Altai collisional system and Northwest China.
Unsteady pitching flat plates
Authors: Granlund Kenneth O. , Ol Michael V. , Bernal Luis P.
Published: September 2013

Direct force measurements and qualitative flow visualization were used to compare flow field evolution versus lift and drag for a nominally two-dimensional rigid flat plate executing smoothed linear pitch ramp manoeuvres in a water tunnel. Non-dimensional pitch rate was varied from 0.01 to 0.5, incidence angle from 0 to 90°, and pitch pivot point from the leading to the trailing edge. For low pitch rates, the main unsteady effect is delay of stall beyond the steady incidence angle. Shifting the time base to account for different pivot points leads to collapse of both lift/drag history and flow field history. For higher rates, a leading edge vortex forms; its history also depends on pitch pivot point, but linear shift in time base is not successful in collapsing lift/drag history. Instead, a phenomenological algebraic relation, valid at the higher pitch rates, accounts for lift and drag for different rates and pivot points, through at least 45° incidence angle.
Global stability of flow in symmetric wavy channels
Authors: Rivera-Alvarez Alejandro , Ordonez Juan C.
Published: September 2013

A two-dimensional global stability analysis is numerically conducted for the basic fully developed steady flow inside symmetric wavy channels. The relative amplitude of channel modulation, defined as ratio of wall modulation amplitude to mean hydraulic diameter, is fixed via the analysis at a large value of 0.15. The relative channel wavelength, defined as the ratio of wall modulation wavelength to mean hydraulic diameter, is varied between 1 and 5. An important feature of the present approach is the detailed consideration of the streamwise conditions imposed on the flow, which allows a tailored restriction of the possible disturbances by modifying the number of channel sections that set the periodicity. Stability of the base flow is determined on the basis of the spectral structure analysis conducted, possible after calculation of the complete eigenvalue spectrum and facilitated by the spectral method employed. Two different destabilization mechanisms have been identified for the geometry studied. For small relative channel wavelengths, with values below approximately 2.7, the flow is destabilized via a Hopf bifurcation produced by a Tollmien–Schlichting wave at Reynolds numbers in the approximated range from 265 to 324. For large relative channel wavelengths, with values above approximately 2.5, a pitchfork bifurcation (or a Hopf bifurcation with very small oscillation frequency), not previously reported in the literature and produced by a symmetric stationary disturbance, is found at Reynolds numbers in the approximated range from 146 to 230.
Bending of elastic fibres in viscous flows: the influence of confinement – CORRIGENDUM
Authors: Wexler Jason S. , Trinh Philippe H. , Berthet Helene , Quennouz Nawal , du Roure Olivia , Huppert Herbert E. , Linder Anke , Stone Howard A.
Published: September 2013

The original version of this article (Wexler et al.2013) was published with author A. Lindner’s name incorrectly spelled. The error has been rectified in the online PDF and HTML copies.
Approaching monumental architecture: mechanics and movement in Archaic Etruscan palaces
Authors: Meyers Gretchen E.
Published: September 2013

This paper reassesses the architectural setting of a group of monumental buildings dating to the sixth centurybcfrom the Etruscan area of central Italy, sometimes referred to as palaces, orpalazzi. Although scholars traditionally have focused on classifying the buildings, the architectural form is here examined through close comparative analysis of spatial mechanics and movement. Focusing on case-studies from Poggio Civitate (Murlo) and Acquarossa, the author reconstructs the architectural processes of movement, particularly between the exterior and interior spaces arranged around a characteristic courtyard, and concludes that the structures are indicative of a unique Etruscan experience rather than that of Mediterranean palaces more generally. The author calls for a shift away from attempts to categorize these monumental structures in favour of a close analysis of spatial experience in order to explore better their architectural impact and function.
Mechanical Response of Dental Cements as Determined by Nanoindentation and Scanning Electron Microscopy
Authors: Saghiri Mohammad Ali , Nazari Amir , Garcia-Godoy Franklin , Asatourian Armen , Malekzadeh Mansour , Elyasi Maryam
Published: September 2013

This study evaluated the effects of nanoindentation on the surface of white mineral trioxide aggregate (WMTA), Bioaggregate and Nano WMTA cements. Cements were mixed according to the manufacturer directions, condensed inside glass tubes, and randomly divided into three groups (n = 8). Specimens were soaked in synthetic tissue fluid (pH = 7.4) and incubated for 3 days. Cement pellets were subjected to nanoindentation tests and observed by scanning electron microscopy. Then, the images were processed and the number of cracks and total surface area of defects on the surface were calculated and analyzed using ImageJ. Data were submitted to one-way analysis of variance and a post hoc Tukey's test. The lowest number of cracks and total surface of defects were detected in Nano WMTA samples; however, it was not significantly different from WMTA samples (p = 0.588), while the highest values were noticed in Bioaggregate specimens that were significantly different from Nano WMTA and WMTA (p = 0.0001). The surface of WMTA and Nano WMTA showed more resistance after exposure to nano-compressive forces which indicated a better surface tolerance against these forces and crack formation. This suggests these substances are more tolerant cement materials which can predictably withstand loaded situations in a clinical scenario.
Is expert opinion enough? A critical assessment of the evidence for potential impacts of climate change on tick-borne diseases
Authors: Randolph Sarah E.
Published: September 2013

Before attributing cause and consequence to climate change, the precise patterns of change must be known. Ground records across much of Europe show a 1–2 °C rise in temperatures in 1989 with no significant rise since then. The timing and spatial uniformity of this pattern, relative to changes in the distribution and incidence of many vector-borne diseases, are sufficient to falsify most simple claims that climate change is the principal cause of disease emergence. Furthermore, age-specific increases in incidence indicate causes other than, or in addition to, climate change. Unfortunately, many public health professionals repeat the received wisdom that climate change is worsening the burden of indirectly transmitted infections; this ‘expert opinion’ soon becomes consensus dogma divorced from quantitative evidence. The pressing need is to gather appropriate data to test the simple concept that the composition and relative importance of disparate multifactorial factors, commonly integrated within a causal nexus, will inevitably vary with the geographical, cultural, socio-economical, wildlife, etc. context. The greatest impact of warming occurs at the geographical limits of current distributions, where low temperatures limit the hazard of infected vectors. Within core endemic regions, changing exposure of humans to this hazard, through changing socio-economic factors is evidently more important amongst both the poor and the wealthy.
Witnessing Suicide-Related Behavior in Prison
Authors: Hales Heidi , Freeman Mona , Edmondson Amanda , Taylor Pamela
Published: September 2013

Background: Rates of suicide and suicide-related behavior (SRB) are high in prison. Those witnessing such behavior may develop psychological morbidity. Most previous studies have been quantitative. Little has been written about the witnesses’ qualitative experience. Aims: The aim of the study was to explore, through interview and then thematic analysis, the core concerns of those witnessing another’s SRB in prison. Method: We interviewed 70 detained young men about their experience of another’s SRB in prison. Results: Three main themes were identified: their experience of another’s SRB; their thoughts of why the victim died by/attempted suicide; and the physical, emotional, and cognitive effects of another’s SRB on them. Responses to questions about the witnesses’ experience of support from others, unmet needs, and peers’ responses are also described. Two categories within the theme ”thoughts of why the victim died by/attempted suicide” were associated with being in prison, all others could be experienced in the community. Over half of the sample reported negative reactions to witnessing another’s SRB. Conclusion: Most themes were unrelated to prison. Though many reported negative reactions to their experience, suggesting a need for support, many denied that need. The implication of this study is that prison discipline and health-care staff need to consider how to provide needed support and care in an acceptable form to young men in prison.
Assignment of the Q-Bands of the Chlorophylls: Coherence Loss via Qx − Qy Mixing
Authors: Reimers Jeffrey R. , Cai Zheng-Li , Kobayashi Rika , Rätsep Margus , Freiberg Arvi , Krausz Elmars
Published: September 2013

We provide a new and definitive spectral assignment for the absorption, emission, high-resolution fluorescence excitation, linear dichroism, and/or magnetic circular dichroism spectra of 32 chlorophyllides in various environments. This encompases all data used to justify previous assignments and provides a simple interpretation of unexplained complex decoherence phenomena associated with Qx → Qy relaxation. Whilst most chlorophylls conform to the Gouterman model and display two independent transitions Qx (S2) and Qy (S1), strong vibronic coupling inseparably mixes these states in chlorophyll-a. This spreads x-polarized absorption intensity over the entireQ-band system to influence all exciton-transport, relaxation and coherence properties of chlorophyll-based photosystems. The fraction of the total absorption intensity attributed to Qx ranges between 7% and 33%, depending on chlorophyllide and coordination and is between 10% and 25% for chlorophyll-a. CAM-B3LYP density-functional-theory calculations of the band origins, relative intensities, vibrational Huang-Rhys factors and vibronic coupling strengths fully support this new assignment.
Regulation of trehalase expression inhibits apoptosis in diapause cysts ofArtemia
Authors: Yang Fan , Chen Su , Dai Zhong-Min , Chen Dian-Fu , Duan Ru-Bing , Wang Hong-Liang , Jia Sheng-Nan , Yang Wei-Jun
Published: September 2013

Trehalase, which specifically hydrolyses trehalose into glucose, plays an important role in the metabolism of trehalose. Large amounts of trehalose are stored in the diapause encysted embryos (cysts) of Artemia, which are not only vital to their extraordinary stress resistance, but also provide a source of energy for development after diapause is terminated. In the present study, a mechanism for the transcriptional regulation of trehalase was described in Artemia parthenogenetica. A trehalase-associated protein (ArTAP) was identified in Artemia-producing diapause cysts. ArTAP was found to be expressed only in diapause-destined embryos. Further analyses revealed that ArTAP can bind to a specific intronic segment of a trehalase gene. Knockdown of ArTAP by RNAi resulted in the release of cysts with coarse shells in which two chitin-binding proteins were missing. Western blotting showed that the level of trehalase was increased and apoptosis was induced in these ArTAP-knockdown cysts compared with controls. Taken together, these results show that ArTAP is a key regulator of trehalase expression which, in turn, plays an important role in trehalose metabolism during the formation of diapause cysts.
The interplay between lipids and dopamine on α-synuclein oligomerization and membrane binding
Authors: Pham Chi L. L. , Cappai Roberto
Published: September 2013

The deposition of α-syn (α-synuclein) as amyloid fibrils and the selective loss of DA (dopamine) containing neurons in the substantia nigra are two key features of PD (Parkinson's disease). α-syn is a natively unfolded protein and adopts an α-helical conformation upon binding to lipid membrane. Oligomeric species of α-syn have been proposed to be the pathogenic species associated with PD because they can bind lipid membranes and disrupt membrane integrity. DA is readily oxidized to generate reactive intermediates and ROS (reactive oxygen species) and in the presence of DA, α-syn form of SDS-resistant soluble oligomers. It is postulated that the formation of the α-syn:DA oligomers involves the cross-linking of DA-melanin with α-syn, via covalent linkage, hydrogen and hydrophobic interactions. We investigate the effect of lipids on DA-induced α-syn oligomerization and studied the ability of α-syn:DA oligomers to interact with lipids vesicles. Our results show that the interaction of α-syn with lipids inhibits the formation of DA-induced α-syn oligomers. Moreover, the α-syn:DA oligomer cannot interact with lipid vesicles or cause membrane permeability. Thus, the formation of α-syn:DA oligomers may alter the actions of α-syn which require membrane association, leading to disruption of its normal cellular function.
Preventive start‐time optimisation of open shortest path first link weights for hose model
Authors: Sandaruwan Ranaweera Ravindra , Mohammad Kamrul Islam , Oki Eiji
Published: September 2013

Optimising link weights in an open shortest path first network is a challenging traffic engineering problem to reduce network congestion. Most of the previous studies have focused on the application of start‐time optimisation (SO) and run‐time optimisation on both pipe and hose models of link weight optimisation. In a more recent study, an efficient policy, preventive start‐time optimisation (PSO), has been introduced for link weight optimisation. However, no studies have been reported on the application of PSO to the hose model where the exact traffic demand between each source and destination node pair does not need to be specified. A PSO policy for the hose model to optimise the link weights against link failures is proposed. The proposed scheme employs a heuristic algorithm to determine a suitable set of link weights to reduce worst‐case congestion for any single link failure. It efficiently selects the worst‐case performance traffic matrix and reduces the worst‐case congestion ratio as compared with a brute‐force scheme which is computationally expensive when searching the link weight space against all the possible traffic matrices and topologies created by single link failures. The numerical results show that the proposed scheme is more effective in the reduction of worst‐case congestion ratio than the scheme utilising SO.
Close form maximum likelihood covariance matrix estimation under a knowledge‐aided constraint
Authors: Tang Bo , Zhang Yu , Tang Jun , Peng Yingning
Published: September 2013

Knowledge‐aided (KA) space–time adaptive processing (STAP) is an appealing scheme for improving the detection performance of slow‐moving target in sample starved heterogeneous environments. The authors address the maximum likelihood (ML) estimation problem of the interference covariance matrix under a KA constraint. To reduce the complexity of interior point method, a close form ML estimator for the interference covariance matrix is derived. Moreover, for the hyper‐parameter selection in the KA constraint, which remains an unsolved open problem, an efficient and fully automatic method based on likelihood function and cross validation is proposed. The authors find that the proposed estimator consists of a prewhitening step and an eigenvalue‐truncation step of the whitened sample covariance matrix (SCM), which is somewhat similar to the existing fast ML with assumed clutter covariance (FMLACC) method. However, different ways for truncating the eigenvalues of the whitened SCM are exploited. The numerical simulations also demonstrate that by appropriately choosing the hyper‐parameter, the proposed estimator can remarkably outperform the FMLACC method in some situations.
Atomistic modeling of bond lengths in random and ordered III-V alloys
Authors: Detz H. , Strasser G.
Published: September 2013

This work provides comprehensive modeling for the bond length and angle distributions in random and spontaneously ordered ternary III-V alloys using empirical interaction potentials. The compounds InxGa1−xAs, GaAs1−xSbx, and InxGa1−xP were used as model systems due to their technological importance and the fact that ordered structures were observed experimentally in these materials. For random alloys, we reproduce the bimodal bond length distribution, which allows linear fits with slopes between 0.087 Å and 0.1059 Å for all bond types. The calculated values for dilute compositions slightly deviate from these functions, causing stronger deformations. In the case of CuPt-ordered structures, the bond length distribution is shown to collapse to four sharp peaks with an area ratio of 1:3:3:1, which originate from a different atom to atom distance within the different (111) planes and perpendicular to these. An essential consequence of this atomic arrangement is the different spacings for the different stacked binaries along the (111) direction, which also leads to strain values up to −0.819% for In0.5Ga0.5P and −1.827% for GaAs0.5Sb0.5. Furthermore, the broad bond angle distributions of random alloys collapse into two peaks for CuPt-like structures. On the other hand, CuAu-type ordering is shown to lead to a sharp bimodal bond length distribution but with five different groups of bond angles, which can be identified with the different atomic configurations in ternary zincblende crystals.
Multiscale structures in solutal Marangoni convection: Three-dimensional simulations and supporting experiments
Authors: Köllner Thomas , Schwarzenberger Karin , Eckert Kerstin , Boeck Thomas
Published: September 2013

Transient solutal Marangoni convection in a closed two-layer system is studied by a combination of numerical simulations and supplementary validation experiments. The initially quiescent, equally sized liquid layers are the phases of a cyclohexanol/water mixture. Butanol is additionally dissolved in the upper organic layer. Its diffusion across the interface is sensitive to the Marangoni instability. Complex convective patterns emerge that develop a hierarchical cellular structure in the course of the mass transfer. Our highly resolved simulations based on a pseudospectral method are the first to successfully reproduce the multiscale flow observed in the experiments. We solve the three-dimensional Navier-Stokes-Boussinesq equations with an undeformable interface, which is modeled using the linear Henry relation for the partition of the weakly surface-active butanol. Length scales in the concentration and velocity fields associated with the small and large-scale cells agree well with our experimental data from shadowgraph images. Moreover, the simulations provide detailed information on the local properties of the flow by which the evolution of the patterns and their vertical structure are analyzed. Apart from relatively weak influences due to buoyancy, the evolution of the convective structures is self-similar between different initial butanol concentrations when length and time are appropriately rescaled.
Cooee bitumen: Chemical aging
Authors: Lemarchand Claire A. , Schrøder Thomas B. , Dyre Jeppe C. , Hansen Jesper S.
Published: September 2013

We study chemical aging in “Cooee bitumen” using molecular dynamic simulations. This model bitumen is composed of four realistic molecule types: saturated hydrocarbon, resinous oil, resin, and asphaltene. The aging reaction is modelled by the chemical reaction: “2 resins → 1 asphaltene.” Molecular dynamic simulations of four bitumen compositions, obtained by a repeated application of the aging reaction, are performed. The stress autocorrelation function, the fluid structure, the rotational dynamics of the plane aromatic molecules, and the diffusivity of each molecule are determined for the four different compositions. The aging reaction causes a significant dynamics slowdown, which is correlated to the aggregation of asphaltene molecules in larger and dynamically slower nanoaggregates. Finally, a detailed description of the role of each molecule types in the aggregation and aging processes is given.
Onset of convection with fluid compressibility and interface movement
Authors: Myint Philip C. , Firoozabadi Abbas
Published: September 2013

The density increase from carbon dioxide (CO2) dissolution in water or hydrocarbons creates buoyancy-driven instabilities that may lead to the onset of convection. The convection is important for both CO2 sequestration in deep saline aquifers and CO2 improved oil recovery from hydrocarbon reservoirs. We perform linear stability analyses to study the effect of fluid compressibility and interface movement on the onset of buoyancy-driven convection in porous media. Compressibility relates to a non-zero divergence of the velocity field. The interface between the CO2 phase and the aqueous or hydrocarbon phase moves with time as a result of the volume change that occurs upon CO2 dissolution. Previous stability analyses have neglected these two aspects by assuming that the aqueous or hydrocarbon phase is incompressible and that the interface remains fixed in position. The stability analyses are used to compute two key quantities: (1) the critical time and (2) the critical wavenumber. Our results indicate that compressibility has a negligible effect on the critical time and the critical wavenumber in CO2-water mixtures. We use thermodynamics to derive an expression which shows that the two opposing physical processes which contribute to the divergence are comparable in magnitude and largely cancel each other. This result explains why compressibility does not significantly affect the onset, and it also demonstrates the link between compressibility and the volume change that causes movement of the interface. Compared to when the interface is fixed in position, a moving interface in CO2-water mixtures may reduce the critical time by up to around 10%, which can be significant in low permeability formations. The decrease in the critical time due to interface movement may be much more pronounced in hydrocarbons than in water. This could have important implications for CO2 improved oil recovery.
Non-invasive estimation of dissipation from non-equilibrium fluctuations in chemical reactions
Authors: Muy S. , Kundu A. , Lacoste D.
Published: September 2013

We show how to extract an estimate of the entropy production from a sufficiently long time series of stationary fluctuations of chemical reactions. This method, which is based on recent work on fluctuation theorems, is direct, non-invasive, does not require any knowledge about the underlying dynamics and is applicable even when only partial information is available. We apply it to simple stochastic models of chemical reactions involving a finite number of states, and for this case, we study how the estimate of dissipation is affected by the degree of coarse-graining present in the input data.
The terahertz characteristics of a sandwich type microplasma structure
Authors: Gao Ruilin , Yuan Chengxun , Wang Ying , Zhou Zhongxiang , Gong Dewei , Fang Yuan , Rong Xianwei
Published: September 2013

Recently, major technical advances in developing intense terahertz (THz) sources have provided us with new opportunities to investigate characteristics of a high density microplasma with THz waves. In this paper, a simple sandwich type microplasma model is established. The finite-difference time-domain method using Z-transforms is utilized to simulate the characteristics of reflection, transmission, and absorption of THz waves in this microplasma structure. The effects of both the microplasma width and the permittivity of the outer medium on the propagation are analyzed, and the results show that the THz waves can be greatly influenced and modulated by the structure of the plasma slab and the outer medium. It is demonstrated that such plasma metamaterials exhibit some extraordinary properties in THz frequency range.
Influence of surface segregation on magnetic properties of FePt nanoparticles
Authors: Lv Hongyan , Lei Yinkai , Datta Aditi , Wang Guofeng
Published: September 2013

Surface segregation leads to chemical disordering in magnetic alloy nanostructures and thus could have profound impact upon the magnetic properties of these nanostructures. In this study, we used the first-principles density functional theory calculation method to determine how Pt surface segregation (exchanging interior Pt with surface Fe atoms) would affect the magnetic properties of L10 ordered FePt nanoparticles. For both cuboid and cuboctahedral FePt nanoparticles, we predicted that the Pt surface segregation process could cause a decrease in total magnetic moments, a change in (easy and/or hard) magnetization axes, and a reduction in magnetic anisotropy.
Formation of highly oriented nanopores via crystallization of amorphous Nb2O5 and Ta2O5
Authors: Nakamura R. , Ishimaru M. , Sato K. , Tanaka K. , Nakajima H. , Konno T. J.
Published: September 2013

Formation of self-oriented and -elongated nanopores in annealed amorphous Nb2O5 and Ta2O5 was analyzed by transmission electron microscopy. Along with their crystal growth, nanopores were spontaneously elongated in the a-axis direction perpendicular to the longitudinal b axis of the orthorhombic structures with strong anisotropy. In addition, the effect of tungsten on the nanovoid formation in annealed amorphous Nb2O5 and Ta2O5 was also studied. Additive tungsten atoms of a few atomic percent into Nb2O5 and Ta2O5 were found to make the aspect ratio of nanopores larger. Electron diffraction experiments revealed that the crystallized regions including elongated nanopores possess a variety of periodicity in the b-axis direction. This structural flexibility in the crystal growth of strong anisotropic structures seems to play an important role on the unidirectional growth of nanopores.
Aluminium coated carbon nanotube film for wavelength-selective surface
Authors: Mukherjee S. , Suri A. , Vani V. K. , Misra A.
Published: September 2013

We report selective optical reflectance in an aluminium (Al) coated flexible carbon nanotube (CNT) thin film over a wide range of wavelengths (500–2500 nm). Selective-wavelength surface is achieved by coating CNT surfaces with Al thin film that presented a maximum optical reflectivity of ∼65% in the infrared region. However, CNT film alone showed a reflectance of 15–20% over a larger range of wavelengths without any structural modification, which has not been realized so far. Moreover, a tailorable reflectance in CNT is shown to be achieved by tuning various parameters, namely, the porosity of the material, angle of an incident light, and refractive index of the materials. Owing to higher infrared reflectivity and thermal diffusivity, Al coated CNT presents a potential for a high efficiency solar collector.
Temperature dependence of electronic behaviors in n-type multiple-channel junctionless transistors
Authors: Ma Liuhong , Han Weihua , Wang Hao , Li Xiaoming , Yang Fuhua
Published: September 2013

The electronic behaviors in the n-type multiple-channel junctionless nanowire transistors are investigated in the thermal range from 10 K to 300 K. At low temperatures (T < 100 K), oscillation current spikes are clearly observed below flatband voltage and attributed to resonant tunneling through donor-induced quantum dot array. There is a minimum value at the critical temperature of 15 K for the drain currents and the electron mobility. The electron mobility increases rapidly above 15 K because of the thermal activation of ionized electrons. The temperature-dependent background trapping at the interface of silicon and silicon dioxide is evaluated by an Arrhenius-type off-state current with the activation energy of approximately 49 meV. As temperatures increasing, the negative shift of the threshold voltage with the slope of 4.0 mV K−1 is given predominantly by the thermal activation of traps.
A reduced model for ion temperature gradient turbulent transport in helical plasmas
Authors: Nunami M. , Watanabe T.-H. , Sugama H.
Published: September 2013

A novel reduced model for ion temperature gradient (ITG) turbulent transport in helical plasmas is presented. The model enables one to predict nonlinear gyrokinetic simulation results from linear gyrokinetic analyses. It is shown from nonlinear gyrokinetic simulations of the ITG turbulence in helical plasmas that the transport coefficient can be expressed as a function of the turbulent fluctuation level and the averaged zonal flow amplitude. Then, the reduced model for the turbulent ion heat diffusivity is derived by representing the nonlinear turbulent fluctuations and zonal flow amplitude in terms of the linear growth rate of the ITG instability and the linear response of the zonal flow potentials. It is confirmed that the reduced transport model is in a good agreement with nonlinear gyrokinetic simulation results for high ion temperature plasmas in the large helical device.
Acceleration of positrons by a relativistic electron beam in the presence of quantum effects
Authors: Niknam A. R. , Aki H. , Khorashadizadeh S. M.
Published: September 2013

Using the quantum magnetohydrodynamic model and obtaining the dispersion relation of the Cherenkov and cyclotron waves, the acceleration of positrons by a relativistic electron beam is investigated. The Cherenkov and cyclotron acceleration mechanisms of positrons are compared together. It is shown that growth rate and, therefore, the acceleration of positrons can be increased in the presence of quantum effects.
Angle dependence of transparent photovoltaics in conventional and optically inverted configurations
Authors: Young Margaret , Traverse Christopher J. , Pandey Richa , Barr Miles C. , Lunt Richard R.
Published: September 2013

Integration of transparent photovoltaics into the building envelope creates unique opportunities to reduce the levelized electricity cost of solar power. However, this integration warrants consideration of the angular dependence of these devices as illumination around the building envelope is rarely at normal incidence. Here we correctly update transfer-matrix and equations to accurately model the quantum efficiency and optical properties under oblique illumination. We use this model to demonstrate the various angular performance characteristics possible for proof-of-concept optimizations of transparent planar-heterojunction solar cells and discuss considerations needed to fully account for optical, electrical, and positional configurations in this optimization.
Coherent summation of Ka-band microwave beams produced by sub-gigawatt superradiance backward wave oscillators
Authors: Sharypov K. A. , El'chaninov A. A. , Mesyats G. A. , Pedos M. S. , Romancheko I. V. , Rostov V. V. , Rukin S. N. , Shpak V. G. , Shunailov S. A. , Ul'masculov M. R. , Yalandin M. I.
Published: September 2013

Coherent summation of microwave beams has been demonstrated for two superradiance Ka-band backward wave oscillators producing over 700 MW of power. The explosive emission cathodes of the e-beam injectors were powered by stable splitted voltage pulses produced by an all-solid-state modulator. The voltage fronts were shortened to 300 ps in controlled delay shock-excited ferrite lines. The standard deviation of the phase difference between the microwave pulses was less than 2% of the oscillations period. The power flux density of the summarized radiation was the same as that of a single generator producing an output power of ∼3 GW.