bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation of macro-operators via investigation of action dependencies in plans
Authors: Chrpa Lukáš
Published: August 2010

There are many approaches for solving planning problems. Many of these approaches are based on ‘brute force’ search methods and they usually do not care about structures of plans previously computed in particular planning domains. By analyzing these structures, we can obtain useful knowledge that can help us find solutions to more complex planning problems. The method described in this paper is designed for gathering macro-operators by analyzing training plans. This sort of analysis is based on the investigation of action dependencies in training plans. Knowledge gained by our method can be passed directly to planning algorithms to improve their efficiency.
Validation and verification issues in a timeline-based planning system
Authors: Cesta Amedeo , Finzi Alberto , Fratini Simone , Orlandini Andrea , Tronci Enrico
Published: August 2010

To foster effective use of artificial intelligence planning and scheduling (P&S)systems in the real world, it is of great importance to both (a) broaden direct access to the technology for the end users and (b) significantly increase their trust in such technology. AutomatedP&Ssystems often bring solutions to the users that are neither ‘obvious’ nor immediately acceptable to them. This is because these tools directly reason on causal, temporal, and resource constraints; moreover, they employ resolution processes designed to optimize the solution with respect to non-trivial evaluation functions. Knowledge engineering environments aim at simplifying direct access to the technology for people other than the original system designers, while the integration of validation and verification (V&V) capabilities in such environments may potentially enhance the users’ trust in the technology. Somehow,V&Vtechniques may represent a complementary technology, with respect toP&S, that contributes to developing richer software environments to synthesize a new generation of robust problem-solving applications. The integration ofV&VandP&Stechniques in a knowledge engineering environment is the topic of this paper. In particular, it analyzes the use of state-of-the-artV&Vtechnology to support knowledge engineering for a timeline-based planning system called MrSPOCK. The paper presents the application domain for which the automated solver has been developed, introduces the timeline-based planning ideas, and then describes the different possibilities to applyV&Vto planning. Hence, it continues by describing the step of addingV&Vfunctionalities around the specialized planner, MrSPOCK. New functionalities have been added to perform both model validation and plan verification. Lastly, a specific section describes the benefits as well as the performance of such functionalities.
Preface to special issue on planning and scheduling
Authors: Barták Roman , Cesta Amedeo , McCluskey Lee , Salido Miguel A.
Published: August 2010

Planning, scheduling and constraint satisfaction are important areas in artificial intelligence (AI) with broad practical applicability. Many real-world problems can be formulated as AI planning and scheduling (P&S) problems, where resources must be allocated to optimize overall performance objectives. Frequently, solving these problems requires an adequate mixture of planning, scheduling and resource allocation to competing goal activities over time in the presence of complex state-dependent constraints. Constraint satisfaction plays an important role in solving such real-life problems, and integrated techniques that manage P&S with constraint satisfaction are particularly useful. Knowledge engineering supports the solution of such problems by providing adequate modelling techniques and knowledge extraction techniques for improving the performance of planners and schedulers. Briefly speaking, knowledge engineering tools serve as a bridge between the real world and P&S systems.
New trends in constraint satisfaction, planning, and scheduling: a survey
Authors: Barták Roman , Salido Miguel A. , Rossi Francesca
Published: August 2010

During recent years, the development of new techniques for constraint satisfaction, planning, and scheduling has received increased attention, and substantial effort has been invested in trying to exploit such techniques to find solutions to real-life problems. In this paper, we present a survey on constraint satisfaction, planning, and scheduling from the Artificial Intelligence point of view. In particular, we present the main definitions and techniques, and discuss possible ways of integrating such techniques. We also analyze the role of constraint satisfaction in planning and scheduling, and hint at some open research issues related to planning, scheduling, and constraint satisfaction.
Herpes zoster in Australia: evidence of increase in incidence in adults attributable to varicella immunization?
Authors: JARDINE A. , CONATY S. J. , VALLY H.
Published: August 2010

Rates of herpes zoster (HZ) hospitalizations, antiviral prescriptions, and New South Wales emergency-department presentations for age groups <20, 20–39, 40–59 and ⩾60 years were investigated. Trends were analysed using Poisson regression to determine if rates increased following funding of varicella immunization in Australia in November 2005. The regression analysis revealed significantly increasing trends of between 2% and 6% per year in both antiviral prescriptions and emergency-department presentations in all except the <20 years age group. When considered together, the differential changes in rates observed by age group provides preliminary evidence to indicate that HZ incidence is increasing in adults aged >20 years. However, it is not possible to attribute the increasing trends in HZ observed directly to the varicella immunization programme, and continued monitoring and analyses of data for a longer duration, both pre- and post-vaccine introduction, is required.
Capacitation status of activated bovine sperm cultured in media containing methyl-β-cyclodextrin affects the acrosome reaction and fertility
Authors: Kato Yoku , Shoei Sugita , Nagao Yoshikazu
Published: August 2010

Mammalian sperm undergo a series of biochemical transformations in the female reproductive tract that are collectively known as capacitation. One of the key processes involved in capacitation is the activation of sperm motility. Here, we investigated the capacitation and fertility status of activated sperm which had been cultured in media containing methyl-β-cyclodextrin (MBCD). In order to do this, single activated sperm were caught using a micropipette and stained with chlortetracycline (CTC). Firstly, we investigated the effects of preincubation upon motility, capacitation of activated sperm and fertility. Culture in preincubation media supplemented with MBCD increased the rates of activation and fertilization compared with sperm cultured by control methods (p < 0.05). Following capture, individual activated sperm mostly exhibited a pattern characteristic of capacitation.

Secondly we examined the effects of culturing sperm in media with or without glucose (G) and pyruvate acid (P) upon activated motility, the capacitation of activated sperm and fertility. Supplementation of culture media with G and P resulted in higher proportions of activated sperm and increased fertilization rates compared to culture without G and P (p < 0.05). Most of the sperm activated by culture in G and P exhibited patterns characteristic of capacitation. Without G and P, individual activated sperm mostly exhibited patterns characteristic of the acrosome reaction (p < 0.05). In conclusion, activated sperm exhibited patterns characteristic of capacitation. In addition, sperm activated in media containing an energy source (glucose and pyruvate acid) appeared to exhibit acrosome reactiveness and fertility.
Training the Wider Workforce in Cognitive Behavioural Self-Help: The SPIRIT (Structured Psychosocial InteRventions in Teams) Training Course
Authors: Williams Chris , Martinez Rebeca , Dafters Rebecca , Ronald Lisa , Garland Anne
Published: August 2010

Background:The use of Cognitive Behavioural Therapy (CBT) self-help materials for depression is increasingly recommended as part of stepped care service models. Such resources can be delivered by both new specialist workers (such as the IAPT services in England), or by introducing this style of working into an existing workforce as described in the current paper. The Structured Psychosocial InteRventions in Teams (SPIRIT) course consists of 38.5 hours of workshops, and 5 hours of clinical supervision in the use of CBT self-help (CBSH).Method:This study describes an evaluation of the effectiveness of the course when offered to community and inpatient mental health staff from a wide range of adult and older adult mental health teams in NHS Greater Glasgow Mental Health Division.Results:Training resulted in both subjective and objective knowledge and skills gains at the end of training that were largely sustained 3 months later. At that time point, 40% of staff still reported use of CBSH in the last week. Satisfaction with the training is high, using validated rating scales.Conclusions:The SPIRIT training has gone some way to increasing access to CBSH for use in everyday clinical practice.
Democracy and Distrust
Authors: Schmitter Philippe C.
Published: August 2010

Pierre Rosanvallon is one of the most important political theorists writing in French. Counter-Democracy: Politics in an Age of Distrust is a book about the limits of conventional understandings of democracy. Rosanvallon argues that while most theories of democracy focus on institutionalized forms of political participation (especially elections), the vitality of democracy rests equally on forms of “counter-democracy” through which citizens dissent, protest, and exert pressure from without on the democratic state. This argument is relevant to the concerns of a broad range of political scientists, most especially students of democratic theory, electoral and party politics, social movements, social capital, and “contentious politics.” The goal of this symposium is to invite a number of political scientists who work on these issues to comment on the book from their distinctive disciplinary, methodological, and theoretical perspectives.—Jeffrey C. Isaac, Editor
Dreaming Blackness: Black Nationalism and African American Public Opinion. By Melanye T. Price
Authors: Gooding-Williams Robert
Published: August 2010

This is a timely, engaging, and illuminating study of Black Nationalism. The book's “fundamental project,” Melanye T. Price writes, “is to systematically understand individual Black Nationalism adherence among African Americans in the post-Civil Rights era” (p. 60). Black Nationalism has a long history in African American politics, but with the demise of Jim Crow and the election of our first black president, we may reasonably wonder whether ordinary African American citizens are disposed to endorse it. Price's book is important because it addresses this question head-on, defending the thesis that a renewal of Black Nationalism remains a viable possibility in post-Obama America.
“There's No One as Irish as Barack O'Bama”: The Policy and Politics of American Multiracialism
Authors: Hochschild Jennifer , Weaver Vesla Mae
Published: August 2010

For the first time in American history, the 2000 United States census allowed individuals to choose more than one race. That new policy sets up our exploration of whether and how multiracialism is entering Americans' understanding and practice of race. By analyzing briefly earlier cases of racial construction, we uncover three factors important to understanding if and how intensely a feedback effect for racial classification will be generated. Using this framework, we find that multiracialism has been institutionalized in the federal government, and is moving toward institutionalization in the private sector and other governmental units. In addition, the small proportion of Americans who now define themselves as multiracial is growing absolutely and relatively, and evidence suggests a continued rise. Increasing multiracial identification is made more likely by racial mixture's growing prominence in American society—demographically, culturally, economically, and psychologically. However, the politics side of the feedback loop is complicated by the fact that identification is not identity. Traditional racial or ethnic loyalties and understandings remain strong, including among potential multiracial identifiers. Therefore, if mixed-race identification is to evolve into a multiracial identity, it may not be at the expense of existing group consciousness. Instead, we expect mixed-race identity to be contextual, fluid, and additive, so that it can be layered onto rather than substituted for traditional monoracial commitments. If the multiracial movement successfully challenges the longstanding understanding and practice of “one drop of blood” racial groups, it has the potential to change much of the politics and policy of American race relations.
Institutional Strangulation: Bureaucratic Politics and Financial Reform in the Obama Administration
Authors: Carpenter Daniel
Published: August 2010

The politics of financial reform represent a genuine test case for American politics and its institutions. The Obama administration's proposed reforms pit common (largely unorganized) interests against well-organized and wealthy minority interests. I describe how the withering and unfolding of financial reform has occurred not through open institutional opposition but through a quieter process that I call institutional strangulation. Institutional strangulation consists of much more than the stoppage of policies by aggregation of veto points as designed in the US Constitution. In the case of financial reform, it has non-constitutional veto points, including committee politics and cultural veto points (gender and professional finance), strategies of partisan intransigence, and perhaps most significantly, the bureaucratic politics of turf and reputation. These patterns can weaken common-interest reforms, especially in the broad arena of consumer protection.
Revised magnetostratigraphy and characteristics of the fluviolacustrine sedimentation of the Kashmir basin, India, during Pliocene‐Pleistocene
Authors: Basavaiah N. , Appel E. , Lakshmi B. V. , Deenadayalan K. , Satyanarayana K. V. V. , Misra Saumitra , Juyal N. , Malik M. A.
Published: August 2010

The Pliocene‐Pleistocene Karewa Group sediments of the Kashmir basin, India, provide an important continental archive for past climatic reconstruction. The present study reevaluates the magnetic polarity stratigraphy and the nature of the depositional environment at a 440‐m‐thick section along Romushi river near Pakharpur (33°48′50″N, 74°45′54″E). Magnetic remanences are predominantly carried by Ti‐rich titanomagnetite and magnetite. We identified eight normal and eight reversed‐polarity magnetozones in this succession, ranging between 4.40 and 0.77 Ma. The polarity sequence includes the new identification of the Cochiti and the Mammoth and their preceding and succeeding reversed/normal as well as the Jaramillo subchrons. Anisotropy of magnetic susceptibility data suggest the existence of northeast‐ and northwest‐flowing fluvial system before 4.18 Ma, indicating the Pir Panjal range at the southwest as the sediment source area. Following this, the valley was under the influence of fluviolacustrine environment between 4.18 and 0.77 Ma. Our results suggest relatively strong flow velocity toward the northeast during the upper Gilbert, Gauss, and lower and middle Matuyama chrons (4.18–1.07 Ma). In the upper Matuyama chron (<1.07 Ma), the prevailing paleocurrent direction in the basin changed toward the northwest with a reduced flow velocity, indicating the emergence of the ancestral Jhelum river. On the basis of the magnetic polarity chronology, the sediment accumulation rate indicates a very low value of ∼4.6 cm kyr−1before 1.95 Ma to ∼33 cm kyr−1between 1.95 and 1.77 Ma and 23 cm kyr−1after 1.77 Ma. We attribute temporal changes in sedimentation rate to the interplay between climate (predominantly westerlies) and tectonics (pulsating Pir Panjal uplift).
High‐speed friction of disaggregated ultracataclasite in rotary shear: Characterization of frictional heating, mechanical behavior, and microstructure evolution
Authors: Kitajima Hiroko , Chester Judith S. , Chester Frederick M. , Shimamoto Toshihiko
Published: August 2010

To understand the frictional behavior of natural faults at seismic slip rates, high‐speed rotary shear experiments were conducted on disaggregated ultracataclasite from the Punchbowl fault. The experimental gouge layers were sheared at normal stresses of 0.2–1.3 MPa and velocities of 0.1–1.3 m/s to total displacements of 1.3–84 m. We employ thermomechanical FEM models and microstructural observations to consider spatial and temporal variation of normal stress and temperature in the samples and understand microprocesses. Four distinct gouge units form during shear. A slightly sheared starting material (Unit 1) and a strongly sheared and foliated gouge (Unit 2) are produced when frictional heating is insignificant and the coefficient of sliding friction is 0.4–0.6. A random fabric gouge with rounded prophyroclasts (Unit 3) and an extremely fine, microfoliated layer (Unit 4) develop when significant frictional heating occurs at greater velocity and normal stress, and the coefficient of sliding friction drops to approximately 0.2. Unit 3 forms at the critical temperature for vaporization of water and is associated with localization of slip to Unit 4 and elevation of temperature. The critical displacement for dynamic weakening in the rotary configuration can be understood as a consequence of the progressive inward migration of the friction‐generated thermal front and the weaker localized slip surface and associated fluidized zone.
Reconstruction and analysis of the Chukchi Sea circulation in 1990–1991
Authors: Panteleev G. , Nechaev D. A. , Proshutinsky A. , Woodgate R. , Zhang J.
Published: August 2010

The Chukchi Sea (CS) circulation reconstructed for September 1990 to October 1991 from sea ice and ocean data is presented and analyzed. The core of the observational data used in this study comprises the records from 12 moorings deployed in 1990 and 1991 in U.S. and Russian waters and two hydrographic surveys conducted in the region in the fall of 1990 and 1991. The observations are processed by a two‐step data assimilation procedure involving the Pan‐Arctic Ice‐Ocean Modeling and Assimilation System (employing a nudging algorithm for sea ice data assimilation) and the Semi‐implicit Ocean Model [utilizing a conventional four‐dimensional variational (4D‐var) assimilation technique]. The reconstructed CS circulation is studied to identify pathways and assess residence times of Pacific water in the region; quantify the balances of volume, freshwater, and heat content; and determine the leading dynamical factors configuring the CS circulation. It is found that in 1990–1991 (high AO index and a cyclonic circulation regime) Pacific water transiting the CS toward the Canada basin followed two major pathways, namely via Herald Canyon (Herald branch of circulation, 0.23 Sv) and between Herald Shoal and Cape Lisburne (central branch of circulation and Alaskan Coastal Current, 0.32 Sv). The annual mean flow through Long Strait was negligible (0.01 Sv). Typical residence time of Pacific water in the region varied between 150 days for waters entering the CS in September and 270 days for waters entering in February/March. Momentum balance analysis reveals that geostrophic balance between barotropic pressure gradient and Coriolis force dominated for most of the year. Baroclinic effects were important for circulation only in the regions with large horizontal salinity gradients associated with the fresh Alaskan and Siberian coastal currents and the Cape Lisburne and Great Siberian polynyas. In the polynyas, the baroclinic effects were due to strong salinification and convection processes associated with sea ice formation.
A multi‐data set analysis of variability and change in Arctic spring snow cover extent, 1967–2008
Authors: Brown Ross , Derksen Chris , Wang Libo
Published: August 2010

A new multi‐data set estimate of Arctic monthly snow cover extent (SCE) in the May–June melt period is derived from 10 data sources covering different time periods from 1967 to 2008. The data sources include visible and microwave satellite observations, objective analyses of surface snow depth observations, reconstructed snow cover from daily temperature and precipitation, and proxy information derived from thaw dates. The new estimates show a more linear reduction in spring SCE than previously characterized by the National Oceanic and Atmospheric Administration weekly snow chart data set, with air temperature explaining 49% of the variability in Arctic SCE in May and 56% of the variability in June. The Arctic Oscillation is only significantly linked to Arctic SCE in May where it explains 25% of the variance in Eurasian sector SCE. Trend analysis of the multi‐data set series (including an annually varying estimate of error) reveals that May and June SCE have decreased 14% and 46%, respectively, over the pan‐Arctic region over the 1967–2008 period in response to earlier snow melt. These results are confirmed with in situ data from Canada, Alaska and Russia that show significant reductions in spring snow cover duration over the last 30 years. The spring snow cover temperature sensitivity over the pan‐Arctic region during this period is estimated to be in the range −0.8 to −1.00 × 106 km2 °C−1. The observed reductions in June SCE over the 1979–2008 period are found to be of the same magnitude as reductions in June sea ice extent with both series significantly correlated to air temperature changes over the Arctic region and to each other. This result underscores the close relationship between the cryosphere and surface air temperatures over the Arctic region in June when albedo feedback potential is at a maximum.
The Influence of Repeated Prestressors on Single Stress Response in Rats
Authors: Yamamotová Anna , Starec Miroslav , Ras˘ková Helena , Rokyta Richard
Published: August 2010

Abstract: The effect of various stressors of different intensity applied in random order before the final single immersion restraint stress was tested in two inbred rat strains, isoprenaline‐sensitive and isoprenaline‐resistant. The isoprenaline‐sensitive strain revealed higher incidence of heart lesions after this single acute stress and low incidence of gastric lesions. The isoprenaline‐resistant strain had the opposite characteristics. These differences were constantly reproducible when this strong stressor was used. After prestress by different stressors (tail‐flick, ether anaesthesia, Porsolt swimming stress) at different time schedules, the incidence of gastric ulcer lesions, the weight of organs (heart, adrenals, spleen) changed substantially in isoprenaline‐sensitive rats only. The most important result was reversal of the extent of gastric lesions. The isoprenaline‐sensitive strain revealed more lesions than the isoprenaline‐resistant one. The repeated different prestressors mainly changed the reactivity of animals, isoprenaline‐sensitive rats becoming more similar to isoprenaline‐resistant rats. These findings urged us to interpret carefully the results obtained in stress research with different and multiple stressors both in animals and humans.
Ceramides that Mediate Apoptosis Reduce Glucose Uptake and Transporter Affinity for Glucose in Human Leukaemic Cell Lines but Not in Neutrophils
Authors: Ahmed Nuzhat , Berridge Michael V.
Published: August 2010

We have demonstrated that CD95‐induced apoptosis in a human leukaemic T‐cell line resulted in loss of glucose transporter function (Berridge et al. 1996). To determine whether ceramide, a mediator of CD95 and tumour necrosis factor‐α‐induced apoptosis, has similar effects on glucose transport, the human leukaemic cell lines, Jurkat and U937, and human peripheral blood neutrophils were treated with ceramide or sphingomyelinase and the effects on glucose transport determined by measuring [3H]‐2‐deoxyglucose uptake. We show that in U937 and Jurkat cells, the cell permeable ceramides, C2 (N‐acetylsphingosine) and C6 (N‐hexanoylsphingosine) inhibit glucose uptake within minutes of initiating ceramide treatment, 60–70% inhibition being observed within 2 hr. Loss of glucose transport correlated with loss of proliferative response, but metabolic activity as measured by 3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyltetrazolium bromide (MTT) reduction, was affected to a much lesser extent. With Jurkat and U937 cells, the inhibitory effects of ceramides on glucose transport were associated with reduced affinity of glucose transporters for glucose (Km). Similar effects were observed with sphingomyelinase. With human peripheral blood neutrophils, C2 and C6‐ceramides inhibited glucose uptake by 70–80% within 30 min. without affecting transporter affinity for glucose, but the maximum velocity of uptake (Vmax) was reduced. These results show that acute regulation of glucose transport is an early effector mechanism of cell death induced by ceramides in human leukaemic cell lines and peripheral blood neutrophils. This is the first study which describes ceramide‐induced early physiological/biochemical events leading to cell death in human cells.
Studies on the Prevention of Nigericin Action in Neuroblastoma X Glioma Hybrid (NG108–15) Cells*
Authors: Doebler Jeffrey A.
Published: August 2010

Electrophysiological analysis of neuroblastoma X glioma hybrid (NG108–15) cells was used as an in vitro neuronal model system to evaluate antagonists of the K+‐selective carboxylic ionophore, nigericin. Changes in membrane electrical characteristics induced by nigericin with and without the simultaneous administration of antagonists were measured using intracellular microelectrode techniques. Bath application of nigericin (3 μM) produced a severe hyperpolarization and blocked the generation of action potentials in response to electrical stimulation. Simultaneous administration of nigericin plus the Na+‐K+ pump inhibitor ouabain or drugs known to influence Ca++ signaling in cells, i.e., quinidine, compound R24571, verapamil or haloperidol, was able to significantly attenuate the hyperpolarization. All antagonists acted in a concentration‐dependent manner. However, nigericin plus maximally effective concentrations of ouabain (1 μM), verapamil (3 μM) and haloperidol (3 and 10 μM) resulted in moderate‐to‐severe depolarization by the end of 24 min. superfusions, suggesting that the concentrations of antagonists were excessive and that NG108–15 cell damage had occurred. In addition, none of the compounds studied was able to effectively prevent nigericin‐induced blockade of action potentials. Thus, none of these antagonists appears suitable for transition to in vivo antidotal protection studies.
Understanding human genetic variation in the era of high‐throughput sequencing
Authors: Knight Julian C.
Published: August 2010

The EMBO/EMBL symposium ‘Human Variation: Cause and Consequence’ highlighted advances in understanding the molecular basis of human genetic variation and its myriad implications for biology, human origins and disease. As high‐throughput sequencing allows us to define genetic variation and its functional consequences at genome‐wide resolution for a large number of people, important questions need to be asked about how to use new technologies to maximize the translational relevance of genetic research for society and the individual patient.
An eruption of European B‐cell biology
Authors: Cancro Michael P.
Published: August 2010

Volcanic ash clouds disrupted the 2010 ESF/EMBO meeting on B cells and protection. Nevertheless, the delegates who did make it to Catalonia put together their own programme of talks covering a range of themes from mutualism to epigenetics.
An extensive case study of hairy‐root cultures for enhanced secondary‐metabolite production through metabolic‐pathway engineering
Authors: Mehrotra Shakti , Rahman Laiq Ur , Kukreja Arun Kumar
Published: August 2010

An intrinsic improvement is taking place in the methodologies for the development of culture systems with first‐rate production of plant‐based molecules. The blending of HR (hairy root) cultures with ME (metabolic engineering) approaches offers new insights into, and possibilities for, improving the system productivity for known and/or novel high‐value plant‐derived active compounds. The introduction and expression of foreign genes in plants results in improvement of cellular activities by manipulating enzymatic, regulatory and transport function of the cell. The rational amendments in the rate‐limiting steps of a biosynthetic pathway as well as inactivating the inefficient pathway(s) for by‐product formation can be accomplished either through single‐step engineering or through the multi‐step engineering. The hierarchical control of any metabolic process can lead the engineer to apply the ME ideas and principles to any of the strata, including transcriptional, moving on to translational and enzymatic activity. The HR culture systems offer a remarkable potential for commercial production of a number of low‐volume, but high‐value, secondary metabolites. Taking HR as a model system, in the present review, we discuss engineering principles and perceptions to exploit secondary‐metabolite pathways for the production of important bioactive compounds. We also talk about requisites and possible challenges that occur during ME, with emphasis on examples of various HR systems. Furthermore, it also highlights the utilization of global information obtained from ‘‐omic’ platforms in order to explore pathway architecture, structural and functional aspects of important enzymes and genes that can support the design of sets of engineering, resulting in the generation of wide‐ranging views of DNA sequence‐to‐metabolite passageway networking and their control to obtain desired results.
Organic‐solvent stability of elastase strain K overexpressed in an Escherichia–Pseudomonas expression system
Authors: Wong Chee Fah , Salleh Abu Bakar , Basri Mahiran , Rahman Raja Noor Zaliha Raja Abd.
Published: August 2010

The structural gene of elastase strain K (elastase from Pseudomonas aeruginosa strain K), namely HindIII1500PstI, was successfully sequenced to contain 1497 bp. The amino acid sequence, deduced from the nucleotide sequence, revealed that the mature elastase consists of 301 amino acids, with a molecular mass of 33.1 kDa, and contains a conserved motif HEXXH, zinc ligands and residues involved in the catalysis of elastase strain K. The structural gene was successfully cloned to a shuttle vector, pUCP19, and transformed into Escherichia coli strains TOP10, KRX, JM109 and Tuner™ pLacI as well as P. aeruginosa strains PA01 (A.T.C.C. 47085) and S5, with detection of significant protein expression. Overexpression was detected from transformants KRX/pUCP19/HindIII1500PstI of E. coli and PA01/pUCP19/HindIII1500PstI of P. aeruginosa, with increases in elastolytic activity to 13.83‐ and 5.04‐fold respectively relative to their controls. In addition, recombinant elastase strain K showed considerable stability towards numerous organic solvents such as methanol, ethanol, acetone, toluene, undecan‐1‐ol and n‐dodecane, which typically pose a detrimental effect on enzymes; our finding provides further information to support the potential application of the enzyme in synthetic industries, particularly peptide synthesis.
Lattice dynamics in the half-space. Energy transport equation
Authors: Dudnikova T. V.
Published: August 2010

We consider the lattice dynamics in the half-space with zero boundary condition. The initial data are random according to a probability measure which enforces slow spatial variation on the linear scale ε−1. We establish two time regimes. For times on the order of ε−κ, 0<κ<1, locally the measure converges to a Gaussian measure, which is time stationary with a covariance inherited from the initial measure (non-Gaussian, in general). For times on the order of ε−1, this covariance changes in time and is governed by a semiclassical transport equation.
Electron irradiation effects on electrical and optical properties of sol-gel prepared ZnO films
Authors: Bhat J. S. , Patil A. S. , Swami N. , Mulimani B. G. , Gayathri B. R. , Deshpande N. G. , Kim G. H. , Seo M. S. , Lee Y. P.
Published: August 2010

The effects of electron beam irradiation on the electrical and the optical properties of zinc oxide (ZnO) and aluminum-doped zinc oxide (ZnO:Al) thin films, prepared by the sol-gel technique, were investigated. The grain size, surface morphology, sheet resistance, optical constants, absorption edge, and direct and indirect optical band gaps of these films were analyzed before and after exposure to electron beam. The decrease in the structural homogeneity and the crystallinity of the films after exposure to electron irradiation is observed. The irradiation causes increase in the sheet resistance and blueshift in the absorption edge for both ZnO and ZnO:Al films. The change in carrier concentration due to doping as well as the exposure to electron beam are responsible for the modified electrical and optical properties.
Chiral metamaterials with negative refractive index based on four “U” split ring resonators
Authors: Li Zhaofeng , Zhao Rongkuo , Koschny Thomas , Kafesaki Maria , Alici Kamil Boratay , Colak Evrim , Caglayan Humeyra , Ozbay Ekmel , Soukoulis C. M.
Published: August 2010

A uniaxial chiral metamaterial is constructed by double-layered four “U” split ring resonators mutually twisted by 90°. It shows a giant optical activity and circular dichroism. The retrieval results reveal that a negative refractive index is realized for circularly polarized waves due to the large chirality. The experimental results are in good agreement with the numerical results.
Growth model of binary alloy nanopowders for thermal plasma synthesis
Authors: Shigeta Masaya , Watanabe Takayuki
Published: August 2010

A new model is developed for numerical analysis of the entire growth process of binary alloy nanopowders in thermal plasma synthesis. The model can express any nanopowder profile in the particle size-composition distribution (PSCD). Moreover, its numerical solution algorithm is arithmetic and straightforward so that the model is easy to use. By virtue of these features, the model effectively simulates the collective and simultaneous combined process of binary homogeneous nucleation, binary heterogeneous cocondensation, and coagulation among nanoparticles. The effect of the freezing point depression due to nanoscale particle diameters is also considered in the model. In this study, the metal–silicon systems are particularly chosen as representative binary systems involving cocondensation processes. In consequence, the numerical calculation with the present model reveals the growth mechanisms of the Mo–Si and Ti–Si nanopowders by exhibiting their PSCD evolutions. The difference of the materials’ saturation pressures strongly affects the growth behaviors and mature states of the binary alloy nanopowder.
Nanostructured electrodes for thermionic and thermotunnel devices
Authors: Tavkhelidze Avto N.
Published: August 2010

Recently, distinctive quantum features have been studied in the area of ridged quantum wells (RQWs). Periodic ridges on the surface of the quantum well layer impose additional boundary conditions on the electron wave function and reduce the quantum state density. Electrons, rejected from forbidden quantum states, have to occupy the states with higher energy. As a result, Fermi energy in RQW increases and work function (WF) decreases. We investigate low WF electrode, composed from a metal RQW layer and a base substrate. The substrate material was selected so that electrons were confined to the RQW. The WF value depends on ridge geometry and electron confinement. We calculate WF in the metal RQW films grown both on a semiconductor and metal substrates. In the case of semiconductor substrate, wide band gap materials are preferable as they allow more reduction in RQW WF. In the case of metal substrate, low Fermi energy materials are preferable. For most material pairs, the WF was reduced dramatically. Such structures, can serve as electrodes for room temperature thermionic and thermotunnel energy converters and coolers.
Ballistic transport through electric field modulated graphene periodic magnetic barriers
Authors: Biswas R. , Biswas A. , Hui N. , Sinha C.
Published: August 2010

The transmission coefficient and the ballistic conductance are studied theoretically for a Dirac fermion through the graphene periodic magnetic barriers modulated by a homogeneous in-plane electric field. The transmission is highly asymmetric for zero and low biased conditions of the system. In contrast, it turns out to be symmetric in case of strongly modulated (by electric field) magnetic barriers and becomes independent of the number of barriers due to the predominant Klein tunneling effect. Interesting electric field effects are noted on the angular transmission properties of the chiral carriers. The conductivity profile exhibits some negative differential conducting regions, the number and the sharpness of the regions being intimately related to the number of barriers and the Fermi energy of the system.
Hugoniot of shocked liquid deuterium up to 300 GPa: Quantum molecular dynamic simulations
Authors: Wang Cong , He Xian-Tu , Zhang Ping
Published: August 2010

Quantum molecular dynamic (QMD) simulations are introduced to study the thermophysical properties of liquid deuterium under shock compression. The principal Hugoniot is determined from the equation of states, where contributions from molecular dissociation and atomic ionization are also added onto the QMD data. At pressures below 100 GPa, our results show that the local maximum compression ratio of 4.5 can be achieved at 40 GPa, which is in good agreement with magnetically driven flyer and convergent-explosive experiments; At the pressure between 100 and 300 GPa, the compression ratio reaches a maximum of 4.95, which agrees well with recent high power laser-driven experiments. In addition, the nonmetal-metal transition and optical properties are also discussed.
Photonic crystal composites-based wide-band optical collimator
Authors: Shi Jinjie , Juluri Bala Krishna , Lin Sz-Chin Steven , Lu Mengqian , Gao Tieyu , Huang Tony Jun
Published: August 2010

Photonic crystal (PC) composites are sequenced series of PCs that feature the same periods but different filling fractions. By properly tuning the filling fractions of the individual PCs and merging the working band of each PC into a continuous frequency range, wide-band self-collimation of optical signals can be realized. The band diagrams and the equal-frequency contours of the PC structures were calculated through the plane wave expansion method and the finite-difference time-domain method was employed to simulate the propagation of electromagnetic waves through the PC structures. Our results show that while a single PC can only collimate optical waves over a narrow frequency range, a PC composite exhibits a much wider collimation band. Such a wide-band optical collimation lens can be useful in applications that demand directional optical energy flow over a long distance, such as optical imaging and biosensing.
The fine structure of SU(2) intertwiners from U(N) representations
Authors: Freidel Laurent , Livine Etera R.
Published: August 2010

In this work, we study the Hilbert space space of N-valent SU(2) intertwiners with fixed total spin, which can be identified, at the classical level, with a space of convex polyhedra with N faces and fixed total boundary area. We show that this Hilbert space provides, quite remarkably, an irreducible representation of the U(N) group. This gives us therefore a precise identification of U(N) as a group of area-preserving diffeomorphisms of polyhedral spheres. We use this result to get new closed formulas for the black hole entropy in loop quantum gravity.
Exact nonadditive kinetic potentials for embedded density functional theory
Authors: Goodpaster Jason D. , Ananth Nandini , Manby Frederick R. , Miller Thomas F.
Published: August 2010

We describe an embedded density functional theory (DFT) protocol in which the nonadditive kinetic energy component of the embedding potential is treated exactly. At each iteration of the Kohn–Sham equations for constrained electron density, the Zhao–Morrison–Parr constrained search method for constructing Kohn–Sham orbitals is combined with the King-Handy expression for the exact kinetic potential. We use this formally exact embedding protocol to calculate ionization energies for a series of three- and four-electron atomic systems, and the results are compared to embedded DFT calculations that utilize the Thomas–Fermi (TF) and the Thomas–Fermi–von Weisacker approximations to the kinetic energy functional. These calculations illustrate the expected breakdown due to the TF approximation for the nonadditive kinetic potential, with errors of 30%–80% in the calculated ionization energies; by contrast, the exact protocol is found to be accurate and stable. To significantly improve the convergence of the new protocol, we introduce a density-based switching function to map between the exact nonadditive kinetic potential and the TF approximation in the region of the nuclear cusp, and we demonstrate that this approximation has little effect on the accuracy of the calculated ionization energies. Finally, we describe possible extensions of the exact protocol to perform accurate embedded DFT calculations in large systems with strongly overlapping subsystem densities.
An experimental methodology to relate local strain to microstructural texture
Authors: Carroll J. , Abuzaid W. , Lambros J. , Sehitoglu H.
Published: August 2010

This paper introduces an experimental methodology for obtaining high resolution full-field strain measurements in polycrystalline metals. The (sub)grain level resolution of these measurements was indispensable for relating measured strain fields to observed microstructure in the material. Microstructural information was obtained through electron backscatter diffraction and the optical technique of digital image correlation (DIC) was used to acquire full-field deformation measurements. By spatially overlaying both sets of results, the effects of different microstructural features such as orientation, grain boundary character, misorientation between grains, and twin boundaries on material response can be quantitatively studied. To obtain the necessary resolution for such measurements, the images used in DIC had to be captured at high magnifications. This necessity reduces the field of view and constrains the area of interest that can be monitored. To address this issue, results from adjacent measurement areas are combined together to create a data set with high spatial strain resolution over a larger region than can otherwise be observed. The procedure for performing this technique is outlined here, along with benefits, drawbacks, possible modifications, and example applications of the technique to cyclic plasticity and fatigue crack growth.
Complete classification of parallel Lorentz surfaces in four-dimensional neutral pseudosphere
Authors: Chen Bang-Yen
Published: August 2010

A Lorentz surface of an indefinite space form is called parallel if its second fundamental form is parallel with respect to the Van der Waerden–Bortolotti connection. Such surfaces are locally invariant under the reflection with respect to the normal space at each point. Parallel surfaces are important in geometry as well as in general relativity since extrinsic invariants of such surfaces do not change from point to point. Parallel Lorentz surfaces in four-dimensional (4D) Lorentzian space forms are classified by Chen and Van der Veken [“Complete classification of parallel surfaces in 4-dimensional Lorentz space forms,” Tohoku Math. J. 61, 1 (2009)]. Recently, explicit classification of parallel Lorentz surfaces in the pseudo-Euclidean 4-space E24 and in the pseudohyperbolic 4-space H24(−1) are obtained recently by Chen et al. [“Complete classification of parallel Lorentzian surfaces in Lorentzian complex space forms,” Int. J. Math. 21, 665 (2010); “Complete classification of parallel Lorentz surfaces in neutral pseudo hyperbolic 4-space,” Cent. Eur. J. Math. 8, 706 (2010)], respectively. In this article, we completely classify the remaining case; namely, parallel Lorentz surfaces in 4D neutral pseudosphere S24(1). Our result states that there are 24 families of such surfaces in S24(1). Conversely, every parallel Lorentz surface in S24(1) is obtained from one of the 24 families. The main result indicates that there are major differences between Lorentz surfaces in the de Sitter 4-space dS4 and in the neutral pseudo 4-sphere S24.
An experimental study of a plasma actuator in absence of free airflow: Ionic wind velocity profile
Authors: Mestiri R. , Hadaji R. , Ben Nasrallah S.
Published: August 2010

In this study, we are interested in the direct current electrical corona discharge created between two wire electrodes. The experimental results are related to some electroaerodynamic actuators based on the direct current corona discharge at the surface of a dielectric material. Several geometrical forms are selected for the dielectric surface, such as a plate, a cylinder, and a NACA 0015 aircraft wing. The current density–electric field characteristics are presented for different cases in order to determine the discharge regimes. The corona discharge produces nonthermal plasma, so it is called plasma discharge. Plasma discharge creates a tangential ionic wind above the surface at the vicinity of the wall. The ionic wind induced by the corona discharge is measured in absence of free external airflow. The ionic wind velocity profiles and the maximum induced tangential force are given for different surface forms, so it is possible to compare the actuators effect based on the span of the ionic wind velocity and thrust values. The higher ionic wind velocity is obtained with the NACA profile, which shows the effectiveness of this actuator for the airflow control.
Phase-breaking effects in double-barrier resonant tunneling diodes with spin-orbit interaction
Authors: Isić Goran , Indjin Dragan , Milanović Vitomir , Radovanović Jelena , Ikonić Zoran , Harrison Paul
Published: August 2010

Several recent theoretical studies showed that the spin-orbit interaction in narrow gap InGaAs/InAlAs double-barrier resonant tunneling structures might yield a highly spin-polarized current in the ballistic limit. In this paper, a nonequilibrium Green’s function model is used to examine the effect of phase-breaking on the spin-dependent transport of carriers. The scattering is described as a local interaction with a bath of scatterers and treated in the self-consistent first Born approximation. Elastic and inelastic scatterers, with scattering strengths that cause a few millielectron volt broadening of quasibound states, have been found to significantly reduce the spin polarization. The magnitude of spin polarization has been found to be dominantly determined by the quasibound state broadening, while the interaction details are not significant.