bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbulent wake past a three-dimensional blunt body. Part 1. Global modes and bi-stability
Authors: Grandemange M. , Gohlke M. , Cadot O.
Published: March 2013

The flow around the three-dimensional blunt geometry presented in the work of Ahmed, Ramm & Faitin (Tech. Rep., 1984) is investigated experimentally at $\mathit{Re}= {U}_{0} H/ \nu = 9. 2\times 1{0}^{4} $ (where ${U}_{0} $ is free-stream velocity, $H$ the height of the body and $\nu $ viscosity). The very large recirculation on the base responsible for the dominant part of the drag is characterized. The analyses of the coherent dynamics of the wake reveal the presence of two very distinctive time scales. At long time scales ${T}_{l} \sim 1{0}^{3} H/ {U}_{0} $, the recirculation region shifts between two preferred reflectional-symmetry-breaking positions leading to a statistically symmetric wake; the sequence of these asymmetric states is random. This bi-stable behaviour is independent of the Reynolds number but occurs only above a critical value of ground clearance. At short time scales ${T}_{s} \sim 5H/ {U}_{0} $, the wake presents weak coherent oscillations in the vertical and lateral directions. They are respectively associated with the interaction of the top/bottom and lateral shear layers; when normalized by the height and width of the body, the Strouhal numbers are close to 0.17. These results suggest an alternate shedding associated with the vertical oscillation and a one-sided vortex shedding in the lateral direction with an orientation linked to the current asymmetric position. Finally, the impact of these coherent wake motions on the base pressure is discussed to motivate further drag reduction strategies.
Radio Continuum Surveys with Square Kilometre Array Pathfinders
Authors: Norris Ray P. , Afonso J. , Bacon D. , Beck Rainer , Bell Martin , Beswick R. J. , Best Philip , Bhatnagar Sanjay , Bonafede Annalisa , Brunetti Gianfranco , Budavári Tamás , Cassano Rossella , Condon J. J. , Cress Catherine , Dabbech Arwa , Feain I. , Fender Rob , Ferrari Chiara , Gaensler B. M. , Giovannini G. , Haverkorn Marijke , Heald George , Van der Heyden Kurt , Hopkins A. M. , Jarvis M. , Johnston-Hollitt Melanie , Kothes Roland , Van Langevelde Huib , Lazio Joseph , Mao Minnie Y. , Martínez-Sansigre Alejo , Mary David , Mcalpine Kim , Middelberg E. , Murphy Eric , Padovani P. , Paragi Zsolt , Prandoni I. , Raccanelli A. , Rigby Emma , Roseboom I. G. , Röttgering H. , Sabater Jose , Salvato Mara , Scaife Anna M. M. , Schilizzi Richard , Seymour N. , Smith Dan J. B. , Umana Grazia , Zhao G.-B. , Zinn Peter-Christian
Published: March 2013

In the lead-up to the Square Kilometre Array (SKA) project, several next-generation radio telescopes and upgrades are already being built around the world. These include APERTIF (The Netherlands), ASKAP (Australia),e-MERLIN (UK), VLA (USA), e-EVN (based in Europe), LOFAR (The Netherlands), MeerKAT (South Africa), and the Murchison Widefield Array. Each of these new instruments has different strengths, and coordination of surveys between them can help maximise the science from each of them. A radio continuum survey is being planned on each of them with the primary science objective of understanding the formation and evolution of galaxies over cosmic time, and the cosmological parameters and large-scale structures which drive it. In pursuit of this objective, the different teams are developing a variety of new techniques, and refining existing ones. To achieve these exciting scientific goals, many technical challenges must be addressed by the survey instruments. Given the limited resources of the global radio-astronomical community, it is essential that we pool our skills and knowledge. We do not have sufficient resources to enjoy the luxury of re-inventing wheels. We face significant challenges in calibration, imaging, source extraction and measurement, classification and cross-identification, redshift determination, stacking, and data-intensive research. As these instruments extend the observational parameters, we will face further unexpected challenges in calibration, imaging, and interpretation. If we are to realise the full scientific potential of these expensive instruments, it is essential that we devote enough resources and careful study to understanding the instrumental effects and how they will affect the data. We have established an SKA Radio Continuum Survey working group, whose prime role is to maximise science from these instruments by ensuring we share resources and expertise across the projects. Here we describe these projects, their science goals, and the technical challenges which are being addressed to maximise the science return.
Effects of resveratrol on changes induced by high-fat feeding on clock genes in rats
Authors: Miranda Jonatan , Portillo María P. , Madrid Juan Antonio , Arias Noemí , Macarulla M. Terasa , Garaulet Marta
Published: March 2013

In mammals, the main component of the circadian system is the suprachiasmatic nucleus in the hypothalamus. However, circadian clocks are also present in most peripheral tissues, such as adipose tissue. The aim of the present study was to analyse the potential effects of resveratrol on changes induced by high-fat feeding in the expression of clock genes and clock-controlled genes in the white adipose tissue from rats. For this purpose, rats were divided into three groups: a control group, fed a standard diet, and two other groups, either fed a high-fat diet supplemented with resveratrol (RSV) or no resveratrol (HF). The expression of clock genes and clock-controlled genes was analysed by RT-PCR. Protein expression and fatty acid synthase (FAS) activity were also analysed. When comparing the controls, the RSV group showed similar patterns of response to the HF group, except for reverse erythroblastosis virus α (Rev-Erbα), which was down-regulated. The expression of this gene reached the same levels as in control rats. The response pattern of protein expression forRev-Erbαwas similar to that found for gene expression. High-fat feeding up-regulated all adipogenic genes and resveratrol did not modify them. In the HF group, the activity of FAS tended to increase, while resveratrol decreased. In conclusion, resveratrol reverses the change induced by high-fat feeding in the expression ofRev-Erbαin adipose tissue, which means that clock machinery is a target for this polyphenol. This change seems to be related to reduced lipogenesis, which might be involved in the body fat-lowering effect of this molecule.
Oligomerised lychee fruit-derived polyphenol attenuates cognitive impairment in senescence-accelerated mice and endoplasmic reticulum stress in neuronal cells
Authors: Sakurai Takuya , Kitadate Kentaro , Nishioka Hiroshi , Fujii Hajime , Ogasawara Junetsu , Kizaki Takako , Sato Shogo , Fujiwara Tomonori , Akagawa Kimio , Izawa Tetsuya , Ohno Hideki
Published: March 2013

Recently, the ability of polyphenols to reduce the risk of dementia and Alzheimer's disease (AD) has attracted a great deal of interest. In the present study, we investigated the attenuating effects of oligomerised lychee fruit-derived polyphenol (OLFP, also called Oligonol) on early cognitive impairment. Male senescence-accelerated mouse prone 8 (SAMP8) mice (4 months old) were given OLFP (100 mg/kg per d) for 2 months, and then conditioned fear memory testing was conducted. Contextual fear memory, which is considered hippocampus-dependent memory, was significantly impaired in SAMP8 mice compared with non-senescence-accelerated mice. OLFP attenuated cognitive impairment in SAMP8 mice. Moreover, the results of real-time PCR analysis that followed DNA array analysis in the hippocampus revealed that, compared with SAMP8 mice, the mRNA expression of Wolfram syndrome 1 (Wfs1) was significantly higher in SAMP8 mice administered with OLFP. Wfs1 reportedly helps to protect against endoplasmic reticulum (ER) stress, which is thought to be one of the causes for AD. The expression of Wfs1 was significantly up-regulated in NG108-15 neuronal cells by the treatment with OLFP, and the up-regulation was inhibited by the treatment of the cells with a c-Jun N-terminal kinase-specific inhibitor rather than with an extracellular signal-regulated kinase inhibitor. Moreover, OLFP significantly attenuated the tunicamycin-induced expression of the ER stress marker BiP (immunoglobulin heavy chain-binding protein) in the cells. These results suggest that OLFP has an attenuating effect on early cognitive impairment in SAMP8 mice, and diminishes ER stress in neuronal cells.
DRAWING MULTISETS OF BALLS FROM TENABLE BALANCED LINEAR URNS
Authors: Mahmoud Hosam M.
Published: March 2013

We investigate the evolution of an urn of balls of two colors, where one chooses a pair of balls and observes rules of ball addition according to the outcome. A nonsquare ball addition matrix of the form$\left( \matrix{a & b \cr c & d \cr e & f}\right)$corresponds to such a scheme, in contrast to pólya urn models that possess a square ball addition matrix. We look into the case of constant row sum (the so-called balanced urns) and identify a linear case therein. Two cases arise in linear urns: the nondegenerate and the degenerate. Via martingales, in the nondegenerate case one gets an asymptotic normal distribution for the number of balls of any color. In the degenerate case, a simpler probability structure underlies the process. We mention in passing a heuristic for the average-case analysis for the general case of constant row sum.
SINGLE-MACHINE MULTIPLE-RECIPE PREDICTIVE MAINTENANCE
Authors: Cai Yiwei , Hasenbein John J. , Kutanoglu Erhan , Liao Melody
Published: March 2013

This paper studies a multiple-recipe predictive maintenance problem with M/G/1 queueing effects. The server degrades according to a discrete-time Markov chain and we assume that the controller knows both the machine status and the current number of jobs in the system. The controller's objective is to minimize total discounted costs or long-run average costs which include preventative and corrective maintenance costs, holdings costs, and possibly production costs. An optimal policy determines both when to perform maintenance and which type of job to process. Since the policy takes into account the machine's degradation status, such control decisions are known as predictive maintenance policies. In the single-recipe case, we prove that the optimal policy is monotone in the machine status, but not in the number of jobs in the system. A similar monotonicity result holds in the two-recipe case. Finally, we provide computational results indicating that significant savings can be realized when implementing a predictive maintenance policies instead of a traditional job-based threshold policy for preventive maintenances.
EXPANSIONS FOR MOMENTS OF COMPOUND POISSON DISTRIBUTIONS
Authors: Nadarajah S. , Withers C.S. , Bakar S.A.A.
Published: March 2013

Expansions for moments of $\overline{X}$, the mean of a random sample of size n, are given for both the univariate and multivariate cases. The coefficients of these expansions are simply Bell polynomials. An application is given for the compound Poisson variable SN, where $S_{n} = n \overline{X}$ and N is a Poisson random variable independent of X1, X2, …, yielding expansions that are computationally more efficient than the Panjer recursion formula and Grubbström and Tang's formula.
WAITING TIME ANALYSIS OF MULTI-CLASS QUEUES WITH IMPATIENT CUSTOMERS
Authors: Sarhangian Vahid , Balciog̃lu Bariş
Published: March 2013

In this paper, we study three delay systems where different classes of impatient customers arrive according to independent Poisson processes. In the first system, a single server receives two classes of customers with general service time requirements, and follows a non-preemptive priority policy in serving them. Both classes of customers abandon the system when their exponentially distributed patience limits expire. The second system comprises parallel and identical servers providing the same type of service for both classes of impatient customers under the non-preemptive priority policy. We assume exponential service times and consider two cases depending on the time-to-abandon distribution being exponentially distributed or deterministic. In either case, we permit different reneging rates or patience limits for each class. Finally, we consider the first-come-first-served policy in single- and multi-server settings. In all models, we obtain the Laplace transform of the virtual waiting time for each class by exploiting the level-crossing method. This enables us to compute the steady-state system performance measures.
Current status of the threatened Olrog’s GullLarus atlanticus: global population, breeding distribution and threats
Authors: YORIO PABLO , PETRACCI PABLO , GARCÍA BORBOROGLU PABLO
Published: March 2013

Olrog’s GullLarus atlanticusbreeds only in Argentina and is currently categorized as “Vulnerable”. Knowledge of the location of colonies and an updated understanding of human activities that may impact their breeding populations are crucial to the development of adequate conservation and management actions. In this paper we update the breeding distribution and abundance of Olrog’s Gull, using information from three aerial surveys (2004, 2007 and 2009) in its main breeding area, Buenos Aires Province, complemented by additional nest counts in southern Chubut Province, covering its entire breeding range. We also provide an updated and more detailed account of threats faced by Olrog’s Gulls at their nesting grounds, and summarise progress made towards their protection. The number of breeding sites was 7–12 per year, with locations differing among years. Five previously unrecorded breeding locations were identified. Colony size ranged from 5 to 3,540 breeding pairs, with the total breeding population 4,860–7,790 pairs, 98% of which nest in southern Buenos Aires Province. The main threats faced by breeding Olrog’s Gulls include coastal development, pollution, sport fishing and unregulated tourism and recreational activities. Recent strengthening of the protected area system in Argentina has resulted in all known breeding sites, with the exception of Isla Brightman, falling within protected areas. We need comprehensive, simultaneous surveys to track global population trends. Despite enhanced protection of Olrog’s Gull breeding populations, efforts are still needed to ensure that guidelines for their protection are included in management plans and that these are implemented effectively.
Frigatebirds on Aldabra Atoll: population census, recommended monitoring protocol and sustainable tourism guidelines
Authors: ŠÚR MICHAL , BUNBURY NANCY , VAN DE CROMMENACKER JANSKE
Published: March 2013

We report the results of a survey of breeding Greater Frigatebird Fregata minor and Lesser Frigatebird F. ariel on Aldabra Atoll, a UNESCO World Heritage site in the Seychelles archipelago, which hosts the largest breeding population of frigatebirds in the Indian Ocean. All four colonies across the atoll were surveyed in 2011 and 2012 by counting adults on nests and chicks, and calculating the number of fledged birds. The breeding population in 2011 consisted of approximately 4,400 pairs of Greater Frigatebird and 6,600 pairs of Lesser Frigatebird. This is a potential increase of at least 10% since the last comparable surveys in 1976/77 and 2000. However, 2012 populations were considerably less than in 2011, highlighting significant annual variation and the need for more data. We also report a new breeding colony on the island of Picard, which was last reported to host breeding frigatebirds a century ago. We outline recommendations for future frigatebird monitoring on Aldabra and elsewhere and revisions to tourist regulations resulting from the census.
Positive association between rat abundance and breeding success of the Critically Endangered Mariana Crow Corvus kubaryi
Authors: AMAR ARJUN , ESSELSTYN JACOB A.
Published: March 2013

Diagnosing the causes of population declines of highly endangered species is vital to ensure that appropriate conservation measures are undertaken. Although experiments can provide critical information on potential causes, these can be time consuming and costly, and so it is important to determine the most plausible hypothesis for such tests. The last wild population of the Critically Endangered Mariana Crow Corvus kubaryi has been declining rapidly on Rota in the Mariana Islands. Because nest predation by introduced rats Rattus spp. has been implicated in the declines of other Pacific island birds, we tested for a correlation between breeding success of Mariana Crows and abundance of rats R. diardii surrounding their nest sites. If rats are a contributing factor in this species’s decline, we predicted that breeding success would be lower in areas where rats were more abundant. In complete contrast to this prediction, we found that breeding success was significantly higher where rats were most abundant, suggesting that rats are unlikely to be a major driving force behind the decline in this species. The positive association between crow breeding success and rat abundance suggests these species may be responding to similar habitat needs or a shared predator. This study illustrates the importance of gathering sufficient knowledge on the ecology of a species prior to undertaking costly, logistically difficult and time consuming experiments.
Robo-Polls: Taking Cues from Traditional Sources?
Authors: Clinton Joshua D. , Rogers Steven
Published: March 2013

After the 2012 Republican New Hampshire primary, 159 poll results were released prior to the subsequent nomination contests in the Republican presidential primary. More than two-thirds of these polls relied on interactive voice response (IVR) software to conduct the interviews. We evaluate the ability of polls to predict the vote-share for the Republican candidates Romney, Santorum, and Gingrich. We find no overall difference in the average accuracy of IVR and traditional human polls, but IVR polls conducted prior to human polls are significantly poorer predictors of election outcomes than traditional human polls even after controlling for characteristics of the states, polls, and electoral environment. These findings provide suggestive, but not conclusive, evidence that pollsters may take cues from one another given the stakes involved. If so, reported polls should not be assumed to be independent of one another and so-called poll-of-polls will be misleadingly precise.
Vote Au Pluriel: How People Vote When Offered to Vote Under Different Rules
Authors: Van der Straeten Karine , Laslier Jean-François , Blais André
Published: March 2013

This article reports on an Internet-based quasi-experiment that took place during the French 2012 presidential election. We designed a website where French voters could vote under different voting rules. Based on the observation of more than 8,000 participants, we find that a substantial minority (10% to 15%) vote differently under the different systems, with 17% of the voters not voting for their preferred candidate in the one-round election, this percentage dropped to 12% in the alternative vote (first choice). Compared to the two-rounds election, at the aggregate level, the top two candidates get slightly more votes under one round, while the minor candidates obtain more first choices under the alternative vote. These findings are consistent with what the literature suggests about the impact of these voting systems on voters' choice.
Sandy the Rainmaker: The Electoral Impact of a Super Storm
Authors: Velez Yamil , Martin David
Published: March 2013

The arrival of Hurricane Sandy within a week of the 2012 presidential election caused unprecedented disruption to the final days of the campaign and Election Day in areas that were affected. The precise impact of the storm on those areas hit hardest was not necessarily clear. Contrary to prior research on the effect of disasters on electoral outcomes, we find that the president's vote share was ultimately increased in storm-affected areas by about four percentage points, plus or minus two points. While those states most heavily affected were unlikely to give their electoral vote to Romney because of other factors, we present counterfactual analyses that show that such a storm could have had a significant impact on swing states: although the storm only affected some areas, we show that Virginia would likely have been won by Romney were it not hit at all, whereas North Carolina would likely have gone for Obama had it been directly in the storm's path.
Teaching the “New Middle East”: Beyond Authoritarianism
Authors: Medani Khalid Mustafa
Published: March 2013

In 2011 the protests in the Middle East and North Africa (MENA) were not only unprecedented in terms of scale and political consequences for the region, they also highlighted a number of long-standing analytical and theoretical misconceptions about Arab politics. In particular, the conventional thesis privileging the idea of a “durable authoritarianism” in the Arab world was partially undermined by a cross-regional civil society that confronted the formidable security and military apparatus of the state. Although in some countries democratic transitions have continued, since they first occurred in Tunisia, other Arab states continue to witness a resilient authoritarianism and strong state repression of civil society activism. These historic events have also set the stage for a new teaching agenda in important ways. Specifically, an agenda for teaching the “new Middle East” must incorporate two important general components: first, a critical review of the influential scholarship on persistent authoritarianism with the objective of addressing past theoretical and methodological misconceptions, and second, the introduction of new conceptual and analytical frameworks relevant to contemporary political developments in the Arab world and the MENA region more generally.
The Bread Revolutions of 2011: Teaching Political Economies of the Middle East
Authors: Moore Pete
Published: March 2013

Whether it was bread-wielding Tunisians, marching Suez workers, or Yemeni protestors chanting against corruption, the 2011 Arab uprisings put political economy issues front and center. Indeed, a critical thread throughout the region's uprisings has been the simple question: “where has the money gone?” And though the field of political economy is multifaceted, the basic refrain “follow the money” unites most of it. Having students engage and debate political economy issues helps counteract much of the popular media's fixation on violence, terrorism, and sectarianism that too often exclusively frames how Americans understand the Middle East. Political economy gets at some of the most important (but certainly not all) factors and dynamics that define social and political life in the Middle East. A political economy approach also reinforces the critical disposition and tools of inquiry to instill in university undergraduates. In particular, the approach stresses to students that the realms of the economy and the political are hardly distinct, and therefore a more complete explanation for the events of 2011, and after, require grasping that interaction (Lindblom 1982; Polanyi 2001).
Where and When Can We Use Google Trends to Measure Issue Salience?
Authors: Mellon Jonathan
Published: March 2013

Google search data have several major advantages over traditional survey data. First, the high costs of running frequent surveys mean that most survey questions are only asked occasionally making comparisons over time difficult. By contrast, Google Trends provides information on search trends measured weekly. Second, there are many countries where surveys are only conducted sporadically, whereas Google search data are available anywhere in the world where sufficient numbers of people use its search engine. The Google Trends website allows researchers to download data for almost all countries at no cost and to download time series of any search term's popularity over time (provided enough people have searched for it). For these reasons, Google Trends is an attractive data source for social scientists.
Using Online Search Traffic to Predict US Presidential Elections
Authors: Granka Laura
Published: March 2013

Predictions of the United States presidential election vote outcome have been growing in scope and popularity in the academic realm. Traditional election forecasting models predict the United States presidential popular vote outcome on a national level based primarily on economic indicators (e.g., real income growth, unemployment), public approval ratings, and incumbency advantage. Many of these forecasting models are rooted in retrospective voting theory (Downs 1957; Fiorina 1981), essentially rewarding the party in office if times are good, punishing it if times are bad. These models have successfully predicted election results by modeling economic performance and incumbent approval ratings (Campbell 2012; Fair 1992; Fair 1996; Klarner 2012). For example, Abramowitz's (2004; 2005) “time for a change model” predicts election results using economic performance during the first half of the election year, the number of years the incumbent party has been in office, and presidential approval. For a full review of 13 presidential forecasts for the US 2012 election, seePS: Political Science and PoliticsOctober 2012 (45 (4): 610–75). Although national models are the most common, researchers have also started to use state-level predictions for presidential and congressional outcomes, with mostly positive success (Berry and Bickers 2012; Jerome and Jerome-Speziari 2012; Klarner 2012; Silver 2012). These models use similar predictors, such as incumbency, economic conditions, and home-state advantage, and predict the per-candidate percentage of popular vote. Unfortunately, with state-level models, many of the economic variables used in predicting national models are unavailable beyond 10–15 election cycles (compounded also by 1959 additions of Alaska and Hawaii), so state-level models naturally have a shorter period of analysis than do national models.
AGRICULTURAL PRODUCTIVITY AND GROWTH IN TURKEY
Authors: İmrohoroğlu Ayşe , İmrohoroğlu Selahattın , Üngör Murat
Published: March 2013

This paper investigates the growth experience of one country in detail in order to enhance our understanding of important factors that affect economic growth. Using a two-sector model, we identify low productivity growth in the agricultural sector as the main reason for the divergence of income per capita between Turkey and its peer countries between 1968 and 2005. An extended model that incorporates distortions in the use of intermediate goods in producing agricultural output indicates that policies that have different effects across sectors and across time may be important in explaining the growth experience of countries.
Darmkrebs-Screening
Authors: Brenner Hermann , Stock Christian , Hoffmeister Michael
Published: March 2013

Darmkrebs ist eine der weltweit häufigsten Krebsarten und Krebstodesursachen. Da Karzinome im Darm überwiegend über langsam wachsende und gut entfernbare Vorstufen (Adenome) entstehen, sind die Möglichkeiten zur Vermeidung und Früherkennung – im Gegensatz zu den meisten anderen Krebsarten – sehr günstig. Die am häufigsten eingesetzten Verfahren zur Erkennung von Adenomen und Karzinomen im Darm sind Tests auf okkultes Blut im Stuhl, die Sigmoidoskopie und die Koloskopie. Die meisten westlichen Länder haben inzwischen ein bevölkerungsweites Screening-Programm für Darmkrebs initiiert mit dem Ziel, eine möglichst große Reduktion der Darmkrebsinzidenz und -mortalität zu erzielen. Hierbei werden unterschiedliche Ansätze bei der Gestaltung des Screening-Programms und den eingesetzten Screening-Verfahren verfolgt. Bisherige Erfahrungen zeigen, dass in einem organisierten Screening-Programm mit Einladung der Teilnahmeberechtigten die höchsten Teilnahmeraten erzielt werden können.
Apoptosis of osteosarcoma cultures by the combination of the cyclin-dependent kinase inhibitor SCH727965 and a heat shock protein 90 inhibitor
Authors: Fu W , Sharma S S , Ma L , Chu B , Bui M M , Reed D , Pledger W J
Published: March 2013

Osteosarcoma (OS) is an aggressive bone cancer typically observed in adolescents and young adults. Metastatic relapse accounts primarily for treatment failure, and obstacles to improving cure rates include a lack of efficacious agents. Our studies show apoptosis of OS cells prepared from localized and metastatic tumors by a novel drug combination: SCH727965 (SCH), a cyclin-dependent kinase inhibitor, and NVP-AUY922 (AUY) or other heat shock protein 90 inhibitor. SCH and AUY induced apoptosis when added simultaneously to cells and when AUY was added to and removed from cells before SCH addition. Sequential treatment was most effective when cells received AUY for ∼12 h and when SCH was presented to cells immediately after AUY removal. The apoptotic protein Bax accumulated in mitochondria of cotreated cells but was primarily cytosolic in cells receiving either agent alone. Additional data show that SCH and AUY cooperatively induce the apoptosis of other sarcoma cell types but not of normal osteoblasts or fibroblasts, and that SCH and AUY individually inhibit cell cycle progression throughout the cell cycle. We suggest that the combination of SCH and AUY may be an effective new strategy for treatment of OS.
The cell cycle and pluripotency
Authors: Hindley Christopher , Philpott Anna
Published: March 2013

PSCs (pluripotent stem cells) possess two key properties that have made them the focus of global research efforts in regenerative medicine: they have unlimited expansion potential under conditions which favour their preservation as PSCs and they have the ability to generate all somatic cell types upon differentiation (pluripotency). Conditions have been defined in vitro in which pluripotency is maintained, or else differentiation is favoured and is directed towards specific somatic cell types. However, an unanswered question is whether or not the core cell cycle machinery directly regulates the pluripotency and differentiation properties of PSCs. If so, then manipulation of the cell cycle may represent an additional tool by which in vitro maintenance or differentiation of PSCs may be controlled in regenerative medicine. The present review aims to summarize our current understanding of links between the core cell cycle machinery and the maintenance of pluripotency in ESCs (embryonic stem cells) and iPSCs (induced PSCs).
Methionine salvage and S-adenosylmethionine: essential links between sulfur, ethylene and polyamine biosynthesis
Authors: Sauter Margret , Moffatt Barbara , Saechao Maye Chin , Hell Rüdiger , Wirtz Markus
Published: March 2013

Both Met (methionine) and SAM (S-adenosylmethionine), the activated form of Met, participate in a number of essential metabolic pathways in plants. The subcellular compartmentalization of Met fluxes will be discussed in the present review with respect to regulation and communication with the sulfur assimilation pathway, the network of the aspartate-derived amino acids and the demand for production of SAM. SAM enters the ethylene, nicotianamine and polyamine biosynthetic pathways and provides the methyl group for the majority of methylation reactions required for plant growth and development. The multiple essential roles of SAM require regulation of its synthesis, recycling and distribution to sustain these different pathways. A particular focus of the present review will be on the function of recently identified genes of the Met salvage cycle or Yang cycle and the importance of the Met salvage cycle in the metabolism of MTA (5′-methylthioadenosine). MTA has the potential for product inhibition of ethylene, nicotianamine and polyamine biosynthesis which provides an additional link between these pathways. Interestingly, regulation of Met cycle genes was found to differ between plant species as shown for Arabidopsis thaliana and Oryza sativa.
Chemical analysis of giant stars in the young open cluster NGC 3114
Authors: Katime Santrich O. J. , Pereira C. B. , Drake N. A.
Published: March 2013

Context. Open clusters are very useful targets for examining possible trends in galactocentric distance and age, especially when young and old open clusters are compared.

Aims. We carried out a detailed spectroscopic analysis to derive the chemical composition of seven red giants in the young open cluster NGC 3114. Abundances of C, N, O, Li, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd were obtained, as well as the carbon isotopic ratio.

Methods. The atmospheric parameters of the studied stars and their chemical abundances were determined using high-resolution optical spectroscopy. We employed the local-thermodynamic-equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. The abundances of the light elements were derived using the spectral synthesis technique.

Results. We found that NGC 3114 has a mean metallicity of [Fe/H] = −0.01 ± 0.03. The isochrone fit yielded a turn-off mass of 4.2 M⊙. The [N/C] ratio is in good agreement with the models predicted by first dredge-up. We found that two stars, HD 87479 and HD 304864, have high rotational velocities of 15.0 km s-1 and 11.0 km s-1; HD 87526 is a halo star and is not a member of NGC 3114.

Conclusions. The carbon and nitrogen abundance in NGC 3114 agree with the field and cluster giants. The oxygen abundance in NGC 3114 is lower compared to the field giants. The [O/Fe] ratio is similar to the giants in young clusters. We detected sodium enrichment in the analyzed cluster giants. As far as the other elements are concerned, their [X/Fe] ratios follow the same trend seen in giants with the same metallicity.
Investigation of A- and B-site Fe substituted BaTiO3 ceramics
Authors: Maikhuri Neelam , Panwar Amrish K. , Jha A. K.
Published: March 2013

In this work, we report the synthesis and investigations of Ba1−xFexTiO3 (BFeT) and BaTi1−x FexO3 (BTFe) ceramics by solid state reaction method. BFeT show relaxor behaviour in the studied frequency range i.e., 10 kHz to 100 kHz with high dielectric constant in a wide temperature range of 75 °C. BTFe shows frequency dispersion at 10 kHz and almost flat dielectric response at 100 kHz and lower dielectric constant value compared to BFeT. Polarization–electric field loops of both BFeT and BTFe shows suppressed ferroelectric behaviour as compared to pristine BaTiO3(BT). Magnetization–magnetic field loops show ferromagnetic behaviour in both BFeT and BTFe at room temperature.
Tungstate sharpening: A versatile method for extending the profile of ultra sharp tungsten probes
Authors: Stone R. , Rosamond M. , Coleman K. , Petty M. , Kolosov O. , Bowen L. , Dubrovskii V. , Zeze D.
Published: March 2013

The benefits of a new electrochemical etching method for the controlled sharpening of sub-micron tungsten probes are demonstrated. The proposed technique only utilizes the insulating effect of the WO42− by-product which offers more practical ways of controlling the process parameters. The electrosharpening method was fully automated through the analysis of the process current, bulk coulometry, shadowgraphs, and time lapse microscopy. Tip radii smaller than 15 nm were maintained over a wide range of controlled lengths up to 4.5 mm with conic angles of less than 1°.
Loop filters as resonant elements for acoustic metamaterials and stop band structures
Authors: Herlan Jonathan W. , LePard Sean S. , Robertson William M.
Published: March 2013

Two geometries of acoustic loop filters side-loaded onto waveguides are explored using audio-frequency impulse response measurements. Finite element modeling is used to elucidate the interference mechanisms in each loop filter configuration. These simulations also yield transmission amplitude results, which are in good agreement with those determined experimentally. The ability to create broad forbidden transmission regions is demonstrated by the use of a sub-wavelength spaced series of slightly detuned filters. Finally, the phase information from the impulse response measurements is analyzed to show that regions of negative bulk modulus exist at frequencies in the vicinity of the loop interference minima.
Mechanical loss and magnetoelectric response in magnetostrictive/interdigitated-electrode/piezoelectric laminated resonators
Authors: Wang Yaojin , Finkel P. , Li Jiefang , Viehland D.
Published: March 2013

The mechanical quality factor and the resonant magnetoelectric (ME) response of multi-push-pull mode Metglas/interdigitated (ID)-electrode/Pb(Zr,Ti)O3 (PZT) ME resonators have been studied as a function of ID-electrode geometry for both sandwich and bimorph configurations. The results show that the mechanical quality factor of the PZT core composite and the effective mechanical quality factor of the ME resonator are increased with increasing ID-electrode spacing. The sandwich resonator was found to exhibit a higher effective mechanical quality factor than the bimorph one.
Characteristics of thermally induced acoustic emission from nanoporous silicon device under full digital operation
Authors: Koshida Nobuyoshi , Hippo Daihei , Mori Masamitsu , Yanazawa Hiroshi , Shinoda Hiroyuki , Shimada Toshikazu
Published: March 2013

The resonance-free frequency response of the thermo-acoustic emission is demonstrated under a full digital drive. The device is composed of a thin-film heater electrode, a nano-porous silicon layer, and a single-crystalline silicon wafer. When sequential electrical pulse trains converted by the density modulation of an analog signal are introduced into the heater electrode, a significant sound pressure is reproduced with a sufficiently low distortion. The characteristic output behaviour in the audible ultrasonic band is clarified in either open- or closed-space. The advantageous features of thermally induced sound emission and its underlying physics have been made clear.
An ultra-thin buffer layer for Ge epitaxial layers on Si
Authors: Kawano M. , Yamada S. , Tanikawa K. , Sawano K. , Miyao M. , Hamaya K.
Published: March 2013

Using an Fe3Si insertion layer, we study epitaxial growth of Ge layers on a Si substrate by a low-temperature molecular beam epitaxy technique. When we insert only a 10-nm-thick Fe3Si layer in between Si and Ge, epitaxial Ge layers can be obtained on Si. The detailed structural characterizations reveal that a large lattice mismatch of ∼4% is completely relaxed in the Fe3Si layer. This means that the Fe3Si layers can become ultra-thin buffer layers for Ge on Si. This method will give a way to realize a universal buffer layer for Ge, GaAs, and related devices on a Si platform.
A chip scale electrocaloric effect based cooling device
Authors: Gu Haiming , Qian Xiaoshi , Li Xinyu , Craven Brent , Zhu Wenyi , Cheng Ailan , Yao S. C. , Zhang Q. M.
Published: March 2013

The recent finding of large electrocaloric effect in several ferroelectric polymers creates unique opportunity for developing compact size solid state cooling cycles beyond the traditional mechanical vapor compression cycles. Here, we show that, by employing regeneration process with solid state regenerators, a chip scale Electrocaloric Oscillatory Refrigeration (ECOR) can be realized. A prototype ECOR is fabricated and characterized. More than 6 K temperature span is obtained near room temperature between the hot and cold sides of a 2 cm long device. Finite volume simulation validates the test results and shows the potential high performance of the ECOR.
Engineering spin-wave channels in submicrometer magnonic waveguides
Authors: Xing XiangJun , Li ShuWei , Huang XiaoHong , Wang ZhenGuo
Published: March 2013

Based on micromagnetic simulations and model calculations, we demonstrate that degenerate well and barrier magnon modes can exist concurrently in a single magnetic waveguide magnetized perpendicularly to the long axis in a broad frequency band, corresponding to copropagating edge and centre spin waves, respectively. The dispersion relations of these magnon modes clearly show that the edge and centre modes possess much different wave characteristics. By tailoring the antenna size, the edge mode can be selectively activated. If the antenna is sufficiently narrow, both the edge and centre modes are excited with considerable efficiency and propagate along the waveguide. By roughening the lateral boundary of the waveguide, the characteristics of the relevant channel can be easily engineered. Moreover, the coupling of the edge and centre modes can be conveniently controlled by scaling the width of the waveguide. For a wide waveguide with a narrow antenna, the edge and centre modes travel relatively independently in spatially-separate channels, whereas for a narrow strip, these modes strongly superpose in space. These discoveries might find potential applications in emerging magnonic devices.
Temperature dependent transport and dielectric properties of cadmium titanate nanofiber mats
Authors: Imran Z. , Rafiq M. A. , Ahmad M. , Rasool K. , Batool S. S. , Hasan M. M.
Published: March 2013

We investigate electrical and dielectric properties of cadmium titanate (CdTiO3) nanofiber mats prepared by electrospinning. The nanofibers were polycrystalline having diameter ∼50 nm-200 nm, average length ∼100 μm and crystallite size ∼25 nm. Alternating current impedance measurements were carried out from 318 K – 498 K. The frequency of ac signal was varied from 2 – 105 Hz. The complex impedance plots revealed two depressed semicircular arcs indicating the bulk and interface contribution to overall electrical behavior of nanofiber mats. The bulk resistance was found to increase with decrease in temperature exhibiting typical semiconductor like behavior. The modulus analysis shows the non-Debye type conductivity relaxation in nanofiber mats. The ac conductivity spectrum obeyed the Jonscher power law. Analysis of frequency dependent ac conductivity revealed presence of the correlated barrier hopping (CBH) in nanofiber mats over the entire temperature range.
Inspecting Regional Economic Structural Changes through Linking Occupations and Industries
Authors: Wan Jun , Kim Jae Hong , Hewings Geoffrey J D
Published: March 2013

The increasing integration of the world economy has demonstrated the critical need to identify industries and associated skill sets that could help regions maintain their competitiveness. The challenge is to align human capital with current and emerging trends of the regional economy. This study presents a framework to explore regional economic structural changes in terms of occupation—industry linkages and deciphers an array of economic signals that generate the dynamics of regional economic changes based upon an enhanced understanding of systematic occupation—industry linkages. Bicausative analysis and hypothetical industry extraction methods are adapted to serve these purposes, with applications to both state and national levels in the US between 2005 and 2008. The findings derived from these linkage studies offer insights into the spatially heterogeneous patterns of economic changes, and help overcome conventional, one-dimensional understandings of the dynamics of economic transformation.
The Expenditure Impacts of Individual Higher Education Institutions and Their Students on the Scottish Economy under a Regional Government Budget Constraint: Homogeneity or Heterogeneity?
Authors: Hermannsson Kristinn , Lisenkova Katerina , McGregor Peter G , Swales J Kim
Published: March 2013

Comparing each of the higher education institutions (HEIs) as a separate sector in the Scottish input—output table suggests that their expenditure patterns are homogenous and that any apparent heterogeneity in their conventional demand impacts depends primarily on scale. However, a disaggregation of their income by source reveals a disparity in their degree of dependence upon funding from the devolved Scottish Government. Acknowledging the binding budget constraint of the Scottish Government, and deriving balanced-expenditure multipliers, reveals large differences in the net-expenditure impact of HEIs upon the Scottish economy, with the source of variation being the origin of income. Applying a novel treatment of student expenditure impacts through identifying the amount of exogenous spending per student further increases the heterogeneity of the overall expenditure effects. These issues have particular importance for many governments facing increasing pressure to reduce their overall budgets.
The Division of Spatial Housing Submarkets: A Theory and the Case of Seoul
Authors: Park Joon
Published: March 2013

This study suggests a basis for the division of spatial housing submarkets in enhancing the understanding of housing markets. The theoretical background of the division is based upon the relationship between commuting patterns and the structure of house prices. An examination of the process of ‘expansion—overlap—merging’ between residential spheres, defined as a unit consisting of a centre of employment and the surrounding residential area, provides an overview of a probable form of merged residential spheres in large cities. In an empirical analysis of Seoul the spatial housing submarkets were identified on the basis of the hierarchies between the local authorities from commuting patterns. The relevance of the division was tested with three statistical procedures: hedonic price models, Chow tests, and weighted standard error tests. The statistical tests suggested that the housing market in Seoul can be divided into three distinct spatial submarkets, which supports the reasoning of the division method suggested in this study.
Valid Cues for Auditory or Somatosensory Targets Affect Their Perception: A Signal Detection Approach
Authors: Van Hulle Lore , Van Damme Stefaan , Crombez Geert
Published: March 2013

We investigated the effects of focusing attention towards auditory or somatosensory stimuli on perceptual sensitivity and response bias using a signal detection task. Participants ( N = 44) performed an unspeeded detection task in which weak (individually calibrated) somatosensory or auditory stimuli were delivered. The focus of attention was manipulated by the presentation of a visual cue at the start of each trial. The visual cue consisted of the word “warmth” or the word “tone”. This word cue was predictive of the corresponding target on two-thirds of the trials. As hypothesised, the results showed that cueing attention to a specific sensory modality resulted in a higher perceptual sensitivity for validly cued targets than for invalidly cued targets, as well as in a more liberal response criterion for reporting stimuli in the valid modality than in the invalid modality. The value of this experimental paradigm for investigating excessive attentional focus or hypervigilance in various non-clinical and clinical populations is discussed.
Toward an atomistic description of the urea-denatured state of proteins
Authors: Candotti Michela , Esteban-Martín Santiago , Salvatella Xavier , Orozco Modesto
Published: March 2013

We present here the characterization of the structural, dynamics, and energetics of properties of the urea-denatured state of ubiquitin, a small prototypical soluble protein. By combining state-of-the-art molecular dynamics simulations with NMR and small-angle X-ray scattering data, we were able to: (
i
) define the unfolded state ensemble, (
ii
) understand the energetics stabilizing unfolded structures in urea, (
iii
) describe the dedifferential nature of the interactions of the fully unfolded proteins with urea and water, and (
iv
) characterize the early stages of protein refolding when chemically denatured proteins are transferred to native conditions. The results presented herein are unique in providing a complete picture of the chemically unfolded state of proteins and contribute to deciphering the mechanisms that stabilize the native state of proteins, as well as those that maintain them unfolded in the presence of urea.