bluuebunny/crossref_metadata_2025 huggingface dataset:
Change
Authors: Ketchen David J.
Published: March 2008

Change presents major opportunities and challenges for executives and the organizations they lead. Significant gaps remain between what we know and what we need to know about change, especially with regard to the role of change within strategic entrepreneurship. This brief article is intended to lay out ideas that can guide and inform investigation of the link between change and strategic entrepreneurship. Copyright © 2008 Strategic Management Society.
Comments on Entrepreneurial pursuits of self and collective interests and Strategic entrepreneurship, collaborative innovation, and wealth creation
Authors: Siegel Donald S.
Published: March 2008

I provide comments on these articles and then place them in the broader context of the burgeoning literatures on technological collaboration and corporate social responsibility. Copyright © 2008 Strategic Management Society.
Entrepreneurship, growth, and Adam Smith
Authors: Michael Steven C.
Published: March 2008

In the canonical work of economics, Adam Smith's Wealth of Nations, he explained that nations grow wealthy through changes in the division of labor. Using Smith's insight, entrepreneurship can be defined as the study of human actions that lead to changes in the division of labor. This definition gives theoretical and empirical meaning to studies examining new venture formation and economic growth, and can be used by scholars for intellectual profit, as illustrated by Baumol and Strom, Casson and Wadeson, and Agarwal, Audretsch, and Sarkar. Copyright © 2008 Strategic Management Society.
Entrepreneurial pursuits of self‐ and collective interests
Authors: Van de Ven Andrew H. , Sapienza Harry J. , Villanueva Jaume
Published: March 2008

Entrepreneurs are often portrayed as rugged individualists who go it alone to build new organizations and programs that maximize their self‐interests. This portrayal is incomplete, because it does not account for the fact that entrepreneurs also pursue collective interests. It fails to recognize a basic paradox in human beings of simultaneously seeking individual and collective interests. We argue that an appreciation of the dialectical nature of human beings leads to fundamentally different conceptions of entrepreneurship than those commonly found in literature on entrepreneurship theory and practice. To illustrate our central premise, we focus on entrepreneurial opportunity realization, resource mobilization, and running in packs. Copyright © 2008 Strategic Management Society.
Zinc Porphyrin‐Driven Assembly of Gold Nanofingers
Authors: Arima Valentina , Blyth Robert I. R. , Matino Francesca , Chiodo Letizia , Sala Fabio Della , Thompson Julie , Regier Tom , Del Sole Roberta , Mele Giuseppe , Vasapollo Giuseppe , Cingolani Roberto , Rinaldi Ross
Published: March 2008

Nanofingers of gold covered by porphyrins are prepared by a combination of atomic manipulation and surface self‐organization. A submonolayer of zinc(II) 5,10,15,20‐tetrakis(4‐tert‐butylphenyl)‐porphyrin (ZnTBPP) axially ligated to a self‐assembled monolayer of 4‐aminothiophenol (4‐ATP) on Au(111) is prepared and studied using a combination of ultrahigh vacuum techniques. Under the electric field produced by the STM tip, the relatively weakly bound Au surface atoms along the discommensuration lines become mobile due to the strong bond to 4‐ATP, while the tendency of the porphyrins towards self‐assembly result in a collective motion of gold clusters. The clusters diffuse onto the surface following well‐defined pathways along the $[{\rm 11}\overline {\rm 2}]$ direction and then reach the step edges where they assembled, thus forming nanofingers. First‐principles density functional theory calculations demonstrate the reduction of the binding energies between the surface gold clusters and the substrate induced by adsorption of thiols. Scanning tunneling microscopy images show assemblies across three adjacent discommensuration lines of the Au(111)‐(22 × √3) reconstruction, which collectively diffuse along these lines to form islands nucleated at step edges.
A vector system for efficient and economical switching of C‐terminal epitope tags in Saccharomyces cerevisiae
Authors: Sung Min‐Kyung , Ha Cheol Woong , Huh Won‐Ki
Published: March 2008

In Saccharomyces cerevisiae, one‐step PCR‐mediated modification of chromosomal genes allows fast and efficient tagging of yeast proteins with various epitopes at the C‐ or N‐terminus. For many purposes, C‐terminal tagging is advantageous in that the expression pattern of epitope tag is comparable to that of the authentic protein and the possibility for the tag to affect normal folding of polypeptide chain during translation is minimized. As experiments are getting complicated, it is often necessary to construct several fusion proteins tagged with various kinds of epitopes. Here, we describe development of a series of plasmids that allow efficient and economical switching of C‐terminally tagged epitopes, using just one set of universal oligonucleotide primers. Containing a variety of epitopes (GFP, TAP, GST, Myc, HA and FLAG tag) and Kluyveromyces lactis URA3 gene as a selectable marker, the plasmids can be used to replace any MX6 module‐based C‐terminal epitope tag with one of the six epitopes. Furthermore, the plasmids also allow additional C‐terminal epitope tagging of proteins in yeast cells that already carry MX6 module‐based gene deletion or C‐terminal epitope tag. Copyright © 2008 John Wiley & Sons, Ltd.
Disruption of Pichia pastoris PMR1 gene decreases its folding capacity on human serum albumin and interferon‐α2b fusion protein
Authors: Zhao Hong Liang , Xue Chong , Wang Yang , Duan Qing Fen , Xiong Xiang Hua , Yao Xue Qin , Liu Zhi Min
Published: March 2008

In an attempt to increase the secretion capacity of Pichia pastoris (Pp), PpPMR1 gene was disrupted with GS115 as parent strain, and the resultant mutant was designated as Pppmr1. Pppmr1 displayed a Ca2+‐dependent growth defect, which was consistent with the PMR1 mutation in other yeasts. HSA–L5–IFNα2b, a human serum albumin (HSA) and inferferon‐α2b (IFNα2b) fusion protein with a flexible linker of 5 amino acid residues, was employed as a reporter to study the effects of PpPMR1 disruption on the secretion of heterologous protein. Because of its decreased viability after induction, Pppmr1 secreted more HSA–L5–IFNα2b only during the early phase (the first 15 hours) of induction. Although HSA–L5–IFNα2b secreted from GS115 and Pppmr1 had similar antiviral activity, the latter was heterogeneous (migrated as doublets on non‐reducing SDS–PAGE) and unstable (prone to aggregation at neutral to mild alkaline pH). Site‐directed mutagenesis revealed that the heterogeneity of HSA–L5–IFNα2b secreted from Pppmr1 was originated from the incomplete disulphide bridge pairing between Cys1 and Cys98 of IFNα2b. To be secreted homogeneously from Pppmr1 and to be stable in aqueous solution, the linker of the fusion protein should be extended to 10 amino acid residues. Copyright © 2008 John Wiley & Sons, Ltd.
Stapled Transanal Rectal Resection for Outlet Obstruction Syndrome: Results and Follow‐up
Authors: Frascio Marco , Stabilini Cesare , Ricci Barbara , Marino Paolo , Fornaro Rosario , De Salvo Luigi , Mandolfino Francesca , Lazzara Fabrizio , Gianetta Ezio
Published: March 2008

Background

The objective of the present study was to assess safety, effectiveness, and long‐term outcomes of stapled transanal rectal resection (STARR) for the cure of outlet obstruction syndrome (OOS).

Methods

Data were collected over a 3‐year period (2004–2007), at the Department of Surgery of the University of Genoa, from 25 consecutive subjects (19 of them females) undergoing STARR because of OOS that had not responded to medical treatment,.

Results

Preoperatively, patients were submitted to clinical examination, defecography, colonoscopy, manometry, and recto‐anal reflexes determination. All patients had mucosal prolapse, 15 rectal intussusception, 15 rectocele. Postoperatively no deaths were observed; one patient had a hemorrhage requiring reintervention. Mean time to resumption of normal activity was 8.5 ± 4.5 days. Patients were followed for a mean of 24.7 ± 10.9 months (range: 6–42 months). Late specific complications included 3 cases of urge to defecate, 8 of incontinence to flatus. Functional outcome was positive for 22 patients (excellent in 4 cases, good in 15, fairly good in 3). Six months postoperatively (25 s), patients had improvement of the mean Constipation Score (p = 0.0002), less pain during evacuation (p = 0.0003), and reduced use of digital assistance to defecate (p < 0.0001). Continence Grading Scale and enema use remained stable after intervention. Patients had increase in basal sphincter pressure (p = 0.0078) and maximal squeeze pressure (p = 0.0051). Recto‐anal reflex study showed increase in abdominal pain threshold (p < 0.0001); anal sphincter relaxation threshold and desire to defecate threshold did not change.

Conclusions

According to the present study, STARR seemed to be a safe and effective treatment for OOS associated with symptomatic rectocele and intussusception.
Floral traits variation, legitimate pollination, and nectar robbing in Polygala vayredae (Polygalaceae)
Authors: Castro Sílvia , Silveira Paulo , Navarro Luis
Published: March 2008

The variation of floral morphology and its effect on the flower visitors of Polygala vayredae Costa (Polygalaceae), a narrow endemic species from the Oriental pre‐Pyrenees, were examined. First, to account for the main floral reward (i.e., nectar), the relationship between the dimensions of the nectar gland and nectar production was investigated. Second, floral traits variation was assessed within and between the three most representative populations of the species. Finally, the role of several floral traits in the female fitness was evaluated. Furthermore, as nectar robbing was highly frequent, preferences of robbers for specific floral traits and their impact on legitimate pollinations were also evaluated. The flowers of this species are characterized by significant variations in floral characteristics and nectar rewards. A significant and positive correlation between the nectar gland dimensions and nectar production per flower was observed, with the gland dimensions being a good measure to infer the rewards offered by the flowers of P. vayredae. In general, corolla traits were significant and positively correlated with each other. Nectar was revealed to be an important trait in flower–visitor interactions, with legitimate pollinations being primarily influenced by this floral reward. Negative correlations between robbing frequency and legitimate pollinations were observed in two of the studied populations, and positive correlations between flower size and robbing frequency were observed in one population. An indirect negative selection over phenotypic floral traits mediated by nectar robbers is proposed.
Erucic Acid is Differentially Taken up and Metabolized in Rat Liver and Heart
Authors: Murphy Cameron C. , Murphy Eric J. , Golovko Mikhail Y.
Published: March 2008

Because X‐linked adrenoleukodystrophy is treated using erucic acid (22:1n‐9), we assessed its metabolism in rat liver and heart following infusion of [14‐14C]22:1n‐9 (170 Ci/kg) under steady‐state‐like conditions. In liver, 2.3‐fold more tracer was taken up as compared to heart, accounted entirely by increased incorporation into the organic fraction (4.2‐fold). The amount of tracer entering the aqueous fraction, which represents β‐oxidation, was not different between groups; however a significantly elevated proportion of tracer was in the heart aqueous fraction. In both tissues, 76% of the radioactivity found in the organic fraction was esterified in neutral lipids, while only about 10% was found esterified into phospholipids. In liver, 56% of lipid radioactivity was found in cholesteryl esters, whereas in heart 64% was found in triacylglycerols. Because 22:1n‐9 can be chain shortened, we assessed tracer metabolism using phenacyl fatty acid derivatives esterified from saponified esterified neutral lipid (triacylglycerol/cholesteryl ester) and phospholipid fractions. In heart esterified neutral lipids, 75% of tracer was recovered as 22:1n‐9 and only 10% as oleic acid (18:1n‐9), while in liver only 25% of the tracer was recovered as 22:1n‐9, while 50% was found as stearic acid (18:0) and 10% as 18:1n‐9. In liver and heart phospholipids, the tracer was distributed amongst the n‐9 fatty acid family. Thus, 22:1n‐9 under went tissue selective metabolism, with conversion to 18:0 the dominant pathway in the liver presumably for export in the neutral lipids, while in heart it was found primarily as 22:1n‐9 in neutral lipids and used for β‐oxidation.
A Pivotal Role of the Human Kidney in Catabolism of HDL Protein Components Apolipoprotein A‐I and A‐IV but not of A‐II
Authors: Graversen Jonas Heilskov , Castro Graciela , Kandoussi Abdelmejid , Nielsen Henning , Christensen Erik Ilsø , Norden Anthony , Moestrup Søren Kragh
Published: March 2008

Renal handling of major HDL components was studied by analyzing urine from patients with Fanconi syndrome, a rare renal proximal tubular reabsorption failure, including dysfunction of the kidney HDL receptor, cubilin. A high urinary excretion of apolipoprotein A‐I and A‐IV corresponding to a major part of the metabolism of these proteins was measured. In contrast, no urinary excretion of apolipoprotein A‐II which is more hydrophobic and tighter bound to HDL was found. Control urines displayed absence of the three apolipoproteins. Urinary excretion of phospholipids, triglycerides, cholesterol and cholesterol esters in patients was as low as in controls. In conclusion, these data indicate that the human kidney is a major site for filtered nascent apolipoprotein A‐I and A‐IV but not for HDL particles.
Physiological concentrations of short-chain fatty acids immediately suppress colonic epithelial permeability
Authors: Suzuki Takuya , Yoshida Shoko , Hara Hiroshi
Published: March 2008

Colonic fermentation products, SCFA, have various effects on colonic functions. Here, we found that physiological concentrations of SCFA immediately promote epithelial barrier function in the large intestine. Solutions of mixed and individual SCFA were applied to the caecal walls mounted on Ussing-type chambers. Transepithelial electrical resistance (TER) increased rapidly and reached a peak 35 % higher than that in the control specimen within 10 min post application of the SCFA mixture (80 acetate, 40 propionate, 20 butyrate (mmol/l)). The Lucifer yellow permeability, a paracellular transport marker, was dose-dependently reduced by the mixed SCFA, acetate and propionate solutions. Inhibition of monocarboxylate transporter-1 did not influence the increase in TER with acetate; however, lowering the pH (from 7·5 to 5·5) clearly enhanced the effect of acetate. Non-metabolizable, bromo and chloro derivatives of SCFA also increased TER. These results suggest that passive diffusion of SCFA is dominant and the metabolism of SCFA is not required for the promotive effect of SCFA on barrier function. We also observed that individual SCFA dose-dependently increased TER in T84 and Caco-2 cells, which indicates that SCFA directly stimulate epithelial cells. Depletion of membrane cholesterol and inhibitors of phosphatidylinositol-3 kinase and Gq protein attenuated the acetate-mediated promotive effect. Finally, we found that the mucosal application of the SCFA mixture dose-dependently suppressed [3H] mannitol transport from the caecal lumen to the mesenteric blood in the anaesthetized rats. We conclude that physiological concentrations of SCFA immediately enhance barrier function of the colonic epithelium through cholesterol-rich microdomain in the plasma membrane.
Instability and focusing of internal tides in the deep ocean
Authors: BÜHLER OLIVER , MULLER CAROLINE J.
Published: March 2008

The interaction of tidal currents with sea-floor topography results in the radiation of internal gravity waves into the ocean interior. These waves are called internal tides and their dissipation due to nonlinear wave breaking and concomitant three-dimensional turbulence could play an important role in the mixing of the abyssal ocean, and hence in controlling the large-scale ocean circulation.

As part of on-going work aimed at providing a theory for the vertical distribution of wave breaking over sea-floor topography, in this paper we investigate the instability of internal tides in a very simple linear model that helps us to relate the formation of unstable regions to simple features in the sea-floor topography. For two-dimensional tides over one-dimensional topography we find that the formation of overturning instabilities is closely linked to the singularities in the topography shape and that it is possible to have stable waves at the sea floor and unstable waves in the ocean interior above.

For three-dimensional tides over two-dimensional topography there is in addition an effect of geometric focusing of wave energy into localized regions of high wave amplitude, and we investigate this focusing effect in simple examples. Overall, we find that the distribution of unstable wave breaking regions can be highly non-uniform even for very simple idealized topography shapes.
Surface breakup and air bubble formation by drop impact in the irregular entrainment region
Authors: TOMITA Y. , SAITO T. , GANBARA S.
Published: March 2008

Drop impact on a water surface can be followed by underwater sounds originating not at the drop impact but when the entrained bubbles oscillate. Although the sound mechanism in the regular bubble entrainment region is well-known, there is less knowledge on the impact phenomena in the irregular bubble entrainment region where various situations can exist, such as many types of bubble formation or even no bubble generation under some conditions. In the present study, the aim is to clarify the dynamics of the water surface after the impact of a primary drop, mainly with diameter 5.2, 5.7 and 6.2mm, each of which is accompanied by a single satellite drop. Special attention was paid to the breakup behaviour of the water surface for Froude number Fr < 300. It was found that three underwater sounds were generated for a single drop impact, besides the sound due to impact itself. The first two were audible to the human ear, but the third one was almost inaudible. The first underwater sound resulted from the oscillation of a single air bubble formed as a result of the satellite drop impact on the bottom of the contracting cavity, and the second sound was due to the oscillation of air bubbles generated during the collapse of the water column. The formation of these air bubbles strongly depends on the Froude number, Weber number (or Bond number) and the aspect ratio of the drop at impact, although involving probability characteristics. Furthermore it is suggested that an air bubble entrapped in a water column plays an important role in increasing the probability of contact between the column surface and the curved free surface. A Japanese Suikinkutsu was introduced as an application of drop-impact-induced sounds. Using an open-type Suikinkutsu an additional experiment was carried out with larger drops with average diameters of 6.2, 7.2 and 7.8, mm.
The geometric properties of high-Schmidt-number passive scalar iso-surfaces in turbulent boundary layers
Authors: DASI L. P. , SCHUERG F. , WEBSTER D. R.
Published: March 2008

The geometric properties are quantified for concentration iso-surfaces of a high-Schmidt-number passive scalar field produced by an iso-kinetic source with an initial finite characteristic length scale released into the inertial layer of fully developed open-channel-flow turbulent boundary layers. The coverage dimension and other measures of two-dimensional transects of the passive scalar iso-surfaces are found to be scale dependent. The coverage dimension is around 1.0 at the order of the Batchelor length scale and based on our data increases in a universal manner to reach a local maximum at a length scale around the Kolmogorov scale. We introduce a new parameter called the coverage length underestimate, which demonstrates universal behaviour in the viscous–convective regime for these data and hence is a potentially useful practical tool for many mixing applications. At larger scales (in the inertial–convective regime), the fractal geometry measures are dependent on the Reynolds number, injection length scale, and concentration threshold of the iso-surfaces. Finally, the lacunarity of the iso-surface structure shows that the instantaneous scalar field is most inhomogenous around the length scale corresponding to the Kolmogorov scale.
Eddy structures in a transitional backward-facing step flow
Authors: RANI H. P. , SHEU TONY W. H. , TSAI ERIC S. F.
Published: March 2008

In the present study, flow simulation has been carried out in a backward-facing step channel defined by an expansion ratio of 2.02 and a spanwise aspect ratio of 8 to provide the physical insight into the longitudinal and spanwise flow motions and to identify the presence of Taylor–Görtler-like vortices. The Reynolds numbers have been taken as 1000 and 2000, which fall in the category of transitional flow. The present simulated results were validated against the experimental and numerical data and the comparison was found to be satisfactory. The simulated results show that the flow becomes unsteady and exhibits a three-dimensional nature with the Kelvin–Helmholtz instability oscillations and Taylor–Görtler-Like longitudinal vortices. The simulated data were analysed to give an in-depth knowledge of the complex interactions among the floor and roof eddies, and the spiralling spanwise flow motion. Destabilization of the present incompressible flow system, with the amplified Reynolds number due to the Kelvin–Helmholtz and Taylor–Görtler instabilities, is also highlighted. A movie is available with the online version of the paper.
Escaping Ethiopia's poverty trap: the case for a second agrarian reform
Authors: Abegaz Berhanu
Published: March 2008

Growth-friendly egalitarian distribution of land and smallholder farming notwithstanding, rural Ethiopia continues to face an ever-deepening livelihoods crisis. This paper synthesises the theoretical and empirical literature on Ethiopian and other comparable land institutions, in search of a coherent economic framework for pinpointing the roots of the problem and a menu for sensible policy options. It argues that land privatisation, as an integral part of a second agrarian reform, is necessary for attaining optimal farm sizes, thicker markets and robust industrialisation. A sordid history of political marginalisation of the peasantry makes freehold a superior alternative to more secure state leasehold. For a thoroughgoing agricultural transformation, however, sufficiency entails substantial increases in public investment that are designed to crowd-in private investment. Ethiopia's market-led agricultural development strategy must focus on boosting sustainable growth while ensuring subsistence for all.
Social and environmental litigation against transnational firms in Africa
Authors: George Frynas Jędrzej
Published: March 2008

As elsewhere in the world, Africa has experienced a rise in litigation against transnational corporations for adverse environmental and social impact. Cape plc and RTZ have been sued in British courts for environmental damage and for breach of employment rights in Africa. Companies which sold products to South Africa's former apartheid regime, such as Fujitsu and IBM, are now being sued in US courts. Shell and Chevron are being sued in US courts for human rights abuses in Nigeria. At the same time, foreign firms have been successfully sued in African courts for social and environmental damage. This article outlines the main relevant court cases and attempts to assess the significance of this litigation. The discussion of litigation in this article is divided into three parts: court cases filed in English, American and African (mainly Nigerian) courts. This is followed by an explanation of the triggers of legal change, a discussion of the impact of litigation and the conclusion.
Speech patterns in Cypriot-Greek late talkers
Authors: PETINOU KAKIA , OKALIDOU ARETI
Published: March 2008

The investigation longitudinally examined the phonetic skills of Cypriot-Greek children with late onset of expressive vocabulary. The rate of phonological development within short time increments and the identification of possible speech constraints motivating slow development of expressive language were examined. Participants were seven Cypriot-Greek children identified as late talkers, and seven age-matched normally developing counterparts. Phonetic skills were examined at ages 30, 33, and 36 months for both groups based on spontaneous language samples. Phonological analyses focused on the construction of all subjects' phonetic inventories over time. Both groups exhibited an increase of specific phoneme use over time. Late talkers had significantly poorer phonetic inventories when compared to the control group. Within the experimental group the analysis revealed the persistent omission of word-initial consonants. Results are discussed in terms of language-specific phonological constraints and their relation to slow development of speech.
Child-centered behaviors of caregivers with 12-month-old infants: Associations with passive joint engagement and later language
Authors: TRAUTMAN CAROL HAMER , ROLLINS PAMELA ROSENTHAL
Published: March 2008

This study investigates three aspects of social communication in 12-month-old infants and their caregivers: (a) caregiver conversational style, (b) caregiver gesture, and (c) infant engagement. Differences in caregiver behavior during passive joint engagement were associated with language outcomes. Although total mean duration of infant time in passive joint engagement was negatively associated with later language, caregiver contingent comments (CCCs) addressed to infants during passive joint engagements related to language learning. CCC utterances were found to co-occur with gesture, suggesting that CCC is an inherently multimodal conversational style. The positive association between CCCs during passive joint engagements and later language suggests that caregiver behavior is important, even at times when infants are not actively engaged with the caregiver.
Effects of bilingualism, noise, and reverberation on speech perception by listeners with normal hearing
Authors: ROGERS CATHERINE L. , LISTER JENNIFER J. , FEBO DASHIELLE M. , BESING JOAN M. , ABRAMS HARVEY B.
Published: March 2008

This study compared monosyllabic word recognition in quiet, noise, and noise with reverberation for 15 monolingual American English speakers and 12 Spanish–English bilinguals who had learned English prior to 6 years of age and spoke English without a noticeable foreign accent. Significantly poorer word recognition scores were obtained for the bilingual listeners than for the monolingual listeners under conditions of noise and noise with reverberation, but not in quiet. Although bilinguals with little or no foreign accent in their second language are often assumed by their peers, or their clinicians in the case of hearing loss, to be identical in perceptual abilities to monolinguals, the present data suggest that they may have greater difficulty in recognizing words in noisy or reverberant listening environments.
The generation of images of surface structures by laser-accelerated
protons
Authors: RUHL H. , COWAN T. , PEGORARO F.
Published: March 2008

Ion acceleration by lasers is one of the most important innovations in
laser-plasma research in recent years. A mechanism that has gained great
attention due to the remarkable properties of the accelerated beam is
laser acceleration of protons from the rear surface of solid targets. A
striking prediction is that these protons are capable of generating images
of micro-structures present on this surface. These images might be useful
to measure properties of the accelerated beam. In this article, we address
the physics of the generation of images of surface structures imprinted
into the target back surface with laser-accelerated protons.
Table-top laser-plasma acceleration as an electron radiography
source
Authors: MANGLES S.P.D. , WALTON B.R. , NAJMUDIN Z. , DANGOR A.E. , KRUSHELNICK K. , MALKA V. , MANCLOSSI M. , LOPES N. , CARIAS C. , MENDES G. , DORCHIES F.
Published: March 2008

A “table-top” high power laser has been used to generate
beams of accelerated electrons up to energy of 20 MeV from interactions
with underdense plasmas. The energy spectrum of these beams was measured
using a magnetic spectrometer and proof-of-principle experiments were
performed to evaluate the suitability of these beams for electron
radiography applications.
Generation and transport of fast electrons inside cone targets
irradiated by intense laser pulses
Authors: NAKAMURA TATSUFUMI , SAKAGAMI HITOSHI , JOHZAKI TOMOYUKI , NAGATOMO HIDEO , MIMA KUNIOKI
Published: March 2008

Fast electrons are effectively generated from solid targets of
cone-geometry by irradiating intense laser pulses, which is applied to
fast ignition scheme. For realizing optimal core heating by those
electrons, understanding the characteristics of electrons emitted from
cone targets is crucial. In this paper, in order to understand the
generation and transport processes of hot electrons inside the cone
target, two-dimensional (2D) particle-in-cell (PIC) simulations were
carried out. It is shown that hot electrons form current layers which are
guided by self-generated surface magnetic field, which results in
effective energy transfer from laser pulse to hot electrons. When the hot
electrons propagate through the steep density gradient at the cone tip,
electrostatic field is induced via Weibel instability. As a result, hot
electrons are confined inside and emitted gradually from the target, as an
electron beam of long duration. Energy spectrum and temporal profile of
hot electrons are also evaluated at the rear side of the target, where the
profile of rear side plasma is taken from the fluid code and the result is
sent to Fokker-Planck code.
Low-energy low-divergence pulsed indium atomic beam by laser ablation
Authors: ALTI KAMLESH , KHARE ALIKA
Published: March 2008

This paper reports the formation of low-energy low-divergence pulsed indium atomic beam via ablation of thin film by illumination from the rear side with second harmonic of Q-switched Nd:YAG laser under high vacuum (∼10−5Torr). Angular divergence of ablated indium atomic, reflectivity modulation of thin film due to ablation, and longitudinal atomic velocity of ablated beam were studied as a function of laser fluence. Atomic force microscope scans of the deposited multiple shots of pulsed atomic beams show the formation of “nano-hills.”
On the theory of spatial photon localization: Fundamentals and the role of near-field plasma screening
Authors: KELLER OLE
Published: March 2008

Starting from the Riemann-Silberstein formulation of classical electrodynamics the Schrödinger equation for the photon energy wave function is discussed. Hereafter, a propagator description of the space-time emission of a polychromatic photon from an atom is presented, paying particular attention to the near-field electrodynamics. When the atom is embedded in a solid-state plasma the photon emission process can be dramatically modified. Limiting the analyses to solid-state plasmas exhibiting translational and rotational symmetry, the near-field atom-photon-plasma interaction is studied paying particular attention to the plasmariton and plasmon excitation processes. It is shown that the transverse and longitudinal parts of the plasma-screened field propagator link in a direct manner to the free-photon propagator and the longitudinal near-field photon propagator. The necessity of keeping both the transverse and longitudinal parts of the plasma screening in a rigorous description of near-field electrodynamics is demonstrated.
Core holes, charge disorder, and transition from metallic to plasma properties in ultrashort pulse irradiation of metals
Authors: FISHER DIMITRI V. , HENIS ZOHAR , ELIEZER SHALOM , MEYER-TER-VEHN JUERGEN
Published: March 2008

We study the details of a gradual change in electron properties from those of a nearly-free-electron (NFE) metal to those of a strongly-coupled plasma, in ultrashort pulse energy deposition in solid metal targets. Time scales shorter than those of a target surface layer expansion are considered. Both the case of an optical laser (visible or near infrared wavelengths range) and of a free electron laser (vacuum ultraviolet or X-ray) are treated. The mechanisms responsible for the change in electron behavior are isochoric melting, lattice charge disordering, and electron mean free path reduction. We find that the transition from metal to plasma usually occurs via an intermediate stage of a charge-disordered solid (solid plasma), in which ions are at their lattice sites but the ionization stages of individual ions differ due to ionization from localized bound states. Charge disordered state formation is very rapid (typically, few femtoseconds or few tens of femtoseconds). Pathway to charge-disordered state differs in simple metals and in noble metals. Probabilities are derived for electron impact ionization and 3-body recombination of a bound ionic state in solid-density medium, applicable both in metal and in plasma regime. An evolution of energy coupling between electron and ion subsystems, from metallic electron-phonon (e-ph) to plasma electron-ion (e-i) coupling, is considered. Substantial increase in coupling parameter is expected as a result of charge disorder.
Monoenergetic electron beam generation from a laser-plasma
accelerator
Authors: KOYAMA K. , ADACHI M. , MIURA E. , KATO S. , MASUDA S. , WATANABE T. , OGATA A. , TANIMOTO M.
Published: March 2008

We have demonstrated the acceleration of a monoenergetic electron beam
by a laser-produced wakefield. Experiments were performed by focusing 2-TW
laser pulses of 50 fs on supersonic gas-jet targets. The focused intensity
was 5 × 1018 W/cm2 (a0
= 1.5). At an electron density of 1.5 × 1020
cm−3, the clear monoenergetic electron beam from the
plasma was obtained at 7 to 15 MeV. The Stokes satellite peak in the
forward scattering explained the energy spectra of electrons at various
plasma densities well. Although the wakefield propagated 500 microns,
which was far beyond the dephasing length, monoenergetic electron beams
were obtained.
Self-focusing in processes of laser generation of highly-charged and
high-energy heavy ions
Authors: LÁSKA L. , JUNGWIRTH K. , KRÁSA J. , KROUSKÝ E. , PFEIFER M. , ROHLENA K. , ULLSCHMIED J. , BADZIAK J. , PARYS P. , WOLOWSKI J. , GAMMINO S. , TORRISI L. , BOODY F.P.
Published: March 2008

Laser-beam interaction with expanding plasma was investigated using
the PALS high-power iodine-laser system. The interaction conditions are
significantly changing with the laser focus spot position. The decisive
role of the laser-beam self-focusing, participating in the production of
ions with the highest charge states, was proved.
Abundance and grazing impacts of krill, salps and copepods along the 140°E meridian in the Southern Ocean during summer
Authors: Tanimura A. , Kawaguchi S. , Oka N. , Nishikawa J. , Toczko S. , Takahashi K.T. , Terazaki M. , Odate T. , Fukuchi M. , Hosie G.
Published: March 2008

Abundance and grazing impacts of krill, salps and herbivorous copepods were investigated in Antarctic waters along the 140°E meridian, south of Australia, during the summers of 2002 and 2003. North of the Southern Boundary of the Antarctic Circumpolar Current (SB-ACC), macrozooplankton comprised species of Salpa thompsoni and large herbivorous copepods, while the area south of the SB-ACC was numerically dominated by Euphausia superba or E. crystallorophias. North of the SB-ACC, the estimate of grazing impact revealed that krill, salps and copepods, Calanoides acutus, Calanus propinquus, Rhincalanus gigas and Metridia gerlachei, are able to remove a maximum of 37% of the total phytoplankton standing stock in early to midsummer, but grazing is negligible in late summer. The high grazing impact is attributed to the relatively high zooplankton abundance and low phytoplankton abundance. South of the SB-ACC, overall daily grazing impact of the three zooplankton groups was low and did not exceed 6% of the total phytoplankton standing stock throughout the investigation period. Present results indicate that the contribution of krill, salps and copepods varies seasonally as well as regionally across the SB-ACC. It seems that the carbon transport from surface to deep water by macro- and mesozooplankton in summer in this area is relatively large north of the SB-ACC but small south of the SB-ACC.
From natural semantics to C: A formal derivation of two STG machines
Authors: DE LA ENCINA ALBERTO , PEÑA RICARDO
Published: March 2008

The Spineless Tag-less G-machine (STG machine) was defined as the target abstract machine for compiling the lazy functional language Haskell. It is at the heart of the Glasgow Haskell Compiler (GHC) which is claimed to be the Haskell compiler that generates the most efficient code. A high-level description of the STG machine can be found in Peyton Jones (In Journal of Functional programming, 2(2), 127–202, 1992), Marlow & Peyton Jones (In Sigplan Not., 39(9), 4–5, 2004), and Marlow & Peyton Jones (In Journal of Functional Programming, 16(4–5), 415–449, 2006). Should the reader be interested in a more detailed view, then the only additional information available is the Haskell code of GHC and the C code of its runtime system.

It is hard to prove that this machine correctly implements the lazy semantics of Haskell. Part of the problem lies in the fact that the STG machine executes a bare-bones functional language, called STGL, much lower level than Haskell. Therefore, part of the correctness should be—and it is—established by showing that the translation from Haskell to STGL preserves Haskell's semantics.

The other part involves showing that the STG machine correctly implements the lazy semantics of STGL. In this paper we provide a step-by-step formal derivation of the STG machine and of its compilation to C, starting from a natural semantics of STGL. Thus, our starting point is higher level than the descriptions found Peyton Jones (In Journal of Functional programming, 2(2), 127–202, 1992) and Marlow & Peyton Jones (In Sigplan Not., 39(9), 4–5, 2004), and our arrival point is lower level than those works. Additionally, there has been substantial changes between the so-called push/enter model of the STG machine described in Peyton Jones (In Journal of Functional programming, 2(2), 127–202, 1992), and the eval/apply model of the STG machine described in Marlow & Peyton Jones (In Sigplan Not., 39(9), 4–5, 2004). So, in fact, we derive two machines instead of one, starting from the same initial semantics.

At each step we provide enough intuitions and explanations in order to understand the refinement, and then the formal definitions and statements proving that the derivation step is sound and complete. The main contribution of the paper is to show that an efficient machine such as the STG can be presented, understood, and formally reasoned about at different levels of abstraction.
Finitude pour les représentations lisses de groupes p-adiques
Authors: Dat Jean-Francois
Published: March 2008

Nous considérons la catégorie des représentations lisses d'un groupe p-adique à coefficients dans un anneau R dans lequel p est inversible. Notre objectif principal est de prouver que cette catégorie est noetherienne si R l'est, généralisant donc un fameux résultat de Bernstein lorsque R = ℂ Dans un premier temps, nous ramenons ce problème à celui de démontrer une propriété de «seconde adjonction» entre foncteurs paraboliques, elle-aussi prouvée par Bernstein lorsque R = ℂ. Puis nous définissons et étudions des «foncteurs parahoriques» entre représentations de groupes de points entiers de certains modèles de G et de leurs «sous-groupes de Levi». Appliquant cela aux modéles de Bruhat-Tits, nous obtenons la seconde adjonction pour les paraboliques minimaux. Pour les paraboliques non minimaux, nous nous restreignons aux groupes classique et appliquons notre étude aux modèles canoniques des groupes de Bushnel-Kutzko et Stevens. Notre étude s'applique aussi aux modèles de Yu, mais il manque un résultat d'exhaustivité pour conclure dans le cas des groupes suffisamment modérés.
Gender Politics in the Dominican Republic: Advances for Women, Ambivalence from Men
Authors: Morgan Jana , Espinal Rosario , Hartlyn Jonathan
Published: March 2008

A considerable body of research has analyzed the influence of the women's movement, changes in women's political representation, and policies promoting women's interests in the developing world. However, we know comparatively less about the degree to which the attitudes and behaviors of the mass public mirror these national patterns. This article explores the evolution of gender differences in citizens' political interest, civic engagement, and support for women in politics in the Dominican Republic over 1994–2004, a period important for the country's democratization as well as one of significant changes in gender-related discourse and policies. We find evidence of a shift from a traditional gender gap to a modern gender gap, but the explanations for changes in women's views are distinct from those of men. We find that sociostructural factors, particularly age and education, and cues from political elites have significantly different effects on men versus women. Women's levels of political interest and support for equality in political participation are more fixed in their youth, whereas men's levels evolve through middle age. The evidence also indicates that reducing the gender gap in political interest would significantly narrow gender differences in civic activism. Most notably, men appear to be more easily swayed by elite cues that favor or oppose women's political participation; women's support for equal participation is much less susceptible to reversals in elite support. The consolidation of advances in gender equity thus depends significantly on contextual factors such as elite discourse.
Subnational Politics in Spain: New Avenues for Feminist Policymaking and Activism
Authors: Ortbals Candice D.
Published: March 2008

In this article, I evaluate how subnational governments pursue feminist policy outputs. To do so, I examine equality policies in the Spanish regions of Andalusia and Galicia during the 1980s and 1990s. Whereas the national Women's Institute in Spain was the driving force behind equality policies during the 1980s, regional administrations gained autonomy in the early 1980s and developed their own equality policies during the 1990s and 2000s. I ask 1) whether leftist political allies are key to feminist policy outputs, 2) whether regional feminist policy outputs increase over time as subnational institutions develop, and 3) whether feminists in society are able to impact such policies. I conclude that subnational administrations do not always advance feminist policy outputs nor do they work cooperatively with all feminist organizations. Whereas the leftist regional administration of Andalusia has been a leader in feminist policymaking, the conservative Galician administration developed equality policies more slowly, and these policies were controversial among feminists and leftist politicians. I explain how regional women's policy agencies led by the Left and Right have nevertheless promoted women's civil society and policies that respond to women's local identities.
Surf zone megaripple orientation: Measurements and models
Authors: Clarke L. B. , Werner B. T. , Okihiro M.
Published: March 2008

Two existing models for bed form orientation are tested against measurements of megaripple crest line orientation from Scripps Beach. Optical time‐averaged images of the surf zone sand bed at 10 min intervals are processed with an automatic crest line tracing algorithm. Flow measurements concurrent with images of the sand bed collected during 3–7 April and 17–23 July 1999 are used as input to the gross bed form normal transport model (bed forms align to maximize gross transport across crests) predicting steady state crest orientation and the defect model (bed forms reorient at a rate proportional to the differential velocity of crest line ends, or defects) predicting a time‐dependent orientation. Generally poor agreement was found between predictions and measurements of crest line orientation. The gross bed form normal transport model predicted crest line normal orientation within 20° of measured orientation for 38% of records, with increased agreement coinciding with longitudinal and oblique bed forms. The defect model predicted crest line normal orientation within 20° of measurements for 22% of records when the ratio between defect and transport event timescales is assumed ≫1 and 14% of the records for the ratio ≪1. Although migration and mean sediment transport direction are assumed to coincide in both models, RMS deviation in bed form migration direction from the calculated 30 min mean sediment transport direction was found to be 38°. Additionally, RMS deviation of megaripple migration direction from crest line normal orientation was 39°.
Excess 210Pb inventories and fluxes along the continental slope and basins of the Gulf of Papua
Authors: Muhammad Zahid , Bentley Samuel J. , Febo Lawrence A. , Droxler André W. , Dickens Gerald R. , Peterson Larry C. , Opdyke Bradley N.
Published: March 2008

Sediment samples were collected from continental slopes and marginal basins in the Gulf of Papua and analyzed for excess 210Pb to elucidate transport processes of fine‐ grained particles to this region. Estimated excess 210Pb fluxes of 1.0–12.8 dpm cm−2 a−1 were derived from measured seabed inventories. Highest sediment accumulation rates (0.28–0.35 cm a−1) were measured along the northeastern shelf edge, and they decrease in seaward directions and along isobaths to the southwest. The excess 210Pb flux could result from either focused deposition of high‐210Pb activity sediments from the continental shelf and upper slope or scavenging of 210Pb brought landward from deep‐sea waters. This sediment flux is concentrated in the northeastern Gulf of Papua, where the shelf is narrow and calcium carbonate contents are lowest. Analysis of sedimentary fabric and 210Pb distributions in cores suggests sediment delivery to the slope occurs on a 100‐year timescale as both diffuse hemipelagic deposition as well as turbidity flows. The flux of sediment in turbidity flows is not well constrained but may be producing additional deep‐sea accumulation in the Moresby Trough, as well as export from the study area.