bluuebunny/crossref_metadata_2025 huggingface dataset:
Social and economic consequences of obstetric fistula: Life changed forever?
Authors: Ahmed S. , Holtz S.A.
Published: August 2007

Objectives

To summarize the social, economic, emotional, and psychological consequences incurred by women with obstetric fistula; present the results of a meta‐analysis for 2 major consequences, divorce/separation and perinatal loss; and report on improvements in health and self‐esteem and on the possibility of social reintegration following successful fistula repair.

Methods

We conducted a review of the literature published between 1985 and 2005 on fistula in developing countries. We then performed a meta‐analysis for 2 of the major consequences of having a fistula, divorce/separation and perinatal child loss.

Results

Studies suggest that surgical treatment usually closes the fistula and improves the physical and mental health of affected women.

Conclusion

With additional social support and counseling, women may be able to successfully reintegrate socially following fistula repair.
Veiled entrapment: a study of social isolation of older Chinese migrants in Brisbane, Queensland
Authors: IP DAVID , LUI CHI WAI , CHUI WING HONG
Published: August 2007

This paper presents the findings of a study of the support and service needs of older Chinese people in Brisbane, the capital city of Queensland, Australia. There were two specific objectives: to ascertain the problems encountered by older Chinese-Australians in their daily lives and social activities; and to develop policy and service development recommendations, with a view to mitigating their problems, meeting their unmet needs, improving their quality of life, and enhancing their participation in Australian society. The study used multiple methods, including a literature review, focus group meetings, and a community survey. The findings indicate that older Chinese people, and particularly women, experience significant restrictions in their activity patterns, social isolation and loneliness. Their lack of proficiency in the English language, and the difficulties they have in accessing language-support and interpretation services, limit their autonomous mobility and make them heavily dependent on their adult children, not least for transport. Their physical and psychological wellbeing is affected further by strained relations with their adult children, and these are compounded by financial concerns. The implications of the findings for welfare policy and practice are discussed at the end of the paper.
Does early retirement lead to longer life?
Authors: LITWIN HOWARD
Published: August 2007

It has been claimed, but not empirically supported, that early retirement leads to longer life. The present investigation addressed this question using data from a 1997 Israeli national household survey of adults aged 60 or more years linked to mortality records from the national death registry, for 2004. The study examined the association between early retirement and seven-year all-cause mortality among the population of older Jewish Israelis who were employed prior to or at baseline (N=2,374). Both the timing of retirement and the reasons for exit from the labour force were considered in the analysis. The initial hazard regression models, adjusted by gender and reason for retirement including poor health, showed that early retirees indeed had lower mortality risk ratios than respondents who had retired ‘on time’. When additional variables were controlled in the final analytic model, however, the association between early retirement and mortality was not supported. Older age, male gender, and having been diagnosed with one or more of five major illnesses were all associated with greater risk for mortality. Medium level education and being employed at baseline were associated with lesser mortality risk. Nevertheless, the timing of retirement, viz. early versus normative exit from the workforce, was not related to survival. In sum, the respondents who had prematurely exited the labour force did not benefit from disproportionately longer lives when compared with the respondents who retired ‘on time’.
The Good and the Right
Authors: ZIMMERMAN MICHAEL J.
Published: August 2007

T. M. Scanlon has revived a venerable tradition according to which something's being good consists in its being such that there is a reason to respond positively towards it. He has presented novel arguments for this thesis. In this article, I first develop some refinements of the thesis with a view to focusing on intrinsic value in particular, then discuss the relation between the thesis and consequentialism, then critically examine Scanlon's arguments for the thesis, and finally turn to the question whether we should reject the thesis on the grounds that, when there is a reason to respond positively towards something, this is so because the thing in question is good. Two appendices follow. In the first, I discuss whether it is good to do right. In the second, I discuss whether an act's being wrong provides a reason not to do it.
Varieties of Hedonism in Feldman's Pleasure and the Good Life
Authors: NORCROSS ALASTAIR
Published: August 2007

In these comments on Fred Feldman's Pleasure and the Good Life, I first challenge the dichotomy between sensory and attitudinal hedonisms as perhaps presenting a false dilemma. I suggest that there may be a form of hedonism that employs the concept of a ‘feel’ that is not purely sensory. Next, I raise some problems for several of the versions of hedonism explored in the book.
LE TRACÉ CONTINU DES SECTIONS CONIQUES À LA RENAISSANCE: APPLICATIONS OPTICO-PERSPECTIVES, HÉRITAGE DE LA TRADITION MATHÉMATIQUE ARABE
Authors: RAYNAUD DOMINIQUE
Published: August 2007

The perfect compass, used by al-Qūhī, al-Sijzī and his successors for the continuous drawing of conic sections, reappeared after a long eclipse in the works of Renaissance mathematicians like Francesco Barozzi in Venice. The resurgence of this instrument seems to have depended on its interest to solve new optico-perspective problems. Having reviewed the various instruments designed for the drawing of conic sections, the article is focused on the sole conic compass. Theoretical and empirical applications are detailed. Contrarily to the common thesis of an independant discovery, various elements suggest a direct descent between the birkār al-tāmm of the Arabic mathematical tradition and the Italian conic compass. Then we present the most probable transmission hypothesis involving: 1° Ibn Yūnus and his disciples of Mosul, 2° Sultan Malik al-Kāmil in Damas, 3° Master Theodore and Frederick II at the court of Sicily, 4° Andalò di Negro and Robert of Anjou in Naples, 5° Lorenzo della Volpaia, Vinci, Sangallo and Michelangelo in Florence, 6° Ausonio, Contarini, Thiene and Francesco Barozzi in Venice.
Development of the peripheral glial cells in Drosophila
Authors: Silies Marion , Edenfeld Gundula , Engelen Daniel , Stork Tobias , Klämbt Christian
Published: August 2007

In complex organisms the nervous system comprises two cell types: neurons and glial cells. Their correct interplay is of crucial importance during both the development of the nervous system and for later function of the nervous system. In recent years tools have been developed for Drosophila that enable genetic approaches to understanding glial development and differentiation. Focusing on peripheral glial cells we first summarize wild-type development, then introduce some of the relevant genes that have been identified. Despite obvious differences between Drosophila and mammalian glial cells, the molecular machinery that controls terminal differentiation appears well conserved.
No pun intended: future directions in invertebrate glial cell migration studies
Authors: Cafferty Patrick , Auld Vanessa J.
Published: August 2007

Glial cells play a wide range of essential roles in both nervous system development and function and has been reviewed recently (Parker and Auld, 2006). Glia provide an insulating sheath, either form or direct the formation of the blood–brain barrier, contribute to ion and metabolite homeostasis and provide guidance cues. Glial function often depends on the ability of glial cells to migrate toward specific locations during nervous system development. Work in nervous system development in insects, in particular in the fruit fly Drosophila melanogaster and the tobacco hornworm Manduca sexta, has provided significant insight into the roles of glia, although the molecular mechanisms underlying glial cell migration are being determined only now. Indeed, many of the processes and mechanisms discovered in these simpler systems have direct parallels in the development of vertebrate nervous systems. In this review, we first examine the developmental contexts in which invertebrate glial cell migration has been observed, we next discuss the characterized molecules required for proper glial cell migration, and we finally discuss future goals to be addressed in the study of glial cell development.
A continuum model of melt pond evolution on Arctic sea ice
Authors: Flocco Daniela , Feltham Daniel L.
Published: August 2007

During the Northern Hemisphere summer, absorbed solar radiation melts snow and the upper surface of Arctic sea ice to generate meltwater that accumulates in ponds. The melt ponds reduce the albedo of the sea ice cover during the melting season, with a significant impact on the heat and mass budget of the sea ice and the upper ocean. We have developed a model, designed to be suitable for inclusion into a global circulation model (GCM), which simulates the formation and evolution of the melt pond cover. In order to be compatible with existing GCM sea ice models, our melt pond model builds upon the existing theory of the evolution of the sea ice thickness distribution. Since this theory does not describe the topography of the ice cover, which is crucial to determining the location, extent, and depth of individual ponds, we have needed to introduce some assumptions. We describe our model, present calculations and a sensitivity analysis, and discuss our results.
Isotope values of atmospheric halocarbons and hydrocarbons from Irish urban, rural, and marine locations
Authors: Redeker K. R. , Davis S. , Kalin R. M.
Published: August 2007

Stable carbon isotope ratios for 37 hydrocarbon, CFC and halocarbon compounds were determined over the course of 1 year (86 samples) from the urban Belfast environment, Northern Ireland (NI). A smaller number of samples were collected from rural locations at Crossgar and Hillsborough, NI, and one marine location at Mace Head, Republic of Ireland. Source δ13C “signatures” suggest that C5 alkanes and ≥C4 alkenes are most likely derived from vehicle emissions. C3–C5 hydrocarbons show significant enrichment of δ13C with iso‐alkanes < n‐alkanes < alkenes < alkynes. There is also significant enrichment of δ13C from propane to n‐butane to n‐pentane. There is no significant separation between n‐pentane, n‐hexane, n‐heptane or methyl‐butane, methyl pentane and methyl hexanes. Calculated hydroxyl reaction kinetic isotope effects and subsequent δ13C enrichment are insufficient to explain shifts in isotopic ratio relative to concentration for all compounds as is differences in origin of air mass. Very few compounds show significant diurnal shifts; however, alkanes and ≥C4 alkenes demonstrate consistent enrichment of isotopic ratios when summer samples are compared to winter samples. Benzene is the sole compound measured that appears to become more depleted in δ13C when summer samples are compared against winter samples. Urban air, sampled at Belfast, which has originated in Europe shows enriched values for hydrocarbons while air which has originated in the Arctic Ocean is most similar to marine air off the Atlantic, sampled at Mace Head, Ireland.
Solar‐QBO interaction and its impact on stratospheric ozone in a zonally averaged photochemical transport model of the middle atmosphere
Authors: McCormack J. P. , Siskind D. E. , Hood L. L.
Published: August 2007

We investigate the solar cycle modulation of the quasi‐biennial oscillation (QBO) in stratospheric zonal winds and its impact on stratospheric ozone with an updated version of the zonally averaged CHEM2D middle atmosphere model. We find that the duration of the westerly QBO phase at solar maximum is 3 months shorter than at solar minimum, a more robust result than in an earlier CHEM2D study due to reduced Rayleigh friction drag in the present version of the model. The modeled solar cycle ozone response, determined via multiple linear regression, is compared with observational estimates from the combined Solar Backscattered Ultraviolet (SBUV/2) data set for the period 1979–2003. We find that a model simulation including imposed solar UV variations, the zonal wind QBO, and an imposed 11‐year variation in planetary wave 1 amplitude produces a lower stratospheric ozone response of ∼2.5% between 0 and 20°S and an upper stratospheric ozone response of ∼1% between 45 and 55 km, in good agreement with the SBUV‐derived ozone response. This simulation also produces an (enhancement/reduction) in the (lower/upper) stratospheric temperature response at low latitudes compared to the effects of solar UV variations alone, which are consistent with model vertical velocity anomalies produced by the solar‐modulated QBO and imposed changes in planetary wave forcing.
Interaction of strong lower and weak middle crust during lithospheric extension in western New Zealand
Authors: Klepeis Keith A. , King Daniel , De Paoli Mathew , Clarke Geoffrey L. , Gehrels George
Published: August 2007

Exhumed sections of the middle and lower crust in western New Zealand reveal how deformation was partitioned within a thermally and rheologically evolving crustal column during Cretaceous continental extension. Structural data,P‐Tdeterminations, and U‐Pb geochronology from central Fiordland and the Paparoa Range in Westland show that extension initiated in the lower crust by ∼114 Ma as a period of arc‐related magmatism waned. Initially, deformation was localized into areas that were weakened by heat and magma. However, these hot, weak zones were ephemeral. During the period 114–111 Ma, lower crustal fabrics record a rapid progression from magmatic flow to high‐temperature deformation at the garnet‐granulite facies (T> 700°C,P= 12 kbar) to cooler deformation at the upper amphibolite facies (T= 550–650°C,P= 7–9 kbar). Lower crustal cooling and compositional contrasts between mafic granulites and hydrous metasedimentary material resulted in a middle crust that was weak relative to the lower crust. Between circa 111 and circa 90 Ma, focused subhorizontal flow and vertical thinning in a weak middle crust led to the collapse of the upper crust and the unroofing of midcrustal material. During this period, arrays of conjugate‐style shear zones transferred displacements vertically and horizontally through the crust, resulting in a structural style that resembles crustal‐scale boudinage. The New Zealand example of continental extension shows that a weak middle crust and a relatively cool, highly viscous lower crust can result in a localized style of extension, including the formation of metamorphic core complexes that exhume the middle crust but not the lower crust.
Pacific meridional mode and El Niño—Southern Oscillation
Authors: Chang Ping , Zhang Li , Saravanan R. , Vimont Daniel J. , Chiang John C. H. , Ji Link , Seidel Howard , Tippett Michael K.
Published: August 2007

We present intriguing evidence that the majority of El Niño events over the past four decades are preceded by a distinctive sea‐surface warming and southwesterly wind anomaly in the vicinity of the Intertropical Convergence Zone (ITCZ) during the boreal spring. This phenomenon, known as the Meridional Mode (MM), is shown to be intrinsic to the thermodynamic coupling between the atmosphere and ocean. The MM effectively acts as a conduit through which the extratropical atmosphere influences ENSO. Modeling results further suggest that the MM plays a vital role in the seasonal phase‐locking behavior of ENSO. The findings provide a new perspective for understanding the important role of thermodynamic ocean‐atmosphere feedback in ENSO and may have profound implications for ENSO prediction, particularly the unresolved issue of the spring predictability barrier.
Intrinsic dynamics and long‐term evolution of a convectively generated oceanic vortex in the Greenland Sea
Authors: Rubino Angelo , Androssov Alexey , Dotsenko Sergey
Published: August 2007

Nonstationary dynamics, realistic long‐term evolution, and influence on local convection characterizing an oceanic vortex similar to those observed in the central Greenland Sea were investigated using in situ data, a hierarchy of numerical models, and an analytical theory. A non‐hydrostatic model for the simulation of convective plumes was nested into a regional ocean‐ice model forced and initialized by a global, atmosphere/ocean/ice model. In the central Greenland Sea, water masses similar to those observed in a convectively‐generated vortex and a corresponding numerically reconstructed 3D velocity were imposed in the non‐hydrostatic model. Under atmospheric/oceanic realistic conditions and forcing, the simulated vortex evolved as an almost circular, nonstationary, long‐lived, predominantly anticyclonically rotating feature. As time elapsed, it detached from the sea surface and became an intermediate vortex, which influenced the local convective preconditioning. Its inertial pulsations, shape, and velocity structure closely resemble corresponding characteristics of recently discovered theoretic nonstationary anticyclones.
Holocene tsunamis from Mount Etna and the fate of Israeli Neolithic communities
Authors: Pareschi Maria Teresa , Boschi Enzo , Favalli Massimiliano
Published: August 2007

Field evidence reveals that the Neolithic village of Atlit‐Yam (Israeli coast) was destroyed in an event which also caused the sudden death of tens of inhabitants. Archaeological evidence and numerical simulations support the notion that the village was destroyed, ∼8.3 ka B.P., by a tsunami triggered by a known Holocene flank collapse of Mt. Etna volcano (Italy). The filling of a water well within the village confirms inundation by a tsunami wave train and a sediment layer, composed of a clayed‐sandy matrix and other detritus including reworked marine sediment, indicates tsunami inundation. This scenario shows that tsunamis generated by sector collapses from coastal volcanoes can seriously threaten near‐shore settlements thousands of kilometres distant from the tsunami source.
Automatic detection and characterization of seismic tremors in northern Cascadia
Authors: Kao Honn , Thompson Philip J. , Rogers Garry , Dragert Herb , Spence George
Published: August 2007

We develop an algorithm that automatically detects and characterizes seismic waveforms associated with episodic tremor and slip (ETS) events in northern Cascadia. For each hour‐long seismogram, the process begins with the calculation of moving average and scintillation index functions. A logic chart is designed to sort the observed waveform patterns into a set of classes based on these functions. An ETS event is always manifest by many station‐hours with coherent tremor (CT) patterns. Automatic analysis of seismic waveforms recorded in the past three years gives results consistent with the work done by tedious visual inspection of seismograms. Our algorithm, which is free from human oversight, is ideal for an automatic tremor monitoring system to give immediate notice of an ETS event.
Negative inotropic effects of endothelin‐1 in mouse cardiomyocytes: evidence of a role for Na+‐Ca2+ exchange
Authors: James A F
Published: August 2007

Endothelin‐1 (ET‐1) is a peptide hormone produced within the myocardium which may modulate myocardial contractility in a paracrine‐autocrine fashion. In the majority of species, ET‐1 has a direct positive inotropic effect on the myocardium that involves both increased myofilament Ca2+ sensitivity and increased Ca2+ transients. Ca2+ entry through reverse‐mode Na+‐Ca2+ exchange, involving both indirect effects via elevation of intracellular [Na+] and direct activation of the Na+‐Ca2+ exchanger, have been suggested to contribute to the increase in Ca2+ transients. Conversely, mouse cardiomyocytes show an exclusively negative inotropic response to ET‐1. Here, Nishimaru and colleagues present novel evidence that the negative inotropic effect of ET‐1 in mouse cardiomyocytes involves both a reduction in myofilament Ca2+ sensitivity and increased Ca2+ extrusion, via Na+‐Ca2+ exchange. Data obtained using the selective Na+‐Ca2+ exchange blocker, SEA0400, suggest that a re‐assessment of the role of the exchanger in Ca2+‐handling by mouse cardiomyocytes may be necessary.

British Journal of Pharmacology (2007) 152, 417–419; doi:10.1038/sj.bjp.0707438; published online 27 August 2007
Phosphorylation of CK1δ: identification of Ser370 as the major phosphorylation site targeted by PKA in vitro and in vivo
Authors: Giamas Georgios , Hirner Heidrun , Shoshiashvili Levani , Grothey Arnhild , Gessert Susanne , Kühl Michael , Henne-Bruns Doris , Vorgias Constantinos E. , Knippschild Uwe
Published: August 2007

The involvement of CK1 (casein kinase 1) δ in the regulation of multiple cellular processes implies a tight regulation of its activity on many different levels. At the protein level, reversible phosphorylation plays an important role in modulating the activity of CK1δ. In the present study, we show that PKA (cAMP-dependent protein kinase), Akt (protein kinase B), CLK2 (CDC-like kinase 2) and PKC (protein kinase C) α all phosphorylate CK1δ. PKA was identified as the major cellular CK1δCK (CK1δ C-terminal-targeted protein kinase) for the phosphorylation of CK1δ in vitro and in vivo. This was implied by the following evidence: PKA was detectable in the CK1δCK peak fraction of fractionated MiaPaCa-2 cell extracts, PKA shared nearly identical kinetic properties with those of CK1δCK, and both PKA and CK1δCK phosphorylated CK1δ at Ser370in vitro. Furthermore, phosphorylation of CK1δ by PKA decreased substrate phosphorylation of CK1δ in vitro. Mutation of Ser370 to alanine increased the phosphorylation affinity of CK1δ for β-casein and the GST (gluthatione S-transferase)–p53 1–64 fusion protein in vitro and enhanced the formation of an ectopic dorsal axis during Xenopus laevis development. Anchoring of PKA and CK1δ to centrosomes was mediated by AKAP (A-kinase-anchoring protein) 450. Interestingly, pre-incubation of MiaPaCa-2 cells with the synthetic peptide St-Ht31, which prevents binding between AKAP450 and the regulatory subunit RII of PKA, resulted in a 6-fold increase in the activity of CK1δ. In summary, we conclude that PKA phosphorylates CK1δ, predominantly at Ser370in vitro and in vivo, and that site-specific phosphorylation of CK1δ by PKA plays an important role in modulating CK1δ-dependent processes.
Resveratrol is a class IA phosphoinositide 3-kinase inhibitor
Authors: Fröjdö Sara , Cozzone Delphine , Vidal Hubert , Pirola Luciano
Published: August 2007

Resveratrol, a polyphenol found in fruits, possesses chemopreventive and chemotherapeutic properties and has been shown to increase lifespan in yeast and metazoans, including mice. Genetic evidence and in vitro enzymatic measurements indicate that the deacetylase Sir2/SIRT1, an enzyme promoting stress resistance and aging, is the target of resveratrol. Similarly, down-regulation of insulin-like pathways, of which PI3K (phosphoinositide 3-kinase) is a key mediator, promotes longevity and is an attractive strategy to fight cancer. We show here that resveratrol inhibits, in vitro and in cultured muscle cell lines, class IA PI3K and its downstream signalling at the same concentration range at which it activates sirtuins. Our observations define class IA PI3K as a target of resveratrol that may contribute to the longevity-promoting and anticancer properties and identify resveratrol as a natural class-specific PI3K inhibitor.
Structural and functional differences among human surfactant proteins SP-A1, SP-A2 and co-expressed SP-A1/SP-A2: role of supratrimeric oligomerization
Authors: Sánchez-Barbero Fernando , Rivas Germán , Steinhilber Wolfram , Casals Cristina
Published: August 2007

SP-A (surfactant protein A) is a membrane-associated SP that helps to maintain the lung in a sterile and non-inflamed state. Unlike SP-As from other mammalian species, human SP-A consists of two functional gene products: SP-A1 and SP-A2. In all the functions examined, recombinant human SP-A1 invariably exhibits lower biological activity than SP-A2. The objective of the present study was to investigate why SP-A2 possesses greater biological activity than SP-A1 and what advantage accrues to having two polypeptide chains instead of one. We analysed structural and functional characteristics of recombinant baculovirus-derived SP-A1, SP-A2 and co-expressed SP-A1/SP-A2 using a wide array of experimental approaches such as analytical ultracentrifugation, DSC (differential scanning calorimetry) and fluorescence. We found that the extent of supratrimeric assembly is much lower in SP-A1 than SP-A2. However, the resistance to proteolysis is greater for SP-A1 than for SP-A2. Co-expressed SP-A1/SP-A2 had greater thermal stability than SP-A1 and SP-A2 and exhibited properties of each protein. On the one hand, SP-A1/SP-A2, like SP-A2, had a higher degree of oligomerization than SP-A1, and consequently had lower Kd for binding to bacterial Re-LPS (rough lipopolysaccharide), higher self-association in the presence of calcium and greater capability to aggregate Re-LPS and phospholipids than SP-A1. On the other hand, SP-A1/SP-A2, like SP-A1, was more resistant to trypsin degradation than SP-A2. Finally, the importance of the supratrimeric assembly for SP-A immunomodulatory function is discussed.
p53 regulates its own activator: transcriptional co-activator PC4, a new p53-responsive gene
Authors: Kishore A. Hari , Batta Kiran , Das Chandrima , Agarwal Shipra , Kundu Tapas K.
Published: August 2007

The tumour suppressor protein p53 regulates the expression of several genes that mediate cell cycle arrest, apoptosis, DNA repair and other cellular responses. Recently, we have shown that human transcriptional co-activator PC4 is a unique activator of p53 function. In the present study, we report that PC4 is a p53-inducible gene. Bioinformatics analysis reveals multiple p53-binding sites in the PC4 promoter. We have found that indeed p53 binds to all the identified sites in vitro and in vivo with varying affinities. p53 acts as an activator of PC4 transcription. Both PC4 mRNA and protein levels increase in response to stimuli that result in p53 induction. Furthermore, PC4 enhances p53 recruitment to the PC4 promoter. Our results thus establish the first report of a positively regulated feedback loop to control p53 function.
Alternative promoters and repetitive DNA elements define the species-dependent tissue-specific expression of theFMO1genes of human and mouse
Authors: Shephard Elizabeth A. , Chandan Pritpal , Stevanovic-Walker Milena , Edwards Mina , Phillips Ian R.
Published: August 2007

In humans, expression of the FMO1 (flavin-containing mono-oxygenase 1) gene is silenced postnatally in liver, but not kidney. In adult mouse, however, the gene is active in both tissues. We investigated the basis of this species-dependent tissue-specific transcription of FMO1. Our results indicate the use of three alternative promoters. Transcription of the gene in fetal human and adult mouse liver is exclusively from the P0 promoter, whereas in extra-hepatic tissues of both species, P1 and P2 are active. Reporter gene assays showed that the proximal P0 promoters of human (hFMO1) and mouse (mFmo1) genes are equally effective. However, sequences upstream (−2955 to −506) of the proximal P0 of mFmo1 increased reporter gene activity 3-fold, whereas hFMO1 upstream sequences (−3027 to −541) decreased reporter gene activity by 75%. Replacement of the upstream sequence of human P0 with the upstream sequence of mouse P0 increased activity of the human proximal P0 8-fold. Species-specific repetitive elements are present immediately upstream of the proximal P0 promoters. The human gene contains five LINE (long-interspersed nuclear element)-1-like elements, whereas the mouse gene contains a poly A region, an 80-bp direct repeat, an LTR (long terminal repeat), a SINE (short-interspersed nuclear element) and a poly T tract. The rat and rabbit FMO1 genes, which are expressed in adult liver, lack some (rat) or all (rabbit) of the elements upstream of mouse P0. Thus silencing of FMO1 in adult human liver is due apparently to the presence upstream of the proximal P0 of L1 (LINE-1) elements rather than the absence of retrotransposons similar to those found in the mouse gene.
Inhibition of calcium-independent phospholipase A2 suppresses proliferation and tumorigenicity of ovarian carcinoma cells
Authors: Song Yuanda , Wilkins Palmer , Hu Wenhui , Murthy Karnam S. , Chen Jing , Lee Zendra , Oyesanya Regina , Wu Jinhua , Barbour Suzanne E. , Fang Xianjun
Published: August 2007

PLA2 (phospholipase A2) enzymes play critical roles in membrane phospholipid homoeostasis and in generation of lysophospholipid growth factors. In the present study, we show that the activity of the cytosolic iPLA2 (calcium-independent PLA2), but not that of the calcium-dependent cPLA2 (cytosolic PLA2), is required for growth-factor-independent, autonomous replication of ovarian carcinoma cells. Blocking iPLA2 activity with the pharmacological inhibitor BEL (bromoenol lactone) induces cell cycle arrest in S- and G2/M-phases independently of the status of the p53 tumour suppressor. Inhibition of iPLA2 activity also leads to modest increases in apoptosis of ovarian cancer cells. The S- and G2/M-phase accumulation is accompanied by increased levels of the cell cycle regulators cyclins B and E. Interestingly, the S-phase arrest is released by supplementing the growth factors LPA (lysophosphatidic acid) or EGF (epidermal growth factor). However, inhibition of iPLA2 activity with BEL remains effective in repressing growth-factor- or serum-stimulated proliferation of ovarian cancer cells through G2/M-phase arrest. Down-regulation of iPLA2β expression with lentivirus-mediated RNA interference inhibited cell proliferation in culture and tumorigenicity of ovarian cancer cell lines in nude mice. These results indicate an essential role for iPLA2 in cell cycle progression and tumorigenesis of ovarian carcinoma cells.
Bounding the errors for convex dynamics on one or more polytopes
Authors: Tresser Charles
Published: August 2007

We discuss the greedy algorithm for approximating a sequence of inputs in a family of polytopes lying in affine spaces by an output sequence made of vertices of the respective polytopes. More precisely, we consider here the case when the greed of the algorithm is dictated by the Euclidean norms of the successive cumulative errors. This algorithm can be interpreted as a time-dependent dynamical system in the vector space, where the errors live, or as a time-dependent dynamical system in an affine space containing copies of all the original polytopes. This affine space contains the inputs, as well as the inputs modified by adding the respective former errors; it is the evolution of these modified inputs that the dynamical system in affine space describes. Scheduling problems with many polytopes arise naturally, for instance, when the inputs are from a single polytope P, but one imposes the constraint that whenever the input belongs to a codimension n face, the output has to be in the same codimension n face (as when scheduling drivers among participants of a carpool). It has been previously shown that the error is bounded in the case of a single polytope by proving the existence of an arbitrary large convex invariant region for the dynamics in affine space: A region that is simultaneously invariant for several polytopes, each considered separately, was also constructed. It was then shown that there cannot be an invariant region in affine space in the general case of a family of polytopes. Here we prove the existence of an arbitrary large convex invariant set for the dynamics in the vector space in the case when the sizes of the polytopes in the family are bounded and the set of all the outgoing normals to all the faces of all the polytopes is finite. It was also previously known that starting from zero as the initial error set, the error set could not be saturated in finitely many steps in some cases with several polytopes: Contradicting a former conjecture, we show that the same happens for some single quadrilaterals and for a single pentagon with an axial symmetry. The disproof of that conjecture is the new piece of information that leads us to expect, and then to verify, as we recount here, that the proof that the errors are bounded in the general case could be a small step beyond the proof of the same statement for the single polytope case.
Brownian motion of an asymmetrical particle in a potential field
Authors: Grima R. , Yaliraki S. N.
Published: August 2007

It is well known that a free ellipsoidal Brownian particle exhibits anisotropic diffusion for short times which changes to isotropic at long times, and, that the long-time diffusion coefficient is an average of the translational diffusion coefficients along the different semiaxes of the particle. We show analytically that in the presence of external forces, the long-time diffusion coefficient is different from that of a free particle. The magnitude of the difference in the two diffusion coefficients is found to increase proportionately with the particle’s asymmetry, being zero only for a perfectly spherical Brownian particle. It is also found that, for asymmetrical particles, the application of external forces can amplify the non-Gaussian character of the spatial probability distributions which consequently delays the transition to the classical behavior. We illustrate these phenomena by considering the quasi-two-dimensional Brownian motion of an ellipsoidal rigid particle in linear and harmonic potential fields. These two examples provide insight into the role played by particle asymmetry in electrophoresis and microconfinement due to a laser trap or due to intracellular macromolecular crowding.
Filamentation instability in a quantum plasma
Authors: Bret A.
Published: August 2007

The growth rate of the filamentation instability triggered when a diluted cold electron beam passes through a cold plasma is evaluated using the quantum hydrodynamic equations. Compared with a cold fluid model, quantum effects reduce both the unstable wave vector domain and the maximum growth rate. Stabilization of large wave vector modes is always achieved, but significant reduction of the maximum growth rate depends on a dimensionless parameter that is provided. Although calculations are extended to the relativistic regime, they are mostly relevant to the nonrelativistic one.
Acceleration of Monte Carlo simulations through spatial updating in the grand canonical ensemble
Authors: Orkoulas G.
Published: August 2007

A new grand canonical Monte Carlo algorithm for continuum fluid models is proposed. The method is based on a generalization of sequential Monte Carlo algorithms for lattice gas systems. The elementary moves, particle insertions and removals, are constructed by analogy with those of a lattice gas. The updating is implemented by selecting points in space (spatial updating) either at random or in a definitive order (sequential). The type of move, insertion or removal, is deduced based on the local environment of the selected points. Results on two-dimensional square-well fluids indicate that the sequential version of the proposed algorithm converges faster than standard grand canonical algorithms for continuum fluids. Due to the nature of the updating, additional reduction of simulation time may be achieved by parallel implementation through domain decomposition.
Effects of gravity, inertia, and surfactant on steady plug propagation in a two-dimensional channel
Authors: Zheng Y. , Fujioka H. , Grotberg J. B.
Published: August 2007

Liquid plugs may form in pulmonary airways during the process of liquid instillation or removal in many clinical treatments. Studies have shown that the effectiveness of these treatments may depend on how liquids distribute in the lung. Better understanding of the fundamental fluid mechanics of liquid plug transport will facilitate treatment strategies. In this paper, we develop a numerical model of steady plug propagation driven by gravity and pressure in a two-dimensional liquid-lined channel oriented at an angle α with respect to gravity. We investigate the effects of gravity through the Bond number, Bo, and α; the plug propagation speed through the capillary number, Ca, or the Reynolds number, Re; the plug length LP, and the surfactant concentration C0. Without gravity, i.e., Bo=0, the plug is symmetric, and there are two regimes for the flow: two wall layers and two trapped vortices in the core. There is no flow interaction between the upper and lower half plug domains. When Bo≠0 and α≠0, π, fluid is found to flow from the upper precursor film, through the core and into the lower trailing film. Then the number of vortices can be zero, one, or two, depending on the flow parameters. The vortices have stagnation points on the interface when C0=0, however when the surfactant is present (C0>0), the vortices detach from the interface and create saddle points inside the core. The front meniscus develops a capillary surface wave extending into the precursor film. This is where the film is thinnest and thus the wall shear stress is highest, as high as ∼100dyn∕cm2 in adult airways, which indicates a significant risk of pulmonary airway epithelial cell damage. Adding surfactant can decrease the peak magnitude of the shear stress, thus reducing the risk of cell damage. The prebifurcation asymmetry of the plug is quantified by the volume ratio, Vr, defined as the ratio of the liquid above to that below the center line of the channel. Vr is found to increase with LP, Ca, Re, and C0, while it decreases with Bo. The total mass left behind in the trailing films increases with Bo for any α at α>2π∕5, Ca and α for any value of Bo>0.
Crystallographic mechanisms of fracture in a textured polycrystalline TiNi shape memory alloy
Authors: Luo J. F. , Mao S. C. , Han X. D. , Zhang Z. , Wu J. , Wu M. H.
Published: August 2007

The crystallographic mechanisms of the crack initiation and propagation in a textured polycrystalline TiNi shape memory alloy were studied using scanning electron microscope and ex situ electron backscattered diffraction techniques. The results indicated that stress-induced martensitic transformation was triggered and formed a sandwich structure at the front of the crack tip prior to the crack initiation in the polycrystalline TiNi alloy. The crack propagated intragranularly and occasionally across the grain boundaries. The closed packed planes of the B2 parent phase such as {110} and {100} were revealed to favor the crack propagation. The stress-induced B2+B19′ sandwich structure determined the crack propagated by a microscopic sawtooth pattern and therefore a ductile feature in this textured polycrystalline TiNi sheet specimen.
Static and dynamic properties of hexagonal multiferroic RMnO3 compounds
Authors: Wesselinowa J. M. , Kovachev St.
Published: August 2007

The magnetic and electric static and dynamic properties of hexagonal multiferroic RMnO3 are studied based on the transverse Ising and Heisenberg models using a Green’s function technique. The influence of the magnetoelectric coupling and the exchange interaction constants is discussed. The coexistence of ferroelectricity and magnetism leads to interplay between the electric and magnetic properties which was found as an anomaly, as a kink in the temperature dependence of different static and dynamic properties in the vicinity of the magnetic phase transition temperature TN. The spin excitations show a novel softening around TN due to the magnetoelectric coupling. The magnetic-field-induced polarization is investigated. The obtained results are in qualitative agreement with the experimental data.
Photoreduction and oxidation behavior of In2O3 nanoparticles by metal organic chemical vapor deposition
Authors: Wang Ch. Y. , Cimalla V. , Kups Th. , Röhlig C.-C. , Romanus H. , Lebedev V , Pezoldt J. , Stauden Th. , Ambacher O.
Published: August 2007

In 2 O 3 nanoparticles were synthesized at low substrate temperatures by the metal organic chemical vapor deposition technique. Nanoparticles with a mean diameter from 3 to 33 nm can be obtained by varying the growth temperature. Photoreduction and oxidation studies were carried out for particle-containing layers exhibiting a resistance change of more than five orders of magnitude after ultraviolet irradiation and oxidation by ozone. A grain boundary model was proposed to understand the photoreduction and oxidation mechanism for the nanoparticle layers. It was suggested that by photoreduction the nanoparticles are reactivated throughout the layer. The Schottky barrier between the nanoparticles decreases inducing a reduction of the space-charge-limited region. After oxidation, a completely depleted space-charge region covering the whole volume of In2O3 nanoparticles is formed. Furthermore, the bulk diffusion process dominates the response of thick layers during the oxidation process. By decreasing the layer thickness down to 10 nm, surface effects dominate, resulting in an ultrafast response to changes in ozone concentration. The typical response time of very thin In2O3 nanoparticle layers was determined to be less than 1 s.
Depth resolved study of impurity sites in low energy ion implanted As in Si
Authors: d’Acapito Francesco , Milita Silvia , Satta Alessandra , Colombo Luciano
Published: August 2007

An extended x-ray absorption fine structure investigation in depth-resolved mode allows us to identify the different sites of the arsenic along its concentration profile in shallow junctions, obtained by low energy arsenic implantation of silicon. In the deeper part of the sample, arsenic mainly occupies substitutional sites and vacancy–arsenic complexes are evidenced, whereas in the region close to the surface a mixed phase of arsenic aggregates and arsenic impurities is present. First principles calculations supporting the observations are presented.
Asymptotic stability for a class of metriplectic systems
Authors: Birtea Petre , Boleantu Mihai , Puta Mircea , Tudoran Razvan Micu
Published: August 2007

Using the framework of metriplectic systems on Rn we will describe a constructive geometric method to add a dissipation term to a Hamilton-Poisson system such that any solution starting in a neighborhood of a nonlinear stable equilibrium converges toward a certain invariant set. The dissipation term depends only on the Hamiltonian function and the Casimir functions.
Phase quantization of chaos in the semiclassical regime
Authors: Takahashi Satoshi , Takatsuka Kazuo
Published: August 2007

Since the early stage of the study of Hamilton chaos, semiclassical quantization based on the low-order Wentzel-Kramers-Brillouin theory, the primitive semiclassical approximation to the Feynman path integrals (or the so-called Van Vleck propagator), and their variants have been suffering from difficulties such as divergence in the correlation function, nonconvergence in the trace formula, and so on. These difficulties have been hampering the progress of quantum chaos, and it is widely recognized that the essential drawback of these semiclassical theories commonly originates from the erroneous feature of the amplitude factors in their applications to classically chaotic systems. This forms a clear contrast to the success of the Einstein-Brillouin-Keller quantization condition for regular (integrable) systems. We show here that energy quantization of chaos in semiclassical regime is, in principle, possible in terms of constructive and destructive interference of phases alone, and the role of the semiclassical amplitude factor is indeed negligibly small, as long as it is not highly oscillatory. To do so, we first sketch the mechanism of semiclassical quantization of energy spectrum with the Fourier analysis of phase interference in a time correlation function, from which the amplitude factor is practically factored out due to its slowly varying nature. In this argument there is no distinction between integrability and nonintegrability of classical dynamics. Then we present numerical evidence that chaos can be indeed quantized by means of amplitude-free quasicorrelation functions and Heller’s frozen Gaussian method. This is called phase quantization. Finally, we revisit the work of Yamashita and Takatsuka [Prog. Theor. Phys. Suppl. 161, 56 (2007)] who have shown explicitly that the semiclassical spectrum is quite insensitive to smooth modification (rescaling) of the amplitude factor. At the same time, we note that the phase quantization naturally breaks down when the oscillatory nature of the amplitude factor is comparable to that of the phases. Such a case generally appears when the Planck constant of a large magnitude pushes the dynamics out of the semiclassical regime.
Evolution of the electrical and structural properties during the growth of Al doped ZnO films by remote plasma-enhanced metalorganic chemical vapor deposition
Authors: Volintiru I. , Creatore M. , Kniknie B. J. , Spee C. I. M. A. , van de Sanden M. C. M.
Published: August 2007

Al-doped zinc oxide (AZO) films were deposited by means of remote plasma-enhanced metalorganic chemical vapor deposition from oxygen/diethylzinc/trimethylaluminum mixtures. The electrical, structural (crystallinity and morphology), and chemical properties of the deposited films were investigated using Hall, four point probe, x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), electron recoil detection (ERD), Rutherford backscattering (RBS), and time of flight secondary ion mass spectrometry (TOF-SIMS), respectively. We found that the working pressure plays an important role in controlling the sheet resistance Rs and roughness development during film growth. At 1.5 mbar the AZO films are highly conductive (Rs<6 Ω∕□ for a film thickness above 1200 nm) and very rough (>4% of the film thickness), however, they are characterized by a large sheet resistance gradient with increasing film thickness. By decreasing the pressure from 1.5 to 0.38 mbar, the gradient is significantly reduced and the films become smoother, but the sheet resistance increases (Rs≈100 Ω∕□ for a film thickness of 1000 nm). The sheet resistance gradient and the surface roughness development correlate with the grain size evolution, as determined from the AFM and SEM analyses, indicating the transition from pyramid-like at 1.5 mbar to pillar-like growth mode at 0.38 mbar. The change in plasma chemistry/growth precursors caused by the variation in pressure leads to different concentration and activation efficiency of Al dopant in the zinc oxide films. On the basis of the experimental evidence, a valid route for further improving the conductivity of the AZO film is found, i.e., increasing the grain size at the initial stage of film growth.
Infrared and Raman spectroscopy of ZnO nanoparticles annealed in hydrogen
Authors: Hlaing Oo W. M. , McCluskey M. D. , Huso J. , Bergman L.
Published: August 2007

The effect of hydrogen on the conductivity of ZnO nanoparticles has implications for nanoscale optoelectronic devices. In this study, infrared reflectance spectra of as-grown and hydrogen-annealed ZnO nanoparticles were measured at near-normal incidence. The as-grown particles were electrically semi-insulating and show reflectance spectra characteristic of insulating ionic crystals. Samples annealed in hydrogen showed a significant increase in electrical conductivity and free-carrier absorption. A difference was observed in the reststrahlen line shape of the conductive sample compared to that of the as-grown sample. The effective medium approximation was applied to model the reflectance and absorption spectra. The agreement between experimental results and the model suggests that the nanoparticles have inhomogeneous carrier concentrations. Exposure to oxygen for several hours led to a significant decrease in carrier concentration, possibly due to the adsorption of negative oxygen molecules on the nanoparticle surfaces.