bluuebunny/crossref_metadata_2025 huggingface dataset:
How Frail Elders Evaluate Their Caregiver's Role Enactment
Authors: Tetz Karen B. , Archbold Patricia G. , Stewart Barbara J. , Messecar Deborah , Hornbrook Mark C. , Lucas Stephanie A.
Published: July 2006

In this validity study, using factor analysis, the authors identified three dimensions (affection, skill, and attentiveness) of the Care Receiver View of Caregiver Role Enactment Scale, a self-report measure designed to elicit an elderly care receiver's evaluation of how well their family member carried out the role of caregiver. The scale is a revision of the Satisfaction With Caregiving Scale. This study was a secondary analysis of data from PREP: Family-based Care for Frail Older Persons. Care receiver mutuality was the variable most highly correlated with caregiver role enactment. Other variables related to good quality care were higher care receiver positive affect, better caregiver physical health, and lower caregiver role strain; husband caregivers were rated as giving poorer quality care.
News and the empowerment of citizens
Authors: Lewis Justin
Published: July 2006

This article argues that we need to take the democratic promise of news seriously and find ways to advance that promise. It begins by considering both the importance of news to democratic citizenship, and its failure to deliver in ways that do not compound social inequalities. It argues against more optimistic accounts of the state of democratic citizenship, but finds that the notion of public service journalism often lapses into a class-specific discourse for the information-rich. Meanwhile, current news values are contradictory and incoherent, allowing us space to build upon the democratic ideals in journalistic philosophy. The article then argues that citizenship should be brought from the margins of news to its centre. This means implicating citizenship into the news’s mode of address, of going beyond the narrow narratives of current news values and addressing broad citizenship concerns.
Something you can actually pick up
Authors: Hof Karina
Published: July 2006

This article is an ethnographic study of scrapbooking as a community of practice. Through interviews with practitioners of the contemporary craft both in the United States and The Netherlands, as well as by analysing surveys, internet resources and secondary literature, it seeks to describe how scrapbooking is both a form and forum of cultural citizenship.

Cultural citizenship is understood as the way in which members of this interpretive community enjoy privileges and fulfil duties in a communal, capitalist and, above all, gendered society. As an output-oriented practice that values the personal touch as well as a community spirit, scrapbooking offers a spectacular way for women to self-reflect on their identities as cultural citizens.
Is Pluralism a Viable Model of Diversity? The Benefits and Limits of Subgroup Respect
Authors: Huo Yuen J. , Molina Ludwin E.
Published: July 2006

In this paper, we focus on a key psychological principle underlying pluralism, subgroup respect, defined as feelings that one's subgroup is recognized, accepted, and valued by members of a common group (e.g. Americans' respect for various ethnic subgroups). Analyzing survey data collected from a large and diverse sample of respondents in two US cities (Oakland, California, and Los Angeles; N = 1,229), we found that subgroup respect was linked to more positive evaluations of America and its ethnic groups, but only among African Americans and Latinos. Among Whites, personal respect (i.e. how Americans feel about the individual) was a better predictor of the assessed attitudes (affect toward Americans, distrust of the justice system, and ingroup favoritism) than subgroup respect. Advocates of pluralism suggest that acknowledgment and regard for valued subgroup identities will have a unifying effect on the social system. The data here, while generally consistent with this perspective, suggests, however, that the unifying influence of subgroup respect is limited to members of ethnic minority groups.
Responding to Discrimination as a Function of Meritocracy Beliefs and Personal Experiences: Testing the Model of Shattered Assumptions
Authors: Foster Mindi D. , Sloto Lisa , Ruby Richard
Published: July 2006

We examined whether the model of shattered assumptions (Janoff-Bulman, 1992) could be applied to the reactions of victims of discrimination. Consistent with this model, it was hypothesized that those whose positive world assumptions are inconsistent with their negative experiences of discrimination would report more negative responses than those whose world assumptions match their experience. Disadvantaged group (both gender and ethnicity) members' responses to discrimination (self-esteem, collective action, intergroup anxiety) were predicted from their meritocracy beliefs and personal experiences of discrimination. Regression analyses showed a significant interaction between meritocracy beliefs and personal discrimination such that among those who reported personal discrimination, stronger beliefs that the meritocracy exists predicted decreased self-esteem and collective action as well as increased intergroup anxiety. Among those who reported little personal discrimination, stronger beliefs that the meritocracy exists predicted increased self-esteem. Implications for promoting a critical view of the social system is discussed.
Reinventing Modernity
Authors: Lee Raymond L.M.
Published: July 2006

Modernity has not collapsed under the weight of postmodern criticisms. On the contrary, it has rebounded with greater vigour as witnessed by the emergence of new terms such as reflexive modernization, liquid modernity and multiple modernities. These terms suggest that modernity can no longer be conceptualized in the singular. Yet the pluralization of modernity does not necessarily imply that there is a new consensus about the meaning of modernity. The appearance of these terms can be regarded as specific attempts to transcend postmodern critiques. Comparison of these new terms provides an understanding of their usage in the context of the decline of postmodernism and the direction of contests over the meaning of modernity.
Assay of the von Willebrand factor (VWF) propeptide to identify patients with type 1 von Willebrand disease with decreased VWF survival
Authors: Haberichter Sandra L. , Balistreri Michael , Christopherson Pamela , Morateck Patricia , Gavazova Stefana , Bellissimo Daniel B. , Manco-Johnson Marilyn J. , Gill Joan Cox , Montgomery Robert R.
Published: July 2006

Type 1 von Willebrand disease (VWD) is characterized by a partial quantitative deficiency of von Willebrand factor (VWF). Few VWF gene mutations have been identified that cause dominant type 1 VWD. The decreased survival of VWF in plasma has recently been identified as a novel mechanism for type 1 VWD. We report 4 families with moderately severe type 1 VWD characterized by low plasma VWF:Ag and FVIII:C levels, proportionately low VWF:RCo, and dominant inheritance. A decreased survival of VWF in affected individuals was identified with VWF half-lives of 1 to 3 hours, whereas the half-life of VWF propeptide (VWFpp) was normal. DNA sequencing revealed a single (heterozygous) VWF mutation in affected individuals, S2179F in 2 families, and W1144G in 2 families, neither of which has been previously reported. We show that the ratio of steady-state plasma VWFpp to VWF:Ag can be used to identify patients with a shortened VWF half-life. An increased ratio distinguished affected from unaffected individuals in all families. A significantly increased VWFpp/VWF:Ag ratio together with reduced VWF:Ag may indicate the presence of a true genetic defect and decreased VWF survival phenotype. This phenotype may require an altered clinical therapeutic approach, and we propose to refer to this phenotype as type-1C VWD.
Presence of neutrophil-bearing antigen in lymphoid organs of immune mice
Authors: Maletto Belkys A. , Ropolo Andrea S. , Alignani Diego O. , Liscovsky Miriam V. , Ranocchia Romina P. , Moron Victor Gabriel , Pistoresi-Palencia María C.
Published: July 2006

Neutrophils play a crucial early role during the innate response, but little is known about their possible contribution when an adaptive immune response is installed. A robust neutrophilia and a T helper 1 (Th1) immune response are present after immunization with Complete Freund Adjuvant (CFA). We show that when FITC-labeled OVA was injected into the footpad of OVA/CFA immunized mice, the main OVA-FITC+ cells recruited in draining popliteal lymph nodes (LNs) were neutrophils, with most of them arriving at the LN by means of lymphatic vessels. The development of this OVA-FITC+ neutrophil influx requires an immune response against OVA. The OVA-FITC+ neutrophils present in LNs displayed mainly intracellular TNF-α, and their depletion resulted in an increase in the specific IL-5 levels. These data provide new evidence about the role played by neutrophils in vivo in adaptive immunity.
Ex vivo gene therapy with lentiviral vectors rescues adenosine deaminase (ADA)–deficient mice and corrects their immune and metabolic defects
Authors: Mortellaro Alessandra , Hernandez Raisa Jofra , Guerrini Matteo M. , Carlucci Filippo , Tabucchi Antonella , Ponzoni Maurilio , Sanvito Francesca , Doglioni Claudio , Serio Clelia Di , Biasco Luca , Follenzi Antonia , Naldini Luigi , Bordignon Claudio , Roncarolo Maria Grazia , Aiuti Alessandro
Published: July 2006

Adenosine deaminase (ADA) deficiency is caused by a purine metabolic dysfunction, leading to severe combined immunodeficiency (SCID) and multiple organ damage. To investigate the efficacy of ex vivo gene therapy with self-inactivating lentiviral vectors (LVs) in correcting this complex phenotype, we used an ADA–/– mouse model characterized by early postnatal lethality. LV-mediated ADA gene transfer into bone marrow cells combined with low-dose irradiation rescued mice from lethality and restored their growth, as did transplantation of wild-type bone marrow. Mixed chimerism with multilineage engraftment of transduced cells was detected in the long term in animals that underwent transplantation. ADA activity was normalized in lymphocytes and partially corrected in red blood cells (RBCs), resulting in full metabolic detoxification and prevention of severe pulmonary insufficiency. Moreover, gene therapy restored normal lymphoid differentiation and immune functions, including antigen-specific antibody production. Similar degrees of detoxification and immune reconstitution were obtained in mice treated early after birth or after 1 month of enzyme-replacement therapy, mimicking 2 potential applications for ADA-SCID. Overall, this study demonstrates the efficacy of LV gene transfer in correcting both the immunological and metabolic phenotypes of ADA-SCID and supports the future clinical use of this approach.
Quaternary structure predictions of transmembrane proteins starting from the monomer: a docking-based approach
Authors: Casciari D , Seeber M , Fanelli F
Published: July 2006

Background

We introduce a computational protocol for effective predictions of the supramolecular organization of integral transmembrane proteins, starting from the monomer. Despite the demonstrated constitutive and functional importance of supramolecular assemblies of transmembrane subunits or proteins, effective tools for structure predictions of such assemblies are still lacking. Our computational approach consists in rigid-body docking samplings, starting from the docking of two identical copies of a given monomer. Each docking run is followed by membrane topology filtering and cluster analysis. Prediction of the native oligomer is therefore accomplished by a number of progressive growing steps, each made of one docking run, filtering and cluster analysis. With this approach, knowledge about the oligomerization status of the protein is required neither for improving sampling nor for the filtering step. Furthermore, there are no size-limitations in the systems under study, which are not limited to the transmembrane domains but include also the water-soluble portions.

Results

Benchmarks of the approach were done on ten homo-oligomeric membrane proteins with known quaternary structure. For all these systems, predictions led to native-like quaternary structures, i.e. with Cα-RMSDs lower than 2.5 Å from the native oligomer, regardless of the resolution of the structural models.

Conclusion

Collectively, the results of this study emphasize the effectiveness of the prediction protocol that will be extensively challenged in quaternary structure predictions of other integral membrane proteins.
Inhibition of cyclooxygenase-2 decreases breast cancer cell motility, invasion and matrix metalloproteinase expression
Authors: Larkins Teri L , Nowell Marchele , Singh Shailesh , Sanford Gary L
Published: July 2006

Background

Cyclooxygenase (COX) is the rate-limiting enzyme that catalyzes the formation of prostaglandins. The inducible isoform of COX (COX-2) is highly expressed in aggressive metastatic breast cancers and may play a critical role in cancer progression (i.e. growth and metastasis). However, the exact mechanism(s) for COX-2-enhanced metastasis has yet to be clearly defined. It is well established that one of the direct results of COX-2 action is increased prostaglandin production, especially prostaglandin E2 (PGE2). Here, we correlate the inhibition of COX-2 activity with decreased breast cancer cell proliferation, migration, invasion and matrix metalloproteinase (MMP) expression.

Methods

Breast cancer cells (Hs578T, MDA-MB-231 and MCF-7) were treated with selective COX-2 inhibitors (NS-398 and Niflumic acid, NA). Cell proliferation was measured by staining with erythrosin B and counting the viable cells using a hemacytometer. Cell migration and invasion were measured using migration and invasion chamber systems. MMP expression was determined by enzyme immunoassay (secreted protein) and real-time quantitative polymerase chain reaction (mRNA).

Results

Our results show that there is a decline in proliferation, migration and invasion by the Hs578T and MDA-MB-231 breast cancer cell lines in the presence of either low concentrations (1 μM or lower) NA or NS-398. We also report that MMP mRNA and protein expression by Hs578T cells is inhibited by NS-398; there was a 50% decrease by 100 μM NS-398. PGE2 completely reversed the inhibitory effect of NS-398 on MMP mRNA expression.

Conclusion

Our data suggests that COX-2-dependent activity is a necessary component for cellular and molecular mechanisms of breast cancer cell motility and invasion. COX-2 activity also modulates the expression of MMPs, which may be a part of the molecular mechanism by which COX-2 promotes cell invasion and migration. The studies suggest that COX-2 assists in determining and defining the metastatic signaling pathways that promote the breast cancer progression to metastasis.
Hydrogeochemistry of seasonal variation of Urmia Salt Lake, Iran
Authors: Alipour Samad
Published: July 2006

Urmia Lake has been designated as an international park by the United Nations. The lake occupies a 5700 km2 depression in northwestern Iran. Thirteen permanent rivers flow into the lake. Water level in the lake has been decreased 3.5 m in the last decade due to a shortage of precipitation and progressively dry climate. Geologically the lake basin is considered to be a graben of tectonic origin. Na, K, Ca, Li and Mg are the main cations with Cl, SO4, and HCO3 as the main anions. F & Br are the other main elements in the lake. A causeway crossing the lake is under construction, which may affect the lake's annual geochemistry. The main object of this project is mainly to consider the potential of K-mineral production along with ongoing salt production.

Seven hundred and four samples were taken and partially analyzed for the main cations and anions. Surface water (0.5 m. depth) was analyzed for Na, K, Mg, Ca, Br and Li, and averaged 87.118 g/lit, 1.48 g/lit, 4.82 g/lit, 4.54 g/lit, 1.19 ppm and 12.7 ppm respectively for the western half of the lake. Sodium ranged between 84 to 91.2 g/lit, and showed higher concentrations in the south than in the north. This unexpected result may be caused by shallower depth in the south and a higher net evaporation effect. Calcium ranged between 4.2 to 5 g/lit, apparently slightly higher in the north. K is higher in the south, possibly due to rivers entering from south that may carry slightly higher K in solution.

In the middle-range samples (0.5–5 m.), K averaged 1.43 g/lit and ranged from 1.40 to 1.46 g/lit. At this intermediate depth the distribution of K is clearly higher to the south of the causeway that is currently under construction. It is not clear whether this increase is the effect of the causeway or the effect of the salty Aji-Chay River to the east, and the Khoy salt domes to the north of the lake. At depth (5 m–10 m), K averaged 1.48 g/lit and ranged from 1.4 to 1.49 g/lit, differing only in the second decimal from the average of the middle and surface samples.

Ignoring the small difference between the averages of the three sample depths, the distribution of K is highly homogeneous in the lake water due to the mixing process. Therefore causeway construction has not yet strongly affected K distribution, or it may be at the starting point. Magnesium concentration ranged from 4.6 to 5-g/lit, and was elevated in the south. This differs somewhat compared to calcium. Lithium, with an average of 12–13 ppm, is slightly higher in the south, and has not shown any significant variation in all three seasons. Iodine was below the detection limit in the lake.

Urmia Lake, geochemically, is highly uniform both to the south and north of the causeway, in both the surface and deep brines. K and Mg, which average 1.48 and 6.6 g/lit in order, could be elements worth production in addition to the NaCl currently being produced from the lake. Br, F, Li and B in the limit of <50 ppm don't look to be in the economical range.
Impairment of chondrocyte biosynthetic activity by exposure to 3-tesla high-field magnetic resonance imaging is temporary
Authors: Sunk Ilse-Gerlinde , Trattnig Siegfried , Graninger Winfried B , Amoyo Love , Tuerk Birgit , Steiner Carl-Walter , Smolen Josef S , Bobacz Klaus
Published: July 2006

The influence of magnetic resonance imaging (MRI) devices at high field strengths on living tissues is unknown. We investigated the effects of a 3-tesla electromagnetic field (EMF) on the biosynthetic activity of bovine articular cartilage. Bovine articular cartilage was obtained from juvenile and adult animals. Whole joints or cartilage explants were subjected to a pulsed 3-tesla EMF; controls were left unexposed. Synthesis of sulfated glycosaminoglycans (sGAGs) was measured by using [35S]sulfate incorporation; mRNA encoding the cartilage markers aggrecan and type II collagen, as well as IL-1β, were analyzed by RT–PCR. Furthermore, effects of the 3-tesla EMF were determined over the course of time directly after exposure (day 0) and at days 3 and 6. In addition, the influence of a 1.5-tesla EMF on cartilage sGAG synthesis was evaluated. Chondrocyte cell death was assessed by staining with Annexin V and TdT-mediated dUTP nick end labelling (TUNEL). Exposure to the EMF resulted in a significant decrease in cartilage macromolecule synthesis. Gene expression of both aggrecan and IL-1β, but not of collagen type II, was reduced in comparison with controls. Staining with Annexin V and TUNEL revealed no evidence of cell death. Interestingly, chondrocytes regained their biosynthetic activity within 3 days after exposure, as shown by proteoglycan synthesis rate and mRNA expression levels. Cartilage samples exposed to a 1.5-tesla EMF remained unaffected. Although MRI devices with a field strength of more than 1.5 T provide a better signal-to-noise ratio and thereby higher spatial resolution, their high field strength impairs the biosynthetic activity of articular chondrocytes in vitro. Although this decrease in biosynthetic activity seems to be transient, articular cartilage exposed to high-energy EMF may become vulnerable to damage.
Other geographies of gentrification
Authors: Phillips Martin
Published: July 2006

This paper considers recent pleas for a ‘geography of gentrification’, arguing that they have been very urban in focus and often enact what, following Soja (1996), might be described as ‘firstspace epistemology’. The paper identifies traces of other, secondspace and thirdspace geographies of gentrification. It is argued that these geographies may not be fully commensurable with each other but that they each may have some commensurability with rural as well as the urban spatialities. The paper goes on to explore these arguments in relation to studies of gentrification of the British countryside, focusing particularly on gentrification in rural Norfolk.
Patient reported outcomes as endpoints in medical research
Authors: Fairclough Diane L
Published: July 2006

This review covers a number of the many design and analytic issues associated with clinical trials that incorporate patient reported outcomes as primary or secondary endpoints. We use a clinical trial designed to evaluate a new therapy for the prevention of migraines to illustrate how endpoints are defined by the objectives of the study, the methods for handling longitudinal assessments with multiple scales or outcomes, and the methods of analysis in the presence of missing data.
Economic endpoints in clinical trials
Authors: Cook John , Drummond Michael , Heyse Joseph F
Published: July 2006

Healthcare decision makers are increasingly requesting information on the cost and cost-effectiveness of new medicines at the time of product launch. In order to provide this information, data on healthcare resource utilization and, in some cases, costs, may be collected in clinical trials. In this paper, we discuss some of the issues statisticians need to address when it is appropriate to include these economic endpoints in the trial. Several design issues are discussed, including the alternative types of and methods for collecting economic endpoint data, sample size and generalizability. Alternative approaches in the analysis of resource utilization, cost and cost-effectiveness are also presented. Finally, several of the analytic approaches are applied to actual data from a clinical trial.
The Use of Cues Depends on Goals: Store Reputation Affects Product Judgments When Social Identity Goals Are Salient
Authors: Lee Kyoungmi , Shavitt Sharon
Published: July 2006

The role that a given cue plays in consumer judgments depends on the motive that is salient for the consumer. We focus on store reputation as a cue whose utilization can depend on salient goals. Research has suggested that store reputation does not influence product judgments when brand and price information are available. In 3 experiments, however, we show that when social identity goals are salient or are perceived as relevant to the product, store reputation (because it conveys image‐relevant information) is used in evaluations of product quality. Specifically, store reputation has an impact on product judgments when either (a) consumers’ social‐image goals are directly heightened or (b) an interdependent self‐construal, characterized by a greater concern with social identity, is salient. The role of product type in moderating these effects is also examined.
Structured coalescent with nonconservative migration
Authors: Sampson Koffi Y.
Published: July 2006

We study the ancestral process of a sample from a subdivided population with stochastically varying subpopulation sizes. The sizes of the subpopulations change very rapidly (almost every generation) with respect to the coalescent time scale. For haploid populations of sizeN, one coalescence time unit corresponds toNgenerations. Coalescence and migration events occur on the same time scale. We show that, when the total population size tends to infinity, the structured coalescent is obtained, thus confirming the robustness of the coalescent. Many population structure models have been shown to converge to the structured coalescent (see Herbots (1997), Hudson (1998), Nordborg (2001), Nordborg and Krone (2002), and Notohara (1990)).
On the value function of the M/Cox(r)/1 queue
Authors: Bhulai Sandjai
Published: July 2006

We consider a single-server queueing system at which customers arrive according to a Poisson process. The service times of the customers are independent and follow a Coxian distribution of orderr. The system is subject to costs per unit time for holding a customer in the system. We give a closed-form expression for the average cost and the corresponding value function. The result can be used to derive nearly optimal policies in controlled queueing systems in which the service times are not necessarily Markovian, by performing a single step of policy iteration. We illustrate this in the model where a controller has to route to several single-server queues. Numerical experiments show that the improved policy has a close-to-optimal value.
Hazard rate ordering of order statistics and systems
Authors: Navarro Jorge , Shaked Moshe
Published: July 2006

Let X = (X1, X2, …, Xn) be an exchangeable random vector, and write X(1:i) = min{X1, X2, …, Xi}, 1 ≤ i ≤ n. In this paper we obtain conditions under which X(1:i) decreases in i in the hazard rate order. A result involving more general (that is, not necessarily exchangeable) random vectors is also derived. These results are applied to obtain the limiting behaviour of the hazard rate function of the lifetimes of various coherent systems in reliability theory. The notions of the Samaniego signatures and the minimal signatures of such systems are extensively used in the paper. An interesting relationship between these two signatures is obtained. The results are illustrated in a series of examples.
A central limit property under a modified Ehrenfest urn design
Authors: Chen Yung-Pin
Published: July 2006

We consider a stochastic process in a modified Ehrenfest urn model. The modification prescribes there to be a minimum number of balls in each urn, and the process records the differences between treatment assignments under a sampling scheme implemented with this modified Ehrenfest urn model. In contrast to the result that the difference process forms a Markov chain and converges to a stationary distribution under the Ehrenfest urn model, the corresponding process under this modified Ehrenfest urn design satisfies the central limit property. We prove this asymptotic normality property using a central limit theorem for dependent random variables, renewal theory, and two Kolmogorov-type maximal inequalities.
An optimal sequential procedure for a buying-selling problem with independent observations
Authors: Sofronov G. , Keith Jonathan M. , Kroese Dirk P.
Published: July 2006

We consider a buying-selling problem when two stops of a sequence of independent random variables are required. An optimal stopping rule and the value of a game are obtained.
Rare events, temporal dependence, and the extremal index
Authors: Segers Johan
Published: July 2006

Classical extreme value theory for stationary sequences of random variables can to a large extent be paraphrased as the study of exceedances over a high threshold. A special role within the description of the temporal dependence between such exceedances is played by the extremal index. Parts of this theory can be generalized not only to random variables on an arbitrary state space hitting certain failure sets, but even to a triangular array of rare events on an abstract probability space. In the case of M4 (maxima of multivariate moving maxima) processes, the arguments take a simple and direct form.
A monotonicity in reversible Markov chains
Authors: Lund Robert , Zhao Ying , Kiessler Peter C.
Published: July 2006

In this paper we identify a monotonicity in all countable-state-space reversible Markov chains and examine several consequences of this structure. In particular, we show that the return times to every state in a reversible chain have a decreasing hazard rate on the subsequence of even times. This monotonicity is used to develop geometric convergence rate bounds for time-reversible Markov chains. Results relating the radius of convergence of the probability generating function of first return times to the chain's rate of convergence are presented. An effort is made to keep the exposition rudimentary.
On the nonoptimality of the foreground-background discipline for IMRL service times
Authors: Aalto S. , Ayesta U.
Published: July 2006

It is known that for decreasing hazard rate (DHR) service times the foreground-background discipline (FB) minimizes the mean delay in the M/G/1 queue among all work-conserving and nonanticipating service disciplines. It is believed that a similar result is valid for increasing mean residual lifetime (IMRL) service times. However, on the one hand, we point out a flaw in an earlier proof of the latter result and construct a counter-example that demonstrates that FB is not necessarily optimal within class IMRL. On the other hand, we prove that the mean delay for FB is smaller than that of the processor-sharing discipline within class IMRL, giving a weaker version of an earlier hypothesis.
On the infinite-horizon probability of (non)ruin for integer-valued claims
Authors: Ignatov Zvetan G. , Kaishev Vladimir K.
Published: July 2006

We consider a compound Poisson process whose jumps are modelled as a sequence of positive, integer-valued, dependent random variables, W1,W2,…, viewed as insurance claim amounts. The number of points up to time t of the stationary Poisson process which models the claim arrivals is assumed to be independent of W1,W2,…. The premium income to the insurance company is represented by a nondecreasing, nonnegative, real-valued function h(t) on [0,∞) such that limt→∞h(t) = ∞. The function h(t) is interpreted as an upper boundary. The probability that the trajectory of such a compound Poisson process will not cross the upper boundary in infinite time is known as the infinite-horizon nonruin probability. Our main result in this paper is an explicit expression for the probability of infinite-horizon nonruin, assuming that certain conditions on the premium-income function, h(t), and the joint distribution of the claim amount random variables, W1,W2,…, hold. We have also considered the classical ruin probability model, in which W1,W2,… are assumed to be independent, identically distributed random variables and we let h(t)=u + ct. For this model we give a formula for the nonruin probability which is a special case of our main result. This formula is shown to coincide with the infinite-horizon nonruin probability formulae of Picard and Lefèvre (2001), Gerber (1988), (1989), and Shiu (1987), (1989).
Tail behavior of negatively associated heavy-tailed sums
Authors: Geluk Jaap , Ng Kai W.
Published: July 2006

Consider a sequence {Xk, k ≥ 1} of random variables on (−∞, ∞). Results on the asymptotic tail probabilities of the quantities , and S(n) = max0 ≤ k ≤ nSk, with X0 = 0 and n ≥ 1, are well known in the case where the random variables are independent with a heavy-tailed (subexponential) distribution. In this paper we investigate the validity of these results under more general assumptions. We consider extensions under the assumptions of having long-tailed distributions (the class L) and having the class D ∩ L, where D is the class of distribution functions with dominatedly varying tails. Some results are also given in the case where Xk, k ≥ 1, are not necessarily identically distributed and/or independent.
Ci-FoxA-ais the earliest zygotic determinant of the ascidian anterior ectoderm and directly activatesCi-sFRP1/5
Authors: Lamy Clement , Rothbächer Ute , Caillol Danièle , Lemaire Patrick
Published: July 2006

This work focuses on the anteroposterior patterning of the ectoderm in the invertebrate chordate Ciona intestinalis. Previous work indicated that, by the eight-cell stage, the anterior and posterior animal blastomeres have acquired different properties, including a differential responsiveness to inducing signals from the underlying mesendoderm. Here, we investigated the molecular basis of this distinction. For this, we studied the regulation of the earliest marker specific for the anterior ectoderm, Ci-sFRP1/5,which is activated at the 64-cell stage. We first found that the activation of this marker in the anterior ectoderm does not involve communication with other lineages. We then identified, by phylogenetic footprinting and deletion analysis, a short conserved minimal enhancer driving the onset of expression of Ci-sFRP1/5. We showed that this enhancer was a direct target of the Ci-FoxA-a gene, a FoxA/HNF3 orthologue expressed in anterior ectodermal and mesendodermal lineages from the eight-cell stage. Gain- and loss-of-function experiments revealed that Ci-FoxA-a is necessary and sufficient within the ectoderm to impose an ectodermal anterior identity,and to repress the posterior programme. Thus, Ci-FoxA-a constitutes a major early zygotic anterior determinant for the ascidian ectoderm, acting autonomously in this territory, prior to the onset of vegetal inductions. Interestingly, while vertebrate FoxA2 are also involved in the regionalization of the ectoderm, they are thought to act during gastrulation to control, in the mesendoderm, the expression of organizer signals. We discuss the evolution of chordate ectodermal patterning in light of our findings.
A translation-independent role ofoskarRNA in earlyDrosophilaoogenesis
Authors: Jenny Andreas , Hachet Olivier , Závorszky Péter , Cyrklaff Anna , Weston Matthew D. J. , Johnston Daniel St , Erdélyi Miklós , Ephrussi Anne
Published: July 2006

The Drosophila maternal effect gene oskar encodes the posterior determinant responsible for the formation of the posterior pole plasm in the egg, and thus of the abdomen and germline of the future fly. Previously identified oskar mutants give rise to offspring that lack both abdominal segments and a germline, thus defining the `posterior group phenotype'. Common to these classical oskar alleles is that they all produce significant amounts of oskar mRNA. By contrast, two new oskar mutants in which oskar RNA levels are strongly reduced or undetectable are sterile, because of an early arrest of oogenesis. This egg-less phenotype is complemented by oskar nonsense mutant alleles,as well as by oskar transgenes, the protein-coding capacities of which have been annulled. Moreover, we show that expression of the oskar 3′ untranslated region (3′UTR) is sufficient to rescue the egg-less defect of the RNA null mutant. Our analysis thus reveals an unexpected role for oskar RNA during early oogenesis, independent of Oskar protein. These findings indicate that oskar RNA acts as a scaffold or regulatory RNA essential for development of the oocyte.
Developmental genetic mechanisms of evolutionary tooth loss in cypriniform fishes
Authors: Stock David W. , Jackman William R. , Trapani Josh
Published: July 2006

The fossil record indicates that cypriniform fishes, a group including the zebrafish, lost oral teeth over 50 million years ago. Despite subsequent diversification of feeding modes, no cypriniform has regained oral teeth,suggesting the zebrafish as a model for studying the developmental genetic basis of evolutionary constraint. To investigate the mechanism of cypriniform tooth loss, we compared the oral expression of seven genes whose mammalian orthologs are involved in tooth initiation in the zebrafish and the Mexican tetra, Astyanax mexicanus, a related species retaining oral teeth. The most significant difference we found was an absence in zebrafish oral epithelium of expression of dlx2a and dlx2b, transcription factors that are expressed in early Astyanax odontogenic epithelium. Analysis of orthologous genes in the Japanese medaka (Oryzias latipes) and a catfish (Synodontis multipunctatus) suggests that expression was lost in cypriniforms, rather than gained in Astyanax. Treatment of Astyanax with an inhibitor of Fibroblast growth factor(Fgf) signaling produced a partial phenocopy of the zebrafish oral region, in that oral teeth, and expression of dlx2a and dlx2b, were lost, whereas shh and pitx2, genes whose expression is present in zebrafish oral epithelium, were unaffected. We hypothesize that a loss of Fgf signaling to oral epithelium was associated with cypriniform tooth loss.
Axis specification and morphogenesis in the mouse embryo requireNap1, a regulator of WAVE-mediated actin branching
Authors: Rakeman Andrew S. , Anderson Kathryn V.
Published: July 2006

Dynamic cell movements and rearrangements are essential for the generation of the mammalian body plan, although relatively little is known about the genes that coordinate cell movement and cell fate. WAVE complexes are regulators of the actin cytoskeleton that couple extracellular signals to polarized cell movement. Here, we show that mouse embryos that lack Nap1, a regulatory component of the WAVE complex, arrest at midgestation and have defects in morphogenesis of all three embryonic germ layers. WAVE protein is not detectable in Nap1 mutants, and other components of the WAVE complex fail to localize to the surface of Nap1 mutant cells; thus loss of Nap1 appears to inactivate the WAVE complex in vivo. Nap1 mutants show specific morphogenetic defects: they fail to close the neural tube, fail to form a single heart tube (cardia bifida), and show delayed migration of endoderm and mesoderm. Other morphogenetic processes appear to proceed normally in the absence of Nap1/WAVE activity: the notochord, the layers of the heart, and the epithelial-to-mesenchymal transition (EMT) at gastrulation appear normal. A striking phenotype seen in approximately one quarter of Nap1 mutants is the duplication of the anteroposterior body axis. The axis duplications arise because Nap1 is required for the normal polarization and migration of cells of the Anterior Visceral Endoderm (AVE), an early extraembryonic organizer tissue. Thus, the Nap1 mutant phenotypes define the crucial roles of Nap1/WAVE-mediated actin regulation in tissue organization and establishment of the body plan of the mammalian embryo.
The calcineurin pathway links hyperpolarization (Kir2.1)-induced Ca2+ signals to human myoblast differentiation and fusion
Authors: Konig Stéphane , Béguet Anne , Bader Charles R. , Bernheim Laurent
Published: July 2006

In human myoblasts triggered to differentiate, a hyperpolarization,resulting from K+ channel (Kir2.1) activation, allows the generation of an intracellular Ca2+ signal. This signal induces an increase in expression/activity of two key transcription factors of the differentiation process, myogenin and MEF2. Blocking hyperpolarization inhibits myoblast differentiation. The link between hyperpolarization-induced Ca2+ signals and the four main regulatory pathways involved in myoblast differentiation was the object of this study. Of the calcineurin,p38-MAPK, PI3K and CaMK pathways, only the calcineurin pathway was inhibited when Kir2.1-linked hyperpolarization was blocked. The CaMK pathway, although Ca2+ dependent, is unaffected by changes in membrane potential or block of Kir2.1 channels. Concerning the p38-MAPK and PI3K pathways, their activity is present already in proliferating myoblasts and they are unaffected by hyperpolarization or Kir2.1 channel block. We conclude that the Kir2.1-induced hyperpolarization triggers human myoblast differentiation via the activation of the calcineurin pathway, which, in turn, induces expression/activity of myogenin and MEF2.
Egfr is essential for maintaining epithelial integrity during tracheal remodelling inDrosophila
Authors: Cela Carolina , Llimargas Marta
Published: July 2006

A fundamental requirement during organogenesis is to preserve tissue integrity to render a mature and functional structure. Many epithelial organs,such as the branched tubular structures, undergo a tremendous process of tissue remodelling to attain their final pattern. The cohesive properties of these tissues need to be finely regulated to promote adhesion yet allow flexibility during extensive tissue remodelling. Here, we report a new role for the Egfr pathway in maintaining epithelial integrity during tracheal development in Drosophila. We show that the integrity-promoting Egfr function is transduced by the ERK-type MAPK pathway, but does not require the downstream transcription factor Pointed. Compromising Egfr signalling, by downregulating different elements of the pathway or by overexpressing the Mkp3 negative regulator, leads to loss of tube integrity,whereas upregulation of the pathway results in increased tissue stiffness. We find that regulation of MAPK pathway activity by Breathless signalling does not impinge on tissue integrity. Egfr effects on tissue integrity correlate with differences in the accumulation of markers for cadherin-based cell-cell adhesion. Accordingly, downregulation of cadherin-based cell-cell adhesion gives rise to tracheal integrity defects. Our results suggest that the Egfr pathway regulates maintenance of tissue integrity, at least in part,through the modulation of cell adhesion. This finding establishes a link between a developmental pathway governing tracheal formation and cell adhesiveness.
Photobehavior of Crystalline 4-Styrylcoumarin Dimorphs: Structure-Reactivity Correlations
Authors: Moorthy Jarugu Narasimha , Venkatesan Kailasam
Published: July 2006

4-Styrylcoumarin crystallizes from chloroform and hexane mixture in two morphologically different modifications. The monoclinic form (needles, P21/c) undergoes stereospecific photodimerization producing anti head-to-tail dimer across pyrone double bond, whereas the triclinic modification (prisms, ) dimerizes yielding photodimer of the same configuration, but across styrenic double bond. Single crystal X-ray analyses of the dimorphs reveal the packing differences permitting rationalization of the regio- and stereochemistry of the photoproducts. The significantly low dimer yield from the prismatic crystals is rationalized.
Synthesis of trans(N)-Carbonatobis(N,N-dimethylglycinato)cobaltate(III) by Decarboxylation of N,N-Dimethylglycine
Authors: Kojima Masaaki , Saito Reiko , Nakajima Kiyohiko , Ouyang Yishan , Fujita Junnosuke
Published: July 2006

Trans(N)-[Co(CO3)(dmgly)2]− and trans(N)-[Co(ox)(dmgly)2]− were prepared and characterized by absorption, circular dichroism, 1H NMR, and 13C NMR spectra, where Hdmgly and H2ox denote N,N-dimethylglycine and oxalic acid, respectively. The carbonato complex was yielded by the reaction of [CoCl(NH3)5]Cl2 and Hdmgly without addition of carbonate or hydrogencarbonate ions; decarboxylation of Hdmgly followed by substitution with CO32− was suggested. The molecular structure of spontaneously resolved (+)589-trans(N)-K[Co(CO3)(dmgly)2]·H2O was determined by the single crystal X-ray diffraction method. The crystal data and final R value are: orthorhombic, P212121, a = 15.483(1), b = 15.624(2), c = 6.092(1) Å, V = 1473.7(3) Å3, Z = 4, R = 0.022 for 2390 reflections. The crystal used had the Λ configuration. The mean Co–N bond length, 1.996 (2) Å is longer than the usual Co–N (primary amine) bond length by 0.03—0.08 Å due to the steric repulsion between the methyl groups and other ligands.
Spectrophotometric Determination of Thiosulfate Based on an Oxidation Reaction in the Presence of Formaldehyde with Iodine in the Organic Phase
Authors: Koh Tomozo , Wakabayashi Hideki , Yonemura Yasunobu
Published: July 2006

Aqueous thiosulfate was shaken in the presence of large amounts of sulfuric acid and formaldehyde with iodine in carbon tetrachloride; thereby, one mol of thiosulfate reacted with one mol of iodine. The organic phase was separated, the excess of iodine was extracted into an aqueous iodide solution as triiodide and the absorbance of the liberated triiodide was measured at 350 nm. The calibration plot obtained for thiosulfate did not form a linear graph and was not affected by a change in the volume of 10 to 27 cm3 of the sample solution. The proposed method could be applied to the determination of thiosulfate in the concentration ranges 5 × 10−7—3.4 × 10−5 mol dm−3 (0.056—3.81 ppm) for a 10 cm3 thiosulfate solution and 1.9 × 10−7—1.36 × 10−5 mol dm−3 (0.021—1.52 ppm) for a 25 cm3 thiosulfate solution. Good recoveries of thiosulfate from hot-spring and lake-water samples, to which various known amounts of thiosulfate had been added, was achieved and the relative standard deviation was 0.86% at the 5.42 × 10−6 mol dm−3 (0.608 ppm) thiosulfate level when applied to a hot-spring sample.
Mössbauer Spectra and Crystal Structure of Dinuclear Iron(II,III) Complex [Fe2(bpmp)(ena)2](BF4)2 of a Septadentate Polypyridine Ligand (Hbpmp): An Example of Fast Electron Interexchange
Authors: Maeda Yonezo , Tanigawa Yuichi , Matsumoto Naohide , Oshio Hiroki , Suzuki Masatatu , Takashima Yoshimasa
Published: July 2006

The Mössbauer spectra, magnetic susceptibilities, cyclic voltammograms, and electronic spectra of the dinuclear iron(II,III) complex, [Fe2(bpmp)(ena)2](BF4)2, were measured and the crystal structure was determined at 293 K, where Hbpmp represents 2,6-bis[bis(2-pyridylmethyl)aminoethyl]-4-methylphenol and Hena is heptanoic acid. The valence states of the irons of the complex are localized below about 200 K in the Mössbauer time scale (10−7 s), and are delocalized above 260 K. The activation energy of the electron interexchange between Fe2+ and Fe3+ was evaluated to be 15 kJ mol−1 at between 200 and 230 K based on an analysis of the Mössbauer spectra. The complex crystallizes in the monoclinic system, space group P2/c, with a = 10.129(4), b = 23.295(30), c = 11.324(7) Å, β = 104.55(4)°, dcalc = 1.34 g cm−3, Z = 2, and molecular formula Fe2F8O5N6C47B2H59. The structure was solved by the heavy-atom method and was refined anisotropically by the least-squares method, employing 1981 unique reflections with |F| > 4σ(Fo). The hydrogen atoms of bpmp were located and refined by an isotropic approximation. The final R and Rw were 7.0 and 8.2%, respectively. The Fe–Fe distance was 3.365 Å, the average Fe–O value 2.033 Å, the average Fe–N value 2.188 Å, and the Fe–O–Fe angle 112.3(4)°. These values support the idea that both iron atoms are in an averaged valence state at 293 K.
Ab initio Study of the Relationship between the Pressure and the Change in the Dipole Moment of a Molecule in a Ferroelectric Crystal
Authors: Kubota Hiroshi , Aoki Yuriko , Imamura Akira
Published: July 2006

The typical properties of a ferroelectric material are piezoelectricity and pyroelectricity. In this study we considered in detail the relationship between the pressure and the change in the dipole moment of a molecule in a ferroelectric crystal from the standpoint of piezoelectricity. We applied ab initio molecular orbital calculations involving the crystal effect to the orthorhombic thiourea ((NH2)2CS) crystal model as the ferroelectric crystal model. The molecular structure obtained by this calculation was in fairly good agreement with the result obtained by X-ray analysis. In order to investigate the substituent effects, we calculated a hypothetical orthorhombic N,N′-difluorothiourea ((NHF)2CS) crystal model in a similar manner.
The Synthesis and Cyclodehydration of 4-(3-Aryl-1,3-dioxopropyl)-5-phenyl-1H-1,2,3-triazoles. Novel Substituted Pyrrolo[1,2-c][1,2,3]triazoles
Authors: Marei Mohamed Gaber , El-Ghanam Moneim , Salem Magdi Mohamed
Published: July 2006

The polyfunctionalized title triazolyl 1,3-diketones have been prepared by the addition-cyclization reaction of sodium azide to 1,5-diaryl-4-pentyne-1,3-diones, in the first instance, in good yields. These intermediate triazoles can readily be cyclodehydrated to the corresponding 3,6-diaryl-4H-pyrrolo[1,2-c][1,2,3]triazol-4-one derivatives. This cyclodehydration furnishes a new method of synthesis of a new class of pyrrolo[1,2-c][1,2,3]triazoles. The structures of the above compounds were confirmed from their spectral characteristics.
Trichloroisocyanuric Acid Oxidation of 2-Chloro Aldehyde Acetals to 2-Chloro Acid Esters
Authors: Boni Monica , Ghelfi Franco , Pagnoni Ugo Maria , Pinetti Adriano
Published: July 2006

2-Chloro acid methyl esters were prepared in good yields treating 2-chloro aldehyde dimethyl acetals with trichloroisocyanuric acid in DMF. Aldehyde dimethyl acetals with the 2-halogen on a tertiary carbon atom were poorly reactive and could be oxidized effeciently only after their transformation into 1,3-dioxolanes.