bluuebunny/crossref_metadata_2025 huggingface dataset:
Allozyme differentiation among populations, stands, and cohorts in Monterey pine
Authors: Plessas Martha E. , Strauss Steven H.
Published: July 2007

Four- to six-year-old trees were sampled from 9 to 10 stands in each of three natural populations of Monterey pine (Pinusradiata D. Don) and studied for genetic diversity at 37 allozyme loci. Among loci, Nei's gene diversity ranged from 73 to 100% within stands, 0 to 10% between stands within populations, and 0 to 27% between populations; average values were 94.9, 1.6, and 3.5%, respectively. F-statistic analyses (B. S. Weir and C. C. Cockerham. 1984. Evolution (Lawrence, Kans.), 38: 1358–1370) indicated higher levels of stand and population differentiation than did Nei's diversity statistics: 2.6 ± 0.7 and 6.2 ± 2.6%, respectively. Homozygotes were significantly in excess relative to expectations under random mating (FIS = 0.065). Most loci showed highly significant variation of allele frequencies among populations; Nei's genetic distance averaged 0.014. Genetic and geographic distances among stands were correlated only at Año Nuevo. Introgression of genes from knobcone pine (Pinusattenuata Lemm.) was evident in the one stand where the species were sympatric. Contrary to inferences from growth and morphological characters, allozyme frequencies and other biochemical characters suggest that the Año Nuevo population diverged prior to Cambria and Monterey. Differentiation among three cohorts was studied at 10 loci. Allele frequencies varied nonsignificantly between cohorts; mean fixation indices, however, decreased monotonically with cohort age, from 0.081 in embryos to 0.038 in 5-year-old trees to −0.119 in 14- to 17-year-old trees. Selection for the more outbred progeny was the outcome of stand development.
Examining short-rotation hybrid poplar investments by using stochastic simulation
Authors: Lothner David C. , Hoganson Howard M. , Rubin Paul A.
Published: July 2007

We examined and compared short-rotation hybrid poplar investments using standard discounted cash flow and stochastic simulation. With stochastic simulation, triangular probability density functions were used to describe the values for three important uncertain factors: product price, product yield, and harvest and transport costs. We found that the net present value per acre could range from a minus $310 to a positive $1010 with a mean value of about $140, using a 4% discount rate. Based on the assumptions we used, product price uncertainty was found to be the major cause of uncertainty surrounding the financial returns from a short-rotation system. Because information on future prices is limited, decisions about short-rotation systems should be made carefully. Analyzing uncertainty by using imprecise input data cannot produce both accurate and precise results, but thinking through the uncertainties and collecting information should help investors make better choices.
Effect of thinning and nitrogen fertilization on diameter growth of pole-size sugar maple
Authors: Stone Douglas M.
Published: July 2007

Diameter growth of pole-size sugar maple crop trees was increased significantly by commercial thinning but not by fertilization treatments applied 3 years after or 3 years before thinning. DBH growth was strongly related to initial DBH both before and after release. Neither urea nor ammonium nitrate increased growth. Fertilizing individual crop trees on medium and better sites is not likely to increase growth significantly because of dilution by large nutrient pools in these soils, uptake by competing trees and understory vegetation, and distribution of absorbed nutrients by leaf dispersal. Commercial thinning removed the small and defective stems, increased diameter growth of residual crop trees by 40%, and provided stand conditions favorable for development of high value sawlogs.
Bioassay of forest floor nitrogen supply for plant growth
Authors: Cleve K. Van , Heal O. W. , Roberts D.
Published: July 2007

Using a bioassay approach, this paper considers the nitrogen-supplying power of forest floors from examples of the major forest types in interior Alaska. Yield and net N uptake by paper birch seedlings grown in standardized mixtures of quartz sand and forest floor organic matter, and separate incubation estimates of N mineralization and nitrification for the forest floors, were employed to evaluate potential N supply. Black spruce and floodplain white spruce forest floors supplied only one-fifth the amount of N taken up by seedlings growing in other forest floors. Incubation estimates showed these forest floors yielded 4 and 15 times less extractable N, respectively, than the more fertile birch forest floors. In comparison with earlier estimates of P supply from these same forest floors, the upland types showed greater deficiency of N whereas floodplain types showed greater deficiency of P in control of seedling yield. The latter condition is attributed to the highly calcareous nature of the floodplain mineral soil, the consequent potential for P fixation, and hence greater potential deficiency of the element compared with N in mineralizing forest floors. Nitrogen concentration of the forest floors was the best predictor of bioassay response.
Incidence of western gall rust infection of lodgepole pine regeneration in different-sized forest openings
Authors: Blenis Peter V. , Bernier Pierre Y.
Published: July 2007

Incidence of western gall rust infection in each of 10 replicated forest openings having diameter height ratios of 2:1, 4:1, and 6:1 was determined along two perpendicular 1-m wide transects. Infection frequencies were not significantly different among the different-sized openings. No pine regeneration was present in openings with diameter:height ratios of 0.5:1 or 1:1, thus precluding direct comparison of our results with those obtained from three other tree host–parasite studies in which disease incidence was greatest in small openings.
The influence of competition on individual white pine thinning response
Authors: Gillespie Andrew R. , Hocker Jr. Harold W.
Published: July 2007

A model predicting white pine (Pinusstrobus L.) diameter growth after thinning included competition, initial diameter, and crown class as independent variables. Model coefficients indicated a decrease in percent 8-year diameter growth with increasing crown suppression, crown competition, or tree size class. Variables selected were superior to age, percent live crown, and prethinning growth. Equations predicting basal area and volume growth were similar in form to diameter growth. Height growth, however, was more closely correlated with crown characteristics and unaffected by competition. Annual growth patterns were similar to periodic growth patterns, revealing decreased growth with increasing competition or crown suppression. Trees having little competition and dominant crowns utilized their growing season longer, with earlier initial growth and faster growth than trees having greater competition or crown suppression. Within a crown class, diameter growth decreased as competition increased. Individual tree competition was seen as the most important factor influencing tree growth that a forester can control.
Preliminary histological investigations of the defense reactions of three pines to Ceratocystisclavigera and two chemical elicitors
Authors: Lieutier François , Berryman Alan A.
Published: July 2007

The histology of defense reactions in individual pine trees belonging to three species, Pinusponderosa, P. contorta, and P. monticola, to inoculation with Ceratocystisclavigera and injection with chitosan and a proteinase inhibitor inducing factor was investigated after resin fixation with cupric acetate. The synthesis of secondary resins was directly associated with parenchyma cells in the phloem and in the rays of both phloem and sapwood. However, these resins were largely located in the lumen of sieve cells and tracheids. In the case of the fungus and chitosan, resin soaking began in the outer phloem and latewood of the last growth rings, then spread into the inner phloem and earlywood. With the proteinase inhibitor inducing factor, resinosis was similar to that of the buffer control, being much less extensive than with the fungus or chitosan, and occurring mainly in the inner phloem and earlywood. In P. monticola, the reaction was complicated by the appearance of fissures in the phloem, probably caused by tension from resin pressure. Phloem resinosis was accompanied by apparent secretion of phenolic compounds, presumably from parenchyma cells. The possible origin of these secondary resins and the potential mode of action of the chemicals used are discussed.
Adjusting estimates in two-way tables by incorporating outside information
Authors: Schreuder H. T. , Li H. G. , Ryan M. G. , Scott C. T.
Published: July 2007

When outside estimates are more reliable than some existing tabular estimates of resource statistics, they should be substituted for or combined with the tabular estimates to yield new estimates. Because of this substitution, cell estimates do not sum to the original marginal or overall totals. Various methods can be used to adjust the unchanged cell values to regain additivity. Classical and bootstrap variance estimators are given for the n × 2 case setting a cell proportion at a presumed known value with fixed marginal totals, and for the n × m case setting a cell proportion at a presumed known value with no marginal constraints except that the table total is fixed. For a 3 × 2 test case only, the bootstrap variance estimator yielded reliable estimates of precision for the other adjusted cell proportions in all cases. For the n × m case, a classical variance estimator was more stable than the bootstrap variance estimator, and both had about the same bias.
Free amino acid concentrations in red pine needles during three successive autumns
Authors: Kim Y. T. , Glerum C.
Published: July 2007

Seasonal free amino acid concentrations in current-year red pine (Pinusresinosa Ait.) needles were determined weekly or biweekly from September to December over a 3-year period. Tryptophan and histidine were the only amino acids that had significant positive trends, increasing in concentration between September and December in all 3 years, while threonine had a significant negative trend, decreasing in concentration in all 3 years. The positive tryptophan trend was the most consistent.
Detecting the response of Douglas-fir to nitrogen fertilization by regression of periodic annual basal area increment against basal area
Authors: Thomson A. J. , Tudor K. D. , Korelus V. J. , Ralph D. R.
Published: July 2007

Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) basal area response to urea fertilization at 112 and 224 kg N/ha was studied on a medium site. Regression of tree periodic annual basal area increment against basal area was used to estimate within-plot growth rates. Higher growth rates were observed in the fertilized plots. The slope coefficients of the regressions were used to investigate spatial and temporal variation in growth rates.
Elevational and spatial variation in daytime ozone concentrations in the Virginia Blue Ridge Mountains: implications for forest exposure
Authors: Gilliam F. S. , Sigmon J. T. , Reiter M. A. , Krovetz D. O.
Published: July 2007

Ozone (O3) concentrations before and during the early growing season were monitored continuously at two closely located areas in the Virginia Blue Ridge Mountains: a deciduous forest watershed (Shaver Hollow) and a predominantly open grassy meadow (Big Meadows). In addition, O3 concentrations and canopy development (percent leaf emergence) were measured simultaneously at three sites along the elevational gradient of the Shaver Hollow watershed. When the canopy at Shaver Hollow was leafless, patterns of O3 concentration were similar between the forest and meadow, increasing steadily toward early spring, with low variability of hourly daytime measurements. Greater differences in O3 concentration between forest and meadow and higher variability occurred during the period May-June, a time when the canopy changed from 15 to 100% leaf emergence. Several factors varying along the elevational gradient, related to both canopy structure and meteorological conditions, appeared to be important in affecting absolute O3 concentrations as well as the variability of daytime means in Shaver Hollow. The high metabolic activity of new leaves may act as a sink for O3; the canopy itself may act as a physical barrier to O3 transport, restricting mixing of O3 to intermittent bursts. The coincidence of seasonal increases in O3 concentration in late spring and early summer with the development of new leaves of dominant deciduous trees in this watershed suggests that O3 may represent a potential problem for eastern hardwood forests.
INTERACTION OF A TWO-LEVEL ATOM WITH A SQUEEZED DISPLACED NUMBER STATE
Authors: DE OLIVEIRA GUILHERME C. , DANTAS CÉLIA M. A. , SALES JOSÉ S.
Published: July 2007

We investigate the interaction of a two-level atom with a cavity field in a squeezed displaced number state: [Formula: see text]. It is shown that this state exhibits interesting features, while generalizing various particular results of the literature. Additional discussions about the influence of phase optimization of a state upon collapse and revivals effects are also considered.
ASYMPTOTICS OF ZEROS OF CERTAIN ENTIRE FUNCTIONS
Authors: ISMAIL MOURAD E. H.
Published: July 2007

We derive representations for some entire q-functions and use it to derive asymptotics and closed form expressions for large zeros of a class of entire functions including the Ramanujan function, and q-Bessel functions.
Rab11-FIP2 regulates differentiable steps in transcytosis
Authors: Ducharme Nicole A. , Williams Janice A. , Oztan Asli , Apodaca Gerard , Lapierre Lynne A. , Goldenring James R.
Published: July 2007

Transcytosis through the apical recycling system of polarized cells is regulated by Rab11a and a series of Rab11a-interacting proteins. We have identified a point mutant in Rab11 family interacting protein 2 (Rab11-FIP2) that alters the function of Rab11a-containing trafficking systems. Rab11-FIP2(S229A/R413G) or Rab11-FIP2(R413G) cause the formation of a tubular cisternal structure containing Rab11a and decrease the rate of polymeric IgA transcytosis. The R413G mutation does not alter Rab11-FIP interactions with any known binding partners. Overexpression of Rab11-FIP2(S229A/R413G) alters the localization of a subpopulation of the apical membrane protein GP135. In contrast, Rab11-FIP2(129-512) alters the localization of early endosome protein EEA1. The distributions of both Rab11-FIP2(S229A/R413G) and Rab11-FIP2(129-512) were not dependent on the integrity of the microtubule cytoskeleton. The results indicate that Rab11-FIP2 regulates trafficking at multiple points within the apical recycling system of polarized cells.
Role of NKT Cells in the Digestive System. I. Invariant NKT cells and liver diseases: is there strength in numbers?
Authors: Ajuebor Maureen N.
Published: July 2007

Information regarding the functional role of the innate immune T cell, invariant natural killer T (iNKT) cells, in the pathophysiology of liver diseases continues to emerge. Results from animal studies suggest that iNKT cells can have divergent roles by specifically promoting the development of proinflammatory or anti-inflammatory responses in liver diseases. In this themes article, I discuss the critical evidence from animal models that demonstrate a vital role for iNKT cells in the pathophysiology of liver diseases with emphasis on viral, autoimmune, and toxin-induced liver diseases. Furthermore, I discuss the controversial issues (including iNKT cell apoptosis) that typify some of these studies. Finally, I highlight areas that require additional investigation.
Slow Temporal Filtering May Largely Explain the Transformation of Stick Insect (Carausius morosus) Extensor Motor Neuron Activity Into Muscle Movement
Authors: Hooper Scott L. , Guschlbauer Christoph , von Uckermann Géraldine , Büschges Ansgar
Published: July 2007

Understanding how nervous systems generate behavior requires understanding how muscles transform neural input into movement. The stick insect extensor tibiae muscle is an excellent system in which to study this issue because extensor motor neuron activity is highly variable during single leg walking and extensor muscles driven with this activity produce highly variable movements. We showed earlier that spike number, not frequency, codes for extensor amplitude during contraction rises, which implies the muscle acts as a slow filter on the time scale of burst interspike intervals (5–10 ms). We examine here muscle response to spiking variation over entire bursts, a time scale of hundreds of milliseconds, and directly measure muscle time constants. Muscle time constants differ during contraction and relaxation, and contraction time constants, although variable, are always extremely slow (200–700 ms). Models using these data show that extremely slow temporal filtering alone can explain much of the observed transform properties. This work also revealed an unexpected (to us) ability of slow filtering to transform steadily declining inputs into constant amplitude outputs. Examination of the effects of time constant variability on model output showed that variation within an SD primarily altered output amplitude, but variation across the entire range also altered contraction shape. These substantial changes suggest that understanding the basis of this variation is central to predicting extensor activity and that the animal could theoretically vary muscle time constant to match extensor response to changing behavioral need.
The Fight Against Illegal Migration
Authors: Broeders Dennis , Engbersen Godfried
Published: July 2007

In recent years, northern European Union (EU) member states have intensified internal surveillance on irregular migrants. Policy innovation has been geared to controlling, identifying, and even reidentifying irregular migrants who settled within their borders. Policy aims are deterrence, exclusion, and, ultimately, expulsion. Developments in labor market, detention, and expulsion policies and surveillance by the EU immigration database are analyzed in relation to the counterstrategies that irregular migrants devise to escape detection and expulsion by the state. The resulting cat and mouse game between the state and irregular migrants seems to result in a serious threat to irregular migrants' room to maneuver and further increases their dependence on informal, and increasingly criminal, networks and institutions.
Human Trafficking, Information Campaigns, and Strategies of Migration Control
Authors: Nieuwenhuys Céline , Pécoud Antoine
Published: July 2007

Information campaigns have been launched since the 1990s in central and eastern Europe to prevent human trafficking and undocumented migration. They attempt to reduce emigration before migrants reach the border and therefore take place within the reinforcement of migration controls. They are designed to discourage potential migrants from leaving by promoting a negative image of migration to western Europe, thus relying on the questionable assumption that information plays a key role in migration decisions. By associating undocumented migration with human trafficking, these campaigns furthermore display moral and political ambiguities. This article discusses their ideological basis and the ethical issues they raise.
Introduction
Authors: Bajc Vida
Published: July 2007

The practice of surveillance under the meta-frame of security is based on acquiring ever more detailed information and parceling out the state territory into different types of enclosures. The state seeks flexibility to follow this information globally and in real time. To be able to act in preemptive ways, the state is reshaping its Weberian bureaucratic structure through internal reorganization, outsourcing, and suprastate security alliances. These developments threaten the relationship between the citizen and the state and raise ethical concerns.
The Audacity of Hope
Authors: Clayton Dewey
Published: July 2007

As the Democratic candidate for the U.S. Senate from Illinois, Barack Obama electrified the country with his keynote address at the Democratic National Convention in 2004. After having served only 2 years in his first term as a U.S. senator from Illinois, Senator Obama in 2007 announced his candidacy for president of the United States of America. He is the rising star in the Democratic Party and regularly draws huge crowds at his campaign events. He is only the third African American of a major political party to run for the office of the president. Obama is extremely charismatic and appeals to voters across racial lines and party lines. The heart of his campaign is a message of hope that transcends race and attempts to bring a divided country together.
Symbolic Spaces: Marginalized Bedouin Women's Art as Self-Expression
Authors: Huss Ephrat
Published: July 2007

The following work was presented at the Imagine Conference in Israel. It aims to show the ways in which the arts can help outsiders (including policy makers) to “imagine” and thus to understand, through the arts, the issues that marginalized Bedouin women face. However, most important, the symbolic depiction of the women's lives, drawn, exhibited, and discussed together among themselves, is shown to enable the women, through “imaging” the problems and oppressions that they face, to “imagine” ways of conceptualizing and solving these problems—understanding them as complex forms of social oppression rather than as manifestations of personal or inherent weaknesses.
Dialogue Between Political Trauma and Personal Defenses
Authors: Al-Ajarma Yousef , Barzilay-Shechter Keren
Published: July 2007

With the war in their home country waging on, the authors found themselves together in the expressive therapies PhD program at Lesley University—an Israeli Jewish woman and a Palestinian Moslem man. During their studies, they have used the healing powers of the arts and delved together into a journey of self-exploration, from which an interactive theater workshop has emerged. Engaged in the creative process, they spiraled from the private to the public domain, discovering and expressing their own version of the Israeli—Palestinian situation. Their artistic dialogue has deepened and expanded, releasing inner occupied territories, on its way toward nonviolent liberation. They have used this creation as the building block of a workshop, which they delivered together at the Imagine Conference in Israel in April 2006. This article presents some aspects of their work together and a description of some of the workshop.
Incentive Alignment, Control, and the Issue of Misleading Financial Disclosures
Authors: Donoher William J. , Reed Richard , Storrud-Barnes Susan F.
Published: July 2007

The accounting scandals of recent years have raised concerns about the efficacy of incentive alignment and control systems. Among matched firms that either did or did not restate misleading financial disclosures during the period 1994-2003, both managerial equity ownership and contingent compensation were positively related to restatements when considered independently of other factors such as firm performance and board characteristics. When these variables were introduced, performance positively moderated the relationship between ownership and restatements, although contingent compensation was no longer significant. Finally, misleading disclosures were less prevalent in firms whose boards had high levels of business experience and long tenure.
Institutional Environments, Staffing Strategies, and Subsidiary Performance
Authors: Gaur Ajai S. , Delios Andrew , Singh Kulwant
Published: July 2007

The authors adopt and develop an institutional perspective to advance understanding of how host country environments influence subsidiary staffing strategies. They propose and find that (a) firms rely more on expatriates in institutionally distant environments for reasons related to the efficient transfer of management practices and firm-specific capabilities and (b) the positive influence of expatriate staffing levels on subsidiary performance is dependent on the institutional distance between the host and home country, and subsidiary experience. The authors' findings are based on their analysis of expatriate employment levels and performance in 12,997 foreign subsidiaries of 2,952 Japanese firms in 48 countries.
Bolivia and Venezuela: the democratic dialectic in new revolutionary movements
Authors: Harris Jerry
Published: July 2007

The beginning of the twenty-first century has witnessed the rise of exciting new revolutionary movements against capitalist globalisation. They are characterised, in Latin America particularly, by qualitatively different strategies from the socialist movements of the last century. Rather than vanguard parties leading a Leninist insurrection or Maoist people's war, these movements are building broad social blocs in a Gramscian war of position and manoeuvre. It is suggested here that these movements are best viewed from the standpoint of a democratic dialectic linking together the roles of the state, the market and civil society. This recognises the need to build institutional power in each sector as well as the play of contradictions within and between each aspect of society. In what follows, an attempt is made to develop theory that can explain and contain the actual social practice of the new revolutionary struggles.
The Transition of Adult Students to Higher Education: Legitimate Peripheral Participation in a Community of Practice?
Authors: O'Donnell Victoria L. , Tobbell Jane
Published: July 2007

This article presents empirical research exploring adult students' transition to higher education (HE) through a program designed to enable that transition. Wenger's Communities of Practice theory has been applied to informal adult learning by Merriam, Courtenay, and Baumgartner (2003), who suggested its potential for understanding formal education. Using this theoretical framework, adults' transition to HE is explored in terms of learning, participation in practices, and identity. Students were interviewed, and qualitative data analysis revealed that although they perceived themselves to be peripheral participants in the community, university regulations, and academic procedures sometimes undermined their feelings of legitimacy. Their experiences of the community's practices were mediated by individual, shifting identities and a sense of belonging. Their experiences are discussed in terms of the power of practice to include or exclude, and the concomitant identity shifts which may lead to fuller participation. Implications for the design of transitional programs are also discussed.
Operationalizing the Entrepreneurial Pipeline Theory: An Empirical Assessment of the Optimal Size Distribution of Local Firms
Authors: Loveridge Scott , Nizalov Denys
Published: July 2007

This article analyzes the relationship between local economic growth and the distribution of businesses across size categories. The distribution is measured by the employment share in businesses of various sizes and by a business distribution index. The index provides a measure of the extent to which the local economy deviates from an equal employment share in each of nine business-size categories. The authors find strong links between a county's business-size distribution and its economic growth rate and also a difference between the optimal income and job growth-enhancing distributions. In addition, the results indicate that the optimal growth-enhancing distribution of employment has a higher share of the smallest businesses (with one to four employees) than the current average. The results support increased policy emphasis on encouraging small business start-ups and development; however, the optimal development strategy depends on the initial distribution of businesses within a local economy.
Steroids and histone deacetylase in ventilation-induced gene transcription
Authors: Dombrowsky H. , Uhlig S.
Published: July 2007

Histone acetylation and deacetylation promote and repress gene transcription, respectively. Recruitment of histone deacetylases (HDAC) to sites of inflammatory gene transcription has been proposed to explain part of the anti-inflammatory activity of steroids. To examine whether this concept extends to other inflammatory conditions, the current authors investigated the role of histone acetylation and the effects of steroids on the ventilation-induced induction of pro-inflammatory genes.

Isolated perfused mouse lungs were ventilated for 180 min with low peak inspiratory pressure of 10 cmH2O or high peak inspiratory pressure of 22.5 cmH2O (overventilation) and treated with the HDAC inhibitor trichostatin A (TSA), the steroid dexamethasone or both.

Overventilation increased histone acetylation at H4K12, as well as gene and protein expression of tumour necrosis factor (TNF), macrophage inflammatory protein (MIP)-2α and interleukin (IL)-6; these effects were reversed by dexamethasone. In the presence or absence of dexamethasone, TSA enhanced overventilation-induced induction of TNF and MIP-2α, but decreased that of IL-6, indicating that the effects of HDAC are gene dependent.

Thus, H4K12 acetylation and its regulation by steroids may be relevant for inflammatory gene transcription during overventilation. Histone deacetylases appear to play an important gene-dependent regulatory role in this process, with the caveat that histones are not the only substrates of histone deacetylase isoenzymes.
Developmentally regulated promoter-switch transcriptionally controls Runx1function during embryonic hematopoiesis
Authors: Pozner Amir , Lotem Joseph , Xiao Cuiying , Goldenberg Dalia , Brenner Ori , Negreanu Varda , Levanon Ditsa , Groner Yoram
Published: July 2007

Background

Alternative promoters usage is an important paradigm in transcriptional control of mammalian gene expression. However, despite the growing interest in alternative promoters and their role in genome diversification, very little is known about how and on what occasions those promoters are differentially regulated. Runx1 transcription factor is a key regulator of early hematopoiesis and a frequent target of chromosomal translocations in acute leukemias. Mice deficient inRunx1lack definitive hematopoiesis and die in mid-gestation. Expression ofRunx1is regulated by two functionally distinct promoters designated P1 and P2. Differential usage of these two promoters creates diversity in distribution and protein-coding potential of the mRNA transcripts. While the alternative usage of P1 and P2 likely plays an important role inRunx1biology, very little is known about the function of the P1/P2 switch in mediating tissue and stage specific expression ofRunx1during development.

Results

We employed mice bearing a hypomorphicRunx1allele, with a largely diminished P2 activity, to investigate the biological role of alternative P1/P2 usage. Mice homozygous for the hypomorphic allele developed to term, but died within a few days after birth. During embryogenesis the P1/P2 activity is spatially and temporally modulated. P2 activity is required in early hematopoiesis and when attenuated, development of liver hematopoietic progenitor cells (HPC) was impaired. Early thymus development and thymopoiesis were also abrogated as reflected by thymic hypocellularity and loss of corticomedullary demarcation. Differentiation of CD4/CD8 thymocytes was impaired and their apoptosis was enhanced due to altered expression of T-cell receptors.

Conclusion

The data delineate the activity of P1 and P2 in embryogenesis and describe previously unknown functions of Runx1. The findings show unequivocally that the role of P1/P2 during development is non redundant and underscore the significance of alternative promoter usage in Runx1 biology.
Community health and medical provision: impact on neonates (the CHAMPION trial)
Authors: Boone Peter , Mann Vera , Eble Alexander , Mendiratta Tarana , Mukherjee Rohini , Figueiredo Ryan , Jayanty Chitra , Frost Chris , Padmanabh M Reddy , Elbourne Diana
Published: July 2007

Background

The trial aims to evaluate whether neonatal mortality can be reduced through systemic changes to the provision and promotion of healthcare. Neonatal mortality rates in India are high compared to other low income countries, and there is a wide variation of rates across regions. There is evidence that relatively inexpensive interventions may be able to prevent up to 75% of these deaths. One area with a particularly high rate is Mahabubnagar District in Andhra Pradesh, where neonatal mortality is estimated to be in the region of 4–9%. The area suffers from a vicious cycle of both poor supply of and small demand for health care services. The trial will assess whether a package of interventions to facilitate systemic changes to the provision and promotion of healthcare may be able to substantially reduce neonatal mortality in this area and be cost-effective. If successful, the trial is designed so that it should be possible to substantially scale up the project in regions with similarly high neonatal mortality throughout Andhra Pradesh and elsewhere.

Methods/Design

This trial will be a cluster-randomised controlled trial involving 464 villages in Mahabubnagar District. The package of interventions will first be introduced in half of the villages with the others serving as controls. The trial will run for a period of three years. The intervention in the trial has two key elements: a community health promotion campaign and a system to contract out healthcare to non-public institutions. The health promotion campaign will include a health education campaign, participatory discussion groups, training of village health workers and midwives, and improved coordination of antenatal services. The intervention group will also have subsidised access to pregnancy-related healthcare services at non-public lth centres (NPHCs).

The primary outcome of the trial will be neonatal mortality. Secondary outcomes will include age at and cause of neonatal death, neonatal morbidity, maternal mortality and morbidity, health service usage, costs and several process and knowledge outcomes.

Discussion

The trial will be run by independent research and service delivery arms and supervised by a trial steering committee. A data monitoring committee will be put in place to monitor the trial and recommend stopping/continuation according to a Peto-Haybittle rule. The primary publication for the trial will follow CONSORT guidelines for cluster randomised controlled trials. Criteria for authorship of all papers, presentations and reports resulting from the study will conform to ICMJE standards.

Trial Registration

Current Controlled Trials ISRCTN24104646
HIV prevention costs and program scale: data from the PANCEA project in five low and middle-income countries
Authors: Marseille Elliot , Dandona Lalit , Marshall Nell , Gaist Paul , Bautista-Arredondo Sergio , Rollins Brandi , Bertozzi Stefano M , Coovadia Jerry , Saba Joseph , Lioznov Dmitry , Du Plessis Jo-Ann , Krupitsky Evgeny , Stanley Nicci , Over Mead , Peryshkina Alena , Kumar SG Prem , Muyingo Sowedi , Pitter Christian , Lundberg Mattias , Kahn James G
Published: July 2007

Background

Economic theory and limited empirical data suggest that costs per unit of HIV prevention program output (unit costs) will initially decrease as small programs expand. Unit costs may then reach a nadir and start to increase if expansion continues beyond the economically optimal size. Information on the relationship between scale and unit costs is critical to project the cost of global HIV prevention efforts and to allocate prevention resources efficiently.

Methods

The "Prevent AIDS: Network for Cost-Effectiveness Analysis" (PANCEA) project collected 2003 and 2004 cost and output data from 206 HIV prevention programs of six types in five countries. The association between scale and efficiency for each intervention type was examined for each country. Our team characterized the direction, shape, and strength of this association by fitting bivariate regression lines to scatter plots of output levels and unit costs. We chose the regression forms with the highest explanatory power (R2).

Results

Efficiency increased with scale, across all countries and interventions. This association varied within intervention and within country, in terms of the range in scale and efficiency, the best fitting regression form, and the slope of the regression. The fraction of variation in efficiency explained by scale ranged from 26% – 96%. Doubling in scale resulted in reductions in unit costs averaging 34.2% (ranging from 2.4% to 58.0%). Two regression trends, in India, suggested an inflection point beyond which unit costs increased.

Conclusion

Unit costs decrease with scale across a wide range of service types and volumes. These country and intervention-specific findings can inform projections of the global cost of scaling up HIV prevention efforts.
Dynamic analysis of contact forces in disc assemblies by the shadow method of caustics
Authors: Li M , Zhang J , Fang J , Shu D W , Stronge W
Published: July 2007

The shadow method of dynamic caustics was utilized to study contact force transfer in circular disc assembles under low-speed impact. Caustic mapping equations were derived to relate the caustic pattern to the stress invariant near the concentrated force on the disc, and a characteristic dimension connecting the extreme points of the caustic curve was proposed to evaluate the magnitude and direction of the resultant contact force in order to determine the normal and tangential contact components. Transient patterns of the caustic shadows were analysed for the disc assemblies of the one-dimensional column, square arrangement, and triangular arrangement. Under impulsive loads, force transmission chains were observed in the two-dimensional assemblies and their transient values were solved to represent the contact histories. The influence of impact mass and impulsive velocity was analysed on the contact forces among the discs in the column assembly to show the typical responses of the aligned particles in the granular systems.
Some applications of combined thermoelastic-photoelastic stress analysis
Authors: Greene R. J , Clarke A B , Turner S , Patterson E. A
Published: July 2007

Combined thermoelasticity-photoelasticity integrates the use of reflection photoelasticity to determine the difference in the principal stresses with thermoelastic stress analysis to evaluate the sum of the principal stresses, the advantage gained from this combination being the independent separation of the principal stresses at all points in the field of view. The principle has been established in prior research and suitable instrumentation designed and employed on classical test specimens. This work is extended here with the analysis of two more complex components, namely a composite panel subject to a biaxial strain field and a compressor blade excited at approximately 250 Hz. The methodology for applying combined thermoelasticity-photoelasticity under these conditions is described and the difficulties encountered highlighted and discussed. The results demonstrate that the technique and instrumentation are relatively robust and can be successfully used in these demanding applications.
Measurement of deflections experienced by electronic chips during soldering
Authors: Sciammarella C A , Lamberti L , Pappalettere C , Volpicella G , Sciammarella F. M
Published: July 2007

Electronic chips may experience, during the soldering process to a circuit board, out-of-plane displacements whose magnitude is not compatible with technological requirements on good bonding. This paper presents an experimental procedure based on the projection computer-aided moiré (PCAM) system in order to contour the distorted shape of electronic chips undergoing a thermal cycle which simulates the soldering process. The PCAM system is an integrated system where a pattern of fringes is transformed via software into a continuous phase distribution from which the distorted shape of the chip can be recovered.

In this study, a number of chips have been heated at different temperatures ranging between 120 and 220°C in order to reproduce conditions that may occur during the real soldering process. Since measurements are carried out when the thermal field has become uniform, the chip deforms in the fashion of a quadric surface (i.e. a hyperboloid).

Analysis of the chip's deformed shape reveals that the largest displacement gradients experienced by the chips tested in this study are such that requirements on good bonding of the welded assembly are met. This finding, together with the fact that handling and investigation of electronic chips usually require special care, supports the conclusion that the PCAM approach may be successfully applied in the industry for the non-destructive testing of delicate components.
Investigation of the dependences of the mechanical characteristics of an alloyed steel on both the strain rate and the microstructure
Authors: Homayonifar M , Zebarjad M , Sajjadi A , Saatian A
Published: July 2007

The mechanical properties of AISI 4140 steel were studied at different strain rates (0.167, 0.833, and 1.667 min-1) for various microstructures. To investigate the influence of microstructure, spheroidizing, normalizing, and quench tempering (single tempered and double tempered) were used to obtain a range of microstructures and strength levels. To study the dependences of the mechanical characteristics of AISI 4140 steel on both the strain rate and the microstructure, tensile tests and microscopic evaluation were performed.

The results showed that not only do the yield and the ultimate strength depend on both the microstructure and the strain rate but also so does the appearance of the yielding phenomenon. Also the results showed that an increase in strain rate causes the strain-hardening exponent n and the strength coefficient K to decrease in both quench-tempered and normalized structures but has a negative effect on the spheroidized structure. In fact, the sensitivity of the spheroidized structure to the strain rate is higher than those of the other structures. Microscopic evaluation proved that the Lüders strain width of the spheroidized microstructure is much lower, because of its soft ferrite matrix.
Numerical simulation and experimental study of a mechanism for Hopkinson bar test interruption
Authors: Essa Y El-Saeid , López-Puente J , Pérez-Castellanos J. L
Published: July 2007

The damage evolution in a material during quasi-static and dynamic tests can be studied by interrupting the test at predetermined elongation values and post-mortem analyses of the specimens. While it is straightforward to interrupt quasi-static tests at a predetermined level of elongation, this interruption presents difficulties at high-strain-rate conditions. In the present work, tests at high strain rate using a split Hopkinson tensile bar have been interrupted by an interruption mechanism as a modification of this device. This interruption mechanism is based on the use of two rings of a soft material that absorb the impact energy by deforming plastically. The influence of the dimensions of damper rings on the stress waves and also the ability of the system to support the interruption of the deformation process were considered in the numerical analyses and verified by the experimental results. The relationship between the recommended ring thickness and maximum reached strain for aluminium alloy A16082 will be presented. Finally, the influence of strain on the damage evolution of the ZC71 particulate-reinforced magnesium matrix was reported.
Comparison of X-ray diffraction measurement of residual elastic strains: Monochromatic beam and image plate versus white beam energy-dispersive analysis
Authors: Vorster W J J , Zhang S Y , Golshan M , Laundy D , Dini D , Korsunsky A. M
Published: July 2007

This paper presents the results of synchrotron X-ray diffraction measurement of residual elastic strains in a bent magnesium alloy bar using two different techniques. In the first technique the sample was scanned transversely to a monochromatic X-ray beam. The scattered X-rays were recorded on a phosphoric image plate that was translated at a proportional speed but in the opposite direction to the sample. This enabled the creation of a two-dimensional recording of one-dimensional diffraction patterns. In the second technique a white X-ray beam is used in combination with an energy-discriminating detector mounted at a fixed angle to record similar patterns at each gauge volume position within the sample.

The motivation for comparing the results of two measurement techniques is to establish whether the same accuracy in a diffraction strain evaluation can be achieved. It was found that the translating image plate arrangement requires a certain amount of care in calibration and interpretation, but provides a quick and efficient method that can be competitive with the white beam energy-dispersive mode which is known to deliver a fast diffraction capability.
Resistance strain gauges for the measurement of steady strains at temperatures above 650°C
Authors: Bertodo R
Published: July 2007

The paper considers the problem of obtaining steady strain data using electrical resistance strain gauges at temperatures above 650°C, in the presence of moderate temperature gradients, from turbojet components operating in oxidizing environments. The characteristics of forty-six metal and alloy systems are briefly outlined and the properties of platinum, and alloys of face centred cubic platinum metals and metals in the VIa group of the periodic table of elements are discussed in detail. The behaviour of colloidal sols, acid and alkali bonded ceramic cements and flame-sprayed oxides at high temperatures is considered and their effect on the short and long term stability and strain sensitivity of strain gauges presented.

Only a limited number of pure oxides possessed an adequately high electrical resistivity at the higher temperatures for use as strain gauge bonding media. Such oxides, when flame-sprayed on to suitably prepared surfaces, developed a bond of sufficient shear strength to transfer the applied strain in a consistent and repeatable manner to the gauge filament. The porosity was low enough to offer some degree of oxidation protection to the strain sensitive grid. The temperature coefficient of resistance, drift rate and strain sensitivity of flat grid, dual-element gauges bonded in this manner to Nimonic specimens are shown and it is concluded that grids of this type, wound from platinum and a commercially available platinum-tungsten alloy, would permit the detection of steady strains within an accuracy of about ±0.5 ton/in2 over the temperature range 600—850°C and within ±1.0 ton/in2 over the approximate range 600—950°C from Nimonic specimens, provided the mean gauge temperature could be determined. Methods of determining this temperature in the presence of moderate temperature gradients along the longitudinal axis of the gauge are discussed and some field data are presented. Drift rates equivalent to less than 0.1 ton/in2/h were noted.

It is thought that a coil wound gauge would offer improved performance over a flat grid gauge for temperature gradients across the element, but the problem of providing a suitable former has not been resolved satisfactorily.
Strains in an annular rock dynamometer
Authors: Jordan D. W.
Published: July 2007

An analysis is given of the elastic behaviour of an annular borehole plug dynamometer for measuring changes in the stress condition of rock about mine workings, consisting of a hollow steel cylinder fitted into a hole drilled in the rock. Increments of rock stress are deduced from the readings of strain gauges placed circum-ferentially about the inner radius. The sensitivity is calculated for the instrument for two cases: when it is cemented into the hole and when it is a sliding fit. The latter case is taken as the possible extreme result of a breakdown in the cementation.