bluuebunny/crossref_metadata_2025 huggingface dataset:
Advanced Theoretical and Numerical Models of Failure Mechanism and Fracture Propagation Around the Boreholes in Hydro‐Fracturing Process of Hot Dry Rock Reservoirs
Authors: Hossein Kohsary Amir , Fatehi Marji Mohammad , Hosseini Nasab Hasan
Published: July 2007

This paper describes progress on the development of theoretical models required for studying failure mechanism, crack initiation and growth around the boreholes driven by hydrofracturing processes in Hot Dry Rock (HDR) reservoirs of geothermal energy. Due to the importance of the stress intensity factor concept (K) in Fracture Mechanics, some advanced modeling techniques for accurate and fast determination of K for relevant problems are proposed. Alternative tools to deal with stress intensity factor determination are developed and assessed from the points of view of accuracy and computational cost. We concentrate on residual strength, crack initiation and crack growth as a means to model and understand experimentally observed behaviors. Several modeling methods such as compounding and weight function techniques, and boundary and finite element modeling for stress intensity factor calculation are discussed. Further to reviews of those techniques, work performed included (i) developing alternative solutions to deal with boundary‐to‐boundary interaction when using the compounding technique, (ii) relating the precision of K calculations with the level of precision of the crack opening displacement of a reference solution, in order to assess the precision of weight function technique, (iii) modeling relevant geometries using the finite element method (FEM), (iv) working on the implementation of direct stress intensity factor K determination in the Higher Order Displacement Discontinuity Method (HODDM), and (v) developing tools to deal with residual stress fields around the boundary of the hydraulically pressurized boreholes.
Ballistic Performance of Alumina/S‐2 Glass‐reinforced Polymer‐matrix Composite Hybrid Lightweight Armor Against Armor Piercing (ap) and Non‐AP Projectiles
Authors: Grujicic M. , Pandurangan B. , Zecevic U. , Koudela K.L. , Cheeseman B.A.
Published: July 2007

The ability of light‐weight all fiber‐reinforced polymer‐matrix composite armor and hybrid composite‐based armor hard‐faced with ceramic tiles to withstand the impact of a non‐Armor‐ Piercing (non‐AP) and AP projectiles is investigated using a transient non‐linear dynamics computational analysis. The results obtained confirm experimental findings that the all‐composite armor, while being able to successfully defeat non‐AP threats, provides very little protection against AP projectiles. In the case of the hybrid armor, it is found that, at a fixed overall areal density of the armor, there is an optimal ratio of the ceramic‐to‐composite areal densities which is associated with a maximum ballistic armor performance against AP threats. The results obtained are rationalized using an analysis based on the shock/blast wave reflection and transmission behavior at the hard‐face/air, hard‐face/backing and backing/air interfaces, projectiles’ wear and erosion and the intrinsic properties of the constituent materials of the armor and the projectiles.
Elastic Analysis for a Finite Cracked Plate of Functionally Graded Materials
Authors: Chen Y.Z. , Lin X.Y.
Published: July 2007

In this paper, elastic analysis for an edge‐cracked plate of functionally graded materials (FGMs) is carried out. The cracked plate is subject to a longitudinal tension. The property of FGMs is assumed to be exponential function form in both x‐ and y‐directions. The finite element method is suggested to solve the boundary value problem. An indirect method, the energy release method, is developed to evaluate the stress intensity factors (SIFs) at the crack tip. Under the applied loading, the amount of the release energy from the crack length “a” to “ a + Δa ” can be evaluated from relevant displacements at the top face of plate. The SIFs can be obtained from a relation between the energy release rate and SIF. The obtained result shows that the property of FGMs has a significant influence to the value of SIF at crack tip. Numerical results are given which are useful for engineer to assess the safety of the cracked plate of FGMs.
A Fem Analysis to Determine Effect of Milling Parameters on Plastic Strain and Plastic Strain‐Rate Distribution When Milling Hastelloy C‐22HS
Authors: Kadirgama K. , Abou‐El‐Hossein K.A. , Mohammad B. , Habeeb H.
Published: July 2007

The Finite Element Method and Response Surface Method are used to find the effect of milling parameters (Cutting speed, Feedrate and Axial depth) on plastic strain when milling Hastelloy C‐22HS. This simulation gain more understanding of the strain distribution in metal cutting. Response surface method (RSM) has been used to minimize the number of simulation. The contour plot from the RSM shows the relationship between variables (cutting speed, feedrate and axial depth) and response (plastic strain ‐ rate).The friction interaction along the tool‐chip interface is modeled with Coulomb friction law.
Deformation Due to Mechanical and Thermal Sources in Magneto‐Micropolar Elastic Medium
Authors: Kumar Rajneesh , Rupender
Published: July 2007

The present investigation is concerned with a two‐dimensional problem in electromagnetic micropolar elasticity for a half‐space whose surface is subjected to mechanical or thermal source in the presence of a transverse magnetic field. Laplace and Fourier transform technique is used to solve the problem. As an application of the approach concentrated/continuous mechanical or thermal source has been taken. The integral transforms have been inverted by using a numerical technique to obtain the components of normal strain, temperature distribution, normal force stress and tangential couple stress in the physical domain. The expressions of these quantities have been given and illustrated graphically to depict the magnetic effect for two different theories of generalized thermoelasticity, Lord and Shulman (L‐S theory) and Green and Lindsay (G‐L theory). Some special cases of interest are also deduced from the present investigation.
The Effect of Wind on the Dispersal of the Hudson River Plume
Authors: Choi Byoung-Ju , Wilkin John L.
Published: August 2007

The dispersal of the Hudson River plume in response to idealized wind forcing is studied using a three-dimensional model. The model domain includes the Hudson River and its estuary, with a realistic coastline and bottom topography of the New York Bight. Steady low river discharge typical of mean conditions and a high-discharge event representative of the spring freshet are considered. Without wind forcing the plume forms a southward coastally trapped current at low river discharge and a large recirculating bulge of low-salinity water during a high-discharge event. Winds affect the freshwater export through the mouth of the estuary, which is the trajectory the plume takes upon entering the waters of the Mid-Atlantic Bight inner shelf, and the rate at which freshwater drains downstream. The dispersal trajectory is also influenced by the particular geography of the coastline in the apex of the New York Bight. Northward wind causes offshore displacement of a previously formed coastally trapped plume and drives a new plume along the Long Island coast. Southward wind induces a strong coastal jet that efficiently drains freshwater to the south. Eastward wind aids freshwater export from the estuary and favors the accumulation of freshwater in the recirculating bulge outside the mouth of Raritan Bay. Westward wind delays freshwater export from Raritan Bay. The momentum balance of the modeled plume shows that buoyancy and wind forces largely determine the pattern of horizontal freshwater dispersal, including the spreading of freshwater over ambient, more saline water and the bulge formation.
Mechanisms Governing Interannual Variability of Upper-Ocean Temperature in a Global Ocean Hindcast Simulation
Authors: Doney Scott C. , Yeager Steve , Danabasoglu Gokhan , Large William G. , McWilliams James C.
Published: August 2007

The interannual variability in upper-ocean (0–400 m) temperature and governing mechanisms for the period 1968–97 are quantified from a global ocean hindcast simulation driven by atmospheric reanalysis and satellite data products. The unconstrained simulation exhibits considerable skill in replicating the observed interannual variability in vertically integrated heat content estimated from hydrographic data and monthly satellite sea surface temperature and sea surface height data. Globally, the most significant interannual variability modes arise from El Niño–Southern Oscillation and the Indian Ocean zonal mode, with substantial extension beyond the Tropics into the midlatitudes. In the well-stratified Tropics and subtropics, net annual heat storage variability is driven predominately by the convergence of the advective heat transport, mostly reflecting velocity anomalies times the mean temperature field. Vertical velocity variability is caused by remote wind forcing, and subsurface temperature anomalies are governed mostly by isopycnal displacements (heave). The dynamics at mid- to high latitudes are qualitatively different and vary regionally. Interannual temperature variability is more coherent with depth because of deep winter mixing and variations in western boundary currents and the Antarctic Circumpolar Current that span the upper thermocline. Net annual heat storage variability is forced by a mixture of local air–sea heat fluxes and the convergence of the advective heat transport, the latter resulting from both velocity and temperature anomalies. Also, density-compensated temperature changes on isopycnal surfaces (spice) are quantitatively significant.
High-Frequency Internal Waves on the Oregon Continental Shelf
Authors: D’Asaro Eric A. , Lien Ren-Chieh , Henyey Frank
Published: August 2007

Measurements of vertical velocity by isopycnal-following, neutrally buoyant floats deployed on the Oregon shelf during the summers of 2000 and 2001 were used to characterize internal gravity waves on the shelf using measurements of vertical velocity. The average spectrum of Wentzel–Kramers–Brillouin (WKB)-scaled vertical kinetic energy has the level predicted by the Garrett–Munk model (GM79), plus a narrow M2 tidal peak and a broad high-frequency peak extending from about 0.1N to N and rising a decade above GM79. The high-frequency peak varies in energy coherently with time across its entire bandwidth. Its energy is independent of the tidal energy. The energy in the “continuum” region between the peaks is weakly correlated with the level of the high-frequency peak energy and is independent of the tidal peak energy. The vertical velocity is not Gaussian but is highly intermittent, with a calculated kurtosis of 19. The vertical kinetic energy varies geographically. Low energy is found offshore and nearshore. The highest energy is found near a small seamount. High energy is found over the rough topography of Heceta Bank and near the shelf break. The highest energy occurs as packets of high-frequency waves, often occurring on the sharp downward phase of the M2 internal tide and called “tidal solibores.” A few isolated waves with high energy are also found. Of the 1-h periods with the highest vertical kinetic energy, 31% are tidal solibores, 8% are isolated waves, and the remainder of the periods appear unorganized. The two most energetic tidal solibores were examined in detail. As compared with the steady, propagating, two-dimensional, inviscid, internal-wave solutions to the equations of motion with no background shear [i.e., the Dubreil–Jacotin–Long (DJL) equation], all but the most energetic observed waveforms are too narrow for their height to be solitary waves. Despite the large near-N peak in vertical kinetic energy, the M2 internal tide contributes over 80% of the energy, ignoring near-inertial waves. The tidal solibores make a very small contribution, 0.5%, to the overall internal-wave energy.
Measuring Coping Strategies Among African Americans: An Exploration of the Latent Structure of the COPE Inventory
Authors: Greer Tawanda M.
Published: August 2007

The purpose of this investigation was to examine the latent factor structure of the Coping With Problems Experienced (COPE) inventory, and to compare this structure to an imposed, culturally relevant latent structure with a sample of African Americans. The alternate, latent structure was derived from an Africentric framework, as well as from empirical findings on coping behaviors of African Americans. Confirmatory factor analysis (CFA) was used to test both models. CFA results indicated that the alternate latent structure represented the best overall fit to the data, with the original latent structure yielding a moderately acceptable fit. Implications for the use of the COPE with African Americans are discussed.
Re-theorizing External Learning: Insights from Economic and Industrial Espionage
Authors: Ferdinand Jason , Simm David
Published: August 2007

This article develops our understanding of external learning by drawing upon evidence of economic and industrial espionage. We draw attention to the normative assumption of authors in the field that organizational learning is necessarily an entirely legitimate activity. We demonstrate that contemporary debate could benefit from research exploring illegal forms of learning. Three vignettes capturing different aspects of economic and industrial espionage are presented to illustrate the limitations of our current conceptualizations of external learning and its ethical dimensions, and to provide a basis for a re-theorization. The article concludes with the presentation of an indicative model of external learning and some suggestions for a revised research agenda.
Responsible Ownership, Shareholder Value and the New Shareholder Activism
Authors: Hendry John , Sanderson Paul , Barker Richard , Roberts John
Published: July 2007

In this paper we use interview data to explore the ‘new shareholder activism’ of mainstream UK institutional investor We describe contemporary practices of corporate governance monitoring and engagement and how they vary across institutions, and explore the motivations behind them Existing studies of shareholder activism mainly assume that it is motivated by a desire to maximize shareholder value, and we find some evidence both of this and of alternative political/moral motivations related to ideas of responsible ownership We conclude, however, that in the current situation both these act primarily as rationalizations rather than as genuine motivators The main driving force behind the new shareholder activism is the institutions' own profit maximisation and the need to position themselves against competitor institutions in the context of political and regulatory changes that have significantly changed the non-financial expectations of their clients.
‘We're Here to Make Money; We're Here to Do Business’: Privatisation and Questions for Trade Unions
Authors: Barton Ruth , Fairbrother Peter
Published: July 2007

Australia has been one of the world's leading proponents of privatisation. One of the key arguments about privatisation is that it would end the inefficient state monopoly of public services and reduce the power of public sector trade unions. Within a relatively short period of the privatisation of the energy and transport sectors in Victoria Australia, there was a reconsolidation of ownership which raised new challenges for the trade unions. After this phase, the main trade unions in these two sectors took steps to meet these new circumstances to renew and rebuild their structures and strengthen their capacity to challenge the new private oligopolies. Thus, paradoxically some unions were able to open up space to renew and rebuild in the post–privatisation world.
The Internationalisation of the French Aerospace Industry: To What Extent Were the 1990s a Break with the Past?
Authors: Carrincazeaux Christophe , Frigant Vincent
Published: July 2007

The 1990S are Often Described as the Decade when the Aerospace Industry Broke with the Past. The Drop in Military Orders that Occurred Early in the Decade, the Adoption in Both the Defence and Civil Markets of More Competitive Modes of Regulation, the Arrival at Maturity of Several Big Civil Programmes and a Host of Privatisations – All Had a Durable Impact on the Aerospace Industry in France. A General Consensus Exists About These Changes, but few Empirical Studies have Actually Tried to Measure the Extent of Their Impact on the Sector. To make up for this, we have Carried out a Statistical Study of the Structural Transformations Befalling the Aerospace Industry Through the Analysis of one Specific Problem: Firms' Internationalisation. We have used four Databases, Including for the first time the Eeig Survey of Intra-Firm Trade, to Assess Whether French Firms did in Fact Deeply Modify their Internationalisation Behaviour over the Period 1993–99. We Come to Mixed Conclusions, the Suggestion Being that what the Sector Experienced was more of an Evolution than a Major Upheaval. Although Certain Components of Firms' Internationalisation Trajectories were Clearly Altered (like the French State's Presence in the Sector or Sales Internationalisation), others Evolved Much More Slowly (like Foreign Companies' Penetration in France and French Companies' Productive Internationalisation). Summarily, we can say that Productive Internationalisation Remained Modest in Comparison with sales Internationalisation.
Ubiquitin conjugating enzymes participate in polyglutamine protein aggregation
Authors: Howard Rebecca A , Sharma Pratima , Hajjar Connie , Caldwell Kim A , Caldwell Guy A , du Breuil Rusla , Moore Rhonda , Boyd Lynn
Published: August 2007

Background

Protein aggregation is a hallmark of several neurodegenerative diseases including Huntington's disease and Parkinson's disease. Proteins containing long, homopolymeric stretches of glutamine are especially prone to form aggregates. It has long been known that the small protein modifier, ubiquitin, localizes to these aggregates. In this report, nematode and cell culture models for polyglutamine aggregation are used to investigate the role of the ubiquitin pathway in protein aggregation.

Results

Ubiquitin conjugating enzymes (Ubc's) were identified that affect polyglutamine aggregates in C. elegans. Specifically, RNAi knockdown of ubc-2 or ubc-22 causes a significant increase in the size of aggregates as well as a reduction in aggregate number. In contrast, RNAi of ubc-1, ubc-13, or uev-1 leads to a reduction of aggregate size and eliminates ubiquitin and proteasome localization to aggregates. In cultured human cells, shRNA knockdown of human homologs of these Ubc's (Ube2A, UbcH5b, and E2-25K) causes similar effects indicating a conserved role for ubiquitination in polyglutamine protein aggregation.

Conclusion

Results of knockdown of different Ubc enzymes indicate that at least two different and opposing ubiquitination events occur during polyglutamine aggregation. The loss of ubiquitin localization after ubc-1, ubc-13, or uev-1 knockdown suggests that these enzymes might be directly involved in ubiquitination of aggregating proteins.
Evolution of ribonuclease H genes in prokaryotes to avoid inheritance of redundant genes
Authors: Kochiwa Hiromi , Tomita Masaru , Kanai Akio
Published: August 2007

Background

A theoretical model of genetic redundancy has proposed that the fates of redundant genes depend on the degree of functional redundancy, and that functionally redundant genes will not be inherited together. However, no example of actual gene evolution has been reported that can be used to test this model. Here, we analyzed the molecular evolution of the ribonuclease H (RNase H) family in prokaryotes and used the results to examine the implications of functional redundancy for gene evolution.

Results

In prokaryotes, RNase H has been classified into RNase HI, HII, and HIII on the basis of amino acid sequences. Using 353 prokaryotic genomes, we identified the genes encoding the RNase H group and examined combinations of these genes in individual genomes. We found that the RNase H group may have evolved in such a way that the RNase HI and HIII genes will not coexist within a single genome – in other words, these genes are inherited in a mutually exclusive manner. Avoiding the simultaneous inheritance of the RNase HI and HIII genes is remarkable when RNase HI contains an additional non-RNase H domain, double-stranded RNA, and an RNA-DNA hybrid-binding domain, which is often observed in eukaryotic RNase H1. This evolutionary process may have resulted from functional redundancy of these genes, because the substrate preferences of RNase HI and RNase HIII are similar.

Conclusion

We provide two possible evolutionary models for RNase H genes in which functional redundancy contributes to the exclusion of redundant genes from the genome of a species. This is the first empirical study to show the effect of functional redundancy on changes in gene constitution during the course of evolution.
Differential effects of synchronous and asynchronous multifinger coactivation on human tactile performance
Authors: Kalisch Tobias , Tegenthoff Martin , Dinse Hubert R
Published: August 2007

Background

Repeated execution of a tactile task enhances task performance. In the present study we sought to improve tactile performance with unattended activation-based learning processes (i.e., focused stimulation of dermal receptors evoking neural coactivation (CA)). Previous studies show that the application of CA to a single finger reduced the stationary two-point discrimination threshold and significantly increased tactile acuity. These changes were accompanied by an expansion of the cortical finger representation in primary somatosensory cortex (SI). Here we investigated the effect of different types of multifinger CA on the tactile performance of each finger of the right hand.

Results

Synchronous and asynchronous CA was applied to all fingers of a subject's dominant hand. We evaluated changes in absolute touch thresholds, static two-point discrimination thresholds, and mislocalization of tactile stimuli to the fingertips. After synchronous CA, tactile acuity improved (i.e., discrimination thresholds decreased) and the frequency of mislocalization of tactile stimuli changed from directly neighboring fingers to more distant fingers. On the other hand, asynchronous CA did not significant improve tactile acuity. In fact, there was evidence of impaired tactile acuity. Multifinger CA with synchronous or asynchronous stimulation did not significantly alter absolute touch thresholds.

Conclusion

Our results demonstrate that it is possible to extend tactile CA to all fingers of a hand. The observed changes in mislocalization of tactile stimuli after synchronous CA indicate changes in the topography of the cortical hand representation. Although single-finger CA has been shown to improve tactile acuity, asynchronous CA of all fingers of the hand had the opposite effect, suggesting the need for synchrony in multifinger CA for improving tactile acuity.
Lack of increases in methylation at three CpG-rich genomic loci in non-mitotic adult tissues during aging
Authors: Chu Michelle W , Siegmund Kimberly D , Eckstam Carrie L , Kim Jung Yeon , Yang Allen S , Kanel Gary C , Tavaré Simon , Shibata Darryl
Published: August 2007

Background

Cell division occurs during normal human development and aging. Despite the likely importance of cell division to human pathology, it has been difficult to infer somatic cell mitotic ages (total numbers of divisions since the zygote) because direct counting of lifetime numbers of divisions is currently impractical. Here we attempt to infer relative mitotic ages with a molecular clock hypothesis. Somatic genomes may record their mitotic ages because greater numbers of replication errors should accumulate after greater numbers of divisions. Mitotic ages will vary between cell types if they divide at different times and rates.

Methods

Age-related increases in DNA methylation at specific CpG sites (termed "epigenetic molecular clocks") have been previously observed in mitotic human epithelium like the intestines and endometrium. These CpG rich sequences or "tags" start unmethylated and potentially changes in methylation during development and aging represent replication errors. To help distinguish between mitotic versus time-associated changes, DNA methylation tag patterns at 8–20 CpGs within three different genes, two on autosomes and one on the X-chromosome were measured by bisulfite sequencing from heart, brain, kidney and liver of autopsies from 21 individuals of different ages.

Results

Levels of DNA methylation were significantly greater in adult compared to fetal or newborn tissues for two of the three examined tags. Consistent with the relative absence of cell division in these adult tissues, there were no significant increases in tag methylation after infancy.

Conclusion

Many somatic methylation changes at certain CpG rich regions or tags appear to represent replication errors because this methylation increases with chronological age in mitotic epithelium but not in non-mitotic organs. Tag methylation accumulates differently in different tissues, consistent with their expected genealogies and mitotic ages. Although further studies are necessary, these results suggest numbers of divisions and ancestry are at least partially recorded by epigenetic replication errors within somatic cell genomes.
Critical role of c-Jun overexpression in liver metastasis of human breast cancer xenograft model
Authors: Zhang Yan , Pu Xiaoyun , Shi Ming , Chen Liyong , Song Yuhua , Qian Lu , Yuan Guogang , Zhang Hao , Yu Ming , Hu Meiru , Shen Beifen , Guo Ning
Published: August 2007

Background

c-Jun/AP-1 has been linked to invasive properties of aggressive breast cancer. Recently, it has been reported that overexpression of c-Jun in breast cancer cell line MCF-7 resulted in increased AP-1 activity, motility and invasiveness of the cells in vitro and tumor formation in nude mice. However, the role of c-Jun in metastasis of human breast cancer in vivo is currently unknown.

Methods

To further investigate the direct involvement of c-Jun in tumorigenesis and metastasis, in the present study, the effects of c-Jun overexpression were studied in both in vitro and in nude mice.

Results

Ectopic overexpression of c-Jun promoted the growth of MCF-7 cells and resulted in a significant increase in the percentage of cells in S phase and increased motility and invasiveness. Introduction of c-Jun gene alone into weakly invasive MCF-7 cells resulted in the transfected cells capable of metastasizing to the nude mouse liver following tail vein injection.

Conclusion

The present study confirms that overexpression of c-Jun contributes to a more invasive phenotype in MCF-7 cells. It indicates an interesting relationship between c-Jun expression and increased property of adhesion, migration and in vivo liver metastasis of MCF-7/c-Jun cells. The results provide further evidence that c-Jun is involved in the metastasis of breast cancer. The finding also opens an opportunity for development of anti-c-Jun strategies in breast cancer therapy.
The contribution of international health volunteers to the health workforce in sub-Saharan Africa
Authors: Laleman Geert , Kegels Guy , Marchal Bruno , Van der Roost Dirk , Bogaert Isa , Van Damme Wim
Published: August 2007

Background

In this paper, we aim to quantify the contribution of international health volunteers to the health workforce in sub-Saharan Africa and to explore the perceptions of health service managers regarding these volunteers.

Methods

Rapid survey among organizations sending international health volunteers and group discussions with experienced medical officers from sub-Saharan African countries.

Results

We contacted 13 volunteer organizations having more than 10 full-time equivalent international health volunteers in sub-Saharan Africa and estimated that they employed together 2072 full-time equivalent international health volunteers in 2005. The numbers sent by secular non-governmental organizations (NGOs) is growing, while the number sent by development NGOs, including faith-based organizations, is mostly decreasing. The cost is estimated at between US$36 000 and US$50 000 per expatriate volunteer per year. There are trends towards more employment of international health volunteers from low-income countries and of national medical staff.

Country experts express more negative views about international health volunteers than positive ones. They see them as increasingly paradoxical in view of the existence of urban unemployed doctors and nurses in most countries. Creating conditions for employment and training of national staff is strongly favoured as an alternative. Only in exceptional circumstances is sending international health volunteers viewed as a defendable temporary measure.

Conclusion

We estimate that not more than 5000 full-time equivalent international health volunteers were working in sub-Saharan Africa in 2005, of which not more than 1500 were doctors. A distinction should be made between (1) secular medical humanitarian NGOs, (2)development NGOs, and (3) volunteer organizations, as Voluntary Service Overseas (VSO) and United Nations volunteers (UNV). They have different views, undergo different trends and are differently appreciated by government officials.

International health volunteers contribute relatively small numbers to the health workforce in sub-Saharan Africa, and it seems unlikely that they will do more in the future. In areas where they play a role, their contribution to service delivery is sometimes very significant.
Breast-conserving surgery with or without radiotherapy in women with ductal carcinoma in situ: a meta-analysis of randomized trials
Authors: Viani Gustavo A , Stefano Eduardo J , Afonso Sérgio L , De Fendi Lígia I , Soares Francisco V , Leon Paola G , Guimarães Flavio S
Published: August 2007

Background

To investigate whether Radiation therapy (RT) should follow breast conserving surgery in women with ductal carcinoma in situ from breast cancer (DCIS) with objective of decreased mortality, invasive or non invasive recurrence, distant metastases and contralateral breast cancer rates. We have done a meta-analysis of these results to give a more balanced view of the total evidence and to increase statistical precision.

Methods

A meta-analysis of randomized controlled trials (RCT) was performed comparing RT treatment for DCIS of breast cancer to observation. The MEDLINE, EMBASE, CANCERLIT, Cochrane Library databases, Trial registers, bibliographic databases, and recent issues of relevant journals were searched. Relevant reports were reviewed by two reviewers independently and the references from these reports were searched for additional trials, using guidelines set by QUOROM statement criteria.

Results

The reviewers identified four large RCTs, yielding 3665 patients. Pooled results from this four randomized trials of adjuvant radiotherapy showed a significant reduction of invasive and DCIS ipsilateral breast cancer with odds ratio (OR) of 0.40 (95% CI 0.33 – 0.60, p < 0.00001) and 0.40 (95% CI 0.31 – 0.53, p < 0.00001), respectively. There was not difference in distant metastases (OR = 1.04, 95% CI 0.57–1.91, p = 0.38) and death rates (OR = 1.08, 95%CI 0.65 – 1.78, p = 0.45) between the two arms. There was more contralateral breast cancer after adjuvant RT (66/1711 = 3.85%) versus observation (49/1954 = 2.5%). The likelihood of contralateral breast cancer was 1.53-fold higher (95% CI 1.05 – 2.24, p = 0.03) in radiotherapy arms.

Conclusion

The conclusion from our meta-analysis is that the addition of radiation therapy to lumpectomy results in an approximately 60% reduction in breast cancer recurrence, no benefit for survival or distant metastases compared to excision alone. Patients with high-grade DCIS lesions and positive margins benefited most from the addition of radiation therapy. It is not yet clear which patients can be successfully treated with lumpectomy alone; until further prospective studies answer this question, radiation should be recommended after lumpectomy for all patients without contraindications.
A protein interaction atlas for the nuclear receptors: properties and quality of a hub-based dimerisation network
Authors: Amoutzias Gregory D , Pichler Elgar E , Mian Nina , De Graaf David , Imsiridou Anastasia , Robinson-Rechavi Marc , Bornberg-Bauer Erich , Robertson David L , Oliver Stephen G
Published: August 2007

Background

The nuclear receptors are a large family of eukaryotic transcription factors that constitute major pharmacological targets. They exert their combinatorial control through homotypic heterodimerisation. Elucidation of this dimerisation network is vital in order to understand the complex dynamics and potential cross-talk involved.

Results

Phylogeny, protein-protein interactions, protein-DNA interactions and gene expression data have been integrated to provide a comprehensive and up-to-date description of the topology and properties of the nuclear receptor interaction network in humans. We discriminate between DNA-binding and non-DNA-binding dimers, and provide a comprehensive interaction map, that identifies potential cross-talk between the various pathways of nuclear receptors.

Conclusion

We infer that the topology of this network is hub-based, and much more connected than previously thought. The hub-based topology of the network and the wide tissue expression pattern of NRs create a highly competitive environment for the common heterodimerising partners. Furthermore, a significant number of negative feedback loops is present, with the hub protein SHP [NR0B2] playing a major role. We also compare the evolution, topology and properties of the nuclear receptor network with the hub-based dimerisation network of the bHLH transcription factors in order to identify both unique themes and ubiquitous properties in gene regulation. In terms of methodology, we conclude that such a comprehensive picture can only be assembled by semi-automated text-mining, manual curation and integration of data from various sources.
An immune response gene expression module identifies a good prognosis subtype in estrogen receptor negative breast cancer
Authors: Teschendorff Andrew E , Miremadi Ahmad , Pinder Sarah E , Ellis Ian O , Caldas Carlos
Published: August 2007

Background

Estrogen receptor (ER)-negative breast cancer specimens are predominantly of high grade, have frequent p53 mutations, and are broadly divided into HER2-positive and basal subtypes. Although ER-negative disease has overall worse prognosis than does ER-positive breast cancer, not all ER-negative breast cancer patients have poor clinical outcome. Reliable identification of ER-negative tumors that have a good prognosis is not yet possible.

Results

We apply a recently proposed feature selection method in an integrative analysis of three major microarray expression datasets to identify molecular subclasses and prognostic markers in ER-negative breast cancer. We find a subclass of basal tumors, characterized by over-expression of immune response genes, which has a better prognosis than the rest of ER-negative breast cancers. Moreover, we show that, in contrast to ER-positive tumours, the majority of prognostic markers in ER-negative breast cancer are over-expressed in the good prognosis group and are associated with activation of complement and immune response pathways. Specifically, we identify an immune response related seven-gene module and show that downregulation of this module confers greater risk for distant metastasis (hazard ratio 2.02, 95% confidence interval 1.2-3.4; P = 0.009), independent of lymph node status and lymphocytic infiltration. Furthermore, we validate the immune response module using two additional independent datasets.

Conclusion

We show that ER-negative basal breast cancer is a heterogeneous disease with at least four main subtypes. Furthermore, we show that the heterogeneity in clinical outcome of ER-negative breast cancer is related to the variability in expression levels of complement and immune response pathway genes, independent of lymphocytic infiltration.
Associations between common mental disorders and the Mental Illness Needs Index in community settings
Authors: Fone David L. , Dunstan Frank , John Ann , Lloyd Keith
Published: July 2007

Background

The relationship between the Mental Illness Needs Index (MINI) and the common mental disorders is not known.

Aims

To investigate associations between the small-area MINI score and common mental disorder at individual level.

Method

Mental health status was measured using the Mental Health Inventory of the Short Form 36 instrument (SF-36). Data from the Caerphilly Health and Social Needs population survey were analysed in multilevel models of 10 653 individuals aged 18–74 years nested within the 2001 UK census geographies of 110 lower super output areas and 33 wards.

Results

The MINI score was significantly associated with common mental disorder after adjusting for individual risk factors. This association was stronger at the smaller spatial scale of the lower super output area and for individuals who were permanently sick or disabled.

Conclusions

The MINI is potentially useful for small-area needs assessment and service planning for common mental disorder in community settings.
Prevalence of dementia in intellectual disability using different diagnostic criteria
Authors: Strydom A. , Livingston G. , King M. , Hassiotis A.
Published: July 2007

Background

Diagnosis of dementia is complex in adults with intellectual disability owing to their pre-existing deficits and different presentation.

Aims

To describe the clinical features and prevalence of dementia and its subtypes, and to compare the concurrent validity of dementia criteria in older adults with intellectual disability.

Method

The Becoming Older with Learning Disability (BOLD) memory study is a two-stage epidemiological survey of adults with intellectual disability without Down syndrome aged 60 years and older, with comprehensive assessment of people who screen positive. Dementia was diagnosed according to ICD-10, DSM-IV and DC-LD criteria.

Results

The DSM – IV dementia criteria were more inclusive. Diagnosis using ICD – 10 excluded people with even moderate dementia. Clinical subtypes of dementia can be recognised in adults with intellectual disability. Alzheimer's dementia was the most common, with a prevalence of 8.6% (95% CI 5.2–13.0), almost three times greater than expected.

Conclusions

Dementia is common in older adults with intellectual disability, but prevalence differs according to the diagnostic criteria used. This has implications for clinical practice.
Relationship between daily suicide counts and temperature in England and Wales
Authors: Page Lisa A. , Hajat Shakoor , Kovats R. Sari
Published: July 2007

Background

Seasonal fluctuation in suicide has been observed in many populations. High temperature may contribute to this, but the effect of short-term fluctuations in temperature on suicide rates has not been studied.

Aims

To assess the relationship between daily temperature and daily suicide counts in England and Wales between 1 January 1993 and 31 December 2003 and to establish whether heatwaves are associated with increased mortality from suicide.

Method

Time-series regression analysis was used to explore and quantify the relationship between daily suicide counts and daily temperature. The impact of two heatwaves on suicide was estimated.

Results

No spring or summer peak in suicide was found. Above 18 °, each 1 ° increase in mean temperature was associated with a 3.8 and 5.0% rise in suicide and violent suicide respectively. Suicide increased by 46.9% during the 1995 heatwave, whereas no change was seen during the 2003 heat wave.

Conclusions

There is increased risk of suicide during hot weather.
New approaches to reimbursement schemes based on patient classification systems and their comparison
Authors: Marazzi Alfio , Gardiol Lucien , Duong Hong Dung
Published: July 2007

We propose reimbursement schemes based on patient classification systems (PCSs) that include adjustments for length of stay (LOS) and exceptional costs and are designed to minimize undesirable effects of economic incentives. In addition, a statistical approach to compare the schemes and the underlying PCSs is proposed, where costs and LOSs for two successive years are used. The first year data provides estimates of the class cost means and the next year's reimbursements which are compared with the second year's costs. This method focuses on the predictive power of a PCS and differs from the usual retrospective analyses based on the proportion of explained variance for single year data.

The approach is applied to discharge data of Swiss hospitals where stays are grouped according to five PCSs: All Patient Diagnosis-Related Groups (AP-DRGs), All Patient Refined Diagnosis-Related Groups (APR-DRGs), International Refined Diagnosis-Related Groups (IR-DRGs), Australian Refined Diagnosis-Related Groups (AR-DRGs), and SQLape.

When adjusting for LOS and outliers, these systems do not differ substantially in their ability to predict cost of stay. Therefore, increasing the number of classes does not necessarily improve cost predictions. However, the payment of a fixed amount per diem (not exceeding the marginal cost) and correcting the reimbursements for exceptional costs substantially reduces the average discrepancy between costs and reimbursements.
Physicians' views on the influence of patient participation on treatment decisions - an explorative study
Authors: Jaakkola Elina
Published: July 2007

While patient participation in treatment decisions is increasingly advocated in medical literature, patient demand has been considered to cause unnecessary prescribing. Using the concept of customer participation as discussed in services marketing and management literature as a theoretical base, the paper analyses the influence of patient participation on the medical service process and treatment decision-making. A qualitative, explorative study was conducted to investigate American and British physicians' views on patient participation in the treatment of osteoporosis and schizophrenia. It became evident that in the cases of both osteoporosis and schizophrenia, patients influence prescribing decisions despite the significant difference in their willingness and ability to participate. The manifestations of patient participation were divided into three groups: (1) resources, such as the patient's condition and information about it, and his/her preconceived notions and preferences, (2) actions, such as preparing for the service, negotiating decisions and implementing the treatment, and (3) the patient's role expectations and inclination to participate. The influence of such manifestations on prescribing decision-making is discussed in detail, and differences between the studied illnesses are explained. Implications to health-care managers and practitioners are discussed.
Success factors in hospital network performance: evidence from Korea
Authors: Kim Kwang-Jum , Burns Lawton R
Published: July 2007

Collaborative networks have become a common organizational strategy to deal with uncertain and dynamic environments. Like their counterparts in the USA, Korean hospitals are establishing cooperative relationships with one another, with varying performance results. This paper analyses some of the sources of variation in hospital network performance and identifies some of the possible success factors. The study finds that the quality of cooperation and information sharing between network partners are critical. The paper concludes with a discussion of the implications for researchers and practitioners.
Evaluating primary care research networks
Authors: Fenton Evelyn , Harvey Janet , Sturt Jackie
Published: July 2007

This paper presents a conceptual framework and tool kit, generated from the evaluation of five primary care research networks (PCRNs) funded by the then London, National Health Service (NHS) Executive.

We employed qualitative methods designed to match the most important characteristics of PCRNs, conducting five contextualized case studies covering the five networks. A conceptual evaluation framework based on a review of the organization science literature was developed and comprised the broad, but inter-related organizational dimensions of structure, processes, boundaries and network self-evaluation as input factors and strategic emphasis as epitomized by network objectives. These dimensions were comprised of more detailed subdimensions designed to capture the potential of the networks to create ideas and knowledge, or intellectual capital, the key construct upon which our evaluation tool kit was based. We considered the congruence, or fit, between network objectives and input factors: greater congruence implied greater ability to achieve implicit and overt objectives.

We conclude that network evaluation must take place, over time, recognizing stage of development and potential for long-term viability, but within a generic framework of inputs and outputs. If there is a good fit or congruence between their input factors and network objectives, networks will be internally coherent and able to operate at optimum effectiveness.
Development and validation of a care process self-evaluation tool
Authors: Vanhaecht Kris , De Witte Karel , Depreitere Roeland , Van Zelm Ruben , De Bleser Leentje , Proost Karin , Sermeus Walter
Published: July 2007

Clinical pathways are used as a method of organizing care processes. Although they are used worldwide, the concept remains unclear, with little understanding of what exactly is being implemented. A recent systematic review revealed that, although a tool exists to score the instrumental qualities of clinical pathways, no tools are available to assess how the clinical pathway influences the process of care. These tools are needed for a better understanding of the impact of clinical pathways on the length of hospital stay and patient outcomes. In this study, a Care Process Self-Evaluation Tool (CPSET), based on the clinical pathway concept, for assessing the organization of the process of care has been developed and tested. Qualitative and quantitative methods, involving 885 professionals and patients, were used in the development and validation. The CPSET is a valid and reliable 29-item instrument for assessing how the process of care is organized. The CPSET has five subscales: patient-focused organization, coordination of care, communication with patients and family, cooperation with primary care and monitoring/follow-up of the care process. The CPSET can be used in the audit and accreditation of care processes and will help managers and clinicians to understand better how care processes are organized.
Multisource feedback: 360-degree assessment of professional skills of clinical directors
Authors: Palmer Robert , Rayner Hugh , Wall David
Published: July 2007

For measuring behaviour of National Health Service (NHS) staff, 360-degree assessment is a valuable tool. The important role of a clinical director as a medical leader is increasingly recognized, and attributes of a good clinical director can be defined. Set against these attributes, a 360-degree assessment tool has been designed. The job description for clinical directors has been used to develop a questionnaire sent to senior hospital staff. The views of staff within the hospital are similar irrespective of gender, post held or length of time in post. Analysis has shown that three independent factors can be distilled, namely operational management, interpersonal skills and creative/strategic thinking. A simple validated questionnaire has been developed and successfully introduced for the 360-degree assessment of clinical directors.