bluuebunny/crossref_metadata_2025 huggingface dataset:
Interspecies Transmission of Simian Foamy Virus in a Natural Predator-Prey System
Authors: Leendertz Fabian H. , Zirkel Florian , Couacy-Hymann Emmanuel , Ellerbrok Heinz , Morozov Vladimir A. , Pauli Georg , Hedemann Claudia , Formenty Pierre , Jensen Siv Aina , Boesch Christophe , Junglen Sandra
Published: May 2008

Simian foamy viruses (SFV) are ancient retroviruses of primates and have coevolved with their host species for as many as 30 million years. Although humans are not naturally infected with foamy virus, infection is occasionally acquired through interspecies transmission from nonhuman primates. We show that interspecies transmissions occur in a natural hunter-prey system, i.e., between wild chimpanzees and colobus monkeys, both of which harbor their own species-specific strains of SFV. Chimpanzees infected with chimpanzee SFV strains were shown to be coinfected with SFV from colobus monkeys, indicating that apes are susceptible to SFV superinfection, including highly divergent strains from other primate species.
Limited Maintenance of Vaccine-Induced Simian Immunodeficiency Virus-Specific CD8 T-Cell Receptor Clonotypes after Virus Challenge
Authors: Smith Miranda Z. , Asher Tedi E. , Venturi Vanessa , Davenport Miles P. , Douek Daniel C. , Price David A. , Kent Stephen J.
Published: May 2008

T-cell receptors (TCRs) govern the specificity, efficacy, and cross-reactivity of CD8 T cells. Here, we studied CD8 T-cell clonotypes from
Mane-A*10
+
pigtail macaques responding to the simian immunodeficiency virus (SIV) Gag KP9 epitope in a setting of vaccination and subsequent viral challenge. We observed a diverse TCR repertoire after DNA, recombinant poxvirus, and live attenuated virus vaccination, with none of 59 vaccine-induced KP9-specific TCRs being identical between macaques. The KP9-specific TCR repertoires remained diverse after SIV or simian-human immunodeficiency virus challenge but, remarkably, exhibited substantially different clonotypic compositions compared to the corresponding populations prechallenge. Within serial samples from individual pigtail macaques, only a small subset (33.9%) of TCRs induced by vaccination were maintained or expanded after challenge. Most (66.1%) of the TCRs induced by vaccination were not detectable after challenge. Our results suggest that some CD8 T cells induced by vaccination are more efficient than others at responding to a viral challenge. These findings have implications for future AIDS virus vaccine studies, which should consider the “fitness” of vaccine-induced T cells in order to generate robust responses in the face of virus exposure.
Suppression of Astrovirus Replication by an ERK1/2 Inhibitor
Authors: Moser Lindsey A. , Schultz-Cherry Stacey
Published: May 2008

Human astroviruses are nonenveloped, positive-sense single-strand RNA viruses associated with self-limiting diarrhea. Although they are recognized as a leading cause of disease in young children, the cellular factors involved in astrovirus replication are not well defined. The extracellular signal-regulated kinase (ERK) pathway has been shown to regulate many viral infections, but its role during astrovirus infection is unknown. In this report, we show that astrovirus activates ERK1/2 early in infection independently of replication. Inhibition of ERK activation with U0126, a specific ERK inhibitor, significantly reduced viral production. Investigations into the mechanism of ERK1/2 regulation revealed that all steps of the viral life cycle, including early and late protein expression as well as subgenomic and genomic RNA transcription, were diminished during U0126 treatment of monolayers. These data support a role for ERK1/2 in a postattachment step, although the precise mechanism remains under investigation.
Murine Gammaherpesvirus 68 Open Reading Frame 75c Tegument Protein Induces the Degradation of PML and Is Essential for Production of Infectious Virus
Authors: Ling Paul D. , Tan Jie , Sewatanon Jaturong , Peng RongSheng
Published: May 2008

Promyelocytic Leukemia nuclear body (PML NB) proteins mediate an intrinsic cellular host defense response against virus infections. Herpesviruses express proteins that modulate PML or PML-associated proteins by a variety of strategies, including degradation of PML or relocalization of PML NB proteins. The consequences of PML-herpesvirus interactions during infection in vivo have yet to be investigated in detail, largely because of the species-specific tropism of many human herpesviruses. Murine gammaherpesvirus 68 (γHV68) is emerging as a suitable model to study basic biological questions of virus-host interactions because it naturally infects mice. Therefore, we sought to determine whether γHV68 targets PML NBs as part of its natural life cycle. We found that γHV68 induces PML degradation through a proteasome-dependent mechanism and that loss of PML results in more robust virus replication in mouse fibroblasts. Surprisingly, γHV68-mediated PML degradation was mediated by the virion tegument protein ORF75c, which shares homology with the cellular formylglycinamide ribotide amidotransferase enzyme. In addition, we show that ORF75c is essential for production of infectious virus. ORF75 homologs are conserved in all rhadinoviruses but so far have no assigned functions. Our studies shed light on a potential role for this unusual protein in rhadinovirus biology and suggest that γHV68 will be a useful model for investigation of PML-herpesvirus interactions in vivo.
DFT and Docking Study of Potential Transition State Analogue Inhibitors of Glycosyltransferases
Authors: Sihelniková Lucie , Kozmon Stanislav , Tvaroška Igor
Published: May 2008

Conformational behavior of the [(2S,3R,4R,5S)-3,4,5-trihydroxy-2-(phenylsulfanyl)tetrahydrofuran-2-yl]methyl sulfate anion (2), which is the potential transition state (TS) analogue of the inverting glycosyltransferases, was studied by means of two-dimensional potential-energy maps, using a density functional theory method at the B3LYP/6-31+G* level. The maps revealed the presence of eight low-energy domains which were refined at the B3LYP/6-311++G** level and led to six conformers in vacuum. In aqueous solution, two conformers dominate at equilibrium. The preferred conformers superimpose well with the transition state structure, as determined previously for glycosyltransferase GnT-I. The conformations of 2 in the active site of glycosyltransferase GnT-I were obtained by docking methods. It was found that one of the two best docking poses mimics the binding mode of TS. These results suggest that the proposed TS mimics 2 have the potential to be used as a scaffold for the design of TS analogue inhibitors.
L-Fucose in Crystal Structures of IgG-Fc: Reinterpretation of Experimental Data
Authors: Kolenko Petr , Skálová Tereza , Dohnálek Jan , Hašek Jindřich
Published: May 2008

Glycosylation of IgG-Fc plays an important role in the activation of the immune system response. Effector functions are modulated by different degrees of deglycosylation of IgG-Fc. However, the geometry of oligosaccharides covalently bound to IgG-Fc does not seem to be in good agreement with electron density in most of the structures deposited in the Protein Data Bank. Our study of correlation between the oligosaccharide geometry, connectivity, and electron density shows several discrepancies, mainly for L-fucose. Revision of refinement of two structures containing the Fc-fragment solved at the highest resolution brings clear evidence for α-L-fucosylation instead of β-L-fucosylation as it was claimed in most of the deposited structures in the Protein Data Bank containing the Fc-fragment, and also in the original structures selected for re-refinement. Our revision refinement results in a decrease in R factors, better agreement with electron density, meaningful contacts, and acceptable geometry of L-fucose.
Moral principles and medical practice: the role of patient autonomy in the extensive use of radiological services
Authors: Hofmann B , Lysdahl K B
Published: May 2008

There has been a significant increase in the use of radiological services in the past 30 years. There are many reasons for this, but one has received little attention: the increased role of patient autonomy in healthcare. Patients demandxrays, CT scans, MRI, and positron emission tomography scans. The key question in this article is how a moral principle, such as respect for patient autonomy, can influence the extension of radiological services. A literature review reveals how patient autonomy is acknowledged in radiology, and how it is used both to explain and to justify the increase in radiological examinations. Furthermore, it also shows how the premises favouring patients’ exercise of their autonomy are not always present, which makes patient autonomy subject to adverse side effects and even abuse. Patient autonomy can be used to reduce the professionals’ responsibility for radiological examinations (by avoiding complaints and lawsuits), to increase the popularity of the profession (by giving the people what they want), to increase the income of the professionals or their institutions, and to promote professional activity. Patient autonomy intended to reduce paternalism, to legitimise otherwise morally unjustifiable actions (such as exposure to radiation), and to protect patients, can easily be used as a moral means for opposite ends. These adverse effects are not peculiar to radiology. However, they emerge particularly clearly in explanations and justifications of the substantial increase in radiological services, as well as in debates on overuse of radiological services.
Genes, race and research ethics: who’s minding the store?
Authors: Hunt L M , Megyesi M S
Published: May 2008

Background:

The search for genetic variants between racial/ethnic groups to explain differential disease susceptibility and drug response has provoked sharp criticisms, challenging the appropriateness of using race/ethnicity as a variable in genetics research, because such categories are social constructs and not biological classifications.

Objectives:

To gain insight into how a group of genetic scientists conceptualise and use racial/ethnic variables in their work and their strategies for managing the ethical issues and consequences of this practice.

Methods:

In-depth semi-structured interviews were conducted with a purposive sample of 30 genetic researchers who use racial/ethnic variables in their research. Standard qualitative methods of content analysis were used.

Results:

Most of the genetic researchers viewed racial/ethnic variables as arbitrary and very poorly defined, and in turn as scientifically inadequate. However, most defended their use, describing them as useful proxy variables on a road to “imminent medical progress”. None had developed overt strategies for addressing these inadequacies, with many instead asserting that science will inevitably correct itself and saying that meanwhile researchers should “be careful” in the language chosen for reporting findings.

Conclusions:

While the legitimacy and consequences of using racial/ethnic variables in genetics research has been widely criticised, ethical oversight is left to genetic researchers themselves. Given the general vagueness and imprecision we found amongst these researchers regarding their use of these variables, they do not seem well equipped for such an undertaking. It would seem imperative that research ethicist move forward to develop specific policies and practices to assure the scientific integrity of genetic research on biological differences between population groups.
A pilot study of bullying and harassment among medical professionals in Pakistan, focussing on psychiatry: need for a medical ombudsman
Authors: Gadit A A M , Mugford G
Published: May 2008

Background:

The magnitude of bullying and harassment among psychiatrists is reportedly high, yet no peer-review published studies addressing this issue could be found. Therefore, it was decided to conduct a pilot study to assess the degree of the problem, the types of bullying/harassment and to provide some insights into the situation.

Methods and Principal Findings:

Following multiple focus group meetings, a yes/no response type questionnaire was developed to assess the degree and type of bullying and harassment experienced by psychiatrists. Over a 3-month period the questionnaire was administered to a random sample of 60 psychiatrists. 57 out of the 60 psychiatrists reported harassment and bullying. Frequencies of the following response variables are presented in descending order: rumours 40% (n  =  24); defamation 20% (n  =  12); passing remarks 20% (n  =  12); false accusations 15% (n  =  9); threats 13.3% (n  =  8); verbal abuse 13.3% (n  =  8); unjustified complaints 13.3% (n  =  8); promotion blocked 13.3% (n  =  8); humiliation 13% (n  =  8); bad reference given 10% (n  =  6); credentials questioned 8.3% (n  =  5); physical attacks 5% (n  =  3); termination 5% (n  =  3); derogatory remarks 1.7% (n  =  1) and 1.7% (n  =  1) were subjected to personal work. As a result of being subjected to harassment, 66.7% of the psychiatrists did not take any action, whereas 33.3% confronted the person(s) they believed responsible. Asked whether the bullying and harassment caused distress, 18.3% of the psychiatrists did not report any effect, 30% reported mild distress, 40% moderate distress and severe distress was reported by 11.7%.

Conclusions:

It was concluded that the magnitude of bullying and harassment among psychiatrists may be quite high, as evidenced by this pilot study. There is a need for extensive systematic studies on this subject and to establish strategies to prevent and address this issue at a national and regulatory level.
Medically valid religious beliefs
Authors: Bock G L
Published: May 2008

Patient requests for “inappropriate” medical treatment (violations of the standard of care) based on religious beliefs should have special standing. Nevertheless, not all such requests should be honored, because some are morally disturbing. The trouble lies in deciding which ones count. This paper proposes criteria that would qualify a religious belief asmedically validto help physicians decide which requests to respect. The four conditions suggested are that the belief (1) is shared by a community, (2) is deeply held, (3) would pass the test of a religious interpreter and (4) does not harm others.
The “future like ours” argument and human embryonic stem cell research
Authors: Kuflik A
Published: May 2008

The most closely argued and widely discussed case against abortion in the philosophical literature today is Don Marquis’s “future like ours” argument. The argument moves from an analysis of why there is a serious presumption against killing someone “like us” to the conclusion that most abortions are seriously wrong for the same reason: they deprive “an individual” of a future of valuable experiences and activities, a “future like ours”. Julian Savulescu has objected that “preventing” such a future could not be as seriously presumptively wrong as Marquis contends for if it were, even contraception and failure to engage in reproductive cloning would be seriously presumptively wrong. Savulescu maintains that there is only a modest presumption against preventing a “future of value like ours” and that in the case of human embryonic stem cell research, it is clearly outweighed by “the enormous potential to save people’s lives and to improve their quality of life”. Marquis defends his strong anti-abortion stance against Savulescu’s “contraception” and “failure to clone” objections but surprisingly says nothing about the implications of the “future like ours” argument for the controversy surrounding human embryonic stem cell research. I argue that key features of Marquis’s response actually support the view that embryos used in stem cell research are not included within the protective scope of the “future like ours” argument. It is significant that the most philosophically rigorous anti-abortion case thus far presented does not entail that human embryonic stem cell research is even presumptively wrong.
Putting it bluntly: communication skills in theIliad
Authors: Marshall R J , Bleakley A
Published: May 2008

In current undergraduate medical curricula, much emphasis is placed on learning the skills of communication. This paper looks at Homer’sIliadand argues that from it we may learn that our skills can be mechanistic, shallow and simplistic. Homer was regarded in the Greek and Roman world as the father of rhetoric. This reputation rested greatly on book 9 of theIliad, the embassy from the Greek leaders to the bitter, wrathful Achilles. The mission of the three emissaries is to persuade him to return to the ranks of the Greeks, who are being routed since his refusal to fight. We learn how the outcome of a conversation may be predetermined by the previous relationship of the speakers, and how a man beyond reason responds to reason; we should reflect that Homer’s audience heard the piece knowing the outcome, giving it a tragic inevitability. We, the audience, cannot analyse the discourse rationally, because in this, as in all communication, reason is disturbed by emotion.
Being Lister: ethos and Victorian medical discourse
Authors: Connor J J , Connor J T H
Published: May 2008

Stylistic analysis and rhetorical theory are used in this study to inform our understanding of impediments to the successful uptake of a new medical idea. Through examination of the work of the Victorian surgeon Joseph Lister, who was described by one biographer as suffering from “stylistic ham-handedness”, the study provides insights into the difficulty that Lister had in explaining his theory of antiseptic surgery. Using three comparisons—Lister’s scientific style in public discourse with that of his students, and Lister’s scientific style in private discourse with those of both a surbordinate and a superior—the study suggests that the rhetorical concept of ethos played a major role in his communication difficulties. In this way, it presents a more nuanced perspective on modern presentations of “model” communications versus communication failures: that is, that problematic written discourse offers as useful a heuristic device as does exemplary discourse.
Statistical Interrelation of Length, Growth, and Scale Circulus Spacing: Use of Ossification to Detect Nongrowing Fish
Authors: Talbot André J. , Doyle Roger W.
Published: May 2008

Estimates of growth over a short period are often difficult to obtain from fish unless individuals are tagged or experimental conditions are highly controlled. We demonstrate that the outer edge of scales (the osseoid layer) in tilapia (Oreochromis sp.) can be used to recognize nongrowing fish. We measured the width of the osseoid tissue at various positions of the anterior edge of the scale as well as inward to the first circulus on the edge of the scale in fed and starved fish. Our results indicated that response of the osseoid layer to growth rates occurred in 1 wk or less. Discriminant analysis based solely on osseoid variables classified over 84% of ail fish correctly on the basis of the feeding treatment after 8 d of growth. This technique was field-tested in cage-cultured tilapia in Java, Indonesia. We were able to classify correctly 86% of the growing and nongrowing fish in the population after a 21-d period. These measurements can supplement the information collected from the spacing of circuli on the calcified portion of the scale to completely specify the recent growth history of individual fish.
Bioavailability of Polychlorinated Dibenzo-p-dioxins in Lake Enclosures
Authors: Servos Mark R. , Muir Derek C. G. , Webster G. R. Barrie
Published: May 2008

The bioavailability of 1,3,6,8-tetra- (T4CDD) and octachlorodibenzo-p-dioxin (O8CDD) was examined in large (40 m3) lake enclosures at the Experimental Lakes Area in northwestern Ontario. The polychlorinated dioxins (PCDDs) were added to replicate enclosures as a sediment slurry at a nominal concentration of 58–59 ng∙L−1. T4CDD was more bioavailable to caged benthic invertebrates and fish (white sucker, Catostomus commersoni) than O8CDD immediately after the addition to the enclosures. However, as the concentration of T4CDD in the water column rapidly declined, the bioavailability of T4CDD also declined. Sorption of PCDD to organic matter and rapid partitioning to sediments might have reduced the uptake of PCDDs directly from the water column. Accumulation of PCDDs in biota appeared to shift from direct equilibrium partitioning during the first few days, when the concentrations in the water column were relatively high, to a detrital food chain transfer as the freely available PCDDs in the water declined. This conclusion is supported by the results of the simple, four-compartment food chain model of Thomann and Connolly based on the uptake kinetics of PCDDs from water and food.
Evolution of Lake Whitefish (Coregonus clupeaformis) in North America during the Pleistocene: Evidence for a Nahanni Glacial Refuge Race in the Northern Cordillera Region
Authors: Foote C. J. , Clayton J. W. , Lindsey C. C. , Bodaly R. A.
Published: May 2008

Lake whitefish (Coregonus clupeaformis) could have survived through (at least) the Illinoisan and Wisconsinan Pleistocene glacial maxima in an area in the vicinity of the present Nahanni National Park in the Northwest Territories of Canada according to the geological evidence. This possibility was addressed by an analysis of the genetic makeup of 43 lake whitefish populations in the Northwest Territories, the Yukon Territory, British Columbia, and Alberta. Populations in the lower Liard, Tetcela, Fraser, and upper Peace River systems as well as the headwaters of the Athabasca River were distinguished from both the Bering glacial refuge race populations inhabiting the Yukon and upper Liard River basins in the Yukon Territory and the Mississippi–Missouri glacial refuge race populations inhabiting most of the Northwest Territories, Alberta, and areas further to the east by a specific combination of electrophoretic mobility alleles. This evidence supports the hypothesis of the survival and subsequent dispersal of lake whitefish from a Nahanni glacial refugium. Possible dispersal routes and the limited extent of introgression among races are discussed.
Use of Dissolved Strontium in Scale Marking of Juvenile Salmonids: Effects of Concentration and Exposure Time
Authors: Snyder Randal J. , McKeown Brian A. , Colbow Konrad , Brown Robert
Published: May 2008

Strontium (Sr), which is chemically similar to calcium and can substitute for this element in bony tissues of fishes, shows promise as an inexpensive and efficient means of chemically marking juvenile salmonids. This study examines the effects of three different Sr concentrations in water (1.8, 3.6, and 5.4 mg/L) and two different exposure times (30 and 60 d) on uptake of Sr into the scales of juvenile rainbow trout (Oncorhynchus mykiss). Doubling and tripling the Sr concentration in the ambient water produced corresponding twofold and threefold increases in final scale (Sr). A twofold increase in exposure time produced nearly the same effect as a twofold increase in concentration. Widespread adoption of this technique will require establishment of optimal concentration and exposure times, validation of methods for compensating for Sr incorporated during seawater residence, and development of hatchery-specific chemical markers using combinations of several different elements.
Effectiveness of Selected Stream Improvement Techniques to Create Suitable Summer and Winter Rearing Habitat for Juvenile Coho Salmon (Oncorhynchus kisutch) in Oregon Coastal Streams
Authors: Nickelson Thomas E. , Solazzi Mario F. , Johnson Steven L. , Rodgers Jeffrey D.
Published: May 2008

We examined the use of constructed pools by juvenile coho salmon (Oncorhynchus kisutch) during summer and winter. Log, gabion, and rock structures placed across the full stream width provided good summer habitat but poor winter habitat for juvenile coho salmon. Rearing densities in constructed habitats during summer and winter were generally similar to those in natural habitats of the same type, except that constructed dammed pools supported lower densities during winter than natural dammed pools. The addition of brush bundles to pools created by full-stream-width structures increased the density of juvenile coho salmon in dammed pools during winter, but not in plunge pools. We concluded that the development of off-channel habitat has the greatest potential to increase production of wild coho salmon smolts in Oregon coastal streams.
Commercial Troll Fishing Vessel Distribution off Vancouver Island during July 1988: Relation to Observed Physical Oceanography
Authors: Thomson Richard E. , Healey Michael C. , Morris John F. T. , Borstad Gary A.
Published: May 2008

We compare distributions of salmon troll fishing vessels obtained using navigational radar observations off southwestern Vancouver Island in mid-July 1988 with the circulation and water property structure derived from concurrent oceanic measurements. Results support the hypothesis that vessels aggregate in clusters within the transition zone formed between the upwelling-induced shelf-break current and buoyancy-driven Vancouver Island coastal current. Dense clusters of vessels within this zone appear to be coincident with mesoscale (10 km) circulation features embedded in the large-scale (100 km) coastal upwelling regime. In all instances, the association of vessel aggregations and oceanic circulation illustrates a response of the salmon to local oceanographic conditions. The circulation features presumably correspond to upwelling-enriched regions with high food organism densities that attract aggregations of salmon.
The Prediction of Consolidation Rates in a Cemented Clay
Authors: Walker L. K , Raymond G P
Published: May 2008

The principal aim of this paper is to compare laboratory settlement and pore pressure dissipation rates of undisturbed Leda clay with those predicted from a modified consolidation theory developed by Raymond (1966a). The theoretical curves have been computed using directly measured values of the soil permeability and incorporate the variation with void ratio of both permeability and compressibility. The experimental data (obtained from the triaxial apparatus) indicate that the predicted rates of consolidation, and especially of pore water dissipation, are likely to be grossly in error owing to the cemented nature of the soil structure. This factor appears to be partially described by the theory of Barden (1965), although quantitative evaluation of the constants involved in this theory has not been possible.The paper also considers two other aspects of the consolidation of Leda clay. (1) The rate of secondary consolidation varies significantly with consolidation pressure and appears to reflect the changes in compressibility revealed by the void ratio vs. log pressure curve. (2) The variation of soil properties with depth at the Ottawa treatment plant site influences all aspects of the consolidation behaviour of the clay.Available field data have been included in the paper where relevant to the discussion.
Analysis of slope stability at Goonyella Mine
Authors: Richards B. G. , Coulthard M. A. , Toh C. T.
Published: May 2008

Since the commencement of mining at the strip coal mine at Goonyella, Queensland, Australia, serious stability problems have been experienced in both the spoil piles and the highwalls. A collaborative investigation was commenced in 1974 and the significant factors influencing stability have now been defined. This paper outlines the results of field and laboratory studies associated with the investigation and describes the various numerical methods used to analyse stability. The main conclusions, which are similar for both the spoil piles and the highwalls, are that the failures generally occur along two or three planar surfaces; that the shear strength in the basal areas is controlled by the sensitivity of the materials to moisture and shear strain prior to failure; and that tensile cracking due to stress relief and blasting is the dominant factor in the upper or escarpment areas. Possible control and remedial measures are discussed briefly.
The behaviour of footings resting on a non-homogeneous soil mass with a crust. Part I. Strip footings
Authors: Rowe R. K. , Booker J. R.
Published: May 2008

A convenient and economical finite layer method of analysing the behaviour of footings on a non-homogeneous soil is outlined. This method of analysis is used to investigate the elastic response of strip footings for a wide range of soil profiles involving a weathered crust overlying a main deposit. The stiffness of the crust is considered to be either constant or to decrease with depth while the stiffness of the underlying deposit increases with depth.The effect of layer depth, crust depth, and the rate of variation of stiffness within the crust and the underlying soil are examined. The influence of this non-homogeneity upon settlement profile, differential settlement, and consolidation settlement are discussed and the results obtained from this detailed analysis are compared with results obtained from the approximate use of existing homogeneous elastic solutions.The results of this study are presented in the form of influence charts which may be used in hand calculations to estimate the settlement of footings for a wide range of practical cases. The applicability of the solutions and the determination of soil parameters is briefly discussed.
The behaviour of footings resting on a non-homogeneous soil mass with a crust. Part II. Circular footings
Authors: Rowe R. K. , Booker J. R.
Published: May 2008

The behaviour of circular footings resting on a non-homogeneous elastic soil with a crust is investigated. The stiffness of the crust is assumed to be either constant or to decrease with depth, whereas the stiffness of the underlying soil increases linearly with depth.Consideration is given to the effect of layer depth, crust depth, and the rate of variation of stiffness within the crust and the underlying soil upon the settlement profile. The behaviour of circular footings is then compared with that of strip footings and the relative importance of the crust and the underlying soil parameters is discussed.The influence of cross-anisotropy upon footing response is briefly examined and the effects of neglecting anisotropy are indicated for a number of soil profiles.The results of this study are presented in the form of influence charts which may be used in hand calculations to estimate the settlement of circular footings for a wide range of practical cases. The use of these charts is illustrated by means of a worked example.
Micromechanisms of deformation in fracture of overconsolidated clays
Authors: Chudnovsky Alexander , Saada Adel , Lesser Alan J.
Published: May 2008

The geotechnical engineering profession is quite familiar with stiff fissured and jointed clays where discontinuities are found on a macroscopic scale. However, there has not been, until recently, a systematic investigation of the crack propagation phenomena involved in the failures of such clays. This paper presents the first phase of an investigation whose aim is to understand, describe, and quantify the mechanisms involved in crack propagation. The experimental investigation indicates that, in a mode II type of fracture, a well-defined damage zone propagates in front of the crack. In this zone, the structure of the clay is shown to be substantially altered. The damage is quantitatively characterized and a thermodynamic approach to the analysis of crack and damage propagation is suggested. Key words: stiff clay, fracture, crack layer, damage zone, strip densification.
The performance of longwall gate roads with soft floors
Authors: Afrouz A. , Hassani F. P. , Scoble M. J.
Published: May 2008

This work stems from field studies of convergence within gate roads leading to three longwall coal faces with different strata and mining conditions. The influence of production on the stability of these roads is illustrated. Empirical time-dependent equations are developed to express and predict the behaviour of the roadways. The particular contribution of the roadway floor and sides to the total closure of the gate roads has also been investigated. The mode of deformation and failure, observed by scanning electron microscopy within the immediate vicinity of underground gate roads, is also described. The application of this analysis is in the planning of production panels in soft tabular deposits, the dimensioning of gate roads, and the stability and performance prediction of such roadways and their supports. Key words: soft mine floors, longwall mining, gate road stability, coal roads, soft underclay floors.
Design and performance evaluation of vertical shafts: rational shaft design method and verification of design method
Authors: Wong R. C. K. , Kaiser P. K.
Published: May 2008

Ground deformations around axisymmetric shafts cannot be determined with the design approaches currently available, which are mostly based on plasticity methods. The convergence–confinement method (usually applied to tunnels), with consideration of gravitational effects and the three-dimensional conditions near a shaft, is proposed as a tool to predict formation pressure on a shaft and radial ground displacements. It is shown that the behaviour of a shaft is governed by (1) the mode of yield initiation dominated by the in situ stress state and the soil strength parameters and (2) the extent of the yield zone that develops if wall displacements are allowed to occur during construction.Closed-form solutions are presented to approximate the pressure–displacement relationship for cohesionless and cohesive soils. Results from this approach compare well with those obtained by finite element analyses. The conventional design methods that provide the minimum support pressures required to maintain stability are not conservative. These pressures are generally less than those actually encountered if ground movements during construction are restricted with good ground control. Key words: shaft, design method, support, interaction, yielding, stress, displacement, earth pressure, arching.
Effects of reinforcing elements on the behavior of weakly cemented sands
Authors: Li Loretta , Mitchell Robert
Published: May 2008

Plane strain test results from weakly cemented sand samples with various types of reinforcement inclusions are reported. Mesh and anchored fibre types of reinforcements are shown to more than double the plane strain shear strength of a 33:1 sand–cement mixture. Other types of inclusions were not as effective, with some actually producing a strength decrease. All inclusions increased the ductility of this weakly cemented sand, allowing the material to absorb strains of 4–6% rather than the 0.5 – 1% of failure strain in the unreinforced material. The application of reinforcements to cemented tailings used for mine backfill is briefly discussed. Key words: reinforced backfill, cemented sand, behavior, mining.
ADAPTIVE COMMUNICATION ARCHITECTURES FOR RUNTIME RECONFIGURABLE SYSTEM-ON-CHIPS
Authors: PIONTECK THILO , ALBRECHT CARSTEN , KOCH ROMAN , MAEHLE ERIK
Published: May 2008

For exploiting the inherent parallelism enclosed in System-on-Chip designs, special architectural prerequisites have to be met. These prerequisites mainly affect the communication infrastructure, as parallel processing of all hardware modules accounts for a continuous and sufficient provision of data. While traditional communication architectures may fulfill these requirements for a fixed System-on-Chip design, changing composition, number and locations of processing modules in runtime reconfigurable System-on-Chips require new communication paradigms. Special communication architectures especially for use in runtime reconfigurable System-on-Chip designs are presented in this article. Their analysis provides a basis for the design of CoNoChi, a runtime reconfigurable Network-on-Chip dedicated for the usage in FPGA-based designs. CoNoChi supports the adaptation of the network topology during runtime by providing mechanisms to add or remove switches from the network during runtime without stopping or stalling the network. The applicability of CoNoChi is shown on the basis of a complex runtime reconfigurable System-on-Chip for networking applications. Prototyping results demonstrate that CoNoChi is a promising alternative to existing communication architectures supporting both a high degree of adaptability during runtime and a high concurrency of data transfers.
AN ORDER DEGREE ALTERNATOR FOR ARBITRARY TOPOLOGIES
Authors: HADDIX F. FURMAN
Published: May 2008

An alternator is an arbitrary set of interacting processes that satisfies three conditions. First, if a process executes its critical section, then no neighbor of that process can execute its critical section at the same state. Second, along any infinite sequence of system states, each process will execute its critical section, an infinite number of times. Third, along any maximally concurrent computation, the alternator will stabilize to a sequence of states in which the processes will execute their critical sections in alternation. A principal reason for interest in alternators is their ability to transform systems correct under serial execution semantics to systems that are correct under concurrent execution semantics. An earlier alternator for arbitrary topology required 2q states where q is the dependency graph circumference and after stabilization would wait 2q steps between critical section executions. In a synchronous environment, this alternator requires only 2d+1 states where d is the degree of the graph of process dependencies for the system and after stabilization will require a wait of 2d+1 steps between critical section executions. In an asynchronous environment, the synchronization properties of this alternator must be supplemented with an asynchronous unison algorithm. The asynchronous unison algorithm requires expansion of the required number of states to dt, where t is the longest chordless cycle in the dependency graph; however, the required wait between critical section executions remains O(d).
CADMIUM TELLURIDE NANOCRYSTALS: SYNTHESIS, GROWTH MODE AND EFFECT OF REACTION TEMPERATURE ON CRYSTAL STRUCTURES
Authors: QI XIAO-YING , PU KAN-YI , FANG CHUN , FAN QU-LI , TANG DUO-FENG , WEN GUI-AN , BOEY FREDDY Y. C. , ZHANG HUA , WANG LIAN-HUI , HUANG WEI
Published: May 2008

A series of cadmium telluride (CdTe) nanocrystals were synthesized by a modified organometallic synthesis method at various reaction temperatures ranging from 130 to 250°C. In this method, octadecylamine (ODA) was introduced as an additional coordinating component to the mixture of trioctylphosphine oxide (TOPO) and trioctylphosphine (TOP). CdO was used as a precursor. The prepared CdTe nanocrystals were studied by the absorption and emission spectra as well as the powder X-ray diffraction (XRD) patterns. The result shows that besides the traditional continuous-growth mode observed frequently at relatively high reaction temperature, a discontinuous-growth mode was confirmed at the initial growth stage of CdTe nanocrystals, arising from the change of the absorption spectra of CdTe nanocrystals with the reaction time at relatively low reaction temperature. The structures of CdTe nanocrystals, e.g., the cubic zinc blende structure at 160°C and the hexagonal wurtzite structure at 250°C, were characterized by XRD.
ELECTRIC-FIELD DEPENDENCE OF MOLECULAR CONFORMATIONS OBSERVED BY USING SCANNING TUNNELING MICROSCOPY
Authors: MA XIAO JING , ZHANG RUI , SHEN YONG TAO , QIU XIAO HUI , YANG YAN LIAN , WANG CHEN
Published: May 2008

We review the progress in observation of electrically induced conformational changes of a range of single molecules and molecular assemblies using scanning tunneling microscopy (STM). Recent results using species with optical active functional groups and supramolecular structures confirmed the previously observed effects that the cholesterol molecules with soft linkers have the conformational bistability when switching the bias polarity, while no discernable changes were observed for the mesogen molecules, containing rigid linking units. In addition, it was also observed that the linker units could have appreciable impacts on the assembling characteristics.
INTER-LAYER INTERACTION IN DOUBLE-WALLED CARBON NANOTUBES EVIDENCED BY SCANNING TUNNELING MICROSCOPY AND SPECTROSCOPY
Authors: GIUSCA CRISTINA E. , TISON YANN , SILVA S. RAVI P.
Published: May 2008

Scanning Tunneling Microscopy and Spectroscopy have been used in an attempt to elucidate the electronic structure of nanotube systems containing two constituent shells. Evidence for modified electronic structure due to the inter-layer interaction in double-walled carbon nanotubes is provided by the experimental tunneling spectra and the contribution of the inner tube to the local density of states of the "composite" double-walled system is identified in agreement with previous theoretical calculations. An explicit correlation between the chirality of the two constituent tubes, the inter-wall interaction and the overall electronic structure for double-walled carbon nanotubes, is demonstrated by our experiments, showing that the effect the inner tube has on the overall electronic structure of double-walled nanotubes cannot be neglected, and is key to the opto-electronic properties of the system. We postulate that previous analysis of the opto-electronic properties on multiple-walled carbon nanotubes based purely on the outer layer chirality of the tube needs significant modification based on new understanding brought forth with our analysis.
Tectonic significance of carbonatite and ultrahigh-pressure rocks in the Pan-African Dahomeyide suture zone, southeastern Ghana
Authors: Attoh Kodjopa , Nude Prosper M.
Published: May 2008

The association of carbonatite and ultrahigh-pressure (UHP) metamorphic rocks in the Dahomeyide suture zone of southeastern Ghana is unique among the Neoproterozoic orogens that surround the West African craton (WAC). Carbonatite occurs in an alkaline complex that decorates the sole thrust of the suture zone and is characterized by high concentrations of incompatible trace elements such as light rare earth elements (LREE), Sr and Ba. Within the suture zone deformed alkaline rocks, including carbonatite, together with mafic granulites form an imbricate stack of thrust panels that involve 2.1 Ga rocks of the WAC basement. The dominant rock unit of the suture zone is composed of mafic granulites in which garnet megacrysts preserve a diagnostic microstructure of UHP metamorphism; it consists of a crystallographically controlled array of exsolved rutile rods in garnet. Metamorphic pressures estimated from Ti concentrations in the inferred precursor garnet indicate
P
>3 GPa, which requires subduction (and exhumation) of the suture zone rocks to and from mantle depths during collisional orogeny on the WAC margin. Available age constraints on carbonatite magmatism suggest that continental rifting, leading to the formation of the passive WAC margin
c
. 700 Ma, occurred
c
. 100 Ma before intrusion of carbonatite, which was preceded by HP and UHP metamorphism at 610±5 Ma.
Petrogenesis and geodynamic evolution of the Late Neoproterozoic post-collisional felsic magmatism in NE Afyon area, western central Turkey
Authors: Gürsu S. , Goncuoglu M. C.
Published: May 2008

In western Turkey, Late Neoproterozoic basement rocks are represented by variably deformed metasedimentary and meta-igneous rocks within different tectonostratigraphical units that make up the Alpine Tauride–Anatolide Platform. In the Kütahya–Bolkar Dagı unit to the NE of Afyon this basement mainly includes garnet-bearing mica schists intruded by metamorphic granitic rocks with relict porphyritic textures. The youngest zircon ages obtained from the granitic rocks by the single zircon evaporation method are 542±5.0 Ma on average, which correlate with the Late Pan-African–Cadomian granitic magmatism. The granitic rocks are rhyodacitic or dacitic and peraluminous in composition, and display geochemical characteristics of I-type (tonalite–trondhjemite–granodiorite (TTG) source) felsic intrusive rocks. Trace and rare earth element patterns with distinct depletion in Rb, K, Nb, Sr, P and Ti relative to the other trace elements correlate very well with a Proterozoic TTG source. The petrogenetic modelling also implies that they were developed by partial melting of a TTG source by 20% fractional melting plus 20% Rayleigh fractional crystallization. The emplacement temperatures estimated by using zircon (790–820 °C), apatite and monazite saturation thermometry are about 827–1035 °C; these are in accordance with I-type rather than S-type granite melts. A geochemical comparison of the NE Afyon granitic rocks with the coeval quartz-porphyries in the Sandikli area of the Geyik Dag tectonic unit suggests that the latter may represent the more evolved felsic part of the Cadomian magmatism. Hence, both basement complexes are parts of the same Gondwanan terrane and represent the eastern continuation of the North African–Southern European terrane assemblage.
The ‘Rich’ group of the Drâa Basin (Lower Devonian, Anti-Atlas, Morocco): an integrated sedimentary and tectonic approach
Authors: Ouanaimi Hassan , Lazreq Nezha
Published: May 2008

In this study, based on a sedimentary analysis, an interpretation in terms of sequence stratigraphy is proposed for the ‘Rich’ group of the Early Devonian Drâa Basin (of Pragian to late Eifelian age). This group is composed of four depositional sequences (third order) containing a transgressive systems tract and a highstand systems tract, both deposited on a storm- and tide-dominated shelf. The depositional sequences are related to global sea-level changes but their geometric architecture is controlled by tectonic subsidence and by sediment supply. The basin forms an ENE–WSW channel with two internal high blocks acting on the depocentre shifts. The channel is surrounded by high points and by marine distal condensed series, and bordered by inherited various regional faulted axes. The regional setting corresponds to an extensional passive margin on the northern edge of the West African craton.