bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurement of boron impurity profiles in Si using glow discharge optical spectroscopy
Authors: Greene J. E. , Sequeda-Osorio F. , Streetman B. G. , Noonan J. R. , Kirkpatrick C. G.
Published: January 2004

Glow discharge optical spectroscopy (GDOS) has been applied to the measurement of impurity profiles in boron-diffused and ion-implanted Si samples. The GDOS technique provides a convenient and sensitive probe of boron impurity profiles; results are presented for concentrations below 5×1017 cm−3. For a Si sample which has been subjected to a 1-h constant source boron diffusion at 1100°C, the measured profile exhibited enhanced diffusion effects typical of previously reported results measured by other techniques. Similarly, a sample implanted with 120-keV B+ ions to a fluence of 1014 cm−2 exhibited a typical boron distribution. The position of the measured peak concentration corresponded well with that predicted by theory, and the implanted distribution exhibited a prominent tail as reported from other measurements.
Q switching and mode locking of CO2 laser with aromatic halogenated hydrocarbons
Authors: Izatt Jerald R. , Caudle George F. , Bean Brent L.
Published: January 2004

Passive Q switching of the CO2 laser by a new class of saturable absorbers is reported. Results are presented for eight representatives of this class: benzene, chlorobenzene, bromobenzene, m-dichlorobenzene o -dichlorobenzene, m -difluorobenzene, pentafluorobenzene, and hexafluorobenzene. These Q-switching agents operate on a large number of lines in both the 9.6- and 10.6-μ bands. Other aromatic halogens selected on the basis of their absorption spectra are expected to display similar Q-switch characteristics. This new class of saturable absorbers provides increased flexibility in the production of CO2 laser pulses.
Propagation of a high-intensity laser pulse with small-scale intensity modulation
Authors: Bliss E. S. , Speck D. R. , Holzrichter J. F. , Erkkila J. H. , Glass A. J.
Published: January 2004

For laser beams of large aperture with power far above the critical power for self-focusing, nonlinear propagation instabilities lead to the growth of small-scale variations in intensity and phase. We report measurements of the growth rate for interference fringes in unpumped ED-2 laser glass as a function of fringe spacing and intensity. Calculations based on the simplest form of linearized small-scale instability theory agree approximately with the measured rates, and a more complete linearized treatment predicts the growth rates within experimental error.
Vacuum ultraviolet holography
Authors: Bjorklund G. C. , Harris S. E. , Young J. F.
Published: January 2004

We report the first demonstration of holographic techniques in the vacuum ultraviolet spectral region. Holograms were produced with coherent 1182-Å radiation. The holograms were recorded in polymethyl methacrylate and examined with an electron microscope. A holographic grating with a fringe spacing of 836 Å was produced and far-field Fraunhofer holograms of submicron particles were recorded.
Metal-diffused optical waveguides in LiNbO3
Authors: Schmidt R. V. , Kaminow I. P.
Published: January 2004

Deposited films of transition metals (Ti, V, and Ni) have been diffused into LiNbO3 crystals to form low-loss TE and TM mode optical waveguides. Using Ti, single-mode low-loss waveguides which confine the guided light to within ∼1 μm of the surface have been constructed. The choice of diffusion parameters allows independent control of important waveguide parameters.
Electron energy distribution and excitation rate calculation in a discharge in CO–He system
Authors: Wu Frank T. , Yu Wai Mao , Lundstrom E. A.
Published: January 2004

The electron energy distribution function has been numerically determined from the Boltzmann equation for some typical discharge conditions in CO and its mixtures. Collisions of the second kind have also been incorporated in the equation and it is found that the consideration of the second kind of collisions is important when the upper states are highly excited. This is, indeed, the case for the laser active medium.
Mode locking of a TEA CO laser
Authors: Nurmikko A. V.
Published: January 2004

Forced mode locking of a TEA CO laser has been achieved on a number of vibrational-rotational transitions. Peak powers have been measured in excess of 1 kW with detector-limited pulsewidths in the nanosecond regime.
Phonon-assisted transitions to a temperature-independent deep level in Co–Si
Authors: Wong David C. , Penchina Claude M.
Published: January 2004

Photoconductivity has been studied in p-type and high-resistivity n-type silicon compensated by cobalt. Threshold energies of 0.505, 0.537, and 0.572 eV are observed to be independent of temperature within the experimental accuracy of ±2 meV. This is the first direct experimental evidence of the temperature independence of a deep level in Si. The photoconductivity which is stronger for p-type samples than for n type leads to its identification as a new deep level 0.521 eV ±2 meV from the valence band; the phototransitions are phonon assisted.
Coherent effects in large arrays of superconducting bridges
Authors: Palmer David William , Mercereau J. E.
Published: January 2004

Series arrays of nearly identical superconducting proximity effect bridges have been fabricated in Nb/Ta thin films. Arrays with up to 500 bridges respond cooperatively to incident radiation and produce voltage steps in response to incident 30–20 000-MHz radiation at V =(number of bridges in array)×(hν/2e).
Monolithic acoustic imaging transducer structures with high spatial resolution
Authors: Auld B. A. , Drake M. E. , Roberts C. G.
Published: January 2004

A method is described for simplifying the construction of high-resolution imaging transducers by using impedance matching transformers on a monolithic plate structure. Simple physical arguments are used to establish the general design criterion that a broad frequency response leads to a wide angular response and high resolution. This conclusion is verified by numerically computed performance curves for a particular air-backed transducer structure.
Alignment of nematics and smectics on evaporated films
Authors: Urbach W. , Boix M. , Guyon E.
Published: January 2004

We discuss the alignment of nematics and smectics on substrates where an obliquely evaporated thin film has been previously deposited. In the planar samples, the surface anchoring energy is substantially larger than with the traditional rubbing technique. We can also uniformly align the liquid crystals obliquely, in particular by coating the evaporated film by a surfactant.
GaAs transmission photocathode grown by hybrid epitaxy
Authors: Gutierrez W. A. , Wilson H. L. , Yee E. M.
Published: January 2004

Transmission GaAs/GaAlAs/GaP photocathodes have been grown by a combination of LPE and VPE (hybrid) epitaxy. The quality of the VPE GaAs material is comparable to that grown by LPE, and the surface uniformity and quality is comparable to that generally obtained by VPE. The GaAs/GaAlAs heterojunction is characterized by low interface recombination velocity.
GaAs–Ga1−xAlxAs double-heterostructure distributed-feedback diode lasers
Authors: Nakamura M. , Aiki K. , Umeda Jun-ichi , Yariv A. , Yen H. W. , Morikawa T.
Published: January 2004

We report laser oscillation at 80–100°K in electrically pumped GaAs–Ga1−xAlxAs double-heterostructure distributed-feedback diode lasers. The feedback for laser oscillation was provided by a corrugated interface between the active GaAs layer and the p-Ga1−xAlxAs layer. The lowest threshold current density was 2.5 kA/cm2 in pulsed operation. The wavelength of laser emission was 8112 Å at 82°K with a half-width of less than 0.3 Å. The temperature dependence of the laser wavelength was found to be smaller than that of the conventional Fabry-Perot laser.
Green electroluminescence in crystals of ZnS0.6Se0.4
Authors: Özsan M. E. , Woods J.
Published: January 2004

Green-light-emitting devices with electrode areas of 1 mm2 have been prepared on crystals of a solid solution of zinc sulfide and selenide with the composition ZnS0.6Se0.4. A luminance of 200 fL was achieved at a bias of 11 V which corresponds to a power efficiency of 0.06%. The emission at room temperature was contained in a braod band with a maximum at 5450 Å (2.27 eV). Preliminary trials with a crystal of zinc sulfide produced a blue (4800 Å, 2.58 eV) emission with a luminance of 90 fL from an area of 1 mm2 for a power dissipation of 600 mW at a bias of 20 V.
Enhanced optical frequency detection with negative differential resistance in metal-barrier-metal point-contact diodes
Authors: Wang S. Y. , Faris S. M. , Siu D. P. , Jain R. K. , Gustafson T. K.
Published: January 2004

Enhanced optically induced voltages have been observed across the junction of metal-barrier-metal point-contact diodes which exhibit a current-controlled negative differential resistance. Responsivities in excess of 5 V/W have been demonstrated when the incident optical beam is focused to ∼1 W/cm2 at the junction. This enhancement is in agreement with the behavior expected from the rectification of the optical field.
cw harmonic generation in the uv using a thin-film waveguide on a nonlinear substrate
Authors: Chen Bor-Uei , Tang C. L. , Telle John M.
Published: January 2004

Phase-matched second harmonic in the thin-film and nonlinear Cerenkov radiation in the substrate have both been observed in the uv on a cw basis in a thin-film waveguide structure consisting of an aluminium-oxide film deposited on a quartz substrate. A sharp resonance in the second-harmonic output was observed as the fundamental wavelength was tuned through the phase-matching point. In contrast, the Cerenkov radiation was found to be broadly and continuously tunable and relatively intense.
Laser propagation through an absorbing transonic flow
Authors: Brown Robert T. , Smith David C.
Published: January 2004

Experiments were carried out to investigate the propagation of a cw CO2 laser beam through an absorbing slightly supersonic flow. A 500-W CO2 beam was propagated through a small blow-down wind tunnel operating with an air/SF6 mixture in order to simulate a high-power beam propagating through the atmosphere. A collinear schlieren system was used to observe the density gradients caused by the absorbed power. Large density gradients were observed at a Mach number of 1.17; however, they were not shock initiated and their magnitude was not inconsistent with a heat-balance analysis. Under the conditions of the experiment no shock waves were observed, even though their occurrence was predicted by a simple one-dimensional analysis. From this study it is concluded that shock waves will not occur under most conditions encountered by high-power cw CO2 laser radiation in the atmosphere. The presence of subshock density gradients and their effect on the propagating beam require further study.
Determination of bulk-trap parameters in MIS structures
Authors: Mar H. A. , Simmons J. G.
Published: January 2004

A new nonsteady-state thermal technique for determining the parameters of traps through which electron-hole pairs are generated in the depletion layer of the silicon in metal-insulator-silicon (MIS) structures has been applied to metal-nitride-oxide-silicon (MNOS) structures. The trapping level involved in the generation process was found to be at 0.55 eV and the carrier lifetime was approximately 3 μsec.
The effect of arsenic in improving lifetime in silicon-on-sapphire films
Authors: McGreivy Denis J. , Viswanathan C. R.
Published: January 2004

Earlier workers reported a considerable increase in the lifetime of phosphorus-doped n -on-n+ silicon-on-sapphire (SOS) films. We report in this paper that a similar improvement in lifetime is obtained on arsenic-doped SOS film comprised of a higher-resistivity layer on top of a nondegenerate lower-resistivity layer. The significance of this work lies in that (a) from the device fabrication point of view arsenic is preferable because of its lower diffusion constant, and therefore will not out-diffuse during subsequent processing steps; and (b) a nondegenerate lower layer is sufficient to produce an improvement in lifetime. It is also shown that the generation lifetime τg increases exponentially with distance from the Al2O3–Si interface.
High-pressure CS2 electric discharge laser
Authors: Nelson L. Y. , Fisher C. H. , Byron S. R.
Published: January 2004

Laser action has been observed at 11.5 and 12.2 μm in electron-beam-stabilized electric discharges using He/CO/CS2 and He/N2/CS2 gas mixtures. Laser operation at 1 atm pressure was possible using He/CO/CS2 mixtures. Laser assignments, aided by the use of 13C-enriched samples, indicate that the 001 to 100 and 0111 to 1110 transitions of CS2 both contribute to the lines observed. Line coincidences, which are very likely for several bands of CS2, may be the cause of the anomalous laser intensity distribution among the rotational states observed at low pressures.
Junction edge region thermally stimulated capacitance (TSCAP) of n -Si doped with phosphorus and bismuth
Authors: Sah C. T. , Wang C. T. , Lee S. H.
Published: January 2004

The high-temperature (T>77°K) thermally stimulated capacitance (TSCAP) from the ionization of impurity centers located in the edge region of a semiconductor (Si) junction doped with two shallow level impurities (P and Bi) where one is the ``deep'' level trap (Bi) is reported for the first time. The theoretically predicted reverse bias voltage dependence of the size of the TSCAP is also verified experimentally.
Disruption of
Ixodes scapularis
anticoagulation by using RNA interference
Authors: Narasimhan Sukanya , Montgomery Ruth R. , DePonte Kathleen , Tschudi Christian , Marcantonio Nancy , Anderson John F. , Sauer John R. , Cappello Michael , Kantor Fred S. , Fikrig Erol
Published: February 2004

Ixodes scapularis
ticks transmit many pathogens, including
Borrelia burgdorferi
,
Anaplasma phagocytophilum
, and
Babesia microti
. Vaccines directed against arthropod proteins injected into the host during tick engorgement could prevent numerous infectious diseases. Salp14, a salivary anticoagulant, poses a key target for such intervention. Salp14 is the prototypic member of a family of potential
I. scapularis
anticoagulants, expressed and secreted in tick saliva during tick feeding. RNA interference was used to assess the role of Salp14 in tick feeding. Salp14 and its paralogs were silenced, as demonstrated by the reduction of mRNA and protein specific for these antigens. Tick salivary glands lacking Salp14 had reduced anticoagulant activity, as revealed by a 60–80% reduction of anti-factor Xa activity. Silencing the expression of
salp14
and its paralogs also reduced the ability of
I. scapularis
to feed, as demonstrated by a 50–70% decline in the engorgement weights. Because ticks have several anticoagulants, it is likely that the expression of multiple anticoagulants in
I. scapularis
saliva would have to be ablated simultaneously to abolish tick feeding. These studies demonstrate that RNA interference can silence
I. scapularis
genes and disrupt their physiologic function
in vivo
, and they identify vaccine candidates that can alter vector engorgement.
A proton-coupled dynamic conformational switch in the HIV-1 dimerization initiation site kissing complex
Authors: Mihailescu Mihaela-Rita , Marino John P.
Published: February 2004

In HIV type 1 (HIV-1), the dimerization initiation site (DIS) is the sequence primarily responsible for initiating the noncovalent linkage of two homologous strands of genomic RNA during viral assembly. The DIS loop contains an autocomplementary hexanucleotide sequence and forms a symmetric homodimer through a loop–loop kissing interaction. In a structural rearrangement catalyzed by the HIV-1 nucleocapsid protein (NCp7) and suggested to be associated with maturation of the budded viral particle, the DIS converts from a metastable kissing dimer to an extended duplex. Here, we demonstrate that the DIS kissing dimer displays localized conformational dynamics that result from the specific protonation of the N1 base nitrogen of the DIS loop residue A272 at near-physiological pH. The rate of NCp7-catalyzed maturation of the DIS kissing dimer is also shown to directly correlate with the observed proton-coupled conformational dynamics, where NCp7 is found to convert the dynamic A272 protonated state with a faster rate. Taken together, these results reveal a previously undescribed role for base protonation in modulating local RNA structure and demonstrate a mechanism for promoting the chaperone-mediated structural rearrangement of a kinetically trapped RNA conformational state.
Learning and teaching policies in higher education: mediations and contradictions of practice
Authors: Clegg Sue
Published: January 2004

Abstract This article utilises Rokeach's categorisation of values (i.e. moral, competency, personal and social) to analyse how values influence the choice of research method. It discusses how the ontological and epistemological position adopted by the researcher is influenced by their competency and personal values. The next section is concerned with the social values (or politics) of educational research, where the debate has polarised between those advocating a value‐neutral approach and those who argue that researchers should instead accept the partisan nature of research. Finally, the issue of research ethics is considered. Moral values are found to play an important role, but other values also influence the ethical decisions that are taken. The article concludes by highlighting how the complex interaction of the researcher's moral, competency, personal and social values has an important influence on the research process. The article contends that research methods cannot be value‐free in their application, but researchers should adopt a reflexive approach and attempt to be honest and open about how values influence their research.
The development of children's early numeracy through key stage 1
Authors: Aubrey Carol , Godfrey Ray
Published: January 2004

Abstract This paper describes a limited longitudinal study of young children's early numeracy development within three testing cycles, at the mid‐point and towards the end of their reception year (at five years‐of‐age) and again at the mid‐point of Year 1 (at six years‐of‐age), located within the broader context of progress through to Key Stage 1 SAT results (at seven years). Assessment was carried out using the Utrecht Early Mathematical Competence Test (Van Luit et al., 1994). This comprised eight sub‐topics, five items in each, including comparison, classification, correspondence, seriation, counting, calculation and real‐life number problem solving. Broadly, one set of sub‐tests related to understanding of relations in shape, size, quantity and order, whilst a second set of sub‐tests related to basic arithmetic. Three hundred pupils were selected from twenty‐one schools, large and small, from rural and urban areas, with high and low concentrations of children eligible for free school meals and/or with special educational needs, as well as representing a broad range of achievements levels based on standards assessment tasks. Whilst this paper focuses upon the performance of English pupils, reference is also made to the larger European sample which involved children from Flemish‐speaking Belgium, Germany, Greece, Slovenia and the Netherlands.

Results showed that children's total scores at around the mid‐point of reception year were indeed predictive of later achievement at the end of KS1 though the combined scores over three testing cycles which extended to the mid‐point of Year 1, were more so. Discriminant analysis confirmed that a combination of a counting sub‐test (one seemed sufficient) and a sub‐test focusing on understanding of relations in shape, size, order or quantity (a different one at each testing cycle), together with the general number knowledge sub‐test was best predictive of final SAT levels.

Comparison with the international data set suggested a different trajectory for English pupils, with more of a bias towards arithmetic sub‐tests than their European counterparts who start school later. Moreover, the pattern of dependence of scores on age in which no advantage was found in including any national differences was especially interesting. These findings are discussed within the context of different school start ages and traditions of preparation for formal schooling. Perhaps what emerged most strongly is the need for young English pupils to maintain a broad and balanced early mathematics curriculum, which places appropriate emphasis on practical problem solving.
The effect of schools and classes on language achievement
Authors: DE Fraine Bieke , Van Damme Jan , Van Landeghem Georges , Opdenakker Marie‐Christine , Onghena Patrick
Published: January 2004

Abstract This study addresses the effects of secondary schools and classes on language achievement in Flanders, Belgium. The results of a three‐level analysis (students within classes within schools) indicate that the group composition at the class level is very important. In classes with a high average initial cognitive ability or a large proportion of girls, the language achievement is higher. These compositional effects are discussed with reference to type ‘A’ and type ‘B’ effects. The analyses show that group composition is more important than educational practices in accounting for differences in language achievement. With whom one is taught has a larger impact than how one is taught. Indications of differential effectiveness of classes related to prior achievement were found, with greater variations in effectiveness between classes for pupils of low prior achievement.
Stimulated recall: a report on its use in naturalistic research
Authors: Lyle John
Published: January 2004

Abstract Stimulated recall (SR) is a family of introspective research procedures through which cognitive processes can be investigated by inviting subjects to recall, when prompted by a video sequence, their concurrent thinking during that event. Variations of the generic approach are widely used and many of the studies treat SR as non‐problematic. The article reviews the strengths and weaknesses of SR and exemplifies its use in a study of non‐deliberative decision‐making by sports coaches. The study reaffirms the potential limitations of subjects reordering their accounts in response to activating deeper memory structures and in order to maintain biases of control and a priori theory affirmation. Nevertheless, the procedure successfully elicited expert accounts of decisions taken and maintained the benefits of the naturalistic context. The article concludes that SR is a valuable tool for investigating cognitive processes, although care has to be taken with research designs. The value is enhanced when there is immediacy of recall, consonance between questions and cognitive organisation, and indirect means of introspection in complex interactive contexts, such as the classroom. It has considerable potential in both research and as the basis of training programmes.
Violence and Institutional Racism in Schools
Authors: Cremin Hilary
Published: January 2004

Book reviewed in this article:

Rethinking Interventions in Racism R. Bhavnani

Conflict Resolution Communication: patterns of promoting peaceful schools M. Lincoln

Working with Disaffected Students: why students lose interest in school and what we can do about it K. Riley & E. Rustique‐Forrester

Violence in Schools: the response in Europe P. K. Smith, (Ed.)
Military corruption & Ugandan politics since the late 1990s
Authors: Tangri Roger , Mwenda Andrew M
Published: January 2004

The paper examines cases of corrupt military procurement in Uganda since the late 1990s. It also considers the illicit business activities of Ugandan army officers in the Democratic Republic of the Congo since 1998. The paper then discusses how military corruption aroused the concern of parliament, and became a matter of importance in the 2001 presidential elections. We argue that the prevalence of military corruption was the result of government and army leaders not being subject to public accountability. Not a single leader has been faced with prosecution or punishment for corrupt military behaviour. We conclude by arguing that military corruption has helped to maintain the National Resistance Movement (NRM) in power, although this has been realised at the cost of building a professional national army in Uganda.
Useful Knowledge for Information Systems Practice: The Contribution of the Participatory Paradigm
Authors: Breu Karin , Peppard Joe
Published: January 2004

Information systems research has become methodologically pluralistic, not least in the hope of achieving greater relevance of scholarly output to practice. Although interventionist approaches have considerable potential for bridging the theory–practice gap, they are dismissed as unscientific because of the purported absence of a philosophical foundation that would justify the interactive research process and the co-productive relationships between researchers and practitioners that are so defining of this type of inquiry. The intention in this paper is to demonstrate that philosophical foundations for interventionist research strategies do exist. This task is pursued by the introduction of the participatory worldview, as articulated in the fields of sociology, philosophy and organization studies. The paper shows its distinctness to other, non-positivist paradigms, describes the participatory research process, presents participatory inquiry methods and extrapolates the distinctness of the knowledge they produce. The application of its paradigmatic principles is illustrated through an empirical example of a participatory research programme and the challenges that this approach presents for research practice are indicated.

… most of our knowledge, and all our primary knowledge, arises as an aspect of activities that have practical, not theoretical objectives; and it is this knowledge, itself an aspect of action, to which all reflective theory must refer.

(Macmurray, 1957, p. 12)
Uganda: lessons for aids control in Africa
Authors: Grundfest Schoepf Brooke
Published: January 2004

Uganda has the one of the oldest recognised AIDS epidemics. The first people found to be sick with AIDS in 1982 in southwestern Uganda became infected in the mid-1970s. For several years, Uganda has been widely recognised as the first and most dramatic African success story, with estimated national HIV prevalence falling from about 15 per cent in 1992 to 5 per cent in 2001. This is truly good news! As the epidemic proceeds through its third decade, many observers suggest that Uganda's prevention efforts are a model to follow. What is the situation there, and what can we learn from Uganda?
The Bush administration & African oil: the security implications of US energy policy
Authors: Volman Daniel
Published: January 2004

‘It's been reliably reported,’ former US Ambassador to Chad Donald R. Norland announced during a House Africa Subcommittee hearing in April 2002, ‘that, for the first time, the two concepts—’Africa‘ and ’U.S national security’—have been used in the same sentence in Pentagon documents.’ When US Deputy Assistant Secretary of Defense for African Affairs Michael A. Westphal held a press briefing that same month, he noted that ‘fifteen per cent of the US's imported oil supply comes from sub-Saharan Africa’ and that ‘this is also a number which has the potential for increasing significantly in the next decade.’ This, Westphal explained, is the main reason that Africa matters to the United States and why ‘we do follow it very closely,’ at the Pentagon. And during his July 2002 visit to Nigeria, US Assistant Secretary of State for Africa Walter Kansteiner declared that ‘African oil is of strategic national interest to us’ and ‘it will increase and become more important as we go forward.’ While American interest in oil and other strategic raw materials from Africa is not new, the Bush Administration's decision to define African oil as a ‘strategic national interest’ and thus, a resource that the United States might choose to use military force to control is completely unprecedented and deeply disturbing.
New information & communication technology use by Muslim Mourides in Senegal
Authors: Gue`ye Cheikh
Published: January 2004

Historically, Senegal has gambled heavily on the potential of New Information & Communication Technologies (NICTs). Indeed, in an environment dominated by oral communication, state-controlled radio broadcasting has been a tool for the reproduction of power (Sagna, 2000). What, then, would be the social and political impact of liberalising and transnationalising the audiovisual media, as well as of ending state control over tools of mass propaganda? The national telecommunications company (SONATEL) undertook a bold initiative, beginning in 1985, to develop the country's telephone service. The resulting system, which was implemented gradually and consists of an all-digital fiber optic network, provides a national coverage which is second to none in West Africa. SONATEL continues to modernise its basic network, providing expanded teleservices and facilitating development of the information superhighway. In the last three years alone, there has been an extraordinary increase in the number of minutes Senegalese have spent online. This revolution in ICTs provides a foundation for a ‘civilisation of the universal’, to use Le´opold Se´dar Senghor's phrase, and poses a major challenge for Senegal's increasingly urban, internationally-oriented society.
Egypt: building an information society for international development
Authors: Wheeler Deborah L.
Published: January 2004

This article examines Egypt's attempt to build an information society for international development as defined by four key variables: an IT infrastructure, a knowledge economy, a public culture of discursive openness, and formal legal institutions which support the digital age. The main finding is that given serious infrastructural challenges, as well as a tendency towards political and economic centralisation, the efforts of a series of government-led projects are unlikely to affect all but the top of the Egyptian social pyramid for the immediate future.
Nuclear and cytoplasmic dynamics of sperm penetration, pronuclear formation and microtubule organization during fertilization and early preimplantation development in the human
Authors: Van Blerkom Jonathan , Davis Patrick , Merriam John , Sinclair Jane
Published: January 2004

This report describes spatial and temporal aspects of sperm penetration and intracytoplasmic migration, pronuclear evolution and the specificity of presyngamic opposition, stage-specific changes in cytoskeletal organization and the relative contribution of maternal and paternal components to mitotic spindle formation. These studies involved observations of living human oocytes during conventional insemination in vitro and after intracytoplasmic deposition of spermatozoa, analysis of chromatin organization and distribution during pronuclear evolution, and detection of actin and α-, rβ- and γ-tubulin by confocal immuno-fluorescence microscopy. Immature and mature oocytes, penetrated but unfertilized oocytes, fertilized but arrested eggs, and cleavage-stage embryos from normal and dispermic fertilizations were examined. The results demonstrate that sperm nuclear migration to the maternal perinuclear region is rapid and linear, occurs in the absence of a detectable cytoskeletal system and appears to be assisted by an unusual configuration of the sperm tail principal piece which results from either retained intracytoplasmic motility or the process by which the sperm tail is progressively incorporated into the oocyte. Our findings also show a specificity of pronuclear alignment that is associated with a polarized distribution of both maternal and paternal chromatin, and with the position of the sperm centrosome and the presence of microtubules nucleated from this structure. The results also indicate that a maternal microtubule nucleating capacity is present in the immature oocyte but is apparently inactive until spindle formation. The poles of the first mitotic spindle appear to be derived from the sperm centrosome, although some maternal contribution cannot be excluded. The sperm tail and centrosome persist in a single cell through the cleavage stages, and the latter serves as a prominent site of cytoplasmic microtubule nucleation. The results provide a detailed understanding of the cellular and nuclear morphodynamics of the human fertilization process and indicate subtle defects that may be responsible for early developmental failure.
Polymorphisms in cytokines and growth factor genes and their association with acute rejection and recurrence of hepatitis C virus disease in liver transplantation
Authors: Mas VR , Fisher RA , Maluf DG , Archer KJ , Contos MJ , Mills SA , Shiffman ML , Wilkinson DS , Oliveros L , Garrett CT , Ferreira‐Gonzalez A
Published: January 2004

Acute rejection (AR) and recurrence of hepatitis C virus (HCV) infection are complications after liver transplantation (LTx). Genetic factors play a role in cytokine production as a consequence of polymorphisms within cytokine genes. Our goal was to identify genetic factors that might be associated with AR and recurrence of HCV in liver transplant recipients (LTxRs). We studied 77 Caucasian LTxRs and 100 Caucasian healthy individuals. We studied single‐nucleotide polymorphisms (SNPs) in tumor necrosis factor‐α[TNF‐α, interleukin‐6 (IL‐6), IL‐10, transforming growth factor‐β1, and angiotensin‐converting enzyme genes by SNaPSHOT™ Multiplex assay. SNPs were classified as high producers (HP), intermediate producers (IP), or low producers (LP), and their association with AR and recurrence of HCV were studied. The frequency of TNF‐α IP and HP genotypes was significantly higher in LTxRs with AR in comparison to patients without AR (TNF‐α HP −238: 63 vs 20%, p < 0.001; TNF‐α HP −308: 47.4 vs 20%, p = 0.02). The frequency of IL‐6 IP and HP genotypes was higher in patients with AR episodes, but the difference was not statistically significant (p = 0.14). However, when we analyzed the simultaneous presence of pro‐inflammatory genotypes in the same patient, we found a significant difference between patients with and without AR, respectively (42.1 vs 14.6%, p = 0.012). Moreover, the frequency of the IL‐10 LP genotype was higher in LTx patients with AR (p = 0.001) compared to patients without AR. There was an association between pro‐inflammatory genotypes and HCV recurrence. Our data suggest that cytokine gene polymorphisms might play a role in AR and HCV recurrence in LTxRs.
Genetic testing in spinocerebellar ataxia in Taiwan: expansions of trinucleotide repeats in SCA8 and SCA17 are associated with typical Parkinson's disease
Authors: Wu YR , Lin HY , Chen CM , Gwinn‐Hardy K , Ro LS , Wang YC , Li SH , Hwang JC , Fang K , Hsieh‐Li HM , Li ML , Tung LC , Su MT , Lu KT , Lee‐Chen GJ
Published: January 2004

DNA tests in normal subjects and patients with ataxia and Parkinson's disease (PD) were carried out to assess the frequency of spinocerebellar ataxia (SCA) and to document the distribution of SCA mutations underlying ethnic Chinese in Taiwan. MJD/SCA3 (46%) was the most common autosomal dominant SCA in the Taiwanese cohort, followed by SCA6 (18%) and SCA1 (3%). No expansions of SCA types 2, 10, 12, or dentatorubropallidoluysian atrophy (DRPLA) were detected. The clinical phenotypes of these affected SCA patients were very heterogeneous. All of them showed clinical symptoms of cerebellar ataxia, with or without other associated features. The frequencies of large normal alleles are closely associated with the prevalence of SCA1, SCA2, MJD/SCA3, SCA6, and DRPLA among Taiwanese, Japanese, and Caucasians. Interestingly, abnormal expansions of SCA8 and SCA17 genes were detected in patients with PD. The clinical presentation for these patients is typical of idiopathic PD with the following characteristics: late onset of disease, resting tremor in the limbs, rigidity, bradykinesia, and a good response to levodopa. This study appears to be the first report describing the PD phenotype in association with an expanded allele in the TATA‐binding protein gene and suggests that SCA8 may also be a cause of typical PD.
The clinical picture of the Börjeson–Forssman–Lehmann syndrome in males and heterozygous females with PHF6 mutations
Authors: Turner G , Lower KM , White SM , Delatycki M , Lampe AK , Wright M , Smith J Clayton‐ , Kerr B , Schelley S , Hoyme HE , De Vries BBA , Kleefstra T , Grompe M , Cox B , Gecz J , Partington M
Published: January 2004

The usual description of the Börjeson–Forssman–Lehmann syndrome (BFLS) is that of a rare, X‐linked, partially dominant condition with severe intellectual disability, epilepsy, microcephaly, coarse facial features, long ears, short stature, obesity, gynecomastia, tapering fingers, and shortened toes. Recently, mutations have been identified in the PHF6 gene in nine families with this syndrome. The clinical history and physical findings in the affected males reveal that the phenotype is milder and more variable than previously described and evolves with age. Generally, in the first year, the babies are floppy, with failure to thrive, big ears, and small external genitalia. As schoolboys, the picture is one of learning problems, moderate short stature, with emerging truncal obesity and gynecomastia. Head circumferences are usually normal, and macrocephaly may be seen. Big ears and small genitalia remain. The toes are short and fingers tapered and malleable. In late adolescence and adult life, the classically described heavy facial appearance emerges. Some heterozygous females show milder clinical features such as tapering fingers and shortened toes. Twenty percent have significant learning problems, and 95% have skewed X inactivation. We conclude that this syndrome may be underdiagnosed in males in their early years and missed altogether in isolated heterozygous females.
The Δ>15 Kb deletion French Canadian founder mutation in familial hypercholesterolemia: rapid polymerase chain reaction‐based diagnostic assay and prevalence in Quebec
Authors: Simard LR , Viel J , Lambert M , Paradis G , Levy E , Delvin EE , Mitchell GA
Published: January 2004

Approximately one in 500 individuals in Western population has autosomal dominant familial hypercholesterolemia due to mutations in the low‐density lipoprotein receptor (LDLR) gene. Screening for these mutations is hampered by their large number, except in founder populations. We identified the breakpoint of the >15 kb deletion involving theLDLRgene promoter and exon 1, responsible for more than 60% of French Canadian hypercholesterolemia cases, as well as the breakpoint of the 5 kb deletion of exons 2 and 3 that accounts for an additional 5% of cases. Both deletions appear to be because of homologous recombination by unequal crossing‐over between the left arms of Alu repeats. Using RepeatMasker, we determined that 55% of theLDLRgene is composed of Alu elements; thus, it is not surprising that most LDLR rearrangements involve at least one Alu. Furthermore, we developed a rapid polymerase chain reaction‐based assay for the French Canadian‐1 (>15 kb) and French Canadian‐5 (5 kb) hypercholesterolemia alleles. Screening a representative population sample of 943 French Canadian youths whose LDL cholesterol levels were above the 50th percentile allowed us to estimate the prevalence of the >15 kb allele as 0.11% (95% confidence interval, 0.03–0.38).
Taking it to the max: The genetic and developmental mechanisms coordinating midfacial morphogenesis and dysmorphology
Authors: Cox TC
Published: January 2004

The rapid proliferative expansion and complex morphogenetic events that coordinate the development of the face underpin the sensitivity of this structure to genetic and environmental insult and provide an explanation for the high incidence of midfacial malformation. Most notable of these malformations is cleft lip with or without cleft palate (CLP) that, with an incidence of between one in 600 and one in 1000 live births, is the fourth most common congenital disorder in humans. Despite the obvious global impact of the disorder and some recent progress in identifying causative genes for some prominent syndromal forms, our knowledge of the key genetic factors contributing to the more common isolated cases of CLP is still remarkably patchy. The current understanding of the molecular and cellular processes that orchestrate morphogenesis of the midface, with emphasis on events leading to fusion of the lip and primary palate, is detailed in this review. The roles of crucial factors identified from relevant animal model systems, including BMP4 and SHH, and the likely events perturbed by key genes pinpointed in human studies [such as PVRL1, IRF6p63, MID1, MSX1, and PTCH1] are discussed in this light. New candidates for human CLP genes are also proposed.
Transfusion of plasma from a blood donor induced hepatitis E in Rhesus monkey
Authors: Xia N.‐S. , Zhang J. , Zheng Y.‐J. , Ge S.‐X. , Ye X.‐Z. , Ou S.‐H.
Published: January 2004

Background and Objectives  Hepatitis E virus (HEV) infection is normally transmitted via the faeco–oral route. The possibility that the infection might be transmissible by blood has been suggested. Direct evidence of blood‐borne transmission of hepatitis E infection is, however, absent.

Materials and Methods  In this report, 10 ml of plasma obtained from a healthy, but hepatitis E viraemic, blood donor was transfused to a Rhesus monkey.

Results  Acute hepatitis E developed following transfusion of blood from the hepatitis E viraemic donor. This was confirmed by virological, immunological, biochemical and histopathological data.

Conclusions  These results, combined with other epidemiological findings previously reported, indicate that transfusion‐associated hepatitis E can occur. The risk of transfusion‐associated HEV infection in endemic areas should be assessed and strategies developed to reduce it.
Frequency analysis of B lymphocytes specific for Rh antigens in naturally immunized Rh‐negative women
Authors: Pasha R. P. K. , Shokrgozar M. A. , Bahrami Z. S. , Shokri F.
Published: January 2004

Background and Objectives  Despite a successful outcome of the anti‐D prophylaxis programme, alloimmunization still occurs. The aim of this study was to estimate the frequency of Rh‐specific B lymphocytes in the peripheral blood of nine Rh‐alloimmunized individuals at different time intervals after parturition.

Materials and Methods  The donors’ B lymphocytes were transformed with Epstein–Barr virus (EBV) and cultured at different cell densities over a feeder of human fetal fibroblasts. Culture supernatants were screened for human immunoglobulin by enzyme‐linked immunosorbent assay (ELISA) and for anti‐Rh antibody by using a direct haemagglutination technique. The percentage of CD19+ B lymphocytes in peripheral blood was determined by flow cytometry, and the frequency of Rh‐specific B lymphocytes was estimated by limiting‐dilution assay (LDA).

Results  The frequency of Rh‐specific B lymphocytes varied from 1 : 150 to 1 : 27 850 in different donors. There was a decrease in this frequency and level of anti‐Rh antibody with increase in time interval between bleeding and last exposure to the antigen. Furthermore, a positive correlation was observed between the titre of Rh‐specific antibody and frequency of Rh‐specific B cells in each of three subjects bled at multiple time‐points postdelivery.

Conclusions  The magnitude of the specific antibody response to Rh antigens varies greatly in Rh‐alloimmunized women, which partly reflects the difference in frequency of specific B cells in these individuals.
Cost‐effectiveness of nucleic acid test screening of volunteer blood donations for hepatitis B, hepatitis C and human immunodeficiency virus in the United States
Authors: Marshall D. A. , Kleinman S. H. , Wong J. B. , AuBuchon J. P. , Grima D. T. , Kulin N. A. , Weinstein M. C.
Published: January 2004

Background and Objectives The aim of this study was to examine the cost‐effectiveness of adding nucleic acid testing (NAT) to serological (antibody and antigen) screening protocols for donated blood in the United States (US) with the purpose of reducing the risks of transfusion‐transmission of hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV).

Materials and Methods The costs, health consequences and cost‐effectiveness of adding either minipool or individual‐donor NAT to serological screening (SS) testing were estimated using a decision‐analysis model.

Results With the given modelling assumptions, adding minipool NAT would avoid an estimated 37, 128 and eight cases of HBV, HCV and HIV, respectively, and save ≈ 53 additional years of life and 102 additional quality adjusted life years (QALYs) compared with SS, at a net cost of $154 million. SS + minipool NAT − p24 compared with SS alone resulted in an incremental cost‐effectiveness ratio of $1·5 million per QALY gained (range in sensitivity analysis $1·0–2·1 million per QALY gained) in this US analysis.

Conclusions The cost effectiveness of adding NAT screening is outside the typical range for most healthcare interventions, but not for established blood safety measures.
A review of general hepatitis C virus lookbacks in Canada
Authors: Bowker S. L. , Smith L. J. , Rosychuk R. J. , Preiksaitis J. K.
Published: January 2004

Background and Objectives This article reviews the Canadian experience with general hepatitis C virus (HCV) lookback programmes.

Materials and Methods Comprehensive literature searches were conducted in PubMed, Medline, HealthSTAR and EMBASE. In addition, bibliographic searches were performed on all retrieved articles, and provinces were contacted to determine whether they had performed general HCV lookbacks.

Results Of the seven Canadian general HCV lookbacks identified, two focused specifically on the paediatric population. The proportion of transfused patients presumed to be alive varied from 48·9 to 97·5%. Between 55·3 and 99·1% of letters were successfully delivered. The proportion of patients tested for HCV and subsequently found to be HCV positive varied considerably (66·2–80·4% and 0·9–5·0%, respectively). Newly diagnosed patients represented 42–58% of cases identified.

Conclusions The Canadian general HCV lookback experience successfully identified previously undiagnosed HCV‐positive patients, but the resources required to notify patients are high and the yield is relatively low. The effectiveness may be greatest in the paediatric population.
A study of blood usage by diagnoses in a Korean university hospital
Authors: Lim Young Ae , Lee Wee Gyo , Cho Sung Ran , Hyun Bong Hak , Sc D.
Published: January 2004

Background and Objectives   There is paucity of comprehensive data on the blood usage with regard to diagnostic categories of Asian recipients. The purpose of this study is to analyse data for blood usage in a korean university hospital in order to obtain additional information on transfusion practices in relation to diagnoses.

Materials and Methods   Data of information on patients discharged during the period from March 1996 to February 2002, who have received packed red blood cells (RBC), fresh frozen plasmas (FFP), and platelet components (PLT) were extracted from the computerized registers. We used only the principal four‐digit diagnostic categories of the Tenth Revision of International Classification of Diseases.

Results   A total of 397 489 units of blood components (RBC 171 916 units; FFP 69 301 units; and PLT 156 272 units) were transfused for 17·2% of all discharged patients. Acute myeloid leukaemia, liver cell carcinoma, advanced gastric cancer, alcoholic or other unspecified cirrhosis of liver were the top 5 diagnoses related with the highest usage of blood component.

Conclusions   The results showed a different blood usage pattern compared to those of previous studies. These provide a baseline transfusion practice at our institution, and the data would help in predicting future blood needs in a variety of diagnostic categories.