bluuebunny/crossref_metadata_2025 huggingface dataset:
Glass formation dependence on casting-atmosphere pressure in Zr65Al7.5Ni10Cu17.5−xPdx (x=0–17.5) alloy system: A resultant effect of quasicrystalline phase transformation and cooling mechanism during mold-casting process
Authors: Setyawan Albertus D. , Kato Hidemi , Saida Junji , Inoue Akihisa
Published: February 2008

A different dependence of apparent glass-forming ability (GFA) on casting-atmosphere pressure is observed in a Zr65Al7.5Ni10Cu17.5−xPdx (x=0–17.5) alloy system. Low-Pd alloys (x<12.5) reveal low GFA dependence, while high-Pd ones (x⩾12.5) show high GFA dependence on atmosphere pressure applied during casting. The phenomenon is suggested to originate from the fact that for the high-Pd alloys, the transformation region of supercooled-liquid to quasicrystalline phase is located at the low-temperature side of the undercooled-liquid region where the atmosphere-pressure dependence of cooling characteristic coincidently takes place. The on-cooling phase transformation in the alloy system and the cooling mechanism during mold-casting process are discussed comprehensively.
Direct numerical simulation of homogeneous nucleation and growth in a phase-field model using cell dynamics method
Authors: Iwamatsu Masao
Published: February 2008

The homogeneous nucleation and growth in a simplest two-dimensional phase field model is numerically studied using the cell dynamics method. The whole process from nucleation to growth is simulated and is shown to follow closely the Kolmogorov-Johnson-Mehl-Avrami (KJMA) scenario of phase transformation. Specifically the time evolution of the volume fraction of new stable phase is found to follow closely the KJMA formula. By fitting the KJMA formula directly to the simulation data, not only the Avrami exponent but the magnitude of nucleation rate and, in particular, of incubation time are quantitatively studied. The modified Avrami plot is also used to verify the derived KJMA parameters. It is found that the Avrami exponent is close to the ideal theoretical value m=3. The temperature dependence of nucleation rate follows the activation-type behavior expected from the classical nucleation theory. On the other hand, the temperature dependence of incubation time does not follow the exponential activation-type behavior. Rather the incubation time is inversely proportional to the temperature predicted from the theory of Shneidman and Weinberg [J. Non-Cryst. Solids 160, 89 (1993)]. A need to restrict thermal noise in simulation to deduce correct Avrami exponent is also discussed.
Temperature dependence of the gain profile for terahertz quantum cascade lasers
Authors: Nelander Rikard , Wacker Andreas
Published: February 2008

We study the rapid decrease of peak gain in resonant-phonon terahertz quantum cascade lasers with increasing temperature. The effect of various microscopic scattering processes on the gain profile as a function of temperature is discussed. We argue that increased broadening, primarily due to increased impurity scattering, and not diminishing population inversion, is the main reason for the reduction of peak gain.
Nonlinear optical absorption and reflection of single wall carbon nanotube thin films by Z-scan technique
Authors: Shimamoto Daisuke , Sakurai Takaaki , Itoh Minoru , Kim Yoong Ahm , Hayashi Takuya , Endo Morinobu , Terrones Mauricio
Published: February 2008

Both the nonlinear optical transmission and reflection characteristics of HiPco-based single wall carbon nanotube (SWNT) thin films are studied by using the Z-scan method with femtosecond laser pulses at a wavelength of 1.46μm. The nonlinear absorption coefficient and nonlinear refractive index are obtained as (5.4±2.0)×10−7cm∕W and (1.1±0.5)×10−11cm2∕W, respectively, which are considerably greater than those of other optical materials. This large optical nonlinearity is ascribed to (a) homogeneously deposited thin nanotube film on optically transparent barium fluoride, (b) just-resonant excitation condition, and (c) intrinsic saturable absorption feature of SWNTs.
Eu
2
+
–
Mn
2
+
phosphor saturation in 5mm light emitting diode lamps
Authors: Setlur A. A. , Shiang J. J. , Happek U.
Published: February 2008

This letter reports on phosphor quenching by saturation, a sublinear phosphor response with excitation intensity, in light emitting diode (LED) packages using 405nm LEDs and Ca5(PO4)3Cl:Eu2+,Mn2+ phosphors. This saturation is due to the high light flux incident on the phosphors in these LED packages and the slow radiative relaxation rate of Mn2+. Apart from known saturation processes of Mn2+ ground state depletion and energy transfer between excited Mn2+ ions, an additional quenching pathway, Eu2+→Mn2+ (excited) energy transfer, is taken into account to quantitatively fit both the efficiency under pulsed operation and the time-resolved luminescence of Ca5(PO4)3Cl:Eu2+,Mn2+.
Relationship between cellular response and behavioral variability in bacterial chemotaxis
Authors: Emonet Thierry , Cluzel Philippe
Published: February 2008

Over the last decades, bacterial chemotaxis in
Escherichia coli
has emerged as a canonical system for the study of signal transduction. A remarkable feature of this system is the coexistence of a robust adaptive behavior observed at the population level with a large fluctuating behavior in single cells [Korobkova E, Emonet T, Vilar JMG, Shimizu TS, Cluzel P (2004)
Nature
428:574–578]. Using a unified stochastic model, we demonstrate that this coexistence is not fortuitous but a direct consequence of the architecture of this adaptive system. The methylation and demethylation cycles that regulate the activity of receptor-kinase complexes are ultrasensitive because they operate outside the region of first-order kinetics. As a result, the receptor-kinase that governs cellular behavior exhibits a sigmoidal activation curve. We propose that the steepness of this kinase activation curve simultaneously controls the behavioral variability in nonstimulated individual bacteria and the duration of the adaptive response to small stimuli. We predict that the fluctuating behavior and the chemotactic response of individual cells both peak within the transition region of this sigmoidal curve. Large-scale simulations of digital bacteria suggest that the chemotaxis network is tuned to simultaneously maximize both the random spread of cells in the absence of nutrients and the cellular response to gradients of attractant. This study highlights a fundamental relation from which the behavioral variability of nonstimulated cells is used to infer the timing of the cellular response to small stimuli.
Epitope discovery in West Nile virus infection: Identification and immune recognition of viral epitopes
Authors: McMurtrey Curtis P. , Lelic Alina , Piazza Paolo , Chakrabarti Ayan K. , Yablonsky Eric J. , Wahl Angela , Bardet Wilfried , Eckerd Annette , Cook Robert L. , Hess Rachael , Buchli Rico , Loeb Mark , Rinaldo Charles R. , Bramson Jonathan , Hildebrand William H.
Published: February 2008

Cytotoxic T lymphocytes (CTL) play an important role in the control and elimination of infection by West Nile virus (WNV), yet the class I human leukocyte antigen (HLA)-presented peptide epitopes that enable CTL recognition of WNV-infected cells remain uncharacterized. The goals of this work were first to discover the peptide epitopes that distinguish the class I HLA of WNV-infected cells and then to test the T cell reactivity of newly discovered WNV epitopes. To discover WNV-immune epitopes, class I HLA was harvested from WNV (NY99 strain)-infected and uninfected HeLa cells. Then peptide epitopes were eluted from affinity-purified HLA, and peptide epitopes from infected and uninfected cells were comparatively mapped by mass spectroscopy. Six virus-derived peptides from five different viral proteins (E, NS2b, NS3, NS4b, and NS5) were discovered as unique to HLA-A*0201 of infected cells, demonstrating that the peptides sampled by class I HLA are distributed widely throughout the WNV proteome. When tested with CTL from infected individuals, one dominant WNV target was apparent, two epitopes were subdominant, and three demonstrated little CTL reactivity. Finally, a sequence comparison of these epitopes with the hundreds of viral isolates shows that HLA-A*0201 presents epitopes derived from conserved regions of the virus. Detection and recovery from WNV infection are therefore functions of the ability of class I HLA molecules to reveal conserved WNV epitopes to an intact cellular immune system that subsequently recognizes infected cells.
Monitoring RNA transcription in real time by using surface plasmon resonance
Authors: Greive Sandra J. , Weitzel Steven E. , Goodarzi Jim P. , Main Lisa J. , Pasman Zvi , von Hippel Peter H.
Published: February 2008

The decision to elongate or terminate the RNA chain at specific DNA template positions during transcription is kinetically regulated, but the methods used to measure the rates of these processes have not been sufficiently quantitative to permit detailed mechanistic analysis of the steps involved. Here, we use surface plasmon resonance (SPR) technology to monitor RNA transcription by
Escherichia coli
RNA polymerase (RNAP) in solution and in real time. We show that binding of RNAP to immobilized DNA templates to form active initiation or elongation complexes can be resolved and monitored by this method, and that changes during transcription that involve the gain or loss of bound mass, including the release of the sigma factor during the initiation–elongation transition, the synthesis of the RNA transcript, and the release of core RNAP and nascent RNA at intrinsic terminators, can all be observed. The SPR method also permits the discrimination of released termination products from paused and other intermediate complexes at terminators. We have used this approach to show that the rate constant for transcript release at intrinsic terminators tR2 and tR′ is ≈2–3 s
−1
and that the extent of release at these terminators is consistent with known termination efficiencies. Simulation techniques have been used to fit the measured parameters to a simple kinetic model of transcription and the implications of these results for transcriptional regulation are discussed.
Whole-genome analysis reveals molecular innovations and evolutionary transitions in chromalveolate species
Authors: Martens Cindy , Vandepoele Klaas , Van de Peer Yves
Published: February 2008

The chromalveolates form a highly diverse and fascinating assemblage of organisms, ranging from obligatory parasites such as
Plasmodium
to free-living ciliates and algae such as kelps, diatoms, and dinoflagellates. Many of the species in this monophyletic grouping are of major medical, ecological, and economical importance. Nevertheless, their genome evolution is much less well studied than that of higher plants, animals, or fungi. In the current study, we have analyzed and compared 12 chromalveolate species for which whole-sequence information is available and provide a detailed picture on gene loss and gene gain in the different lineages. As expected, many gene loss and gain events can be directly correlated with the lifestyle and specific adaptations of the organisms studied. For instance, in the obligate intracellular Apicomplexa we observed massive loss of genes that play a role in general basic processes such as amino acid, carbohydrate, and lipid metabolism, reflecting the transition of a free-living to an obligate intracellular lifestyle. In contrast, many gene families show species-specific expansions, such as those in the plant pathogen oomycete
Phytophthora
that are involved in degrading the plant cell wall polysaccharides to facilitate the pathogen invasion process. In general, chromalveolates show a tremendous difference in genome structure and evolution and in the number of genes they have lost or gained either through duplication or horizontal gene transfer.
DNA instability in postmitotic neurons
Authors: Gonitel Roman , Moffitt Hilary , Sathasivam Kirupa , Woodman Ben , Detloff Peter J. , Faull Richard L. M. , Bates Gillian P.
Published: February 2008

Huntington's disease (HD) is caused by a CAG repeat expansion that is unstable upon germ-line transmission and exhibits mosaicism in somatic tissues. We show that region-specific CAG repeat mosaicism profiles are conserved between several mouse models of HD and therefore develop in a predetermined manner. Furthermore, we demonstrate that these synchronous, radical changes in CAG repeat size occur in terminally differentiated neurons. In HD this ongoing mutation of the repeat continuously generates genetically distinct neuronal populations in the adult brain of mouse models and HD patients. The neuronal population of the striatum is particularly distinguished by a high rate of CAG repeat allele instability and expression driving the repeat upwards and would be expected to enhance its toxicity. In both mice and humans, neurons are distinguished from nonneuronal cells by expression of MSH3, which provides a permissive environment for genetic instability independent of pathology. The neuronal mutations described here accumulate to generate genetically discrete populations of cells in the absence of selection. This is in contrast to the traditional view in which genetically discrete cellular populations are generated by the sequence of random variation, selection, and clonal proliferation. We are unaware of any previous demonstration that mutations can occur in terminally differentiated neurons and provide a proof of principle that, dependent on a specific set of conditions, functional DNA polymorphisms can be produced in adult neurons.
Comparison of gd-dtpa-induced signal enhancements in rat brain c6 glioma among different pulse sequences in 3-tesla magnetic resonance imaging
Authors: Sato H. , Enmi J. , Teramoto N. , Hayashi T. , Yamamoto A. , Tsuji T. , Naito H. , Iida H.
Published: February 2008

Background: T1-shortening contrast media are routinely used in magnetic resonance (MR) examinations for the diagnosis of brain tumors. Although some studies show a benefit of 3 Tesla (T) compared to 1.5T in delineation of brain tumors using contrast media, it is unclear which pulse sequences are optimal.

Purpose: To compare gadopentetate dimeglumine (Gd-DTPA)-induced signal enhancements in rat brain C6 glioma in the thalamus region among different pulse sequences in 3T MR imaging.

Material and Methods: Five rats with a surgically implanted C6 glioma in their thalamus were examined. T1-weighted brain images of the five rats were acquired before and after Gd-DTPA administration (0.1 mmol/kg) using three clinically available pulse sequences (spin echo [SE], fast SE [FSE], fast spoiled gradient echo [FSPGR]) at 3T. Signal enhancement in the glioma (ET) was calculated as the signal intensity after Gd-DTPA administration scaled by that before administration. Pulse sequences were compared using the Tukey-Kramer test.

Results: ET was 1.12±0.05 for FSE, 1.26±0.11 for FSPGR, and 1.20±0.11 for SE. FSPGR showed significantly higher signal enhancement than FSE and comparable enhancement to SE.

Conclusion: FSPGR is superior to FSE and comparable to SE in its ability to delineate rat brain C6 glioma in the thalamus region.
Digital amorphous silicon flat-panel detector radiography at different exposure doses versus mammography film: possibility of radiation dose reduction in detecting rheumatologic bone defects
Authors: Zähringer M. , Reineck S. , Perniok A. , Krüger K. , Andermahr J. , Rubbert A. , Winnekendonk G.
Published: February 2008

Background: Radiographic examinations of the skeleton are the most commonly performed radiologic procedures, even outnumbering examinations of the chest. The imaging systems used in skeletal radiography must meet high standards in terms of contrast and spatial resolution to effectively visualize the high contrast between bone and soft tissue as well as fine bone structures.

Purpose: To determine the performance of amorphous silicon flat-panel detector radiography compared to mammography film in detecting rheumatologic bone defects at different exposure doses.

Material and Methods: The study enrolled 44 patients with known or presumed skeletal changes of the hand associated with inflammatory rheumatic diseases. Following a clinically indicated radiographic examination of the peripheral extremities using mammography film, a survey radiograph of one hand was taken in the posteroanterior (PA) view by digital radiography, at the same exposure dose and at a dose reduced to one quarter of the mammography film doses. Four independent radiologists scored the resultant images using the Sharp/van der Heijde and Ratingen scoring methods. The study received University of Cologne Ethics Committee and German Federal Radiation Protection Agency approval.

Results: Compared to mammography film, digital flat-panel detector radiography produced a significantly better image quality at identical uptake doses. A greater number of erosions were detected with the digital flat-panel detector than with mammography film at the same and at reduced doses.

Conclusion: Although the spatial resolution of the digital flat-panel system used in this study was poorer than mammography film, this was compensated for by its wider dynamic range and improved contrast resolution, even at the reduced dose.
Isolated tubal torsion: specific signs on preoperative computed tomography and magnetic resonance imaging
Authors: Park B. K. , Kim C. K. , Kim B.
Published: February 2008

Isolated torsion of the fallopian tube is a rare cause of lower abdominal pain and commonly occurs after menarche. Prompt identification of this entity can prevent irreversible vascular damage, but the diagnosis is rarely made before surgery due to nonspecific clinical and imaging features. We report a case of isolated tubal torsion with specific imaging features on preoperative computed tomography and magnetic resonance imaging.
Cost-effectiveness analysis (cea) of intravenous urography (ivu) and unenhanced multidetector computed tomography (mdct) for initial investigation of suspected acute ureterolithiasis
Authors: Eikefjord E. , Askildsen J. E. , Rørvik J.
Published: February 2008

Background: It is important to compare the cost and effectiveness of multidetector computed tomography (MDCT) and intravenous urography (IVU) to determine the most cost-effective alternative for the initial investigation of acute ureterolithiasis.

Purpose: To analyze the task-specific variable costs combined with the diagnostic effect of MDCT and IVU for patients with acute flank pain, and to determine which is most cost effective.

Material and Methods: 119 patients with acute flank pain suggestive of stone disease (ureterolithiasis) were examined by both MDCT and IVU. Variable costs related to medical equipment, consumption material, equipment control, and personnel were calculated. The diagnostic effect was assessed.

Results: The variable costs of MDCT versus IVU were EUR 32 and EUR 117, respectively. This significant difference was mainly due to savings in examination time, higher annual examination frequency, lower material costs, and no use of contrast media. As for diagnostic effect, MDCT proved considerably more accurate in the diagnosis of stone disease than IVU and markedly more accurate concerning differential diagnoses.

Conclusion: MDCT had lower differential costs and a higher capacity to determine correctly stone disease and differential diagnoses, as compared to IVU, in patients with acute flank pain. Consequently, MDCT is a dominant alternative to IVU when evaluated exclusively from a cost-effective perspective.
Coraco- or costoclavicular paraosteoarthropathies in patients with severe central neurological disorders
Authors: Lacout A. , Mompoint D. , Perrier Y. , Vallee C. A. , Carlier R. Y.
Published: February 2008

Background: Paraosteoarthropathy (POA) is a frequent disabling orthopedic complication after severe central neurological impairment. The hip is the most frequently affected joint (32.1%) followed by the elbow and the shoulder (25%).

Purpose: To evaluate coraco- and costoclavicular paraosteoarthropathy in patients with severe central neurological disorders.

Material and Methods: We report a series of five consecutive patients with severe central neurological disorders who developed a POA of the clavicular region (coracoclavicular or costoclavicular POA). Every patient underwent a clinical, radiological, and computed tomographic (CT) examination of the shoulder region.

Results: Four patients had a history of traumatic brain injury (TBI), and one an acute disseminated encephalomyelitis (ADEM). They developed POA of the clavicular region, although not around the glenohumeral joint. The patients complained of shoulder pain and of moderate limitation of movements. Radiological and CT examinations showed the presence of a bony formation in the coracoclavicular space in four cases and extending from the clavicle to the first rib around the costoclavicular joint in one case.

Conclusion: In patients with severe brain lesions suffering from shoulder pain and moderate limitation of joint movements, POAs of the clavicular region are rare but should be considered.
Three-dimensional time-of-flight (3d tof) magnetic resonance angiography (mra) and contrast-enhanced mra of intracranial aneurysms treated with platinum coils
Authors: Wikström J. , Ronne-Engström E. , Gal G. , Enblad P. , Tovi M.
Published: February 2008

Background: Contrast-enhanced magnetic resonance angiography (CE-MRA) is less prone to flow-related signal intensity loss than three-dimensional time-of-flight (3D TOF) MRA and may therefore be more sensitive for detection of residual patency in platinum coil-treated intracranial aneurysms.

Purpose: To compare MRA and CE-MRA in the follow-up of intracranial aneurysms treated with platinum coils.

Material and Methods: CE-MRA and 3D TOF MRA (pre- and postcontrast injection) of the intracranial vasculature was performed at 1.5T in 38 patients (47 aneurysms) referred for DSA in the follow-up of coiled intracranial aneurysms.

Results: DSA showed aneurysm patency in 22/47 investigations. Patent aneurysm components were observed with CE-MRA in 18/22 cases, and with 3D TOF MRA in 21/22 cases. There was no significant difference in patent aneurysm component size between CE-MRA and 3D TOF MRA. In addition, CE-MRA showed six, 3D TOF MRA before contrast injection showed seven, and 3D TOF MRA after contrast injection showed eight cases with patent aneurysm components not observed on DSA.

Conclusion: 3D TOF MRA was highly sensitive for detection of patent aneurysm components, and at least as sensitive as CE-MRA. Residual aneurysm patency seems to be better visualized with MRA than with DSA in some cases.
Ankle brachial index <0.9 underestimates the prevalence of peripheral artery occlusive disease assessed with whole-body magnetic resonance angiography in the elderly
Authors: Wikström J. , Hansen T. , Johansson L. , Lind L. , Ahlström H.
Published: February 2008

Background: Whole-body magnetic resonance angiography (WBMRA) permits noninvasive vascular assessment, which can be utilized in epidemiological studies.

Purpose: To assess the relation between a low ankle brachial index (ABI) and high-grade stenoses in the pelvic and leg arteries in the elderly.

Material and Methods: WBMRA was performed in a population sample of 306 subjects aged 70 years. The arteries below the aortic bifurcation were graded after the most severe stenosis according to one of three grades: 0–49% stenosis, 50–99% stenosis, or occlusion. ABI was calculated for each side.

Results: There were assessable WBMRA and ABI examinations in 268 (right side), 265 (left side), and 258 cases (both sides). At least one ⩾50% stenosis was found in 19% (right side), 23% (left side), and 28% (on at least one side) of the cases. The corresponding prevalences for ABI <0.9 were 4.5%, 4.2%, and 6.6%. An ABI cut-off value of 0.9 resulted in a sensitivity, specificity, and positive and negative predictive value of 20%, 99%, 83%, and 84% on the right side, and 15%, 99%, 82%, and 80% on the left side, respectively, for the presence of a ⩾50% stenosis in the pelvic or leg arteries.

Conclusion: An ABI <0.9 underestimates the prevalence of peripheral arterial occlusive disease in the general elderly population.
Neonatal hip instability: a prospective comparison of clinical examination and anterior dynamic ultrasound
Authors: Finnbogason T. , Jorulf H. , Söderman E. , Rehnberg L.
Published: February 2008

Background: Ultrasound is increasingly being used to complement the clinical examination in assessing neonatal hip instability. The clinical examination, although highly sensitive in detecting hip instability, can lead to considerable overtreatment.

Purpose: To compare anterior dynamic ultrasound and clinical examination in the assessment of neonatal hip instability and regarding treatment rates.

Material and Methods: 536 newborn infants (out of a population of 18,031) were selected, on the basis of a combination of risk factors, clinical signs of hip instability or ambiguous clinical findings, to undergo an anterior dynamic ultrasound examination of the hip, by a method developed by our group. This examination, performed by one out of seven experienced examiners, was compared with the standard clinical hip examination conducted by one of four pediatric orthopedic surgeons. The clinical examination was carried out both prior to and within a few hours after the ultrasound examination.

Results: The clinical examination diagnosed 81.7% of the hips as normal, 14.5% as unstable, and 3.8% as dislocatable or dislocated. With the dynamic ultrasound method, the corresponding figures were 87.8%, 10.4%, and 1.8%, respectively. Use of the criteria of the clinical examination resulted in treatment of 147 infants. Using the dynamic ultrasound examination as a criterion meant that 87 infants would receive treatment. The calculated treatment rate was 0.85% when based on the clinical stress test and 0.49% when based on the dynamic ultrasound.

Conclusion: The dynamic ultrasound results reduced the treatment rate by over 40% when used as a basis for the decision regarding treatment.
Book Reviews
Authors: Hammerlund Klara Prucha
Published: February 2008

CT Teaching Manual: A Systematic Approach to CT Reading. 3rd edition. Edited by M. Hofer. Stuttgart, New York: Thieme Medical Publishers, 2007. ISBN 978-3-13-124353-9. 224 pages, 650 figures. Price paperback: EUR 48.90
How does Prior Knowledge Affect Implicit and Explicit Concept Learning?
Authors: Ziori Eleni , Dienes Zoltán
Published: February 2008

Two experiments investigated the effect of prior knowledge on implicit and explicit learning. Implicit as opposed to explicit learning is sometimes characterized as unselective or purely statistical. During training, one group of participants was presented with category exemplars whose features could be tied together by integrative knowledge, whereas another group saw category exemplars with unrelated feature combinations. Half of the participants in each group learned these categories under a secondary-task condition (meant to discourage explicit learning), and the remaining half performed the categorization task under a single-task condition (meant to favour explicit learning). In a test phase, participants classified only the individual features of the training exemplars. Secondary- as opposed to single-task conditions impaired explicit but not implicit knowledge (as determined by subjective measures). Importantly, prior knowledge resulted in increased amounts of both implicit and explicit knowledge.
Scalar Properties in Human Timing: Conformity and Violations
Authors: Wearden J. H. , Lejeune Helga
Published: February 2008

Data from studies of timing in human participants were reviewed with respect to their conformity to the two scalar properties of timing: mean accuracy and the scalar property of variance. Results reviewed were taken from studies of temporal generalization, temporal bisection, discrimination methods, and “classical” timing tasks such as the reproduction, production, and verbal estimation of duration. Evidence for one or both scalar properties was found in many studies, including those using children and elderly participants, but systematic violations were sometimes noted. These violations occurred (a) when very short durations (<100 ms) were timed, (b) in situations in which timing tasks varying in difficulty were compared, (c) when classical timing tasks were employed, and (d) in situations where highly practised observers exhibited unusual patterns of variance. A later section attempted to reconcile some of these violations with an underlying scalar-consistent timing mechanism.
The Influence of Argument Structure on Judgements of Argument Strength, Function, and Adequacy
Authors: Ricco Robert B.
Published: February 2008

The present study explored the extent to which lay adults consider aspects of argument structure in judging the strength and function of informal arguments and in constructing arguments to meet specific adequacy goals. Across two experiments, college students were presented with base (one-premise) arguments, which were then expanded into convergent, coordinate, and subordinate arguments closely matched in terms of content, believability, and strength. Coordinate arguments were associated with the greatest gains in argument strength via their construction and the greatest loss in strength when one of their premises was falsified. To some degree, the argument types were also judged to perform different functions and to serve different goals. The construction of convergent arguments was associated with building independent lines of support while the construction of subordinate arguments was associated with providing justification for premises. Expansion into a coordinate argument was seen as the best way to improve an argument's persuasiveness. The construction of both coordinate and subordinate arguments was associated with building relevance, explicating assumptions, and completing the meaning of a base argument. Results are discussed in terms of argumentation theory and research.
Short Article: Hebb Learning, Verbal Short-Term Memory, and the Acquisition of Phonological forms in Children
Authors: Mosse Emma K. , Jarrold Christopher
Published: February 2008

Recent work using the Hebb effect as a marker for implicit long-term acquisition of serial order has demonstrated a functional equivalence across verbal and visuospatial short-term memory. The current study extends this observation to a sample of five- to six-year-olds using verbal and spatial immediate serial recall and also correlates the magnitude of Hebb learning with explicit measures of word and nonword paired-associate learning. Comparable Hebb effects were observed in both domains, but only nonword learning was significantly related to the magnitude of Hebb learning. Nonword learning was also independently related to individuals’ general level of verbal serial recall. This suggests that vocabulary acquisition depends on both a domain-specific short-term memory system and a domain-general process of learning through repetition.
Short Article: Coding Strategies in Number Space: Memory Requirements Influence Spatial–Numerical Associations
Authors: Lindemann Oliver , Abolafia Juan M. , Pratt Jay , Bekkering Harold
Published: February 2008

The tendency to respond faster with the left hand to relatively small numbers and faster with the right hand to relatively large numbers ( spatial numerical association of response codes, SNARC effect) has been interpreted as an automatic association of spatial and numerical information. We investigated in two experiments the impact of task-irrelevant memory representations on this effect. Participants memorized three Arabic digits describing a left-to-right ascending number sequence (e.g., 3– 4– 5), a descending sequence (e.g., 5– 4– 3), or a disordered sequence (e.g., 5– 3– 4) and indicated afterwards the parity status of a centrally presented digit (i.e., 1, 2, 8, or 9) with a left/right keypress response. As indicated by the reaction times, the SNARC effect in the parity task was mediated by the coding requirements of the memory tasks. That is, a SNARC effect was only present after memorizing ascending or disordered number sequences but disappeared after processing descending sequences. Interestingly, the effects of the second task were only present if all sequences within one experimental block had the same type of order. Taken together, our findings are inconsistent with the idea that spatial–numerical associations are the result of an automatic and obligatory cognitive process but do suggest that coding strategies might be responsible for the cognitive link between numbers and space.
Short Article: Learning to Fail: Reoccurring Tip-of-the-Tongue States
Authors: Beth Warriner Amy , Humphreys Karin R.
Published: February 2008

This experiment looked at elicited tip-of-the-tongue (TOT) states to test the hypothesis that making an error once makes people more likely to make it again, via an implicit learning mechanism. We present a methodology that allows us to determine whether error reoccurrences are due to error learning or to the fact that some items tend to pose repeated difficulty to participants. We elicited TOTs by asking participants to supply the word that fitted a given definition. Each time participants indicated that they were experiencing a TOT they were randomly assigned a delay of either 10 or 30 seconds, during which they were asked to keep trying to retrieve the item. After the delay, the correct answer was supplied. We argue that this longer delay in a TOT state amounts to greater implicit learning of the erroneous state. A period of 48 hours later, participants returned to the laboratory and were asked to supply the words for the same definitions as those seen on Day 1. Results showed that TOTs were almost twice as likely to reoccur on words that had elicited a TOT and been followed by a long delay than on those that had been followed by a short delay.
Integration of Golgi trafficking and growth factor signaling by the lipid phosphatase SAC1
Authors: Blagoveshchenskaya Anastasia , Cheong Fei Ying , Rohde Holger M. , Glover Greta , Knödler Andreas , Nicolson Teresa , Boehmelt Guido , Mayinger Peter
Published: February 2008

When a growing cell expands, lipids and proteins must be delivered to its periphery. Although this phenomenon has been observed for decades, it remains unknown how the secretory pathway responds to growth signaling. We demonstrate that control of Golgi phosphatidylinositol-4-phosphate (PI(4)P) is required for growth-dependent secretion. The phosphoinositide phosphatase SAC1 accumulates at the Golgi in quiescent cells and down-regulates anterograde trafficking by depleting Golgi PI(4)P. Golgi localization requires oligomerization of SAC1 and recruitment of the coat protein (COP) II complex. When quiescent cells are stimulated by mitogens, SAC1 rapidly shuttles back to the endoplasmic reticulum (ER), thus releasing the brake on Golgi secretion. The p38 mitogen-activated kinase (MAPK) pathway induces dissociation of SAC1 oligomers after mitogen stimulation, which triggers COP-I–mediated retrieval of SAC1 to the ER. Inhibition of p38 MAPK abolishes growth factor–induced Golgi-to-ER shuttling of SAC1 and slows secretion. These results suggest direct roles for p38 MAPK and SAC1 in transmitting growth signals to the secretory machinery.
Membrane-anchored growth factor, HB-EGF, on the cell surface targeted to the inner nuclear membrane
Authors: Hieda Miki , Isokane Mayumi , Koizumi Michiko , Higashi Chiduru , Tachibana Taro , Shudou Masachika , Taguchi Tomohiko , Hieda Yohki , Higashiyama Shigeki
Published: February 2008

Heparin-binding EGF-like growth factor (HB-EGF) is synthesized as a type I transmembrane protein (proHB-EGF) and expressed on the cell surface. The ectodomain shedding of proHB-EGF at the extracellular region on the plasma membrane yields a soluble EGF receptor ligand and a transmembrane-cytoplasmic fragment (HB-EGF-CTF). The cytoplasmic domain of proHB-EGF (HB-EGF-cyto) interacts with transcriptional repressors to reverse their repressive activities. However, how HB-EGF-cyto accesses transcriptional repressors is yet unknown. The present study demonstrates that, after exposure to shedding stimuli, both HB-EGF-CTF and unshed proHB-EGF translocate to the nuclear envelope. Immunoelectron microscopy and digitonin-permeabilized cells showed that HB-EGF-cyto signals are at the inner nuclear membrane. A short sequence element within the HB-EGF-cyto allows a transmembrane protein to localize to the nuclear envelope. The dominant-active form of Rab5 and Rab11 suppressed nuclear envelope targeting. Collectively, these data demonstrate that membrane-anchored HB-EGF is targeted to the inner nuclear membrane via a retrograde membrane trafficking pathway.
FOXO-regulated transcription restricts overgrowth of Tsc mutant organs
Authors: Harvey Kieran F. , Mattila Jaakko , Sofer Avi , Bennett F. Christian , Ramsey Matthew R. , Ellisen Leif W. , Puig Oscar , Hariharan Iswar K.
Published: February 2008

FOXO is thought to function as a repressor of growth that is, in turn, inhibited by insulin signaling. However, inactivating mutations in Drosophila melanogaster FOXO result in viable flies of normal size, which raises a question over the involvement of FOXO in growth regulation. Previously, a growth-suppressive role for FOXO under conditions of increased target of rapamycin (TOR) pathway activity was described. Here, we further characterize this phenomenon. We show that tuberous sclerosis complex 1 mutations cause increased FOXO levels, resulting in elevated expression of FOXO-regulated genes, some of which are known to antagonize growth-promoting pathways. Analogous transcriptional changes are observed in mammalian cells, which implies that FOXO attenuates TOR-driven growth in diverse species.
The MHC class I peptide repertoire is molded by the transcriptome
Authors: Fortier Marie-Hélène , Caron Étienne , Hardy Marie-Pierre , Voisin Grégory , Lemieux Sébastien , Perreault Claude , Thibault Pierre
Published: February 2008

Under steady-state conditions, major histocompatibility complex (MHC) I molecules are associated with self-peptides that are collectively referred to as the MHC class I peptide (MIP) repertoire. Very little is known about the genesis and molecular composition of the MIP repertoire. We developed a novel high-throughput mass spectrometry approach that yields an accurate definition of the nature and relative abundance of unlabeled peptides presented by MHC I molecules. We identified 189 and 196 MHC I–associated peptides from normal and neoplastic mouse thymocytes, respectively. By integrating our peptidomic data with global profiling of the transcriptome, we reached two conclusions. The MIP repertoire of primary mouse thymocytes is biased toward peptides derived from highly abundant transcripts and is enriched in peptides derived from cyclins/cyclin-dependent kinases and helicases. Furthermore, we found that ∼25% of MHC I–associated peptides were differentially expressed on normal versus neoplastic thymocytes. Approximately half of those peptides are derived from molecules directly implicated in neoplastic transformation (e.g., components of the PI3K–AKT–mTOR pathway). In most cases, overexpression of MHC I peptides on cancer cells entailed posttranscriptional mechanisms. Our results show that high-throughput analysis and sequencing of MHC I–associated peptides yields unique insights into the genesis of the MIP repertoire in normal and neoplastic cells.
Intrathymic expression of Flt3 ligand enhances thymic recovery after irradiation
Authors: Kenins Linda , Gill Jason W. , Boyd Richard L. , Holländer Georg A. , Wodnar-Filipowicz Aleksandra
Published: February 2008

Hematopoietic stem cell transplantation (HSCT) requires conditioning treatments such as irradiation, which leads to a severely delayed recovery of T cell immunity and constitutes a major complication of this therapy. Currently, our understanding of the mechanisms regulating thymic recovery is limited. It is known that a subpopulation of bone marrow (BM)–derived thymic immigrant cells and the earliest intrathymic progenitors express the FMS-like tyrosine kinase 3 (Flt3) receptor; however, the functional significance of this expression in the thymus is not known. We used the BM transplant model to investigate the importance of Flt3 ligand (FL) for the regeneration of the T cell compartment. We show that FL is expressed in the adult mouse thymus on the surface of perivascular fibroblasts. These cells surround the proposed thymic entry site of Flt3 receptor–positive T cell progenitors. After irradiation, perivascular FL expression is up-regulated and results in an enhanced recovery of thymic cellularity. Thymic grafting experiments confirm an intrathymic requirement for FL. Collectively, these results show that thymic stromal cell–mediated FL–Flt3 receptor interactions are important in the reconstitution of thymopoiesis early after lethal irradiation and HSCT, and provide a functional relevance to the expression of the Flt3 receptor on intrathymic T cell progenitors.
Mao‐to Prolongs the Survival of and Reduces TNF‐α Expression in Mice with Viral Myocarditis
Authors: Shijie Zhu , Moriya Junji , Yamakawa Jun’ichi , Chen Rui , Takahashi Takashi , Sumino Hiroyuki , Nakahashi Takeshi , Iwai Kunimitsu , Morimoto Shigeto , Yamaguchi Nobuo , Kanda Tsugiyasu
Published: February 2008

Goal of this study was to evaluate effects of Mao‐to on development of myocarditis induced by encephalomyocarditis (EMC) virus in mice. Mice were randomly divided into five groups. Group N included uninfected controls (n = 18), while group A, B and C underwent intraperitoneal injection of EMC virus. Group A was administered oral saline from day 0 to day 4. Group B was administered oral Mao‐to (500 mg−1 kg−1 day−1) from day 0 to day 4. Group C was administered Mao‐to from day 2 to day 6. Group D was administered Mao‐to from day 5 to day 10. Treated mice were followed for survival rates during 2 weeks after infection. Body weight (BW) and organ weights including heart (HW), lungs, thymus and spleen were examined on days 4, 6 and 14. Survival rate of group C (36.4%) was significantly improved compared with group A, B or D (0% of each, P < 0.05). HW and HW/BW ratio in group C was significantly (P < 0.05) lower than those in group A, B or D. Viral titers of hearts were significantly different among groups A, B and C. Cardiac expression in tumor necrosis factor‐α (TNF‐α) was significantly reduced in group C in comparison with group A, B or D on day 6 by immunohistochemical study. Administration of Mao‐to starting on day 2 improves mortality resulting from viral myocarditis in mice with reduced expression of cardiac TNF‐α. These findings suggest that timing of Mao‐to is crucial for preventing cardiac damage in mice with viral myocarditis.
Strategic Interaction and Interstate Crises: A Bayesian Quantal Response Estimator for Incomplete Information Games
Authors: Esarey Justin , Mukherjee Bumba , Moore Will H.
Published: February 2008

Private information characteristics like resolve and audience costs are powerful influences over strategic international behavior, especially crisis bargaining. As a consequence, states face asymmetric information when interacting with one another and will presumably try to learn about each others' private characteristics by observing each others' behavior. A satisfying statistical treatment would account for the existence of asymmetric information and model the learning process. This study develops a formal and statistical framework for incomplete information games that we term the Bayesian Quantal Response Equilibrium Model (BQRE model). Our BQRE model offers three advantages over existing work: it directly incorporates asymmetric information into the statistical model's structure, estimates the influence of private information characteristics on behavior, and mimics the temporal learning process that we believe takes place in international politics.
Things to think with: words and objects as material symbols
Authors: Roepstorff Andreas
Published: February 2008

This paper integrates archaeology, anthropology and functional brain imaging in an examination of the cognition of words and objects. Based on a review of recent brain imaging experiments, it is argued that in cognition and action, material symbols may be the link between internal representations and objects and words in the world. This principle is applied to the sapient paradox, the slow development of material innovation at the advent of the anatomically modern human. This translates the paradox into a long-term build-up of extended and distributed cognition supported by development in the complexity of material symbols.
First radiation hybrid map of the river buffalo X chromosome (BBUX) and comparison with BTAX
Authors: Ianella P. , Venancio L. P. R. , Stafuzza N. B. , Miziara M. N. , Agarwala R. , Schäffer A. A. , Riggs P. K. , Womack J. E. , Amaral M. E. J.
Published: February 2008

We report the first radiation hybrid map of the river buffalo X chromosome generated from a recently constructed river buffalo (Bubalus bubalis) whole‐genome radiation hybrid panel (BBURH5000). This map contains a total of 33 cattle‐derived markers, including 10 genes, four ESTs and 19 microsatellites. The markers are distributed in two linkage groups: LG1 contains eight markers spanning 125.6 cR, and LG2 contains 25 markers spanning 366.3 cR. LG1 contains six markers in common with bovine sequence assembly build 3.1. With the exception of BMS2152, the order of these markers on our BBUX map is shuffled when compared to the cow X chromosome (Bos taurus; BTAX). From LG2, two markers (AMELX and BL22) map to a more distal portion of BTAX compared to BBUX. In addition, two pairs of LG2 markers exhibit inversions compared to BTAX (ILSTS017 and ATRX; XBM38 and PPEF1). Alternatively, when compared to the most recent bovine RH map (Bov‐Gen 3000rads), BL1098 and BMS2227 from LG1 as well as PLS3 and BMS1820 from LG2 showed inverted positions on the BBUX map. These discrepancies in buffalo and cattle maps may reflect evolutionary divergence of the chromosomes or mapping errors in one of the two species. Although the set of mapped markers does not cover the entire X chromosome, this map is a starting point for the construction of a high‐resolution map, which is necessary for characterization of small rearrangements that might have occurred between the Bubalus bubalis and Bos taurus X chromosomes.