bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal Features of Spectral Integration in the Inferior Colliculus: Effects of Stimulus Duration and Rise Time
Authors: Gans Donald , Sheykholeslami Kianoush , Peterson Diana Coomes , Wenstrup Jeffrey
Published: April 2009

This report examines temporal features of facilitation and suppression that underlie spectrally integrative responses to complex vocal signals. Auditory responses were recorded from 160 neurons in the inferior colliculus (IC) of awake mustached bats. Sixty-two neurons showed combination-sensitive facilitation: responses to best frequency (BF) signals were facilitated by well-timed signals at least an octave lower in frequency, in the range 16–31 kHz. Temporal features and strength of facilitation were generally unaffected by changes in duration of facilitating signals from 4 to 31 ms. Changes in stimulus rise time from 0.5 to 5.0 ms had little effect on facilitatory strength. These results suggest that low frequency facilitating inputs to high BF neurons have phasic-on temporal patterns and are responsive to stimulus rise times over the tested range. We also recorded from 98 neurons showing low-frequency (11–32 kHz) suppression of higher BF responses. Effects of changing duration were related to the frequency of suppressive signals. Signals <23 kHz usually evoked suppression sustained throughout signal duration. This and other features of such suppression are consistent with a cochlear origin that results in masking of responses to higher, near-BF signal frequencies. Signals in the 23- to 30-kHz range—frequencies in the first sonar harmonic—generally evoked phasic suppression of BF responses. This may result from neural inhibitory interactions within and below IC. In many neurons, we observed two or more forms of the spectral interactions described here. Thus IC neurons display temporally and spectrally complex responses to sound that result from multiple spectral interactions at different levels of the ascending auditory pathway.
Reproducible Measurement of Human Motoneuron Excitability With Magnetic Stimulation of the Corticospinal Tract
Authors: Martin Peter G. , Hudson Anna L. , Gandevia Simon C. , Taylor Janet L.
Published: April 2009

It is difficult to test responses of human motoneurons in a controlled way or to make longitudinal assessments of adaptive changes at the motoneuron level. These studies assessed the reliability of responses produced by magnetic stimulation of the corticospinal tract. Cervicomedullary motor evoked potentials (CMEPs) were recorded in the first dorsal interosseus (FDI) on 2 separate days. On each day, four sets of stimuli were delivered at the maximal output of the stimulator, with the final two sets ≥10 min after the initial sets. Sets of stimuli were also delivered at different stimulus intensities to obtain stimulus-response curves. In addition, on the second day, responses at different stimulus intensities were evoked during weak voluntary contractions. Responses were normalized to the maximal muscle compound action potential ( Mmax). CMEPs evoked in the relaxed FDI were small, even when stimulus intensity was maximal (3.6 ± 2.5% Mmax) but much larger during a weak contraction (e.g., 26.2 ± 10.2% Mmax). CMEPs evoked in the relaxed muscle at the maximal output of the stimulator were highly reproducible both within (ICC = 0.83, session 1; ICC = 0.87, session 2) and between sessions (ICC = 0.87). ICCs for parameters of the input-output curves, which included measures of motor threshold, slope, and maximal response size, ranged between 0.87 and 0.62. These results suggest that responses to magnetic stimulation of the corticospinal tract can be assessed in relaxation and contraction and can be reliably obtained for longitudinal studies of motoneuronal excitability.
E2F1 Expression Is Deregulated and Plays an Oncogenic Role in Sporadic Burkitt's Lymphoma
Authors: Molina-Privado Irene , Rodríguez-Martínez María , Rebollo Patricia , Martín-Pérez Daniel , Artiga María-Jesús , Menárguez Javier , Flemington Erik K. , Piris Miguel A. , Campanero Miguel R.
Published: April 2009

Current treatments of sporadic Burkitt's lymphoma (sBL) are associated with severe toxicities. A better understanding of sBL formation would facilitate development of less toxic therapies. The etiology of sBL remains, however, largely unknown, C-MYC up-regulation being the only lesion known to occur in all sBL cases. Several studies examining the role of C-MYC in the pathogenesis of BL have concluded that C-MYC translocation is not the only critical event and that additional unidentified factors are expected to be involved in the formation of this tumor. We herein report that a gene distinct from C-MYC, E2F1, is involved in the formation of all or most sBL tumors. We found that E2F1 is highly expressed in Burkitt's lymphoma cell lines and sBL lymphoma specimens. Our data indicate that its elevated expression is not merely the consequence of the presence of more cycling cells in this tumor relative to other cell lines or to other neoplasias. In fact, we show that reduction of its expression in sBL cells inhibits tumor formation and decreases their proliferation rate. We also provide data suggesting that E2F1 collaborates with C-MYC in sBL formation. E2F1 expression down-regulation did not affect, however, the proliferation of human primary diploid fibroblasts. Because E2F1 is not needed for cell proliferation of normal cells, our results reveal E2F1 as a promising therapeutic target for sBL. [Cancer Res 2009;69(9):4052–8]
Midas: A Nanotechnological Exploration of Touch
Authors: Thomas Paul
Published: April 2009

The Midas project investigates the trans-mediational space between skin and gold. Research for the project was conducted through the analysis of data recorded with an Atomic Force Microscope (AFM). The AFM, in its force spectroscopy mode, gathers data by picking up the surface vibrations as the cantilever touches the cell. The Midas project culminated in an installation that included data projection and audio work utilizing subsonic speakers to make the data from the atomic vibrations audible and palpable.
Educating the New Makers: Cross-Disciplinary Creativity
Authors: Gross Mark D. , Do Ellen Yi-Luen
Published: April 2009

Making computationally embedded things demands cross-disciplinary creativity, and creative designers must master many materials and methods. The studio-laboratory workspace is essential for learning to engage in such creative endeavors. In this kind of environment, students are encouraged to define their own problem statements and decide what to design. The faculty encourages tinkering, design and the play instinct. In this paper, the authors present their interest in building methods and tools that can open new design spaces in the studio-laboratory environment. They reflect on the distinctive characteristics of this learning environment and how these qualities aid design and foster creative engagement.
Body Matters: The Palpability of Invisible Computing
Authors: Schiphorst Thecla
Published: April 2009

There is an emerging recognition of the value of designing for technology as experience, and of the point that the body matters in the context of technology design. Mark Weiser coined the term invisible computing, remarking that the most profound technologies disappear into the fabric of everyday life. This paper offers a framework from the field of somatics to contribute to the discourse of embodiment and experience in technology, particularly with regard to the body in everyday life. Somatics brings with it epistemologies of practice and embodied approaches to learning and interacting that focus on attention, context and awareness. This paper presents a set of design examples that demonstrate ways in which somatics can be applied to technology design.
Performative Art: The Politics of Doubleness
Authors: Cho Hyunkyoung , Yoon Joonsung
Published: April 2009

Performative art comes from two major ideas. One concerns the performativity as what happens in the collaborative action of human and computer; the other, the doubleness of technology as one insight overcoming the human-subject centered dichotomy. As the linking point where two ideas meet, performative art critiques the politics of contemporary technology-based art in the humanist context.
Faces of the Teouma Lapita People: Art, Accuracy and Facial Approximation
Authors: Hayes Susan , Valentin Frédérique , Buckley Hallie , Spriggs Matthew , Bedford Stuart
Published: April 2009

In 2008 we completed facial approximations of four individuals from the early Lapita Culture, a seafaring people who were the first to settle the islands of the Western Pacific circa 3000 years ago. Typically an approximation is performed as a 3D sculpture or using computer graphics. We chose to sketch what we have been able to determine from the remains because the artistic conventions of drawing work with visual perception in ways that are more complementary to the knowledge, theories and methods that make up the facial approximation of human remains.
Making a Pronoun: Fake Indexicals as Windows into the Properties of Pronouns
Authors: Kratzer Angelika
Published: April 2009

This article argues that natural languages have two binding strategies that create two types of bound variable pronouns. Pronouns of the first type, which include local fake indexicals, reflexives, relative pronouns, and PRO, may be born with a “defective” feature set. They can acquire the features they are missing (if any) from verbal functional heads carrying standard λ-operators that bind them. Pronouns of the second type, which include long-distance fake indexicals, are born fully specified and receive their interpretations via context-shifting λ-operators (Cable 2005). Both binding strategies are freely available and not subject to syntactic constraints. Local anaphora emerges under the assumption that feature transmission and morphophonological spell-out are limited to small windows of operation, possibly the phases of Chomsky 2001. If pronouns can be born underspecified, we need an account of what the possible initial features of a pronoun can be and how it acquires the features it may be missing. The article develops such an account by deriving a space of possible paradigms for referential and bound variable pronouns from the semantics of pronominal features. The result is a theory of pronouns that predicts the typology and individual characteristics of both referential and bound variable pronouns.
Evaluating the Complexity of Optimality Theory
Authors: Heinz Jeffrey , Kobele Gregory M. , Riggle Jason
Published: April 2009

Idsardi (2006) claims that Optimality Theory (OT; Prince and Smolensky 1993, 2004) is “in general computationally intractable” on the basis of a proof adapted from Eisner 1997a. We take issue with this conclusion on two grounds. First, the intractability result holds only in cases where the constraint set is not fixed in advance (contra usual definitions of OT), and second, the result crucially depends on a particular representation of OT grammars. We show that there is an alternative representation of OT grammars that allows for efficient computation of optimal surface forms and provides deeper insight into the sources of complexity of OT. We conclude that it is a mistake to reject OT on the grounds that it is computationally intractable.
Gapping Is Not (VP-) Ellipsis
Authors: Johnson Kyle
Published: April 2009

Pseudogapping is no misnomer. Despite their many tempting similarities, gapping and pseudogapping are distinct constructions. Pseudogapping is a special instance of VP-ellipsis, while gapping, I argue, is a special instance of across-the-board movement. Squeezing gapping into across-the-board movement has its own discomforts, however, which I suggest can be remedied by retailoring our syntax to include string-based output constraints. I sketch one such alteration that involves apparent Left Branch Condition violations.
Effects of potential predator and competitor cues and sibship on wood frog (Rana sylvatica) embryos
Authors: Dibble Christopher , Kauffman Jamie , Zuzik Evan , Smith Geoffrey , Rettig Jessica
Published: May 2009

Chemical cues emitted from predators or competitors are often important for
animals living in aquatic ecosystems as they allow potential prey to assess
predation risk and make appropriate risk-sensitive responses. In our
experiment, we examined if wood frog (Rana sylvatica) embryos exposed to
potential predator and competitor cues would alter their time to hatching,
size at hatching, or survivorship. Eggs from four different sibships were
subjected to a variety of cues including dragonfly larvae (potential tadpole
predator), mosquitofish (Gambusia affinis; a non-native potential egg and
tadpole predator), and overwintered tadpoles of Rana sp. (potential
competitors). We found no significant effects of any of the cues. However,
we did find significant variation in mean time to hatching and mean
hatchling size among sibships. Our results suggest that wood frog embryos
may have limited ability to respond to some cues at the embryonic stage, at
least for the concentrations and conditions used in this experiment. Our
results do indicate genetic or parental effects can affect embryonic wood
frog development rate and hatchling size.
Annular Variability and Eddy–Zonal Flow Interactions in a Simplified Atmospheric GCM. Part I: Characterization of High- and Low-Frequency Behavior
Authors: Sparrow Sarah , Blackburn Michael , Haigh Joanna D.
Published: April 2009

Experiments have been performed using a simplified, Newtonian forced, global circulation model to investigate how variability of the tropospheric jet can be characterized by examining the combined fluctuations of the two leading modes of annular variability. Eddy forcing of this variability is analyzed in the phase space of the leading modes using the vertically integrated momentum budget. The nature of the annular variability and eddy forcing depends on the time scale. At low frequencies the zonal flow and baroclinic eddies are in quasi equilibrium and anomalies propagate poleward. The eddies are shown primarily to reinforce the anomalous state and are closely balanced by the linear damping, leaving slow evolution as a residual. At high frequencies the flow is strongly evolving and anomalies are initiated on the poleward side of the tropospheric jet and propagate equatorward. The eddies are shown to drive this evolution strongly: eddy location and amplitude reflect the past baroclinicity, while eddy feedback on the zonal flow may be interpreted in terms of wave breaking associated with baroclinic life cycles in lateral shear.
Causes of Reduced North Atlantic Storm Activity in a CAM3 Simulation of the Last Glacial Maximum
Authors: Donohoe Aaron , Battisti David S.
Published: April 2009

The aim of this paper is to determine how an atmosphere with enhanced mean-state baroclinity can support weaker baroclinic wave activity than an atmosphere with weak mean-state baroclinity. As a case study, a Last Glacial Maximum (LGM) model simulation previously documented to have reduced baroclinic storm activity, relative to the modern-day climate (simulated by the same model), despite having an enhanced midlatitude temperature gradient, is considered. Several candidate mechanisms are evaluated to explain this apparent paradox.

A linear stability analysis is first performed on the jet in the modern-day and the LGM simulation; the latter has relatively strong barotropic velocity shear. It was found that the LGM mean state is more unstable to baroclinic disturbances than the modern-day mean state, although the three-dimensional jet structure does stabilize the LGM jet relative to the Eady growth rate. Next, feature tracking was used to assess the storm track seeding and temporal growth of disturbances. It was found that the reduction in LGM eddy activity, relative to the modern-day eddy activity, is due to the smaller magnitude of the upper-level storms entering the North Atlantic domain in the LGM. Although the LGM storms do grow more rapidly in the North Atlantic than their modern-day counterparts, the storminess in the LGM is reduced because storms seeding the region of enhanced baroclinity are weaker.
Rossby Waves and the Interannual and Interdecadal Variability of Temperature and Salinity off California
Authors: Dottori Marcelo , Clarke Allan J.
Published: April 2009

Previous work has shown that large-scale interannual Rossby waves, largely remotely generated by equatorial winds, propagate westward from the coast off southern California. These waves have a large-scale anomalous alongshore velocity field that is proportional to the time derivative of the interannual sea level anomaly. Using these results, a theory is developed for interannual perturbations to a mean density field that varies both vertically and alongshore, like that for the California Current region off southern California. Because both the anomalous vertical and alongshore currents are proportional to the time derivative of the interannual sea level, the theory suggests that the anomalous currents associated with the Rossby waves, acting on the mean temperature field, should induce temperature fluctuations proportional to the anomalous dynamic height. The alongshore and vertical advections contribute to the temperature fluctuations in the same sense, a higher-than-normal sea level, for example, resulting in downward and poleward displacement of warmer water and a local higher-than-normal temperature. Near the surface, alongshore advection dominates vertical advection but both contribute comparably near the thermocline and below. The correlation of observed temperature and dynamic height anomalies from the California Cooperative Oceanic Fisheries Investigation (CalCOFI) data is positive, which is consistent with the theory. The correlation is highest (r ≈ 0.8) near 100-m depth in the thermocline. Although the correlation falls toward the surface, it is still between 0.5 and 0.6, suggesting that the advection mechanism is a major contributor to the temperature anomalies there.

The anomalous Rossby wave currents, acting on the mean background salinity gradient, also induce salinity anomalies. At halocline depths of 100–200 m, consistent with the theory, the correlation of observed CalCOFI salinity and dynamic height anomalies is negative and large in magnitude (r ≈ −0.8). However, the surface salinity anomaly is not due to Rossby wave dynamics; instead, much of it is driven by the alongshore wind stress, which it lags by 4 months.
Marginal Instability?
Authors: Thorpe S. A. , Liu Zhiyu
Published: April 2009

Some naturally occurring, continually forced, turbulent, stably stratified, mean shear flows are in a state close to that in which their stability changes, usually from being dynamically unstable to being stable: the time-averaged flows that are observed are in a state of marginal instability. By “marginal instability” the authors mean that a small fractional increase in the gradient Richardson number Ri of the mean flow produced by reducing the velocity and, hence, shear is sufficient to stabilize the flow: the increase makes Rimin, the minimum Ri in the flow, equal to Ric, the critical value of this minimum Richardson number. The value of Ric is determined by solving the Taylor–Goldstein equation using the observed buoyancy frequency and the modified velocity. Stability is quantified in terms of a factor, Φ, such that multiplying the flow speed by (1 + Φ) is just sufficient to stabilize it, or that Ric = Rimin/(1 + Φ)2.

The hypothesis that stably stratified boundary layer flows are in a marginal state with Φ < 0 and with |Φ| small compared to unity is examined. Some dense water cascades are marginally unstable with small and negative Φ and with Ric substantially less than ¼. The mean flow in a mixed layer driven by wind stress on the water surface is, however, found to be relatively unstable, providing a counterexample that refutes the hypothesis. In several naturally occurring flows, the time for exponential growth of disturbances (the inverse of the maximum growth rate) is approximately equal to the average buoyancy period observed in the turbulent region.
Measuring Storm Surge with an Airborne Wide-Swath Radar Altimeter
Authors: Wright C. W. , Walsh E. J. , Krabill W. B. , Shaffer W. A. , Baig S. R. , Peng M. , Pietrafesa L. J. , Garcia A. W. , Marks F. D. , Black P. G. , Sonntag J. , Beckley B. D.
Published: April 2009

Over the years, hurricane track forecasts and storm surge models, as well the digital terrain and bathymetry data they depend on, have improved significantly. Strides have also been made in the knowledge of the detailed variation of the surface wind field driving the surge. The area of least improvement has been in obtaining data on the temporal/spatial evolution of the mound of water that the hurricane wind and waves push against the shore to evaluate the performance of the numerical models. Tide gauges in the vicinity of the landfall are frequently destroyed by the surge. Survey crews dispatched after the event provide no temporal information and only indirect indications of the maximum water level over land. The landfall of Hurricane Bonnie on 26 August 1998, with a surge less than 2 m, provided an excellent opportunity to demonstrate the potential benefits of direct airborne measurement of the temporal/spatial evolution of the water level over a large area. Despite a 160-m variation in aircraft altitude, an 11.5-m variation in the elevation of the mean sea surface relative to the ellipsoid over the flight track, and the tidal variation over the 5-h data acquisition interval, a survey-quality global positioning system (GPS) aircraft trajectory allowed the NASA scanning radar altimeter carried by a NOAA hurricane research aircraft to demonstrate that an airborne wide-swath radar altimeter could produce targeted measurements of storm surge that would provide an absolute standard for assessing the accuracy of numerical storm surge models.
Initial Condition Sensitivity of Western Pacific Extratropical Transitions Determined Using Ensemble-Based Sensitivity Analysis
Authors: Torn Ryan D. , Hakim Gregory J.
Published: April 2009

An ensemble Kalman filter based on the Weather Research and Forecasting (WRF) model is used to generate ensemble analyses and forecasts for the extratropical transition (ET) events associated with Typhoons Tokage (2004) and Nabi (2005). Ensemble sensitivity analysis is then used to evaluate the relationship between forecast errors and initial condition errors at the onset of transition, and to objectively determine the observations having the largest impact on forecasts of these storms. Observations from rawinsondes, surface stations, aircraft, cloud winds, and cyclone best-track position are assimilated every 6 h for a period before, during, and after transition. Ensemble forecasts initialized at the onset of transition exhibit skill similar to the operational Global Forecast System (GFS) forecast and to a WRF forecast initialized from the GFS analysis. WRF ensemble forecasts of Tokage (Nabi) are characterized by relatively large (small) ensemble variance and greater (smaller) sensitivity to the initial conditions. In both cases, the 48-h forecast of cyclone minimum SLP and the RMS forecast error in SLP are most sensitive to the tropical cyclone position and to midlatitude troughs that interact with the tropical cyclone during ET. Diagnostic perturbations added to the initial conditions based on ensemble sensitivity reduce the error in the storm minimum SLP forecast by 50%. Observation impact calculations indicate that assimilating approximately 40 observations in regions of greatest initial condition sensitivity produces a large, statistically significant impact on the 48-h cyclone minimum SLP forecast. For the Tokage forecast, assimilating the single highest impact observation, an upper-tropospheric zonal wind observation from a Mongolian rawinsonde, yields 48-h forecast perturbations in excess of 10 hPa and 60 m in SLP and 500-hPa height, respectively.
Self-Regulated Learning and Instructional Factors in the Scientific Inquiry of Scientifically Gifted Korean Middle School Students
Authors: Yoon Cho-Hee
Published: April 2009

This correlational study investigated the direct and indirect effects of instructional factors and motivational and cognitive components of self-regulated learning on scientific inquiry performance in a sample of scientifically gifted middle school students. A total of 166 students were selected from nine gifted classes in the public school system with after-school enrichment programs in Korea. Students responded to self-report measures of mastery-oriented learning goals, self-efficacy, self-regulatory strategy use, and inquiry activities in science class. Performance data were obtained from work on a scientific inquiry task. Results of a path analysis revealed that students' self-efficacy and perceived degree of inquiry activities in science class were the only factors directly influencing their scientific inquiry skills. Whereas open inquiry learning that allows for choices and decisions in students' inquiry procedure directly influenced use of self-regulatory strategies, the extent of inquiry activities directly influenced self-efficacy. Self-regulatory strategy use was not a significant predictor for scientific inquiry skills. Based on the results, implications for future science gifted education are discussed.

Putting the Research to Use: This study, by incorporating instructional factors in the framework of self-regulated learning of gifted students, extended the previous research that had examined the relationships among the components of self-regulated learning in relation to achievement. Also, it explored such relationships in a much less studied area, science, and extended the scope of science achievement by including scientific inquiry skills as a criterion of academic performance. In general, it reveals that inquiry learning increases gifted students' scientific inquiry skills while open inquiry does not contribute much to this process and that the only learner characteristic influencing scientific inquiry skills is self-efficacy. For educators working with scientifically gifted students, this study urges them to plan open inquiry learning more systematically and make it accessible to students, by providing assistance and guidance with the inquiry process at the outset of learning and increasingly incorporating the open nature of inquiry. Motivational beliefs of gifted students in their abilities also need to be encouraged and fostered in the classroom.
Human Papillomavirus and Head and Neck Squamous Cell Carcinoma: Recent Evidence and Clinical Implications
Authors: Hennessey P.T. , Westra W.H. , Califano J.A.
Published: April 2009

Over the past 20 years, high-risk human papilloma-virus (HPV) infection has been established as a risk factor for developing head and neck squamous cell carcinoma, independent of tobacco and alcohol use. In particular, HPV is strongly associated with the development of oropharyngeal cancer and a small minority of oral cavity cancers. In this review, we summarize what is currently known about the biology of HPV, the mechanisms by which it effects malignant transformation, and the potential impact of HPV status on the clinical management of persons with head and neck cancer.
Replication and Assembly of Human Papillomaviruses
Authors: Conway M.J. , Meyers C.
Published: April 2009

Human papillomaviruses (HPVs) are small dsDNA tumor viruses, which are the etiologic agents of most cervical cancers and are associated with a growing percentage of oropharyngeal cancers. The HPV capsid is non-enveloped, having a T=7 icosahedral symmetry formed via the interaction among 72 pentamers of the major capsid protein, L1. The minor capsid protein L2 associates with L1 pentamers, although it is not known if each L1 pentamer contains a single L2 protein. The HPV life cycle strictly adheres to the host cell differentiation program, and as such, native HPV virions are only produced in vivo or in organotypic “raft” culture. Research producing synthetic papillomavirus particles—such as virus-like particles (VLPs), papillomavirus-based gene transfer vectors, known as pseudovirions (PsV), and papillomavirus genome-containing quasivirions (QV)—has bypassed the need for stratifying and differentiating host tissue in viral assembly and has allowed for the rapid analysis of HPV infectivity pathways, transmission, immunogenicity, and viral structure.
Phenotypic Variation in FAM83H-associated Amelogenesis Imperfecta
Authors: Wright J.T. , Frazier-Bowers S. , Simmons D. , Alexander K. , Crawford P. , Han S.T. , Hart P.S. , Hart T.C.
Published: April 2009

FAM83H gene mutations are associated with autosomal-dominant hypocalcified amelogenesis imperfecta (ADHCAI), which is typically characterized by enamel having normal thickness and a markedly decreased mineral content. This study tested the hypothesis that there are phenotype and genotype associations in families with FAM83H-associated ADHCAI. Seven families segregating ADHCAI (147 individuals) were evaluated. Phenotyping included clinical, radiographic, histological, and biochemical studies, and genotyping was by mutational analysis. Multiple novel FAM83H mutations were identified, including two 2-bp-deletion mutations, the first non-nonsense mutations identified. Craniofacial deviation from normal was more prevalent in the affected individuals. Affected individuals having truncating FAMH3H mutations of 677 or fewer amino acids presented a generalized ADHCAI phenotype, while those having mutations capable of producing a protein of at least 694 amino acids had a unique and previously unreported phenotype affecting primarily the cervical enamel. This investigation shows that unique phenotypes are associated with specific FAM83H mutations.
Polypeptide-catalyzed Biosilicification of Dentin Surfaces
Authors: Goldberg A.J. , Advincula M.C. , Komabayashi T. , Patel P.A. , Mather P.T. , Goberman D.G. , Kazemi R.B.
Published: April 2009

In situ formation of mineral particles by biocatalysis would be advantageous for occluding dentin tubules to reduce permeability or for sealing of material-tooth interfaces. One approach would require that the peptide-catalyst remain functional on the dentin surface. Based on recent observations of retained activity on other surfaces, we hypothesized that poly(L-lysine) (PLL), an analog of the protein catalyst responsible for silica formation in primitive marine species, would remain functional on dentin. PLL was applied to dentin discs along with a pre-hydrolyzed silica precursor, tetramethyl orthosilicate (TMOS). Discs were analyzed microscopically (scanning electron microscopy, SEM) and chemically (x-ray photoelectron spectroscopy, XPS). The treated discs, but not the negative controls, exhibited partial distinct coating whose XPS survey was consistent with that of silica, demonstrating that the polypeptide was required and retained its mediating activity. Peptide-catalysts that mediate mineral formation can retain functionality on dentin, suggesting a wide range of preventive and treatment strategies.
Healthy Eating Index Is a Predictor of Early Childhood Caries
Authors: Nunn M.E. , Braunstein N.S. , Kaye E.A. Krall , Dietrich T. , Garcia R.I. , Henshaw M.M.
Published: April 2009

Early childhood caries (ECC) is a preventable form of dental caries that affects very young children, particularly among low-income families and certain racial/ethnic minorities. The current study examined the relationship of dietary quality, as measured by the Healthy Eating Index (HEI), to the prevalence of ECC in 2- to 5-year-old children. Data from the Third National Health and Nutrition Examination Survey (NHANES III) were used for the study. We used logistic regression to compute adjusted odds ratios (OR) for ECC and 95% confidence intervals (CI). Children with the best dietary practices (uppermost tertile of the HEI) were 44% less likely to exhibit severe ECC compared with children with the worst dietary practices (lowest tertile of the HEI). A healthy eating pattern geared for promotion of optimal child development and prevention of chronic disease in later life may also reduce the risk of early childhood caries, particularly severe early childhood caries.
Adult Rat Odontoblasts Lack Noxious Thermal Sensitivity
Authors: Yeon K.Y. , Chung G. , Shin M.S. , Jung S.J. , Kim J.S. , Oh S.B.
Published: April 2009

Dentin hypersensitivity is a common symptom treated in the dental clinic, yet the underlying cellular and molecular mechanisms are not clear. We hypothesized that odontoblasts detect noxious thermal stimuli by expressing temperature-sensing molecules, and investigated whether temperature-activated TRP channels (thermo-TRP channels), which are known to initiate temperature signaling, mediate temperature sensing in odontoblasts. mRNA expression of dentin sialophosphoprotein and collagenase type 1, odontoblast-specific proteins, was shown in acutely isolated adult rat odontoblasts by single-cell RT-PCR, while TRPV1, TRPV2, TRPM8, and TRPA1 were not detected. Application of noxious temperatures of 42°C and 12°C, as well as capsaicin, menthol, and icilin, agonists of thermo-TRP channels, failed to increase intracellular calcium concentration. Immunohistochemical study also revealed no expression of TRPV1. Thus, it is unlikely that odontoblasts serve as thermal sensors in teeth via thermo-TRP channels.
Glycemic Control and Implant Stabilization in Type 2 Diabetes Mellitus
Authors: Oates T.W. , Dowell S. , Robinson M. , McMahan C.A.
Published: April 2009

Diabetes mellitus is considered a relative contra-indication for implant therapy. However, the effect of glycemic level on implant integration in persons with diabetes remains poorly understood. The hypothesis of this research was that poor glycemic control is directly related to short-term-impairment implant stabilization. This prospective clinical study evaluated 10 non-diabetic individuals (12 implants) and 20 persons with type 2 diabetes (30 implants). Glycated hemoglobin (HbA1c) levels ranged from 4.7–12.6%. Implant stability was assessed by resonance frequency analysis over 4 months following placement. Minimum stability levels were observed 2–6 weeks following placement for all 42 implants. Persons with HbA1c ≥ 8.1% had a greater maximum decrease in stability from baseline and required a longer time for healing, as indicated by return of stability level to baseline. This study demonstrates alterations in implant stability consistent with impaired implant integration for persons with type 2 diabetes mellitus in direct relation to hyperglycemic conditions.
DPPI May Activate KLK4 during Enamel Formation
Authors: Tye C.E. , Pham C.T. , Simmer J.P. , Bartlett J.D.
Published: April 2009

Kallikrein-4 (KLK4) is a serine protease expressed during enamel maturation, and proteolytic processing of the enamel matrix by KLK4 is critical for proper enamel formation. KLK4 is secreted as an inactive zymogen (pro-KLK4), and identification of its activator remains elusive. Dipeptidyl peptidase I (DPPI) is a cysteine aminopeptidase that can activate several serine proteases. In this study, we sought to examine DPPI expression in mouse enamel organ and determine if DPPI could activate KLK4. Real-time PCR showed DPPI expression throughout amelogenesis, with highest expression at maturation, and immunohistochemical staining of mouse incisors confirmed DPPI expression by ameloblasts. We demonstrate in vitro that DPPI activates pro-KLK4 to cleave a fluorogenic peptide containing a KLK4 cleavage site. Examination of mature enamel from DPPI null mice by FTIR showed no significant accumulation of protein; however, microhardness testing revealed that loss of DPPI expression significantly reduced enamel hardness.
Anti-biofilm Effect of Dental Adhesive with Cationic Monomer
Authors: Li F. , Chai Z.G. , Sun M.N. , Wang F. , Ma S. , Zhang L. , Fang M. , Chen J.H.
Published: April 2009

The incorporation of polymerizable cationic monomers has been attempted to generate dental resinous materials with antibacterial activity. This study tested the hypothesis that a dental adhesive containing a cationic monomer, methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB), would influence biofilm formation and gtf gene expression of Streptococcus mutans. The effect of the photo-polymerized DMAE-CB-incorporated adhesive on in vitro biofilm accumulation was investigated with spectrophotometry and scanning electron microscopy. The relative level of gtf gene expression by Streptococcus mutans in the biofilm was quantified by real-time reverse-transcription polymerase chain-reaction. The DMAE-CB-incorporated adhesive significantly decreased bio-film accumulation on its surface ( P < 0.05), and suppressed the expression of gtfB and gtfC of Streptococcus mutans in the biofilm ( P < 0.05). The results suggest that the cured DMAE-CB-incorporated adhesive may hamper biofilm accumulation via selective down-regulation of the expression of gtf genes in Streptococcus mutans.
CTGF and Apoptosis in Mouse Osteocytes Induced by Tooth Movement
Authors: Sakai Y. , Balam T.A. , Kuroda S. , Tamamura N. , Fukunaga T. , Takigawa M. , Takano-Yamamoto T.
Published: April 2009

It is known that experimental tooth movement stimulates the gene expression of connective tissue growth factor (CTGF) and induces apoptosis in osteocytes in rats. We hypothesized that there is a relationship between CTGF expression and the induction of apoptosis in osteocytes, to play a significant role in triggering bone remodeling during experimental tooth movement. In this study, CTGF mRNA expression was detected at 2 hours in osteocytes on the pressure side, followed by apoptosis at 6 hours after tooth movement in mice. The number of empty lacunae significantly increased on day 1 after mechanical stimulation. Thereafter, the number of osteoclasts significantly increased on the pressure side of the alveolar bone on day 3. Tooth movement increased rapidly on day 10. These findings suggest that CTGF expression, followed by apoptosis in osteocytes in response to mechanical stimulation, might play a significant role in triggering bone remodeling during tooth movement.
Synergistic Roles of Amelogenin and Ameloblastin
Authors: Hatakeyama J. , Fukumoto S. , Nakamura T. , Haruyama N. , Suzuki S. , Hatakeyama Y. , Shum L. , Gibson C. W. , Yamada Y. , Kulkarni A. B.
Published: April 2009

Amelogenin and ameloblastin, the major enamel matrix proteins, are important for enamel mineralization. To identify their synergistic roles in enamel development, we generated Amel X −/− /Ambn −/− mice. These mice showed additional enamel defects in comparison with Amel X −/− or Ambn −/− mice. In 7-day-old Amel X −/− /Ambn −/− mice, not only was the ameloblast layer irregular and detached from the enamel surface, as in Ambn −/−, but also, the enamel width was significantly reduced in the double-null mice as compared with Amel X −/− or Ambn −/− mice. Proteomic analysis of the double-null teeth revealed increased levels of RhoGDI (Arhgdia), a Rho-family-specific guanine nucleotide dissociation inhibitor, which is involved in important cellular processes, such as cell attachment. Both Amel X −/− /Ambn −/− mice and Ambn −/− mice displayed positive staining with RhoGDI antibody in the irregularly shaped ameloblasts detached from the matrix. Ameloblastin-regulated expression of RhoGDI suggests that Rho-mediated signaling pathway might play a role in enamel formation.
TGF-β1 Inhibits TLR-mediated Odontoblast Responses to Oral Bacteria
Authors: Horst O.V. , Tompkins K.A. , Coats S.R. , Braham P.H. , Darveau R.P. , Dale B.A.
Published: April 2009

TGF-β1 exerts diverse functions in tooth development and tissue repair, but its role in microbial defenses of the tooth is not well-understood. Odontoblasts extending their cellular processes into the dentin are the first cells to recognize signals from TGF-β1 and bacteria in carious dentin. This study aimed to determine the role of TGF-β1 in modulating odontoblast responses to oral bacteria. We show that these responses depend upon the expression levels of microbial recognition receptors TLR2 and TLR4 on the cell surface. Porphyromonas gingivalis, Prevotella intermedia, and Fusobacterium nucleatum activated both TLRs, but TLR4 played a greater role. Lack of cell-surface TLR2 was associated with poor response to Streptococcus mutans, Enterococcus faecalis, and Lactobacillus casei. TGF-β1 inhibited TLR2 and TLR4 expression and attenuated odontoblast responses. Our findings suggest that the balance between TLR-mediated inflammation and TGF-β1 anti-inflammatory activity plays an important role in pulpal inflammation.
Iatrogenic Severe Depression of High‐Density Lipoprotein Cholesterol
Authors: Mymin D. , Dembinski T. , Friesen M. H.
Published: April 2009

The authors present 5 cases of paradoxical depression of high‐density lipoprotein (HDL) cholesterol induced by fibrate drugs. In a 24‐month review of all cases seen in one physician's practice at the Winnipeg Health Sciences Centre Lipid Clinic, 492 patients made a total of 1187 visits. Sixty‐eight of them were given a fibrate drug (14%). Ten patients had HDL cholesterol levels that were less than 0.5 mmol/L (2%), and of these, 5 cases were due to exposure to fenofibrate (1%). These 5 cases comprised 7.4% of the 68 patients who were given any fibrate drug during that period. Mean levels were as follows: HDL cholesterol on fenofibrate 0.27, off fenofibrate 1.0 mmol/L and apo A1 on fenofibrate 0.41, off fenofibrate 1.17 g/L. A literature review revealed documented cases in 37 patients involving fibrates alone or in combination with other drugs known to cause decreased HDL cholesterol levels. In 13 patients, exposure was to fibrate therapy alone; in those exposed to combinations, the effect was clearly attributable to fibrates in 9; in 14, the nonfibrates (mostly rosiglitazone) were the attributable drugs; and in 1, it was impossible to tell. Thus, fibrate therapy should always be suspected as a cause of profoundly depressed HDL cholesterol.
Stigma Management and Well-Being: The Role of Perceived Social Support, Emotional Processing, and Suppression
Authors: Beals Kristin P. , Peplau Letitia Anne , Gable Shelly L.
Published: April 2009

Lesbians and gay men frequently make decisions about concealing or disclosing their stigmatized identity. Past research has found that disclosing one's sexual orientation is often beneficial. This study aimed to answer the question, “why?”. Specifically, this study tested a model in which perceived social support, emotional processing, and suppression mediate the association between disclosure and well-being. To capture disclosure decisions in real time, participants completed a 2-week daily diary study and a 2-month follow-up survey. As expected, participants generally reported greater well-being on days when they disclosed (vs. concealed) their sexual orientation. Perceived social support was a consistent predictor of well-being and mediator of the association between disclosure and well-being. Although less consistent across time and measures, emotional processing and to a lesser extent suppression were also significantly associated with disclosure and well-being. This research advances the scientific understanding of concealable stigmatized identities and their impact on individual well-being.
The Simple Life: On the Benefits of Low Self-Complexity
Authors: McConnell Allen R. , Strain Laura M. , Brown Christina M. , Rydell Robert J.
Published: April 2009

This article examines the spillover amplification hypothesis, which proposes that because people lower in self-complexity experience stronger responses to life events they will show relatively better well-being in the presence of positive factors (e.g., better social support) and relatively poorer well-being in the presence of negative factors (e.g., a history of negative experiences). Across three studies, support for spillover amplification was found. Specifically, people lower in self-complexity revealed greater self-esteem, less depression, and fewer illnesses when they had greater social support (Study 1) and more desirable personality characteristics (Study 2), yet they had poorer well-being if they had a history of many negative life events (Study 3). Thus, how one's self-concept is represented in memory moderates the relationship between many well-established factors and well-being.
The Source Effect: Person Descriptions by Self versus Others Have Differential Effects on Impression Formation
Authors: Brandt Aafje C. , Vonk Roos , van Knippenberg Ad
Published: April 2009

Self-presentation via favorable self-descriptions may not lead to the desired impression, whereas positive descriptions by others may be more effective because they seem less susceptible to motivated bias. In four experiments, we investigated whether person descriptions have more impact on impressions when provided by third parties than by targets themselves. Results showed that target impressions were consistently more in line with the target description when positive sociability-related or positive competency-related information was given by a third party than by the target. This source effect always occurred for ratings of claimed traits. In addition, ratings of the target's sociability were also affected when the claim was about competency. Source effects were not obtained for negative self-descriptions. The results are discussed in terms of the presumed underlying process on the basis of mediation data.
Interaction in instrumental learning: the influence of interpersonal dynamics on parents
Authors: Creech Andrea , Hallam Susan
Published: April 2009

The research reported here forms part of a UK study that investigated the impact of interpersonal interaction on teaching and learning outcomes, in the context of learning a musical instrument. This article presents the findings relating to parents, exploring how parental involvement, self-efficacy and personal satisfaction were influenced by parent—pupil and parent—teacher interactions. Systems theory provided a framework whereby interaction was interpreted as a product of a communicative system. Interpersonal dynamics were conceptualized as control and responsiveness, and treated as possible predictors of involvement, self-efficacy and personal satisfaction. Personal satisfaction of parents was found to be the outcome most vulnerable to interpersonal factors. Perceived teacher leadership and parental ambition (underlying dimensions of the control scale), together with reciprocity (underlying dimension of the responsiveness scale) had the greatest positive effects. This article points to the potential for parents and teachers to reframe their modes of relating within learning partnerships, thus (according to systems theory) effecting change in communication patterns and potentially fostering enhanced outcomes for all.
Peer learning and reflection: strategies developed by vocal students in a transforming tertiary setting
Authors: Latukefu Lotte
Published: April 2009

The focus of this article is on the analysis of reflection and peer learning in the pedagogical environment. The research draws on findings from a three-year Australian study, which aimed to develop and critically evaluate a model of vocal pedagogy influenced by sociocultural theories. The model sought to position Vygotsky's theories in the environment of university-level vocal instruction. To capture the developmental nature of this pedagogical project, a design-based development research methodology was employed. Central to this approach was flexibility of the design, multiple dependent variables and capturing social interaction. The students were not the subject of experimentation, but were co-participants in the design and analysis. The results of the study suggest that there is value in peer learning for both classical and non-classical singers at an undergraduate level. In particular, the data from the student journals in the present study also suggests that if the environment is arranged in such a way that peer learning is encouraged and purposely mediated, singing students find this extremely helpful as a learning strategy.