The impact of COVID-19 on the well-being of Victorian children born with cleft lip and/or palate

BACKGROUND

A longitudinal cohort study was established to investigate the well-being of children born with cleft lip and/or palate (CL/P) during the COVID-19 pandemic, in Victoria, Australia.

MATERIALS AND METHODS

The Royal Children's Hospital cleft service database was used to identify children aged between 4 and 17 years old born with an isolated CL/P. Families of eligible children who consented to participate were asked to complete the Strengths and Difficulties Questionnaire (SDQ) between October and December 2020 and again 6-month later. SDQ results from typically developing Australian children during the COVID-19 pandemic were utilized from a previously published study.

RESULTS

63 parents completed the baseline questionnaire, with 44 completing the 6-month follow-up. For participants at baseline, the mean age was 8.9 years, with 55% male. All outcome domains of the SDQ improved between baseline and timepoint 2, with the difference in total difficulties scores being statistically significant, indicating a reduction in total difficulties at timepoint 2, associated with the easing of COVID-19 restrictions. When compared with the Australian population during the COVID-19 pandemic, Victorian children born with CL/P had lower SDQ scores for all difficulties outcome domains, with statistically significant results for conduct problems, hyperactivity, peer problems and total difficulties, indicating fewer difficulties for children born with CL/P.

CONCLUSIONS

Children born with CL/P experienced fewer difficulties when compared with the typically developing Australian population during the COVID-19 pandemic. The level of restrictions imposed because of the pandemic also had little influence on the well-being of these children.

Mental health, psychological distress and burnout in Australian dental practitioners

BACKGROUND

Dental practitioners are known to experience a high level of stress, but little is known about the mental health of Australian dental practitioners. The aim of this study was to investigate the prevalence of mental health conditions among Australian dental practitioners.

METHODS

A cross sectional survey of 1483 Australian dental practitioners was carried out from October to December 2021. Participants reported aspects of mental health including depression, anxiety disorder, burnout (Sydney Burnout Measure) and psychological distress (Kessler Psychological Distress Scale and General Health Questionnaire 12).

RESULTS

Self-reported psychological distress was high, with 32.0% rated as having moderate or severe psychological distress and 59.4% a high likelihood of minor (or more severe) psychological distress. One in four participants (24.8%) were classified as likely to be experiencing burnout, with 25.9% reporting ever having a diagnosis of depression, 11.4% a current diagnosis of depression, 23.1% ever having a diagnosis of anxiety disorder and 12.9% a current diagnosis of anxiety disorder.

CONCLUSION

Australian dental practitioners reported a high burden of psychological distress, burnout and mental health issues, suggesting a need for education and programmes to support their mental health and wellbeing. © 2023 Australian Dental Association.

Australian dental practitioners experience of burnout

BACKGROUND

The aim of this study was to investigate factors associated with burnout in Australian dental practitioners.

METHODS

A cross-sectional survey of 1483 Australian dental practitioners was conducted from Oct to Dec 2021. Participants reported burnout using the Sydney Burnout Measure, and aspects of mental health including psychological distress, depression, and anxiety disorders. Predictors of burnout were explored using a generalized linear model with a stepped approach including demographic, health and risk factor variables.

RESULTS

One in four participants were classified as likely to be experiencing burnout. Burnout was associated with working in a regional/rural location (β = 2.82, p < 0.001), an academic/non-clinical role (β = 5.01, p = 0.037), more years of experience as a dental practitioner (β = 0.08, p = 0.022), a current diagnosis of depression (β = 2.38, p = 0.049), moderate/severe psychological distress (β = 7.16, p < 0.001), poor self-rated physical health (β = 5.84, p < 0.001) and increasing alcohol consumption (β = 0.17, p = 0.020). Participants who scored high on resilience (β = -0.23, p = 0.002) or perfectionism (β = -0.24, p < 0.001) had lower burnout scores.

CONCLUSION

Australian dental practitioners appear to be at high risk of burnout which may impact on their health and wellbeing and ability to deliver patient care. There is a need for support services to manage burnout and education to address workplace and environmental factors that may contribute to burnout.

Recommendations for Reducing Heterogeneity in Handgrip Strength Protocols

Handgrip dynamometers are widely used to measure handgrip strength (HGS). HGS is a safe and easy to obtain measure of strength capacity, and a reliable assessment of muscle function. Although HGS provides robust prognostic value and utility, several protocol variants exist for HGS in clinical settings and translational research. This lack of methodological consistency could threaten the precision of HGS measurements and limit comparisons between the growing number of studies measuring HGS. Providing awareness of the protocol variants for HGS and making suggestions to reduce the implications of these variants will help to improve methodological consistency. Moreover, leveraging recent advancements in HGS equipment may enable us to use more sophisticated HGS dynamometer technologies to better assess muscle function. This Special Article will 1) highlight differences in HGS protocols and instrumentation, 2) provide recommendations to better specify HGS procedures and equipment, and 3) present future research directions for studies that measure HGS. We also provided a minimum reporting criteria framework to help future research studies avoid underreporting of HGS procedures.

Older American Women May Especially Benefit from Distributing and Consuming Protein for Decreasing Odds of Functional Limitations

OBJECTIVES

Protein is a key macronutrient for preserving physical function, but the role of protein intake on functional status may differ in men and women. We sought to examine the associations of daily protein intake and distribution on functional limitations in older American men and women.

DESIGN

Cross-sectional.

SETTING

Population-based survey.

PARTICIPANTS

The analytic sample included 3,976 men and 4,081 women aged ≥60-years from the 2007-2016 waves of the National Health and Nutrition Examination Survey.

MEASUREMENTS

Participants reported their ability to perform basic activities of daily living, instrumental activities of daily living, leisure and social activities, lower extremity mobility activities, and general physical tasks. Those reporting difficulty or an inability in completing such functional tasks were considered as having a functional limitation. Protein intake was determined with dietary recalls and participants revealed functional limitations. Protein recommendations of ≥0.80, ≥1.00, and ≥1.50 g/kg/day were used. Based on these cut-points, we also investigated distribution of protein across 4 eating occasions at ≥0.20, ≥0.25, and ≥0.38 g/kg/meal, respectively.

RESULTS

Older women meeting each recommendation had decreased odds for functional limitations: 0.55 (95% confidence interval (CI): 0.40-0.75) for ≥0.80 g/kg/day, 0.75 (CI: 0.58-0.97) for ≥1.00 g/kg/day, and 0.72 (CI: 0.55-0.94) for ≥1.5 g/kg/day. No significant associations were observed in older men. Further, older women with protein consumption ≥0.20 g/kg/meal had decreased odds for functional limitations: 0.24 (CI: 0.10-0.61) for 1 occasion, 0.20 (CI: 0.08-0.49) for 2 occasions, 0.16 (CI: 0.07-0.40) for 3 occasions, and 0.12 (CI: 0.04-0.32) for 4 occasions. A similar trend was observed for intake ≥0.25 g/kg/meal: 0.31 (CI: 0.16-0.62) for 2 occasions, 0.30 (CI: 0.14-0.61) for 3 occasions, and 0.31 (CI: 0.12-0.78) for 4 occasions. Women with 1 and 2 eating occasions at ≥0.38 g/kg/meal of protein had 0.66 (CI: 0.48-0.91) and 0.54 (CI: 0.37-0.79) decreased odds for functional limitations, respectively.

CONCLUSION

Trials that are powered to detect the effects of protein on functional status in women will help to establish causality.

Weakness Is Associated with Time to Incident Chronic Heart Failure in Aging Americans

OBJECTIVE

Handgrip strength is considered a biomarker of nutritional status and strength capacity, which are both linked to heart complications. However, it is not well understood how weakness, as measured by handgrip strength, factors into common heart conditions seen in aging adults such as chronic heart failure (CHF). The purpose of this study was to determine the association between weakness and incident CHF for aging Americans.

DESIGN

Longitudinal-Panel.

SETTING

Physical measures were completed during enhanced face-to-face interviews. The core interview was typically conducted over the telephone.

PARTICIPANTS

Data from 17,431 adults aged at least 50 years who identified as Black or White, completed interviews without a proxy, and participated in at least one wave of the 2006-2014 waves of the Health and Retirement Study were included.

MEASUREMENTS

Handgrip strength was measured with a hand-held dynamometer. Healthcare provider diagnosed CHF was self-reported at each wave. Sex- and race-specific maximal handgrip strength cut-points were used for determining weakness (Black men: <40-kilograms, Black women: <31-kilograms, White men: <35-kilograms, White women: <22-kilograms). A covariate-adjusted Cox model analyzed the association between weakness and incident CHF.

RESULTS

Of those included, 5,397 (31.0%) were weak and 327 (1.9%) developed CHF during the mean follow-up of 4.7±2.7 years. Those who were weak had a 35% higher risk (hazard ratio: 1.35; 95% confidence interval: 1.05, 1.74) of developing CHF, compared to those who were not-weak.

CONCLUSION

Measures of handgrip strength should be utilized by healthcare providers for assessing age-related weakness, nutritional status, and CHF risk. Likewise, interventions aiming to prevent or treat CHF in aging adults should incorporate measures of handgrip strength for helping to determine efficacy of intervention programs.

Decreased Handgrip Strength is Associated With Impairments in Each Autonomous Living Task for Aging Adults in the United States

OBJECTIVES

The primary purpose of this study was to determine the time-varying associations between decreased handgrip strength (HGS) and individual instrumental activities of daily living (IADL) impairments for a nationally-representative sample of aging adults in the United States.

DESIGN

Longitudinal-Panel.

SETTING

Detailed interviews were completed in person and core interviews were typically completed over the telephone.

PARTICIPANTS

A total of 15,336 participants aged at least 50 years who participated in the 2006 wave of the Health and Retirement Study were followed biennially for 8-years.

MEASUREMENTS

A hand-held dynamometer assessed HGS and performance in IADLs were self-reported.

RESULTS

Every 5-kilogram decrease in HGS was associated with an increased odds ratio for the following IADL impairments: 1.11 (95% confidence interval (CI): 1.09, 1.13) for using a map, 1.10 (CI: 1.07, 1.12) for grocery shopping, 1.09 (CI: 1.05, 1.14) for taking medications, 1.07 (CI: 1.05, 1.09) for preparing hot meals, 1.06 (CI: 1.04, 1.08) for managing money, and 1.05 (CI: 1.02, 1.09) for using a telephone.

CONCLUSIONS

Decreased HGS was associated with each IADL impairment, and slightly different associations were observed in individual IADL tasks for aging adults in the United States. Our findings suggest that decreased HGS, which is reflective of reduced function of the neuromuscular system, is associated with diminished performance in autonomous living tasks during aging. Losses in HGS may lead to the development of an IADL impairment. Therefore, health-care providers working with aging adults should utilize measures of HGS as a screening tool for identifying future deficits in neuromuscular functioning. Interventions designed to preserve IADLs in aging adults should also include measures of HGS for detecting early changes in IADL capacity, and intervening at the onset of HGS declines may help aging adults retain their ability to live autonomously.

The Burden of Functional Disabilities for Middle-Aged and Older Adults in the United States

OBJECTIVES

Understanding the role of functional capacity on longevity is important as the population in the United States ages. The purpose of this study was to determine the burden of instrumental activities of daily living (IADL) and activities of daily living (ADL) disabilities for a nationally-representative sample of middle-aged and older adults in the United States.

DESIGN

Longitudinal-Panel.

SETTING

Core interviews were often performed in person or over the telephone.

PARTICIPANTS

A sub-sample of 31,055 participants aged at least 50 years from the 1998-2014 waves of the Health and Retirement Study who reported having a functional disability were included.

MEASUREMENTS

Ability to perform IADLs and ADLs were self-reported at each wave. The National Death Index was used to ascertain date of death. The number of years of life that were lost (YLLs) and years lived with a disability (YLDs) were summed for the calculation of disability-adjusted life years (DALYs). Sampling weights were used in the analyses to make the DALYs nationally-representative. The results for YLLs, YLDs, and DALYs are reported in thousands.

RESULTS

Of the participants included, 14,990 had an IADL disability and 13,136 had an ADL disability. Men and women with an IADL disability had 236,037 and 233,772 DALYs, respectively; whereas, there were 178,594 DALYs for males and 253,630 DALYs for females with an ADL disability. Collectively, there were 469,809 years of healthy life lost from IADL impairments, and 432,224 years of healthy life lost from ADL limitations.

CONCLUSIONS

These findings should be used to inform healthcare providers and guide interventions aiming to preserve the functional capacity of aging adults. Prioritizing health-related resources for mitigating the burden of functional disabilities may help aging adults increase their quality of life and life expectancy over time.

Coverage-dependent structural phase transformations in the adsorption of pentacene on an aperiodically modulated Cu film

Surface ordering of pentacene molecules adsorbed on an aperiodic Cu surface has been studied with density functional theory (DFT) and scanning tunnelling microscopy as a function of coverage. Below 0.73 ML (5.3 × 10¹³ molecules cm^-2), the adsorbate structure is row-like with the molecular axes aligned with the rows in the Cu structure. Between this coverage and 1 ML (7.3 × 10¹³ molecules cm^-2), a structural phase with a checkerboard structure is seen. At this coverage region, the molecules are very close to each other which leads to unusual bending. At higher coverages, a further phase transition to a high-density row structure is seen for most of the film. DFT with van der Waals functionals is employed to study how the molecule-molecule and molecule-surface interactions evolve as a function of coverage.

Influence of leaching on surface composition, microstructure, and valence band of single grain icosahedral Al-Cu-Fe quasicrystal

The use of quasicrystals as precursors to catalysts for the steam reforming of methanol is potentially one of the most important applications of these new materials. To develop application as a technology requires a detailed understanding of the microscopic behavior of the catalyst. Here, we report the effect of leaching treatments on the surface microstructure, chemical composition, and valence band of the icosahedral (i-) Al-Cu-Fe quasicrystal in an attempt to prepare a model catalyst. The high symmetry fivefold surface of a single grain i-Al-Cu-Fe quasicrystal was leached with NaOH solution for varying times, and the resulting surface was characterized by x-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The leaching treatments preferentially remove Al producing a capping layer consisting of Fe and Cu oxides. The subsurface layer contains elemental Fe and Cu in addition to the oxides. The quasicrystalline bulk structure beneath remains unchanged. The subsurface gradually becomes Fe3O4 rich with increasing leaching time. The surface after leaching exhibits micron sized dodecahedral cavities due to preferential leaching along the fivefold axis. Nanoparticles of the transition metals and their oxides are precipitated on the surface after leaching. The size of the nanoparticles is estimated by high resolution transmission microscopy to be 5-20 nm, which is in agreement with the AFM results. Selected area electron diffraction (SAED) confirms the crystalline nature of the nanoparticles. SAED further reveals the formation of an interface between the high atomic density lattice planes of nanoparticles and the quasicrystal. These results provide an important insight into the preparation of model catalysts of nanoparticles for steam reforming of methanol.

Quantitative adsorbate structure determination for quasicrystals using x-ray standing waves

The quantitative structure determination of adsorbed species on quasicrystal surfaces has so far appeared to present insurmountable problems. The normal incidence standing x-ray wave field technique offers a simple solution, without extensive data sets or large computations. Its application to quasicrystals raises several conceptual difficulties that are related to the phase problem in x-ray diffraction. We demonstrate their solution for the case of Si atoms adsorbed on the decagonal Co-rich modification of the Al-Co-Ni quasicrystal to determine the local structure, comprising 6-atom clusters in particular hollow sites.

Templated quasicrystalline ordering of single elements and molecules

We have used quasicrystals as templates for the exploration of new epitaxial phenomena. Several interesting results have been observed in the growth on surfaces of the common Al-based quasicrystals [1]. These include pseudomorphic monolayers, quasiperiodically modulated multilayer structures, and fivefold-twinned islands with magic heights influenced by quantum size effects [1]. Here we present our recent works on the growth of various elements and molecules on a new substrate, icosahedral (i) Ag-In-Yb quasicrystal, which have resulted in various epitaxial phenomena not observed previously. The growth of Pb on the five-fold surface of i-Ag-In-Yb yields a film which possesses quasicrystalline ordering in three-dimension [2]. Using scanning tunneling microscopy (STM) and DFT calculations of adsorption energies, we find that lead atoms occupy the positions of atoms in the rhombic triacontahedral (RTH) cluster, the building block of the substrate, and thus grow in layers with different heights and adsorption energies. The adlayer–adlayer interaction is crucial for stabilizing the epitaxial quasicrystalline structure. We will also present the first example of quasicrystalline molecular layers. Pentacene adsorbs at tenfold-symmetric sites of Yb atoms around surface-bisected RTH clusters, yielding quasicrystalline order [3]. Similarly, C-60 growth on the five-fold surface of i-Al-Cu-Fe at elevated temperature produces quasicrystalline layer, where the growth is mediated by Fe atoms on the substrate surface [3]. The finding of quasicrystalline thin films of single elements and molecules opens an avenue for further investigation of the impact of the aperiodic atomic order over periodic order on the physical and chemical properties of materials.

Crystalline and quasicrystalline allotropes of Pb formed on the fivefold surface of icosahedral Ag-In-Yb

Crystalline and quasicrystalline allotropes of Pb are formed by evaporation on the fivefold surface of the icosahedral (i) Ag-In-Yb quasicrystal under ultra-high vacuum. Lead grows in three dimensional quasicrystalline order and subsequently forms fivefold-twinned islands with the fcc(111) surface orientation atop of the quasicrystalline Pb. The islands exhibit specific heights (magic heights), possibly due to the confinement of electrons in the islands. We also study the adsorption behavior of C60 on the two allotropes of Pb. Scanning tunneling microcopy reveals that a high corrugation of the quasicrystalline Pb limits the diffusion of the C60 molecules and thus produces a disordered film, similar to adsorption behavior of the same molecules on the clean substrate surface. However, the sticking coefficient of C60 molecules atop the Pb islands approaches zero, regardless of the overall C60 coverage.

Templated quasicrystalline molecular ordering

Quasicrystals are materials with long-range ordering but no periodicity. We report scanning tunneling microscopy (STM) observations of quasicrystalline molecular layers on 5-fold quasicrystal surfaces. The molecules adopt positions and orientations on the surface consistent with the quasicrystalline ordering of the substrate. Carbon-60 adsorbs atop sufficiently separated Fe atoms on icosahedral Al-Cu-Fe to form a unique quasicrystalline lattice, whereas further C60 molecules decorate remaining surface Fe atoms in a quasi-degenerate fashion. Pentacene (Pn) adsorbs at 10-fold symmetric points around surface-bisected rhombic triacontahedral clusters in icosahedral Ag-In-Yb. These systems constitute the first demonstrations of quasicrystalline molecular ordering on a template.

Structure of the twofold surface of the icosahedral Ag-In-Yb quasicrystal

The structure of the twofold surface of the icosahedral (i-)Ag-In-Yb quasicrystal has been investigated using low energy electron diffraction (LEED) and scanning tunneling microscopy (STM). The LEED confirms that the surface exhibits quasicrystalline long range order with the twofold rotational symmetry expected from the bulk. STM images reveal a step-terrace structure with terrace size comparable to that of the other high symmetry surfaces of the same quasicrystal. The distribution of step heights and high resolution STM images of terraces suggest that the surface terminates at bulk planes that intersect the center of rhombic triacontahedral clusters, the building blocks of the system, as in the case of the threefold and fivefold surfaces of the system. These planes are rich in Yb and In. No facets are observed on the surface, suggesting that the twofold surface is as stable as the other high symmetry surfaces.

Scanning tunneling microscopy of a polygrain Al–Pd–Re quasicrystal: study of the relative surface stability

Scanning tunneling microscopy and x-ray photoemission spectroscopy on a polygrain icosahedral (i-) Al–Pd–Re quasicrystal (QC) show the formation of the twofold surfaces with symmetry and composition expected from the bulk. The predominant occurrence of the twofold surface on the polygrain i-QC having random grain orientation, as well as preferential formation of terrace edges, kinks and voids along the twofold axes, consistently indicates that the twofold surface, which has the highest atomic density, is the most stable among all the crystallographic planes.

The atomic structure of the threefold surface of the icosahedral Ag-In-Yb quasicrystal

We report a study of the atomic structure of the threefold icosahedral (i-)Ag-In-Yb quasicrystal surface using scanning tunneling microscopy (STM) and low energy electron diffraction (LEED). The LEED confirms that the surface exhibits quasicrystalline long-range order with the threefold symmetry expected from the bulk. The STM reveals large atomically flat terraces separated by steps of different heights. A comparison of atomically resolved STM images for the terraces and the step-height distribution with the bulk structure of isostructural i-Cd-Yb shows that the terraces are formed at bulk planes intersecting the centers of the rhombic triacontahedral clusters that make up the bulk structure of the system. However, the stability of particular terraces may be influenced by the density of atoms in the interstices (glue atoms that bind the clusters) in the terraces and also by the chemical environment in the underlying atomic plane. The surface exhibits screw dislocations, which is explained in terms of a continuous atomic density along the threefold axis.

Lymphoma, thymoma and the wooden man: stiff-person syndrome post-thymoma excision and non-Hodgkin lymphoma remission

Stiff-person syndrome (SPS) is an uncommon yet under-diagnosed, neuromuscular disorder characterised by progressive muscle rigidity with superimposed painful muscle spasms triggered by tactile, auditory or emotional stimulation. We describe the world's first case report of typical SPS in a patient with previously excised thymoma and treated non-Hodgkin lymphoma. This is of relevance because of the increasingly elucidated autoimmune aetiology of SPS.

Epitaxial Bi allotropes on quasicrystal surfaces as templates for adsorption of pentacene and fullerene

The growth of Bi on surfaces of Al-based quasicrystals yields a quasicrystalline monolayer which is followed by the formation of crystalline islands of various forms depending on coverage, deposition flux and substrate temperature. We have used the Bi thin films consisting of both crystalline and quasicrystalline allotropes as substrates to study the deposition of C(60) and pentacene molecules. Scanning tunneling microscopy (STM) reveals substrate-dependent differences in molecular adsorption.

The memory of surfaces: epitaxial growth on quasi-crystals

If crystal structures can be viewed as repositories of information, then crystal surfaces offer a pathway by which this information can be used to grow new structures through the process of epitaxy. The information transfer process is one of self-organization, and the kinetic and energetic factors influencing this are complex. They include the relative strengths of the adsorbate-adsorbate and adsorbate-substrate interactions, the flux of incoming species and the temperature of the system. In this brief review, we explore how the interplay of these factors influences the degree to which the epitaxial structures retain the 'memory' of the template, illustrating the discussion with examples from epitaxy on quasi-crystal surfaces.

Clustered, Terraced And Mixed Surface Phases Of The Al70Pd21Mn9 Quasicrystal

The five-fold surface of the Al70 Pd21 Mn9 quasicrystal has been studied using STM, LEED and AES. STM images from surfaces which have been sputtered and annealed to 875 K reveal 20-30 Å protrusions that have been identified by others as Mackay-type clusters. Higher-resolution images reveal substructures in these clusters having dimensions 2-3 Å. Longer annealing times at 875 K produced large areas having flat terraces which were imaged with atomic resolution. The LEED pattern from this surface has sharp spots on a low background, and AES indicates that the surface is deficient in Mn relative to the bulk. For surfaces annealed to 1050 K for less than 2 hours, STM images indicate that cluster and terrace phases coexist, and a third phase having aligned arrays of clusters is identified which appears to be intermediate between the cluster and terrace phases.

Structure and reactivity of Bi allotropes on the fivefold icosahedral Al-Pd-Mn quasicrystal surface

The growth of Bi on a pseudomorphic Bi monolayer on the fivefold surface of the icosahedral Al-Pd-Mn quasicrystal has been investigated using low energy electron diffraction and scanning tunnelling microscopy. Initially randomly oriented pseudocubic islands are formed with a preference for an even number of layers. Subsequently a morphological transformation takes place to hexagonal Bi islands, which align along high symmetry directions of the substrate. The Bi flux is found to have a strong effect on which island structure is preferred. When C(60) is adsorbed on the three different allotropes of Bi present in this system, hexagonal C(60) islands are formed in each case. On the pseudocubic and hexagonal islands, the C(60) islands are aligned with the substrate. We discuss the energetic, kinetic and geometrical factors which influence the morphological transformation referred to above.

The surface science of quasicrystals

The surfaces of quasicrystals have been extensively studied since about 1990. In this paper we review work on the structure and morphology of clean surfaces, and their electronic and phonon structure. We also describe progress in adsorption and epitaxy studies. The paper is illustrated throughout with examples from the literature. We offer some reflections on the wider impact of this body of work and anticipate areas for future development.

Surface geometry of C(60) on Ag(111)

The geometry of adsorbed C(60) influences its collective properties. We report the first dynamical low-energy electron diffraction study to determine the geometry of a C(60) monolayer, Ag(111)-(2 square root of 3 x 2 square root of 3) 30 degrees -C(60), and related density functional theory calculations. The stable monolayer has C(60) molecules in vacancies that result from the displacement of surface atoms. C(60) bonds with hexagons down, with their mirror planes parallel to that of the substrate. The results indicate that vacancy structures are the rule rather than the exception for C(60) monolayers on close-packed metal surfaces.

Single-molecule solvation-shell sensing

We present a new route to single-molecule sensing via solvation shells surrounding a current-carrying backbone molecule. As an example, we show that the presence of a water solvation shell "gates" the conductance of a family of oligothiophene-containing molecular wires, and that the longer the oligothiophene, the larger is the effect. For the longest example studied, the molecular conductance is over 2 orders of magnitude larger in the presence of a shell comprising just 10 water molecules. A first principles theoretical investigation of electron transport through the molecules, using the nonequilibrium Green's function method, shows that water molecules interact directly with the thiophene rings, significantly shifting transport resonances and greatly increasing the conductance. This reversible effect is confirmed experimentally through conductance measurements performed in the presence of moist air and dry argon.

Pseudomorphic growth of a single element quasiperiodic ultrathin film on a quasicrystal substrate

An ultrathin film with a periodic interlayer spacing was grown by the deposition of Cu atoms on the fivefold surface of the icosahedral Al70Pd21Mn9 quasicrystal. For coverages from 5 to 25 monolayers, a distinctive quasiperiodic low-energy electron diffraction pattern is observed. Scanning tunneling microscopy images show that the in-plane structure comprises rows having separations of S=4.5+/-0.2 A and L=7.3+/-0.3 A, whose ratio equals tau=1.618... within experimental error. The sequences of such row separations form segments of terms of the Fibonacci sequence, indicative of the formation of a pseudomorphic Cu film.

Near-threshold production of the multistrange Xi- hyperon

The yield for the multistrange Xi(-) hyperon has been measured in 6A GeV Au+Au collisions via reconstruction of its decay products pi(-) and Lambda, the latter also being reconstructed from its daughter tracks of pi(-) and p. The measurement is rather close to the threshold for Xi(-) production and therefore provides an important test of model predictions. The measured yield for Xi(-) and Lambda are compared for several centralities. In central collisions the Xi(-) yield is found to be in excellent agreement with statistical and transport model predictions, suggesting that multistrange hadron production approaches chemical equilibrium in high baryon density nuclear matter.

Comparison of source images for protons, pi-'s, and lambda's in 6A GeV Au+Au collisions

Source images are extracted from two-particle correlations constructed from strange and nonstrange hadrons produced in 6A GeV Au+Au collisions. Very different source images result from pp vs p Lambda vs pi(-)pi(-) correlations. Scaling by transverse mass can describe the apparent source size ratio for p/pi(-) but not for Lambda/pi(-) or Lambda/p. These observations suggest important differences in the space-time emission histories for protons, pions, and neutral strange baryons produced in the same events.

Longitudinal flow of protons from (2-8)A GeV central Au+Au collisions

Rapidity distributions of protons from central 197Au+197Au collisions measured by the E895 Collaboration in the energy range from (2-8)A GeV at the Brookhaven AGS are presented. Longitudinal flow parameters derived using a thermal model including collective longitudinal expansion are extracted from these distributions. The results show an approximately linear increase in the longitudinal flow velocity, <betagamma>(L), as a function of the logarithm of beam energy.

Model-independent source imaging using two-pion correlations in (2 to 8)a GeV Au+Au collisions

We report a particle source imaging analysis based on two-pion correlations in high multiplicity Au+Au collisions at beam energies between 2A and 8A GeV. We apply the imaging technique introduced by Brown and Danielewicz, which allows a model-independent extraction of source functions with useful accuracy out to relative pion separations of about 20 fm. The extracted source functions have Gaussian shapes. Values of source functions at zero separation are almost constant across the energy range under study. Imaging results are found to be consistent with conventional source parameters obtained from a multidimensional Hanburg-Brown-Twiss analysis.

Stability of polar oxide surfaces

The structures of the polar surfaces of ZnO are studied using ab initio calculations and surface x-ray diffraction. The experimental and theoretical relaxations are in good agreement. The polar surfaces are shown to be very stable; the cleavage energy for the (0001)-Zn and (0001;)-O surfaces is 4.0 J/m(2) comparable to 2.32 J/m(2) for the most stable nonpolar (1010) surface. The surfaces are stabilized by an electronic mechanism involving the transfer of 0.17 electrons between them. This leads to 2D metallic surface states, which has implications for the use of the material in gas sensing and catalytic applications.

Directed flow of lambda hyperons in (2-6 )A GeV Au+Au collisions

Directed flow measurements for Lambda hyperons are presented and compared to those for protons produced in the same Au+Au collisions (2A, 4A, and 6A GeV; b<5-6 fm). The measurements indicate that Lambda hyperons flow consistently in the same direction but with smaller magnitudes. A strong positive flow [for Lambdas] has been predicted in calculations which include the influence of the Lambda-nucleon potential. The experimental flow ratio Lambda/p is in qualitative agreement with expectations (approximately 2/3) from the quark counting rule at 2A GeV but is found to decrease with increasing beam energy.

Physical map and characterization of transcripts in the candidate interval for familial chondrocalcinosis at chromosome 5p15.1

The gene for familial chondrocalcinosis (MIM 118600; gene symbol CCAL2) has been localized to a 0.8-cM interval on the short arm of chromosome 5, between the polymorphic microsatellite markers D5S416 and D5S2114. We have undertaken the physical and transcript mapping of this interval, as well as regions telomeric to the interval, in an attempt to define ultimately the gene for this disorder. The physical map is composed of YAC, BAC, PAC, and cosmid resources and spans a physical distance of approximately 0.3 Mb. Using cDNA selection, we have identified eight novel transcripts in and around the interval; two of the selected transcripts reside in the candidate interval. We have also more precisely placed several expressed sequence tags (ESTs) that were previously mapped by radiation hybrid analysis and were reported to reside in or near the candidate interval. Two of the ESTs analyzed overlap with the selected cDNAs that reside in the candidate interval. All of the selected cDNAs are expressed partial transcripts, as determined by Northern blot analysis, and using RT-PCR analysis, we have determined that the cDNAs that reside in the candidate interval are expressed in cartilage and synovium, tissues that are presumably relevant to the chondrocalcinosis phenotype.

Transcriptional activation of the alpha1(I) procollagen gene and up-regulation of alpha1(I) and alpha1(III) procollagen messenger RNA in dermal fibroblasts from tight skin 2 mice

OBJECTIVE

To investigate the levels of expression of type I and type III collagen genes in dermal fibroblasts from tight skin 2 (Tsk2) and normal mice and to examine the transcriptional regulation of the alpha1(I) procollagen gene (COL1A1) in these cells.

METHODS

Dermal fibroblasts from Tsk2 mice and from normal age- and sex-matched control mice were studied. Steady-state levels of alpha1(I) and alpha1(III) procollagen messenger RNA (mRNA) were evaluated by Northern and dot-blot hybridization analyses. The transcriptional regulation of COL1A1 was examined by transient transfection experiments with deletion constructs containing portions of the COL1A1 promoter ligated to the chloramphenicol acetyltransferase reporter gene. To identify DNA binding proteins that interact with regulatory elements within the COL1A1 promoter, gel mobility shift assays were performed with nuclear extracts prepared from normal and Tsk2 dermal fibroblasts.

RESULTS

Synthesis of collagen was almost 100% higher in Tsk2 dermal fibroblasts than in control fibroblasts. Up-regulation of mRNA for 2 extracellular matrix proteins was observed in the Tsk2 dermal fibroblasts compared with the normal cells: the alpha1(I) procollagen mRNA steady-state levels were 50% higher, and those of the alpha1(III) procollagen mRNA 100% higher, in Tsk2 cells. The results of transient transfection experiments with COL1A1 promoter constructs demonstrated that the elevated levels of alpha1(I) collagen mRNA in Tsk2 cells were largely due to increased transcriptional activity of the corresponding gene. Electrophoretic mobility shift assays performed with a probe encompassing a relevant COL1A1 promoter region revealed increased DNA-protein binding activities in nuclear extracts prepared from Tsk2 fibroblasts compared with normal fibroblasts. Competition experiments using consensus Spl and nuclear factor 1 (NF-1) oligonucleotides and supershift experiments using anti-Sp1 and anti-NF-1 antibodies indicated that at least 2 transcription factors, Sp1 and NF-1, or their homologs are involved in the up-regulated transcriptional activity of the COL1A1 promoter in Tsk2 fibroblasts.

CONCLUSION

Dermal fibroblasts from Tsk2 mice display increased collagen synthesis and up-regulation of alpha1(I) and alpha1(III) procollagen mRNA in vitro. The data also directly demonstrate the transcriptional activation of COL1A1 in dermal fibroblasts from Tsk2 mice and suggest that the transcription factors Sp1 and NF-1 or their homologs play an important role in the upregulated expression of this gene in Tsk2 fibroblasts. These findings are similar to those described for fibroblasts from humans with systemic sclerosis and validate the use of Tsk2 as a model for the study of the connective tissue alterations in this disease.