137 research outputs found
Aging and the visual perception of exocentric distance
AbstractThe ability of 18 younger and older adults to visually perceive exocentric distances was evaluated. The observers judged the extent of fronto-parallel and in-depth spatial intervals at a variety of viewing distances from 50cm to 164.3cm. Most of the observers perceived in-depth intervals to be significantly smaller than fronto-parallel intervals, a finding that is consistent with previous studies. While none of the individual observersâ judgments of exocentric distance were accurate, the judgments of the older observers were significantly more accurate than those of the younger observers. The precision of the observersâ judgments across repeated trials, however, was not affected by age. The results demonstrate that increases in age can produce significant improvements in the visual ability to perceive the magnitude of exocentric distances
Dust Size Growth and Settling in a Protoplanetary Disk
We have studied dust evolution in a quiescent or turbulent protoplanetary
disk by numerically solving coagulation equation for settling dust particles,
using the minimum mass solar nebular model. As a result, if we assume an
ideally quiescent disk, the dust particles settle toward the disk midplane to
form a gravitationally unstable layer within 2x10^3 - 4x10^4 yr at 1 - 30 AU,
which is in good agreement with an analytic calculation by Nakagawa, Sekiya, &
Hayashi (1986) although they did not take into account the particle size
distribution explicitly. In an opposite extreme case of a globally turbulent
disk, on the other hand, the dust particles fluctuate owing to turbulent motion
of the gas and most particles become large enough to move inward very rapidly
within 70 - 3x10^4 yr at 1 - 30 AU, depending on the strength of turbulence.
Our result suggests that global turbulent motion should cease for the
planetesimal formation in protoplanetary disks.Comment: 27 pages, 8 figures, accepted for publication in the Ap
Orthodontic and orthopaedic treatment for anterior open bite in children (Review)
Background: Anterior open bite occurs when there is a lack of vertical overlap of the upper and lower incisors. The aetiology is multifactorial including: oral habits, unfavourable growth patterns, enlarged lymphatic tissue with mouth breathing. Several treatments have been proposed to correct this malocclusion, but interventions are not supported by strong scientific evidence. Objectives: The aim of this systematic review was to evaluate orthodontic and orthopaedic treatments to correct anterior open bite in children. Search methods: The following databases were searched: the Cochrane Oral Health Group's Trials Register (to 14 February 2014); the Cochrane Central Register of Controlled Trials (CENTRAL)(The Cochrane Library 2014, Issue 1); MEDLINE via OVID (1946 to 14 February 2014); EMBASE via OVID (1980 to 14 February 2014); LILACS via BIREME Virtual Health Library (1982 to 14 February 2014); BBO via BIREME Virtual Health Library (1980 to 14 February 2014); and SciELO (1997 to 14 February 2014). We searched for ongoing trials via ClinicalTrials.gov (to 14 February 2014). Chinese journals were handsearched and the bibliographies of papers were retrieved. Selection criteria: All randomised or quasi-randomised controlled trials of orthodontic or orthopaedic treatments or both to correct anterior open bite in children. Data collection and analysis: Two review authors independently assessed the eligibility of all reports identified. Risk ratios (RRs) and corresponding 95% confidence intervals (CIs) were calculated for dichotomous data. The continuous data were expressed as described by the author. Main results: Three randomised controlled trials were included comparing: effects of Frankel's function regulator-4 (FR-4) with lip-seal training versus no treatment; repelling-magnet splints versus bite-blocks; and palatal crib associated with high-pull chincup versus no treatment.The study comparing repelling-magnet splints versus bite-blocks could not be analysed because the authors interrupted the treatment earlier than planned due to side effects in four of ten patients.FR-4 associated with lip-seal training (RR = 0.02 (95% CI 0.00 to 0.38)) and removable palatal crib associated with high-pull chincup (RR = 0.23 (95% CI 0.11 to 0.48)) were able to correct anterior open bite.No study described: randomisation process, sample size calculation, there was not blinding in the cephalometric analysis and the two studies evaluated two interventions at the same time. These results should be therefore viewed with caution. Authors' conclusions: There is weak evidence that the interventions FR-4 with lip-seal training and palatal crib associated with high-pull chincup are able to correct anterior open bite. Given that the trials included have potential bias, these results must be viewed with caution. Recommendations for clinical practice cannot be made based only on the results of these trials. More randomised controlled trials are needed to elucidate the interventions for treating anterior open bite
Perspectives on the Trypanosoma cruzi-host cell receptor interaction
Chagas disease is caused by the parasite Trypanosoma cruzi. The critical initial event is the interaction of the trypomastigote form of the parasite with host receptors. This review highlights recent observations concerning these interactions. Some of the key receptors considered are those for thromboxane, bradykinin, and for the nerve growth factor TrKA. Other important receptors such as galectin-3, thrombospondin, and laminin are also discussed. Investigation into the molecular biology and cell biology of host receptors for T. cruzi may provide novel therapeutic targets
An ALMA molecular inventory of warm Herbig Ae disks: I. Molecular rings, asymmetries and complexity in the HD 100546 disk
Observations of disks with the Atacama Large Millimeter/submillimeter Array
(ALMA) allow us to map the chemical makeup of nearby protoplanetary disks with
unprecedented spatial resolution and sensitivity. The typical outer Class II
disk observed with ALMA is one with an elevated C/O ratio and a lack of
oxygen-bearing complex organic molecules, but there are now some interesting
exceptions: three transition disks around Herbig Ae stars all show oxygen-rich
gas traced via the unique detections of the molecules SO and CH3OH. We present
the first results of an ALMA line survey at 337 to 357 GHz of such disks and
focus this paper on the first Herbig Ae disk to exhibit this chemical signature
- HD 100546. In these data, we detect 19 different molecules including NO, SO
and CH3OCHO (methyl formate). We also make the first tentative detections of
H213CO and 34SO in protoplanetary disks. Multiple molecular species are
detected in rings, which are, surprisingly, all peaking just beyond the
underlying millimeter continuum ring at 200 au. This result demonstrates a
clear connection between the large dust distribution and the chemistry in this
flat outer disk. We discuss the physical and/or chemical origin of these
sub-structures in relation to ongoing planet formation in the HD 100546 disk.
We also investigate how similar and/or different the molecular make up of this
disk is to other chemically well-characterised Herbig Ae disks. The line-rich
data we present motivates the need for more ALMA line surveys to probe the
observable chemistry in Herbig Ae systems which offer unique insight into the
composition of disk ices, including complex organic molecules.Comment: Accepted to AJ, 25 pages, 11 figure
An ALMA molecular inventory of warm Herbig Ae disks: II. Abundant complex organics and volatile sulphur in the IRS 48 disk
The Atacama Large Millimeter/submillimeter Array (ALMA) can probe the
molecular content of planet-forming disks with unprecedented sensitivity. These
observations allow us to build up an inventory of the volatiles available for
forming planets and comets. Herbig Ae transition disks are fruitful targets due
to the thermal sublimation of complex organic molecule (COM) and likely
H2O-rich ices in these disks. The IRS 48 disk shows a particularly rich
chemistry that can be directly linked to its asymmetric dust trap. Here, we
present ALMA observations of the IRS 48 disk where we detect 16 different
molecules and make the first robust detections of H213CO, 34SO, 33SO and
c-H2COCH2 (ethylene oxide) in a protoplanetary disk. All of the molecular
emissions, aside from CO, are colocated with the dust trap and this includes
newly detected simple molecules such as HCO+, HCN and CS. Interestingly, there
are spatial offsets between different molecular families, including between the
COMs and sulphur-bearing species, with the latter being more azimuthally
extended and located radially further from the star. The abundances of the
newly detected COMs relative to CH3OH are higher than the expected protostellar
ratios, which implies some degree of chemical processing of the inherited ices
during the disk lifetime. These data highlight IRS 48 as a unique astrochemical
laboratory to unravel the full volatile reservoir at the epoch of planet and
comet formation and the role of the disk in (re)setting chemical complexity.Comment: Accepted to AJ, 21 pages, 7 figure
Assessing the clinical utility of measuring Insulin-like Growth Factor Binding Proteins in tissues and sera of melanoma patients
<p>Abstract</p> <p>Background</p> <p>Different Insulin-like Growth Factor Binding Proteins (IGFBPs) have been investigated as potential biomarkers in several types of tumors. In this study, we examined both IGFBP-3 and -4 levels in tissues and sera of melanoma patients representing different stages of melanoma progression.</p> <p>Methods</p> <p>The study cohort consisted of 132 melanoma patients (primary, n = 72; metastatic, n = 60; 64 Male, 68 Female; Median Age = 56) prospectively enrolled in the New York University School of Medicine Interdisciplinary Melanoma Cooperative Group (NYU IMCG) between August 2002 and December 2006. We assessed tumor-expression and circulating sera levels of IGFBP-3 and -4 using immunohistochemistry and ELISA assays. Correlations with clinicopathologic parameters were examined using Wilcoxon rank-sum tests and Spearman-rank correlation coefficients.</p> <p>Results</p> <p>Median IGFBP-4 tumor expression was significantly greater in primary versus metastatic patients (70% versus 10%, p = 0.01) A trend for greater median IGFBP-3 sera concentration was observed in metastatic versus primary patients (4.9 Îźg/ml vs. 3.4 Îźg/ml, respectively, p = 0.09). However, sera levels fell within a normal range for IGFBP-3. Neither IGFBP-3 nor -4 correlated with survival in this subset of patients.</p> <p>Conclusion</p> <p>Decreased IGFBP-4 tumor expression might be a step in the progression from primary to metastatic melanoma. Our data lend support to a recently-described novel tumor suppressor role of secreting IGFBPs in melanoma. However, data do not support the clinical utility of measuring levels of IGFBP-3 and -4 in sera of melanoma patients.</p
Structure and Instabilities of an Irradiated Viscous Protoplanetary Disk
We investigate the structure and the stabilities of a protoplanetary disk,
which is heated by viscous process in itself and by its central star. The disk
is set to rotate with the Keplerian velocity and has the surface density
distribution of the minimum mass solar nebula. We assume the vertical
hydrostatic equilibrium and the radiative equilibrium at each point, and solve
the two-dimensional radiative transfer equation by means of the Short
Characteristic method in the spherical coordinate in order to determine the
disk structure. Our calculation shows that at the outer region of the disk with
a distance from the central star of x>1AU the radiative heating from the inner
disk dominates the viscous heating even near the midplane. It is because of the
high temperature distribution in the optically thin surface layer and the
relatively high disk height as a consequence of the irradiation from the inner
hot region of the disk. In addition, we examine the convective and the
magnetorotational instabilities of the disk. As a result, the whole disk is
convectively stable since the dusty region is not heated by the viscous
dissipation from the midplane but by the radial radiative heating. On the other
hand, almost all the disk is magnetorotationally unstable except for the region
near the equatorial plane of from 2AU to 10AU. Finally we discuss the growth
and the size distribution of dust particles in the disk, which suggests that
there exist cm-sized particles in the surface layer, namely, in the exposed
region of the disk.Comment: 23 pages, 5 figures, accepted by ApJ (Vol. 567, 2002
Development of a food frequency questionnaire to estimate habitual dietary intake in Japanese children
<p>Abstract</p> <p>Background</p> <p>Food frequency questionnaires (FFQ) are used for epidemiological studies. Because of the wide variations in dietary habits within different populations, a FFQ must be developed to suit the specific group. To date, no FFQ has been developed for Japanese children. In this study, we developed a FFQ to assess the regular dietary intake of Japanese children. The FFQ included questions regarding both individual food items and mixed dishes.</p> <p>Methods</p> <p>Children (3-11 years of age, n = 621) were recruited as subjects. Their parents or guardians completed a weighed dietary record (WDR) for each subject in one day. We defined FOOD to be not only as a single food item but also as a mixed dish. The dieticians conceptually grouped similar FOODs as FOOD types. We used a contribution analysis and a multiple regression analysis to select FOOD types.</p> <p>Results</p> <p>We obtained a total of 586 children's dietary data (297 boys and 289 girls). In addition, we obtained 1,043 FOODs. Dieticians grouped into similar FOODs, yielding 275 FOOD types. A total of 115 FOOD types were chosen using a contribution analysis and a multiple regression analysis, then we excluded overlapping items. FOOD types that were eaten by fewer than 15 subjects were excluded; 74 FOOD types remained. We also added liver-based dishes that provided a high amount of retinol. A total of 75 FOOD types were finally determined for the FFQ. The frequency response formats were classified into four type categories: seven, eight, nine and eleven, according to the general intake frequency of each FOOD type. Information on portion size was obtained from the photographs of each listed FOOD type in real scale size, which was the average amount of the children's portion sizes.</p> <p>Conclusions</p> <p>Using both a contribution analysis and a multiple regression analysis, we developed a 75-food item questionnaire from the study involving 586 children. The next step will involve the verification of FFQ reproducibility and validity.</p
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