Prenatal selection and dermatoglyphic patterns

Although human dermatoglyphics have been extensively studied, little is known of the prenatal origins of dermatoglyphic patterns. Digital patterns, i.e., loops, whorls, and arches, were obtained from 81 human abortuses, ranging in age from 11 to 25 weeks post-fertilization. Patterns were discernible with the earliest indications of epidermal ridge development. Findings indicate that pattern frequencies during early prenatal development differ from those of later fetal and postnatal periods. Furthermore, a high frequency of arches is seen associated with spontaneous abortion, suggesting evidence for prenatal selection in human abortuses.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37580/1/1330480105_ftp.pd

Prenatal Rotational Field Involving Deciduous Lateral Incisors

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66516/2/10.1177_00220345760550022501.pd

Adjacency Effects in Developmental Correlations Among Tooth Organs in Human Fetuses

This study explores whether the "distance gradient" model shown for embryonic development and postnatal tooth growth is also characteristic of the fetal period. Histologic data and ratings from 26 human fetuses show that, unlike the embryonic and postnatal periods, changes occurring in two tooth germs are significantly alike, regardless of the number of intervening teeth.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67281/2/10.1177_00220345810600021401.pd

Three-Dimensional Computed Tomography Analysis of Airway Volume Changes Between Open and Closed Jaw Positions

Introduction Airway dimensions are closely linked to the bone and soft-tissue craniofacial anatomy. Reduction of the airway is seen with airway disorders and can impair function. The purpose of this retrospective study was to determine whether changing from open to closed jaw position affects the volume of the nasal cavity, nasopharynx, and oropharynx; the soft palate; the soft-tissue thickness of the airway; and the most constricted area of the airway. Methods Following reliability studies, in this retrospective study, we analyzed cone-beam computed tomography scans taken in both closed and open jaw positions of 60 subjects who were undergoing diagnosis and treatment of temporomandibular disorders. On each scan, condyle-fossa measurements, volumes of airway segments (nasal cavity, nasopharynx, oropharynx), soft palate areas, soft tissue thicknesses of the airway, and the most constricted area of the airway and its location were measured using Dolphin imaging software (version 11.5; Patterson Dental Supply, Chatsworth, Calif). Differences between the 2 jaw positions were analyzed with paired t tests, accepting P ≤0.05 as significant. Results Significant changes in airway dimensions were found between the closed and open jaw positions. With jaw opening, the nasopharynx volume increased, whereas the oropharynx volume decreased. Significant decreases were also found for measurements of basion to posterior airway wall, cervical vertebrae to posterior airway wall, most constricted area, nasal cavity volume, and soft palate area when the jaw was open. Conclusions Changing jaw position significantly affects airway dimensions

Male advancement in prenatal hand development

Male advancement in the developing hand was evidenced by 66 grossly and microscopically normal embryos in the 15–75 mm crown-rump range. Male advancement was particularly pronounced in the younger (15–30 mm) embryos, both in the proximal hand region including the round bones of the wrist and in the distal hand region, comprising the metacarpals and phalanges. Thirty-four additional embryos, abnormal in implantation or development or representing spontaneous abortion similarly evidenced male advancement in the early hand skeleton.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/37548/1/1330410302_ftp.pd

Greater female communalities in prenatal hand and dental development

As shown in 15 male and 17 female developmentally-normal, 6-9 week (15-47 mm crown-rump length) embryos, intercorrelations (communalities) involving both mesial and distal deciduous teeth and proximal and distal segments of the developing hand were systematically higher in female embryos than in male embryos, without exception, a finding in surprising accordance with postnatal dimensional and temporal development of the dentition and of the appendicular skeleton.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22346/1/0000792.pd

Identifying Young Stellar Objects in the Outer Galaxy: l = 224 deg Region in Canis Major

We study a very young star-forming region in the outer Galaxy that is the most concentrated source of outflows in the Spitzer Space Telescope GLIMPSE360 survey. This region, dubbed CMa-l224, is located in the Canis Major OB1 association. CMa-l224 is relatively faint in the mid-infrared, but it shines brightly at the far-infrared wavelengths as revealed by the Herschel Space Observatory data from the Hi-GAL survey. Using the 3.6 and 4.5 $\mu$m data from the Spitzer/GLIMPSE360 survey, combined with the JHK$_s$ 2MASS and the 70-500 $\mu$m Herschel/Hi-GAL data, we develop a young stellar object (YSO) selection criteria based on color-color cuts and fitting of the YSO candidates' spectral energy distributions with YSO 2D radiative transfer models. We identify 293 YSO candidates and estimate physical parameters for 210 sources well-fit with YSO models. We select an additional 47 sources with GLIMPSE360-only photometry as `possible YSO candidates'. The vast majority of these sources are associated with high H$_2$ column density regions and are good targets for follow-up studies. The distribution of YSO candidates at different evolutionary stages with respect to Herschel filaments supports the idea that stars are formed in the filaments and become more dispersed with time. Both the supernova-induced and spontaneous star formation scenarios are plausible in the environmental context of CMa-l224. However, our results indicate that a spontaneous gravitational collapse of filaments is a more likely scenario. The methods developed for CMa-l224 can be used for larger regions in the Galactic plane where the same set of photometry is available.Comment: Accepted for publication in the Astrophysical Journal Supplement Series; 54 pages including appendice

Dust and Gas in the Magellanic Clouds from the HERITAGE Herschel Key Project. II. Gas-to-Dust Ratio Variations across ISM Phases

The spatial variations of the gas-to-dust ratio (GDR) provide constraints on the chemical evolution and lifecycle of dust in galaxies. We examine the relation between dust and gas at 10-50 pc resolution in the Large and Small Magellanic Clouds (LMC and SMC) based on Herschel far-infrared (FIR), H I 21 cm, CO, and Halpha observations. In the diffuse atomic ISM, we derive the gas-to-dust ratio as the slope of the dust-gas relation and find gas-to-dust ratios of 380+250-130 in the LMC, and 1200+1600-420 in the SMC, not including helium. The atomic-to-molecular transition is located at dust surface densities of 0.05 Mo pc-2 in the LMC and 0.03 Mo pc-2 in the SMC, corresponding to AV ~ 0.4 and 0.2, respectively. We investigate the range of CO-to-H2 conversion factor to best account for all the molecular gas in the beam of the observations, and find upper limits on XCO to be 6x1020 cm-2 K-1 km-1 s in the LMC (Z=0.5Zo) at 15 pc resolution, and 4x 1021 cm-2 K-1 km-1 s in the SMC (Z=0.2Zo) at 45 pc resolution. In the LMC, the slope of the dust-gas relation in the dense ISM is lower than in the diffuse ISM by a factor ~2, even after accounting for the effects of CO-dark H2 in the translucent envelopes of molecular clouds. Coagulation of dust grains and the subsequent dust emissivity increase in molecular clouds, and/or accretion of gas-phase metals onto dust grains, and the subsequent dust abundance (dust-to-gas ratio) increase in molecular clouds could explain the observations. In the SMC, variations in the dust-gas slope caused by coagulation or accretion are degenerate with the effects of CO-dark H2. Within the expected 5--20 times Galactic XCO range, the dust-gas slope can be either constant or decrease by a factor of several across ISM phases. Further modeling and observations are required to break the degeneracy between dust grain coagulation, accretion, and CO-dark H2

Spitzer Survey of the Large Magellanic Cloud, Surveying the Agents of a Galaxy's Evolution (SAGE) I: Overview and Initial Results

We are performing a uniform and unbiased, ~7x7 degrees imaging survey of the Large Magellanic Cloud (LMC), using the IRAC and MIPS instruments on board the Spitzer Space Telescope in order to survey the agents of a galaxy's evolution (SAGE), the interstellar medium (ISM) and stars in the LMC. The detection of diffuse ISM with column densities >1.2x10^21 H cm^-2 permits detailed studies of dust processes in the ISM. SAGE's point source sensitivity enables a complete census of newly formed stars with masses >3 solar masses that will determine the current star formation rate in the LMC. SAGE's detection of evolved stars with mass loss rates >1x10^-8 solar masses per year will quantify the rate at which evolved stars inject mass into the ISM of the LMC. The observing strategy includes two epochs in 2005, separated by three months, that both mitigate instrumental artifacts and constrain source variability. The SAGE data are non-proprietary. The data processing includes IRAC and MIPS pipelines and a database for mining the point source catalogs, which will be released to the community in support of Spitzer proposal cycles 4 and 5. We present initial results on the epoch 1 data with a special focus on the N79 and N83 region. The SAGE epoch 1 point source catalog has ~4 million sources. The point source counts are highest for the IRAC 3.6 microns band and decrease dramatically towards longer wavelengths consistent with the fact that stars dominate the point source catalogs and that the dusty objects, e.g. young stellar objects and dusty evolved stars that detected at the longer wavelengths, are rare in comparison. We outline a strategy for identifying foreground MW stars, that may comprise as much as 18% of the source list, and background galaxies, that may comprise ~12% of the source list.Comment: Accepted by the Astronomical Journa

Spitzer survey of the Large Magellanic Cloud, surveying the agents of a galaxy's evolution (SAGE). IV. Dust properties in the interstellar medium

The goal of this paper is to present the results of a preliminary analysis of the extended infrared (IR) emission by dust in the interstellar medium (ISM) of the Large Magellanic Cloud (LMC). We combine Spitzer Surveying the Agents of Galaxy Evolution (SAGE) and Infrared Astronomical Satellite (IRAS) data and correlate the infrared emission with gas tracers of H I, CO, and Hα. We present a global analysis of the infrared emission as well as detailed modeling of the spectral energy distribution (SED) of a few selected regions. Extended emission by dust associated with the neutral, molecular, and diffuse ionized phases of the ISM is detected at all IR bands from 3.6 μm to 160 μm. The relative abundance of the various dust species appears quite similar to that in the Milky Way (MW) in all the regions we have modeled. We construct maps of the temperature of large dust grains. The temperature map shows variations in the range 12.1-34.7 K, with a systematic gradient from the inner to outer regions, tracing the general distribution of massive stars and individual H II regions as well as showing warmer dust in the stellar bar. This map is used to derive the far-infrared (FIR) optical depth of large dust grains. We find two main departures in the LMC with respect to expectations based on the MW: (1) excess mid-infrared (MIR) emission near 70 μm, referred to as the 70 μm excess, and (2) departures from linear correlation between the FIR optical depth and the gas column density, which we refer to as FIR excess emission. The 70 μm excess increases gradually from the MW to the LMC to the Small Magellanic Cloud (SMC), suggesting evolution with decreasing metallicity. The excess is associated with the neutral and diffuse ionized gas, with the strongest excess region located in a loop structure next to 30 Dor. We show that the 70 μm excess can be explained by a modification of the size distribution of very small grains with respect to that in the MW, and a corresponding mass increase of ≃13% of the total dust mass in selected regions. The most likely explanation is that the 70 μm excess is due to the production of large very small grains (VSG) through erosion of larger grains in the diffuse medium. This FIR excess could be due to intrinsic variations of the dust/gas ratio, which would then vary from 4.6 to 2.3 times lower than the MW values across the LMC, but X_(CO) values derived from the IR emission would then be about three times lower than those derived from the Virial analysis of the CO data. We also investigate the possibility that the FIR excess is associated with an additional gas component undetected in the available gas tracers. Assuming a constant dust abundance in all ISM phases, the additional gas component would have twice the known H I mass. We show that it is plausible that the FIR excess is due to cold atomic gas that is optically thick in the 21 cm line, while the contribution by a pure H_2 phase with no CO emission remains a possible explanation