188 research outputs found
Home Study Course: Autumn 2000
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75118/1/j.1526-0976.2000.44012.x.pd
Fingerprinting an natürlichen und angepflanzten Schilf-Beständen (Phragmites australis) Nordwestdeutschlands
In Folge der Erweiterung des Bremer Flughafens mußte der Flußlauf der Ochtum (Alte Ochtum) verlegt werden (Neue Ochtum). Im Mittelpunkt des Projektes stehen natürliche und artifizielle Schilfbestände der Alten und Neuen Ochtum westlich von Bremen. Mit Hilfe der RAPD-Fingerprinting Methode wurden 13 Phragmites australis Bestände Nordwestdeutschlands untersucht. Die angepflanzten jungen Bestände der Neuen Ochtum unterscheiden sich nicht wesentlich von den spontan angesiedelten Populationen. Die neuen Bestände (Neue Ochtum) sind genetisch variabler als die älteren natürlichen Bestände (Alte Ochtum, sowie zum Vergleich Dümmer, Rubbenbruchsee). Einzelne Stichproben aus den angepflanzten Beständen können eindeutig Ancestorpopulationen (Alte Ochtum) zugeordnet werden. In manchen Beständen der Neuen Ochtum kann ein bedeutender Prozentsatz (bis zu 13%) an Merkmalen identifiziert werden, die in den Beständen der Alten Ochtum nicht vertreten sind. Es muß zu einem Neueintrag von außerhalb gekommen sein, der durch Anschwemmung von Saatgut erfolgt sein könnte. Möglicherweise erfolgte die artifizielle Bepflanzung mit Material, das nicht, wie angegeben, aus autochthonen Beständen der Alten Ochtum stammte. Innerhalb der Populationen sind Stichproben terrestrischer Bereiche von denen überfluteter Bereiche zu unterscheiden. Die Dümmerpopulationen sowie die Rubbenbruchpopulation sind deutlich verschieden von den Ochtum Populationen. Die Bestände der Neuen Ochtum und der Alten Ochtum bilden keine getrennten Cluster.Subsequent to the airport extension near Bremen the course of the river Ochtum (Alte Ochtum) has been moved to another place (Neue Ochtum). Our task was to compare the artificial and natural new stands (Neue Ochtum) with the natural old stands (Alte Ochtum) at the river Ochtum west of Bremen. With RAPD fingerprinting we studied the relationships within and between 13 reed stands of north-west Germany. The planted new stands do not differ essentially from the spontaneous new stands. The new stands (Neue Ochtum) are generally more variable than the old stands (Alte Ochtum, in comparison with Dümmer, Rubbenbruchsee). Single probes from the planted stands have nearly the same RAPD pattern as old stands (Alte Ochtum, ancestral genotypes). Some stands of the Neue Ochtum developed new RAPD markers (up to 13%) which do not occur in the Alte Ochtum populations. This is explained by an input of new genotypes from outside by washed up seeds or air borne pollen. The artificially planted material of the Neue Ochtum is possibly not an outcome of autochthonous stands of the Alte Ochtum as stated in the literature. Within some populations terrestrial and flooded genotypes can be determined. Populations from the Dümmer and the Rubbenbruchsee are clearly distinct from Ochtum populations. Neue Ochtum and Alte Ochtum stands do not create distinct clusters
Use Of XR Technologies to Trigger Interest in High School Students in a Construction Management Career
The construction management skilled workforce in the United States is shrinking as a big number of its employees approach retirement and are not being replaced quickly enough by younger generations. According to the literature, pre-college educational programs can help address this issue by attracting a broader and more varied pool of students into Construction Management and related programs. The literature also indicates that the application of Extended Reality (XR) modalities generates student benefits such as increased engagement and self-efficacy that could be derived from bringing these modalities into educational settings. These benefits, in turn, help recruitment efforts for these domains. Georgia Tech’s School of Building Construction developed a Building Construction Summer Camp in 2022 using the Model of Domain (MDL) educational framework and its theory on triggering situational interest in students, to recruit students to the Bachelor of Science in Building Construction program. To trigger interest, memorable situational activities must be incorporated. As such, all camp activities were carefully selected to be engaging and memorable and included hands-on activities such as building a masonry wall with professional masons and use of advanced technology, such as Building Information Modeling (BIM) technology such as REVIT and Masonry iQ, infrared cameras, laser scanners, and various XR modalities.
Pre- and post-surveys for the entire summer camp and shorter surveys after three specific activities using XR modalities were conducted to evaluate the effectiveness of the camp in triggering interest in the participants into pursuing a career in construction management. This thesis summarizes the evidence-based research results on the impact of these specific activities that used XR modalities as well as the overall camp on triggering situational interest in students. The post-camp survey results show a significant increase in the participants’ interest in a career in Construction Management after the camp. The findings contribute to the body of knowledge regarding the use of hands-on and XR-technology-based educational activities, specifically in the context of a summer camp for student recruitment purposes. Moreover, the findings provide an empirical foundation for developing a pre-college educational program to intrigue high school students' interests in the construction management domain. Analysis of the results also presents findings and recommendations useful to academia with respect to proper selection of XR modalities when different educational objectives and priorities are considered, such as student comfort. A limitation of the study is the small sample size, but data from future camps will be used to verify these findings.M.S
The Spatial Evolution of Stellar Structures in the LMC/SMC
We present an analysis of the spatial distribution of various stellar
populations within the Large and Small Magellanic Clouds. We use optically
selected stellar samples with mean ages between ~9 and ~1000 Myr, and existing
stellar cluster catalogues to investigate how stellar structures form and
evolve within the LMC/SMC. We use two statistical techniques to study the
evolution of structure within these galaxies, the -parameter and the
two-point correlation function (TPCF). In both galaxies we find the stars are
born with a high degree of substructure (i.e. are highly fractal) and that the
stellar distribution approaches that of the 'background' population on
timescales similar to the crossing times of the galaxy (~80/150 Myr for the
SMC/LMC respectively). By comparing our observations to simple models of
structural evolution we find that 'popping star clusters' do not significantly
influence structural evolution in these galaxies. Instead we argue that general
galactic dynamics are the main drivers, and that substructure will be erased in
approximately the crossing time, regardless of spatial scale, from small
clusters to whole galaxies. This can explain why many young Galactic clusters
have high degrees of substructure, while others are smooth and centrally
concentrated. We conclude with a general discussion on cluster 'infant
mortality', in an attempt to clarify the time/spatial scales involved.Comment: 6 pages, conference contribution to IAU Symposium 256, van Loon J.T.
& Oliviera J.M., ed
A 3D Monte Carlo Photoionization Code for Modeling Diffuse Ionized Gas
We have developed a three dimensional Monte Carlo photoionization code
tailored for the study of Galactic H II regions and the percolation of ionizing
photons in diffuse ionized gas. We describe the code, our calculation of
photoionization, heating & cooling, and the approximations we have employed for
the low density H II regions we wish to study. Our code gives results in
agreement with the Lexington H II region benchmarks. We show an example of a 2D
shadowed region and point out the very significant effect that diffuse
radiation produced by recombinations of helium has on the temperature within
the shadow.Comment: MNRAS accepte
Fidelity in sensory integration intervention research.
OBJECTIVE: We sought to assess validity of sensory integration outcomes research in relation to fidelity (faithfulness of intervention to underlying therapeutic principles).
METHOD: We identified core sensory integration intervention elements through expert review and nominal group process. Elements were classified into structural (e.g., equipment used, therapist training) and therapeutic process categories. We analyzed 34 sensory integration intervention studies for consistency of intervention descriptions with these elements.
RESULTS: Most studies described structural elements related to therapeutic equipment and interveners\u27 profession. Of the 10 process elements, only 1 (presentation of sensory opportunities) was addressed in all studies. Most studies described fewer than half of the process elements. Intervention descriptions in 35% of the studies were inconsistent with one process element, therapist-child collaboration.
CONCLUSION: Validity of sensory integration outcomes studies is threatened by weak fidelity in regard to therapeutic process. Inferences regarding sensory integration effectiveness cannot be drawn with confidence until fidelity is adequately addressed in outcomes research
The Extended Environment of M17: A Star Formation History
M17 is one of the youngest and most massive nearby star-formation regions in
the Galaxy. It features a bright H II region erupting as a blister from the
side of a giant molecular cloud (GMC). Combining photometry from the Spitzer
GLIMPSE survey with complementary infrared (IR) surveys, we identify candidate
young stellar objects (YSOs) throughout a 1.5 deg x 1 deg field that includes
the M17 complex. The long sightline through the Galaxy behind M17 creates
significant contamination in our YSO sample from unassociated sources with
similar IR colors. Removing contaminants, we produce a highly-reliable catalog
of 96 candidate YSOs with a high probability of association with the M17
complex. We fit model spectral energy distributions to these sources and
constrain their physical properties. Extrapolating the mass function of 62
intermediate-mass YSOs (M >3 Msun), we estimate that >1000 stars are in the
process of forming in the extended outer regions of M17.
From IR survey images from IRAS and GLIMPSE, we find that M17 lies on the rim
of a large shell structure ~0.5 deg in diameter (~20 pc at 2.1 kpc). We present
new maps of CO and 13CO (J=2-1) emission, which show that the shell is a
coherent, kinematic structure associated with M17 at v = 19 km/s. The shell is
an extended bubble outlining the photodissociation region of a faint, diffuse H
II region several Myr old. We provide evidence that massive star formation has
been triggered by the expansion of the bubble. The formation of the massive
cluster ionizing the M17 H II region itself may have been similarly triggered.
We conclude that the star formation history in the extended environment of M17
has been punctuated by successive waves of massive star formation propagating
through a GMC complex.Comment: 31 pages, 15 figures, accepted for publication in ApJ. For a version
with higher-quality figures, see
http://www.astro.wisc.edu/glimpse/Povich2009_M17.pd
Spitzer Space Telescope observations of the Carina Nebula: The steady march of feedback-driven star formation
We report the first results of imaging the Carina Nebula with Spitzer/IRAC,
providing a catalog of point sources and YSOs based on SED fits. We discuss
several aspects of the extended emission, including dust pillars that result
when a clumpy molecular cloud is shredded by massive star feedback. There are
few "extended green objects" (EGOs) normally taken as signposts of outflow
activity, and none of the HH jets detected optically are seen as EGOs. A
population of "extended red objects" tends to be found around OB stars, some
with clear bow-shocks. These are dusty shocks where stellar winds collide with
flows off nearby clouds. Finally, the relative distributions of O stars and
subclusters of YSOs as compared to dust pillars shows that while some YSOs are
located within pillars, many more stars and YSOs reside just outside pillar
heads. We suggest that pillars are transient phenomena, part of a continuous
outwardly propagating wave of star formation driven by massive star feedback.
As pillars are destroyed, they leave newly formed stars in their wake, which
are then subsumed into the young OB association. Altogether, the current
generation of YSOs shows no strong deviation from a normal IMF. The number of
YSOs suggests a roughly constant star-formation rate over the past 3Myr,
implying that star formation in pillars constitutes an important mechanism to
construct unbound OB associations. Accelerated pillars may give birth to O-type
stars that, after several Myr, could appear to have formed in isolation.Comment: 25 pages, 15 figures, MNRAS accepte
Gender differences in the association between adiposity and probable major depression: a cross-sectional study of 140,564 UK Biobank participants
<b>Background</b><p></p>
Previous studies on the association between adiposity and mood disorder have produced contradictory results, and few have used measurements other than body mass index (BMI). We examined the association between probable major depression and several measurements of adiposity: BMI, waist circumference (WC), waist-hip-ratio (WHR), and body fat percentage (BF%).<p></p>
<b>Methods</b><p></p>
We conducted a cross-sectional study using baseline data on the sub-group of UK Biobank participants who were assessed for mood disorder. Multivariate logistic regression models were used, adjusting for potential confounders including: demographic and life-style factors, comorbidity and psychotropic medication.<p></p>
<b>Results</b><p></p>
Of the 140,564 eligible participants, evidence of probable major depression was reported by 30,145 (21.5%). The fully adjusted odds ratios (OR) for obese participants were 1.16 (95% confidence interval (CI) 1.12, 1.20) using BMI, 1.15 (95% CI 1.11, 1.19) using WC, 1.09 (95% CI 1.05, 1.13) using WHR and 1.18 (95% CI 1.12, 1.25) using BF% (all p <0.001). There was a significant interaction between adiposity and gender (p = 0.001). Overweight women were at increased risk of depression with a dose response relationship across the overweight (25.0-29.9 kg/m2), obese I (30.0-34.9 kg/m2), II (35.0-39.9 kg/m2) and III (≥40.0 kg/m2) categories; fully adjusted ORs 1.14, 1.20, 1.29 and 1.48, respectively (all p < 0.001). In contrast, only obese III men had significantly increased risk of depression (OR 1.29, 95% CI 1.08, 1.54, p = 0.006).<p></p>
<b>Conclusion</b><p></p>
Adiposity was associated with probable major depression, irrespective of the measurement used. The association was stronger in women than men. Physicians managing overweight and obese women should be alert to this increased risk
Ionisation feedback in star formation simulations: The role of diffuse fields
We compare the three-dimensional gas temperature distributions obtained by a
dedicated radiative transfer and photoionisation code, MOCASSIN, against those
obtained by the recently-developed Smooth Particle Hydrodynamics (SPH) plus
ionisation code iVINE for snapshots of an hydrodynamical simulation of a
turbulent interstellar medium (ISM) irradiated by a nearby O star. Our tests
demonstrate that the global ionisation properties of the region are correctly
reproduced by iVINE, hence validating further application of this code to the
study of feedback in star forming regions. However we highlight potentially
important discrepancies in the detailed temperature distribution. In particular
we show that in the case of highly inhomogenous density distributions the
commonly employed on-the-spot (OTS) approximation yields unrealistically sharp
shadow regions which can affect the dynamical evolution of the system. We
implement a simple strategy to include the effects of the diffuse field in
future calculations, which makes use of physically motivated temperature
calibrations of the diffuse-field dominated regions and can be readily applied
to similar codes. We find that while the global qualitative behaviour of the
system is captured by simulations with the OTS approximation, the inclusion of
the diffuse field in iVINE (called DiVINE) results in a stronger confinement of
the cold gas, leading to denser and less coherent structures. This in turn
leads to earlier triggering of star formation. We confirm that turbulence is
being driven in simulations that include the diffuse field, but the efficiency
is slightly lower than in simulations that use the OTS approximation.Comment: 11 pages, 10 Figures, Accepted for publication in MNRA
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