3,071 research outputs found
Articulating Learning Objectives for an Undergraduate Teaching Assistant Program: Merging Teaching Practicum, Leadership Seminar, and Service Learning
Since its inception in 2009, the Undergraduate Teaching Assistant Program (in the Department of Focused Inquiry at Virginia Commonwealth University) has evolved and expanded into an amalgamation of three distinct but overlapping elements: (i) teaching practicum, (ii) leadership seminar, and (iii) service learning experience. But only recently have we begun to fully and systematically itemize and map the precise learning objectives of the program. This task is particularly important, and particularly challenging, as the program merges learning objectives typically associated with each of the aforementioned elements. This essay seeks to more fully and more systematically articulate the precise learning objectives of this program, first by collating the observations and best practices of faculty who participate in the program into a list of seven skill sets and twenty-one subordinate classroom activities and modes of engagement, second by wedding those results with the âABCâ framework of experiential learning discussed by Carver (1996), and third by further mapping specific learning objectives within that framework through a process of triangulation. It is hoped that this process can be deployed in any similar undergraduate teaching assistant or peer mentoring program in order to reveal the interconnections among various programmatic elements and particular learning objectives
Time-Resolved Intraband Relaxation of Strongly-Confined Electrons and Holes in Colloidal PbSe Nanocrystals
The relaxation of strongly-confined electrons and holes between 1P and 1S
levels in colloidal PbSe nanocrystals has been time-resolved using femtosecond
transient absorption spectroscopy. In contrast to II-VI and III-V semiconductor
nanocrystals, both electrons and holes are strongly confined in PbSe
nanocrystals. Despite the large electron and hole energy level spacings (at
least 12 times the optical phonon energy), we consistently observe picosecond
time-scale relaxation. Existing theories of carrier relaxation cannot account
for these experimental results. Mechanisms that could possibly circumvent the
phonon bottleneck in IV-VI quantum dots are discussed
Trace metal fluxes to the ocean: The importance of highâstanding oceanic islands
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94592/1/grl16149.pd
X-ray Point Sources in The Central Region of M31 as seen by Chandra
We report on \chandra observations of the central region of M31. By combining
eight \chandra ACIS-I observations taken between 1999 and 2001, we have
identified 204 X-ray sources within the central region of
M31, with a detection limit of \lum. Of these 204 sources,
22 are identified with globular clusters, 2 with supernova remnants, 9 with
planetary nebula, and 9 as supersoft sources. By comparing individual images,
about 50% of the sources are variable on time scales of months. We also found
13 transients, with light curves showing a variety of shapes. We also extracted
the energy spectra of the 20 brightest sources; they can be well fit by a
single power-law with a mean photon index of 1.8. The spectral shapes of 12
sources are shown to be variable, suggesting that they went through state
changes. The luminosity function of all the point sources is consistent with
previous observations (a broken power-law with a luminosity break at
\lum). However, when the X-ray sources in different regions
are considered separately, different luminosity functions are obtained. This
indicates that the star-formation history might be different in different
regions.Comment: 42 pages, 9 figures, ApJ, accepted, Higher-resolution figures
available on reques
Systemic ablation of Camkk2 impairs metastatic colonization and improves insulin sensitivity in TRAMP mice : Evidence for cancer cell-extrinsic CAMKK2 functions in prostate cancer
Despite early studies linking calcium-calmodulin protein kinase kinase 2 (CAMKK2) to prostate cancer cell migration and invasion, the role of CAMKK2 in metastasis in vivo remains unclear. Moreover, while CAMKK2 is known to regulate systemic metabolism, whether CAMKK2âs effects on whole-body metabolism would impact prostate cancer progression and/or related comorbidities is not known. Here, we demonstrate that germline ablation of Camkk2 slows, but does not stop, primary prostate tumorigenesis in the TRansgenic Adenocarcinoma Mouse Prostate (TRAMP) genetic mouse model. Consistent with prior epidemiological reports supporting a link between obesity and prostate cancer aggressiveness, TRAMP mice fed a high-fat diet exhibited a pronounced increase in the colonization of lung metastases. We demonstrated that this effect on the metastatic spread was dependent on CAMKK2. Notably, diet-induced lung metastases exhibited a highly aggressive neuroendocrine phenotype. Concurrently, Camkk2 deletion improved insulin sensitivity in the same mice. Histological analyses revealed that cancer cells were smaller in the TRAMP;Camkk2â/â mice compared to TRAMP;Camkk2+/+ controls. Given the differences in circulating insulin levels, a known regulator of cell growth, we hypothesized that systemic CAMKK2 could promote prostate cancer cell growth and disease progression in part through cancer cell-extrinsic mechanisms. Accordingly, host deletion of Camkk2 impaired the growth of syngeneic murine prostate tumors in vivo, confirming nonautonomous roles for CAMKK2 in prostate cancer. Cancer cell size and mTOR signaling was diminished in tumors propagated in Camkk2-null mice. Together, these data indicate that, in addition to cancer cell-intrinsic roles, CAMKK2 mediates prostate cancer progression via tumor-extrinsic mechanisms. Further, we propose that CAMKK2 inhibition may also help combat common metabolic comorbidities in men with advanced prostate cancer
Peripheral sympathectomy and adrenal medullectomy do not alter cerebrospinal fluid norepinephrine
Despite a blood-brain barrier for norepinephrine, the concentration of norepinephrine in plasma and cerebrospinal fluid has been observed to be similar. This relationship between plasma and cerebrospinal fluid norepinephrine levels suggests that peripheral sympathetic neurons innervating blood vessels to brain and spinal cord may contribute significantly to cerebrospinal fluid norepinephrine levels, and questions the validity of cerebrospinal fluid norepinephrine as an index of central nervous system noradrenergic activity. We demonstrate that extensive destruction of the peripheral sympathetic nervous system and the adrenal medulla has no effect on rat cerebrospinal fluid norepinephrine. It is therefore unlikely that peripheral sources of norepinephrine contribute significantly to cerebrospinal fluid norepinephrine levels.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26232/1/0000312.pd
Histologic Abnormalities in Children with Nonalcoholic Fatty Liver Disease and Normal or Mildly Elevated Alanine Aminotransferase Levels.
Objectives: To investigate the histological spectrum of nonalcoholic fatty liver disease (NAFLD) in children with normal, mildly elevated (26â50 U/L boys, 23â44 U/L girls), or elevated (> 50 boys, > 44 girls) serum alanine aminotransferase (ALT) levels. Study design: The Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) enrolls children 5â18 years with NAFLD. We analyzed baseline clinical and histological data from 91 children with suspected NAFLD and normal or mildly elevated ALT and liver biopsy within 180 days of ALT, and compared them with 392 children with elevated ALT. Results: Of 91 children, 17 (19%) had normal and 74 (81%) had mildly elevated ALT levels. Overall, 45% of biopsies had â„ 33% steatosis, lobular inflammation grade was â„ 2 in 22%, 81% had portal inflammation, 29% had ballooned hepatocytes, 35% had âsuspicious/borderlineâ steatohepatitis, and 8% had definite NASH, 34% had NAFLD activity score (NAS) â„ 4. Overall, 46% had fibrosis (38% mild/moderate and 8% bridging/cirrhosis). Marked steatosis (50% vs 24%) and fibrosis (54% vs 12%) were significantly more common in mildly elevated vs normal, with no difference in ballooning, inflammation, or NAS â„ 4. Fibrosis stage 3/4 was seen in none of the children with normal ALT, and in 9% of the mildly elevated and 15% of the elevated. Conclusions: Liver biopsies of children with NAFLD with normal or mildly elevated ALT levels show significant histologic abnormalities, including advanced fibrosis in children with mildly elevated ALT. ALT thus may underestimate liver injury in NAFLD. Appropriate ALT cut-off levels can help identify children at risk for more severe disease
Measurement of the Î(0)(b) lifetime in pp collisions at sâ=7 TeV
This is the publisher's version, also available electronically from http://link.springer.com/article/10.1007%2FJHEP07%282013%29163.A measurement of the Î(0)(b) lifetime using the decay Î(0)(b)âJ/ÏÎ in protonproton collisions at sâ=7 TeV is presented. The data set, corresponding to an integrated luminosity of about 5 fb(â1), was recorded with the CMS experiment at the Large Hadron Collider using triggers that selected dimuon events in the J/Ï mass region. The Î(0)(b) lifetime is measured to be 1.503 ± 0.052 (stat.) ± 0.031 (syst.) ps
The Absolute Magnitude of RRc Variables From Statistical Parallax
We present the first definitive measurement of the absolute magnitude of RR
Lyrae c-type variable stars (RRc) determined purely from statistical parallax.
We use a sample of 247 RRc selected from the All Sky Automated Survey (ASAS)
for which high-quality light curves, photometry and proper motions are
available. We obtain high-resolution echelle spectra for these objects to
determine radial velocities and abundances as part of the Carnegie RR Lyrae
Survey (CARRS). We find that M_(V,RRc) = 0.52 +/- 0.11 at a mean metallicity of
[Fe/H] = -1.59. This is to be compared with previous estimates for RRab stars
(M_(V,RRab) = 0.75 +/- 0.13 and the only direct measurement of an RRc absolute
magnitude (RZ Cephei, M_(V, RRc) = 0.27 +/- 0.17). We find the bulk velocity of
the halo to be (W_pi, W_theta, W_z) = (10.9,34.9,7.2) km/s in the radial,
rotational and vertical directions with dispersions (sigma_(W_pi),
sigma_(W_theta), sigma_(W_z)) = (154.7, 103.6, 93.8) km/s. For the disk, we
find (W_pi, W_theta, W_z) = (8.5, 213.2, -22.1) km/s with dispersions
(sigma_(W_pi), sigma_(W_theta), sigma_(W_z)) = (63.5, 49.6, 51.3) km/s.
Finally, we suggest that UCAC2 proper motion errors may be overestimated by
about 25%Comment: Submitted to ApJ. 11 pages including 6 figure
Search for new physics in events with same-sign dileptons and b jets in pp collisions at sâ=8 TeV
This is the publisher's version, also available electronically from http://link.springer.com/article/10.1007%2FJHEP03%282013%29037.A search for new physics is performed using events with isolated same-sign leptons and at least two bottom-quark jets in the final state. Results are based on a sample of proton-proton collisions collected at a center-of-mass energy of 8 TeV with the CMS detector and corresponding to an integrated luminosity of 10.5 fb(â1). No excess above the standard model background is observed. Upper limits are set on the number of events from non-standard-model sources and are used to constrain a number of new physics models. Information on acceptance and efficiencies is also provided so that the results can be used to confront an even broader class of new physics models
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