Lie groupoids determined by their orbit spaces

Given a Lie groupoid, we can form its orbit space, which carries a natural diffeology. More generally, we have a quotient functor from the Hilsum-Skandalis category of Lie groupoids to the category of diffeological spaces. We introduce the notion of a lift-complete Lie groupoid, and show that the quotient functor restricts to an equivalence of the categories: of lift-complete Lie groupoids with isomorphism classes of surjective submersive bibundles as arrows, and of quasi-\'{e}tale diffeological spaces with surjective local subductions as arrows. In particular, the Morita equivalence class of a lift-complete Lie groupoid, alternatively a lift-complete differentiable stack, is determined by its diffeological orbit space. Examples of lift-complete Lie groupoids include quasifold groupoids and \'{e}tale holonomy groupoids of Riemannian foliations.Comment: 31 pages, comments welcom

The Basic de Rham Complex of a Singular Foliation

A singular foliation $\mathcal F$ gives a partition of a manifold $M$ into leaves whose dimension may vary. Associated to a singular foliation are two complexes, that of the diffeological differential forms on the leaf space $M / \mathcal F$, and that of the basic differential forms on $M$. We prove the pullback by the quotient map provides an isomorphism of these complexes in the following cases: when $\mathcal F$ is a regular foliation, when points in the leaves of the same dimension assemble into an embedded (more generally, diffeological) submanifold of $M$, and, as a special case of the latter, when $\mathcal F$ is induced by a linearizable Lie groupoid.Comment: 24 pages. Added sources in Introduction, corrected typo

Ab initio simulations of excited carrier dynamics in carbon nanotubes

Combining time-dependent density functional calculations for electrons with molecular dynamics simulations for ions, we investigate the dynamics of excited carriers in a (3,3) carbon nanotube at different temperatures. Following an hv=6.8 eV photoexcitation, the carrier decay is initially dominated by efficient electron-electron scattering. At room temperature, the excitation gap is reduced to nearly half its initial value after ~230 fs, where coupling to phonons starts dominating the decay. We show that the onset point and damping rate in the phonon regime change with initial ion velocities, a manifestation of temperature dependent electron-phonon coupling.Comment: 8 pages, 3 figures, 1 EPAPS supplementary fil

Concurrent Chemoradiation for Vaginal Cancer

Background: It is not known whether the addition of chemotherapy to radiation therapy improves outcomes in primary vaginal cancer. Here, we review clinical outcomes in patients with primary vaginal cancer treated with radiation therapy (RT) or concurrent chemoradiation therapy (CRT). Methods: Seventy-one patients with primary vaginal cancer treated with definitive RT with or without concurrent chemotherapy at a single institution were identified and their records reviewed. A total of 51 patients were treated with RT alone; 20 patients were treated with CRT. Recurrences were analyzed. Overall survival (OS) and disease-free survival (DFS) rates were estimated using the Kaplan-Meier method. Cox regression analysis was performed. Results: The median age at diagnosis was 61 years (range, 18–92 years) and the median follow-up time among survivors was 3.0 years. Kaplan-Meier estimates for OS and DFS differed significantly between the RT and CRT groups (3-yr OS = 56% vs. 79%, log-rank p = 0.037; 3-yr DFS = 43% vs. 73%, log-rank p = 0.011). Twenty-three patients (45%) in the RT group had a relapse at any site compared to 3 (15%) in the CRT group (p = 0.027). With regard to the sites of first relapse, 10 patients (14%) had local only, 4 (6%) had local and regional, 9 (13%) had regional only, 1 (1%) had regional and distant, and 2 (3%) had distant only relapse. On univariate analysis, the use of concurrent chemotherapy, FIGO stage, tumor size, and date of diagnosis were significant predictors of DFS. On multivariate analysis, the use of concurrent chemotherapy remained a significant predictor of DFS (hazard ratio 0.31 (95% CI, 0.10–0.97; p = 0.04)). Conclusions: Vaginal cancer results in poor outcomes. Adequate radiation dose is essential to ensure curative management. Concurrent chemotherapy should be considered for vaginal cancer patients

Improving Permeability and Salt Leaching in Irrigated Sports Fields: Exploratory Testing

Many sports fields developed in the El Paso Valley and some in uplands became salinized when irrigated with water containing 800 to 1,200 mg/L of dissolved salts. The soil types, which were salinized, include compacted soils, clayey Entisols, stony sediments along foothills, and some areas containing an indurated calcic horizon. Salinity of these soils was initially less than 3 dS m-1 in the saturation extract, and has increased over a decade or two in excess of 10 dS m-1, sufficient to deter growth of most turf grass species. The study reported here was preformed for evaluating various mechanical means of improving soil permeability for enhancing salt leaching. Observation included two municipal parks consisting of sandy alluvial soils, five sports fields consisting of clayey alluvial soils, sports fields consisting of topdressed stony alluvial soils or developed on an indurated calcic horizon through topsoiling. The equipment tested included a rotary tiller, a vibratory spike, aerifiers, a minimum-till surface chisel, a subsoiler, a backhoe, and a front-end loader. Field management practices were left to discretion of cooperators. Soil salinity and photo records of turf response were used as the primary means of the treatment impact. The most significant reduction in soil salinity was found when stratified silty clay was either inverted to the new profile sequence of loamy sand over the fractured silty clay clods or mixed with the loamy sand layer below. Replacement of clays with sandy soils in a corrugated surface to permit lateral drainage was also highly effective in salt leaching in deep clay. Subsoiling of Glendale and Saneli silty clay loam followed by topdressing with a thin layer of sand also resulted in good salt leaching, especially when flood-irrigated using the Rio Grande water. The subsoiling shanks penetrated 20 to 30 inches deep, or almost to the full extent of the clay layer. It is uncertain if salt leaching can be improved when used in deeper clay, such as Tigua silty clay. The use of minimum-till shallow chisels provided an excellent fracturing of the surface clay layer (6 to 8 inches deep), but salt leaching was limited due to internal drainage impairment. The use of aerifiers did not improve salt leaching, at least at our test sites. Nonetheless, surface implements, especially minimumtill shallow chisels can be used advantageously for renovation or for sustaining high use fields consisting of loam. These preliminary test results are consistent with an earlier finding that soil salinization problems are closely tied with clayey soil textures. Test results also indicate that drainage impairment caused by the clay layer is probably as common as the difficulties with water intake for leaching salts. Since soil improvement measures to be used depend upon soil type, the field should be surveyed for soil type and its distribution prior to planning soil improvement activities. Irrigation systems and scheduling should also be checked. The primary goal of soil improvement activities is to improve soil permeability, water movement and salt leaching, and must be complemented by prudent turf management practices to obtain turf response. There is a need to examine the existing codes or specifications for construction of new fields for improved salt leaching. The current construction codes for sports fields emphasize soil strength and stability, but not salt leaching

Spectroscopic characterization of Stone-Wales defects in nanotubes

We combined resonant photoabsorption and vibration spectroscopy with scanning tunneling microscopy (STM) to unambiguously identify the presence of Stone-Wales (SW) defects in carbon and boron nitride nanotubes. Based on extensive time-dependent ab initio density functional calculations, we propose to resonantly photoexcite SW defects in the infrared and ultraviolet regime as a means of their identification. Onset of nonradiative decay to a local defect vibration with a frequency of 1962 cm-1 serves as a fingerprint of such defects in carbon nanotubes. The bias dependence of the STM images shows distinct features associated with the presence of SW defects.Y.M. was supported by NAREGI Nanoscience Project, Ministry of Education, Culture, Sports, Science and Technology, Japan. A.R. acknowledges support from the EC grants (HPRN-CT-2000-00128 and HPRN-CT-2000-00167) and Spain MCyT. M.Y. and D.T. acknowledge partial support by NSF-NIRT grant DMR- 0103587.Peer reviewe

Systemic Metabolomic Changes in Blood Samples of Lung Cancer Patients Identified by Gas Chromatography Time-of-Flight Mass Spectrometry.

Lung cancer is a leading cause of cancer deaths worldwide. Metabolic alterations in tumor cells coupled with systemic indicators of the host response to tumor development have the potential to yield blood profiles with clinical utility for diagnosis and monitoring of treatment. We report results from two separate studies using gas chromatography time-of-flight mass spectrometry (GC-TOF MS) to profile metabolites in human blood samples that significantly differ from non-small cell lung cancer (NSCLC) adenocarcinoma and other lung cancer cases. Metabolomic analysis of blood samples from the two studies yielded a total of 437 metabolites, of which 148 were identified as known compounds and 289 identified as unknown compounds. Differential analysis identified 15 known metabolites in one study and 18 in a second study that were statistically different (p-values <0.05). Levels of maltose, palmitic acid, glycerol, ethanolamine, glutamic acid, and lactic acid were increased in cancer samples while amino acids tryptophan, lysine and histidine decreased. Many of the metabolites were found to be significantly different in both studies, suggesting that metabolomics appears to be robust enough to find systemic changes from lung cancer, thus showing the potential of this type of analysis for lung cancer detection

XRHAMM Functions in Ran-Dependent Microtubule Nucleation and Pole Formation during Anastral Spindle Assembly

Background: The regulated assembly of microtubules is essential for bipolar spindle formation. Depending on cell type, microtubules nucleate through two different pathways: centrosome-driven or chromatin-driven. The chromatin-driven pathway dominates in cells lacking centrosomes.Results: Human RHAMM (receptor for hyaluronic-acid-mediated motility) was originally implicated in hyaluronic-acid-induced motility but has since been shown to associate with centrosomes and play a role in astral spindle pole integrity in mitotic systems. We have identified the Xenopus ortholog of human RHAMM as a microtubule-associated protein that plays a role in focusing spindle poles and is essential for efficient microtubule nucleation during spindle assembly without centrosomes. XRHAMM associates both with γ-TuRC, a complex required for microtubule nucleation and with TPX2, a protein required for microtubule nucleation and spindle pole organization.Conclusions: XRHAMM facilitates Ran-dependent, chromatin-driven nucleation in a process that may require coordinate activation of TPX2 and γ-TuRC

A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: IV. Modeling the Sagittarius Tidal Tails

M giants recovered from the Two Micron All-Sky Survey (2MASS) have recently been used to map the position and velocity distributions of tidal debris from the Sagittarius (Sgr) dwarf spheroidal galaxy entirely around the Galaxy. We compare this data set to both test particle orbits and N-body simulations of satellite destruction run within a variety of rigid Milky Way potentials and find that the mass of the Milky Way within 50 kpc of its center should be 3.8-5.6 x 10^11 Msun in order for any Sgr orbit to simultaneously fit the velocity gradient in the Sgr trailing debris and the apocenter of the Sgr leading debris. Orbital pole precession of young debris and leading debris velocities in regions corresponding to older debris provide contradictory evidence in favor of oblate/prolate Galactic halo potentials respectively, leading us to conclude that the orbit of Sgr has evolved over the past few Gyr. Based upon the velocity dispersion and width along the trailing tidal stream we estimate the current bound mass of Sgr to be M_Sgr = 2 - 5 x 10^8 Msun independant of the form of the Galactic potential; this corresponds to a range of mass to light ratios (M/L)_Sgr = 14 - 36 (M/L)_Sun for the Sgr core. Models with masses in this range best fit the apocenter of leading Sgr tidal debris when they orbit with a radial period of roughly 0.85 Gyr and have periGalactica and apoGalactica of about 15 kpc and 60 kpc respectively. These distances will scale with the assumed distance to the Sgr dwarf and the assumed depth of the Galactic potential. The density distribution of debris along the orbit in these models is consistent with the M giant observations, and debris at all orbital phases where M giants are obviously present is younger (i.e. was lost more recently from the satellite) than the typical age of a Sgr M giant star.Comment: 42 pages, 13 figures; Accepted for publication by ApJ (October 08, 2004; originally submitted May 10, 2004). Fixed typos and added references. PDF file with high resolution figures may be downloaded from http://www.astro.caltech.edu/~drlaw/Papers/Sgr_paper4.pd