5,244 research outputs found
Draft Programmatic Agreement for Buildings and Structures at Cold War Era Dedicated Instrumentation Sites: White Sands Missile Range, New Mexico
Since 1966, when the National Historic Preservation Act (NHPA) was signed into law, federal agencies have been required to consider their impact to known or potential historic resources under their jurisdiction. As a potentially costly and onerous process for large government installations such as the military, the law allows for procedures known as “program alternatives” which allow federal agencies to streamline the requirements for inventorying and evaluating categories of, or similar resources (in this case, buildings and structures) for their potential as historic resources.
This Capstone project seeks to capture a category of such resources, building and structures at Cold War Era dedicated instrumentation sites on the Ranges of White Sands Missile Range. By creating a historic context in which to identify these resources and put them into historical perspective, as well as identifying close to two hundred of such repetitive resources, a draft Programmatic Agreement was crafted to provide an alternative to the costly effort of individually inventorying and evaluating each property for National Register of Historic Places eligibility
Spatial scales of interactions among bacteria and between bacteria and the leaf surface.
Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5-20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions
Properties of optically selected BL Lac candidates from the SDSS
\textbf{Context.} Deep optical surveys open the avenue for find large numbers
of BL Lac objects that are hard to identify because they lack the unique
properties classifying them as such. While radio or X-ray surveys typically
reveal dozens of sources, recent compilations based on optical criteria alone
have increased the number of BL Lac candidates considerably. However, these
compilations are subject to biases and may contain a substantial number of
contaminating sources. \textbf{Aims.} In this paper we extend our analysis of
182 optically selected BL Lac object candidates from the SDSS with respect to
an earlier study. The main goal is to determine the number of bona fide BL Lac
objects in this sample. \textbf{Methods.} We examine their variability
characteristics, determine their broad-band radio-UV SEDs, and search for the
presence of a host galaxy. In addition we present new optical spectra for 27
targets with improved S/N with respect to the SDSS spectra. \textbf{Results.}
At least 59% of our targets have shown variability between SDSS DR2 and our
observations by more than 0.1-0.27 mag de- pending on the telescope used. A
host galaxy was detected in 36% of our targets. The host galaxy type and
luminosities are consistent with earlier studies of BL Lac host galaxies.
Simple fits to broad-band SEDS for 104 targets of our sample derived
synchrotron peak frequencies between with a peak at
. Our new optical spectra do not reveal any new
redshift for any of our objects. Thus the sample contains a large number of
bona fide BL Lac objects and seems to contain a substantial fraction of
intermediate-frequency peaked BL Lacs.Comment: Accepted for publication in A\&
Contributing Factors to Diaper Dermatitis in the NICU
ABSTRACT
Purpose: Describe the prevalence of diaper dermatitis (DD) and clinical characteristics of the infants in the Neonatal Intensive Care Unit (NICU) that develop DD. Explore the relationships between clinical characteristics and the development of DD.
Design: Retrospective, exploratory, descriptive study
Setting: Level IV NICU in an urban community in Southeast Wisconsin.
Participants: A convenience sample of 611 infants who were born and admitted to the NICU within 12 hours of life and discharged from the same NICU. A final total of 537 infants remained after exclusion criteria were met.
Methods: Data were collected from the participant’s electronic health records from birth until the infant was discharged to home.
Results: The prevalence of DD among the 537 infants was 34% (n = 180). A logistic regression demonstrated length of stay was significant, (B = 0.02, OR = 1.02, p = .002), indicating the odds of developing DD increased by ~2% for each additional day in the NICU. Days from birth to full feedings was also significant (B = -0.03, OR = 0.97, p = .023), indicating the odds of developing DD decreased by ~3% for each additional day to full feedings.
Conclusions: Increased preventative measures among preterm infants at risk for an extended length of stay can potentially decrease the prevalence of DD
Excitonic - vibronic coupled dimers: A dynamic approach
The dynamical properties of exciton transfer coupled to polarization
vibrations in a two site system are investigated in detail. A fixed point
analysis of the full system of Bloch - oscillator equations representing the
coupled excitonic - vibronic flow is performed. For overcritical polarization a
bifurcation converting the stable bonding ground state to a hyperbolic unstable
state which is basic to the dynamical properties of the model is obtained. The
phase space of the system is generally of a mixed type: Above bifurcation chaos
develops starting from the region of the hyperbolic state and spreading with
increasing energy over the Bloch sphere leaving only islands of regular
dynamics. The behaviour of the polarization oscillator accordingly changes from
regular to chaotic.Comment: uuencoded compressed Postscript file containing text and figures. In
case of questions, please, write to [email protected]
Temporal studies into attachment, VE-cadherin perturbation, and paracellular migration of human umbilical mesenchymal stem cells across umbilical vein endothelial monolayers
Mesenchymal stem cells from Wharton’s jelly of human umbilical cords (WJ-MSC) are a valuable alternate source of stem cells. Their role in situ and whether they can interact and cross intact endothelial monolayers requires elucidation. The aim of this study was to investigate the dynamic interactions between WJ-MSC and human umbilical vein endothelial cells (HUVEC), including attachment, transit times, extravasation pathway, and the effects of WJ-MSC on junctional vascular endothelial (VE)-cadherin. HUVEC were grown to near confluence in endothelial media and to full confluence in mixed media before the addition of PKH26-labelled WJ-MSC. Time lapse fluorescence microscopy showed stem cells undergoing membrane blebbing followed by amoeboid movement on HUVEC monolayers before rounding up and changing shape toward the spindleshaped morphology during/after transmigration to subendothelial positions. Cells demonstrated a time lag of 60 min before paracellular extravasation, confirmed by confocal microscopy. Forty-six percent of attached cells crossed in the first 2 h. By 16 h, a majority of cells had transmigrated with > 96% of cells crossing by 22 h. There were concomitant changes in endothelial junctional VE-cadherin with statistically significant increases in discontinuous staining at 2 h, return to control values at 16 h, even as from 22 h onward HUVEC displayed increased percentage of junctions with continuous staining and upregulation of protein. Our data suggests that WJ-MSC crosses the endothelial barrier through the paracellular pathway and can influence junctional organization of HUVEC with discreet perturbation of VE-cadherin preceding transmigration followed by upregulation once the adluminal side is reached. The latter may reflect a perivascular support function of WJ-MSC in the umbilical cord
Femtosecond study of the interplay between excitons, trions, and carriers in (Cd,Mn)Te quantum wells
We present an absorption study of the neutral and positively charged exciton
(trion) under the influence of a femtosecond, circularly polarized, resonant
pump pulse. Three populations are involved: free holes, excitons, and trions,
all exhibiting transient spin polarization. In particular, a polarization of
the hole gas is created by the formation of trions. The evolution of these
populations is studied, including the spin flip and trion formation processes.
The contributions of several mechanisms to intensity changes are evaluated,
including phase space filling and spin-dependent screening. We propose a new
explanation of the oscillator strength stealing phenomena observed in p-doped
quantum wells, based on the screening of neutral excitons by charge carriers.
We have also found that binding heavy holes into charged excitons excludes them
from the interaction with the rest of the system, so that oscillator strength
stealing is partially blockedComment: 4 pages, 4 figure
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