7,512 research outputs found
Universal Access to a Quality Education: Research and Recommendations for the Elimination of Curricular Stratification
This policy brief makes the case for schools across the country to put an end to policies that cast off students into unchallenging, low-track classrooms. The authors recommend a clear process for the phasing out of curricular stratification in grades K-10, beginning with the lowest track and granting meaningful access to AP and IB courses to all students. The brief includes model statutory language to implement its recommendations
Evidence of polariton induced transparency in a single organic quantum wire
The resonant interaction between quasi-one dimensional excitons and photons
is investigated. For a single isolated organic quantum wire, embedded in its
single crystal monomer matrix, the strong exciton-photon coupling regime is
reached. This is evidenced by the suppression of the resonant excitonic
absorption arising when the system eigenstate is a polariton. These
observations demonstrate that the resonant excitonic absorption in a
semiconductor can be understood in terms of a balance between the exciton
coherence time and the Rabi period between exciton-like and photon-like states
of the polariton.Comment: 9 pages and 4 figure
Nod1 signaling overcomes resistance of S. pneumoniae to opsonophagocytic killing
Airway infection by the Gram-positive pathogen Streptococcus pneumoniae (Sp) leads to recruitment of neutrophils but
limited bacterial killing by these cells. Co-colonization by Sp and a Gram-negative species, Haemophilus influenzae (Hi),
provides sufficient stimulus to induce neutrophil and complement-mediated clearance of Sp from the mucosal surface
in a murine model. Products from Hi, but not Sp, also promote killing of Sp by ex vivo neutrophil-enriched peritoneal
exudate cells. Here we identify the stimulus from Hi as its peptidoglycan. Enhancement of opsonophagocytic killing
was facilitated by signaling through nucleotide-binding oligomerization domain-1 (Nod1), which is involved in
recognition of γ-D-glutamyl-meso-diaminopimelic acid (meso-DAP) contained in cell walls of Hi but not Sp. Neutrophils
from mice treated with Hi or compounds containing meso-DAP, including synthetic peptidoglycan fragments, showed
increased Sp killing in a Nod1-dependent manner. Moreover, Nod1-/- mice showed reduced Hi-induced clearance of Sp
during co-colonization. These observations offer insight into mechanisms of microbial competition and demonstrate
the importance of Nod1 in neutrophil-mediated clearance of bacteria in vivo
Classification of specimen density in Laser Powder Bed Fusion (L-PBF) using in-process structure-borne acoustic process emissions
Currently, the laser powder bed fusion (L-PBF) process cannot offer a reproducible and predefined quality of the processed parts. Recent research on process monitoring focuses strongly on integrated optical measurement technology. Besides optical sensors, acoustic sensors also seem promising. Previous studies have shown the potential of analyzing structure-borne and air-borne acoustic emissions in laser welding. Only a few works evaluate the potential that lies in the usage during the L-PBF process.
This work shows how the approach to structure-borne acoustic process monitoring can be elaborated by correlating acoustic signals to statistical values indicating part quality. Density measurements according to Archimedes’ principle are used to label the layer-based acoustic data and to measure the quality. The data set is then treated as a classification problem while investigating the applicability of existing artificial neural network algorithms to match acoustic data with density measurements. Furthermore, this work investigates the transferability of the approach to more complex specimens
A Conserved Mechanism for Hormesis in Molecular Systems
Hormesis refers to dose-response phenomena where low dose treatments elicit a response that is opposite the response observed at higher doses. Hormetic dose-response relationships have been observed throughout all of biology, but the underlying determinants of many reported hormetic dose-responses have not been identified. In this report, we describe a conserved mechanism for hormesis on the molecular level where low dose treatments enhance a response that becomes reduced at higher doses. The hormetic mechanism relies on the ability of protein homo-multimers to simultaneously interact with a substrate and a competitor on different subunits at low doses of competitor. In this case, hormesis can be observed if simultaneous binding of substrate and competitor enhances a response of the homo-multimer. We characterized this mechanism of hormesis in binding experiments that analyzed the interaction of homotrimeric proliferating cell nuclear antigen (PCNA) with uracil DNA glycosylase (UNG2) and a fluorescein-labeled peptide. Additionally, the basic features of this molecular mechanism appear to be conserved with at least two enzymes that are stimulated by low doses of inhibitor: dimeric BRAF and octameric glutamine synthetase 2 (GS2). Identifying such molecular mechanisms of hormesis may help explain specific hormetic responses of cells and organisms treated with exogenous compounds
Research Notes : United States : Response of tolerant and susceptible soybean cultivars to Columbia lance nematode
Columbia lance nematode, CLN [Hoplolaimus columbus Sher], is a migratory endo-and ectoparasite of soybean and commonly causes yield reductions of up to 30% in tolerant cultivars. Complete crop failure may occur on moisture-stressed or susceptible cultivars. First recognized as a major parasite of cotton and soybean in 1967 (Fassultiotis et al., 1968), CLN now infests a large portion of the coastal plain of South Carolina, Georgia, and North Carolina. .pd
Physics Analysis Expert PAX: First Applications
PAX (Physics Analysis Expert) is a novel, C++ based toolkit designed to
assist teams in particle physics data analysis issues. The core of PAX are
event interpretation containers, holding relevant information about and
possible interpretations of a physics event. Providing this new level of
abstraction beyond the results of the detector reconstruction programs, PAX
facilitates the buildup and use of modern analysis factories. Class structure
and user command syntax of PAX are set up to support expert teams as well as
newcomers in preparing for the challenges expected to arise in the data
analysis at future hadron colliders.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 7 pages, LaTeX, 10 eps figures. PSN
THLT00
Vitamin B6 deficiency experimentally-induced bone and joint disorder: microscopic, radiographic and biochemical evidence
In the present study the effect of pyridoxine deficiency on the utrastructure and morphology of bone and its metabolism was examined in the rapidly growing chick. Pyridoxine-deficient animals had tibias of reduced dry weight and cortical thickness. Histomorphometry demonstrated a disproportionately high eroded surface, lower amount of osteoid tissue and reduced mineralized trabecular width. Anterior-posterior radiographs of the tibiotarsometatarsal joint showed reduced secondary ossification centres and coarse trabeculation. Decalcified metaphyseal cartilage showed irregular trabeculas and a markedly reduced amount of Fast-green counterstain matrix suggesting that there is less collagen present and in turn less availability for matrix to be laid down for later calcification. Plasma activity of the bone alkaline phosphatase isoenzyme (EC) 3. 1.3.1) was decreased. Plasma Ca and PO4 levels did not vary. The present bone study referring to a pseudo-lathyritic state in which collagen maturation is not completely achieved supports the hypothesis that pyridoxine is an essential nutrient for the connective tissue matri
Making GDPR Usable: A Model to Support Usability Evaluations of Privacy
We introduce a new model for evaluating privacy that builds on the criteria
proposed by the EuroPriSe certification scheme by adding usability criteria.
Our model is visually represented through a cube, called Usable Privacy Cube
(or UP Cube), where each of its three axes of variability captures,
respectively: rights of the data subjects, privacy principles, and usable
privacy criteria. We slightly reorganize the criteria of EuroPriSe to fit with
the UP Cube model, i.e., we show how EuroPriSe can be viewed as a combination
of only rights and principles, forming the two axes at the basis of our UP
Cube. In this way we also want to bring out two perspectives on privacy: that
of the data subjects and, respectively, that of the controllers/processors. We
define usable privacy criteria based on usability goals that we have extracted
from the whole text of the General Data Protection Regulation. The criteria are
designed to produce measurements of the level of usability with which the goals
are reached. Precisely, we measure effectiveness, efficiency, and satisfaction,
considering both the objective and the perceived usability outcomes, producing
measures of accuracy and completeness, of resource utilization (e.g., time,
effort, financial), and measures resulting from satisfaction scales. In the
long run, the UP Cube is meant to be the model behind a new certification
methodology capable of evaluating the usability of privacy, to the benefit of
common users. For industries, considering also the usability of privacy would
allow for greater business differentiation, beyond GDPR compliance.Comment: 41 pages, 2 figures, 1 table, and appendixe
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