2,097 research outputs found
Equity is more than recruitment and access: Supporting the success of Black and Latinx students in advanced placement coursework
Many school districts are making concerted efforts to increase participation of Black and Latinx student populations in Advanced Placement classes. Although overall enrollments are increasing for Black and Latinx students, they are less successful than their White and Asian counterparts in achieving a three or better on AP exams. This embedded case study focused on one district and examined the practices of two diverse high schools within that district. Through the Systemic Racial Equity framework, this case study examined antiracist school leadership practices that focus on supporting Black and Latinx studentsâ access to and success in Advanced Placement classes.
Through the use of secondary survey data, school leader and teacher interviews, and student focus groups, the finding showed that once enrolled in AP coursework, Black and Latinx students were still forced to navigate racial barriers both in and outside of the classroom. For the most part, the district and school leaders relied on technical fixes and colorblind decision making within the curriculum and individual school buildings. However, the issues that prove to be the most challenging for Black and Latinx students are entrenched within an educational system that is deferential to dominant, White culture. This research asserted that school leaders who wish to create racial equity within their schools must go beyond technical fixes, develop personal competencies such as public reflection and racial consciousness, and implement practices that involve all stakeholders in both dialogue and action that focuses on addressing the deeply embedded oppression of Whiteness in schools. This case study contended if the goal for school leaders is to create whole access for all students, then they must be willing to upset and redesign systems that have traditionally benefitted only one group
Seasonal distribution of genetic types of planktonic foraminifer morphospecies in the Santa Barbara Channel and its paleoceanographic implications
We present data on the temporal distribution of planktonic foraminifer genotypes (small subunit (SSU) ribosomal (r) RNA gene) and morphospecies (sediment traps) collected during 1999 in the Santa Barbara Channel. The sampling was undertaken with special emphasis on paleoceanographically important morphospecies, predominantly Globigerina bulloides. We found the same genotype of G. bulloides (type IId) in all the changing hydrographic regimes associated with this region throughout the annual cycle with the exception of January, when we recorded the additional presence of the high-latitude G. bulloides type IIa. We identified three new genotypes: Neogloboquadrina dutertrei type Ic, N. pachyderma dextral type II, and Turborotalita quinqueloba type IId. Our data suggest that G. bulloides type IId and possibly even the new genotypes listed above may be associated specifically with the complex hydrography or other environmental features characteristic of this area. Since G. bulloides type IId occurs throughout the year and its peak fluxes are related to different hydrographic regimes, we argue that the physical properties of the water column are not the major factor influencing the distribution and growth of this genotype. In sediment trap samples we found a skewed coiling ratio for G. bulloides (most likely representing type IId), which is related neither to sea surface temperature nor to genotypic difference. This study illustrates the necessity to map both the spatial and temporal distribution of the genetic types, especially in areas of paleoceanographic interest, where geochemical and paleontological proxies are being calibrated
Deviations from plastic barriers in BiSrCaCuO thin films
Resistive transitions of an epitaxial BiSrCaCuO thin
film were measured in various magnetic fields (), ranging from 0
to 22.0 T. Rounded curvatures of low resistivity tails are observed in
Arrhenius plot and considered to relate to deviations from plastic barriers. In
order to characterize these deviations, an empirical barrier form is developed,
which is found to be in good agreement with experimental data and coincide with
the plastic barrier form in a limited magnetic field range. Using the plastic
barrier predictions and the empirical barrier form, we successfully explain the
observed deviations.Comment: 5 pages, 6 figures; PRB 71, 052502 (2005
Measurement of Electromagnetic Activity of Yeast Cells at 42 GHz
This paper discusses the possibility of using a device composed of a resonant cavity, preamplifiers, and a spectrum analyzer to detect electromagnetic emission of yeast cells at a frequency of about 42 GHz. Measurement in this frequency range is based on the Frohlich\'s postulate of coherent polar oscillations as a fundamental biophysical property of biological systems and on the experiments of Grundler and Keilmann who disclosed effects of exposure to the electromagnetic field at 42 GHz on the growth rate of yeast cells. This article includes a detailed description of the laboratory equipment and the methods used to evaluate the obtained results
In Vitro Evaluation and Characterization of Newly Designed Alkylamidophospholipid Analogues as Anti-Human Immunodeficiency Virus Type 1 Agents
Our laboratories first reported two novel classes of complex synthetic lipids, including alkylamidophosphocholines (PC lipid; CP-51) and alkylamidophosphate ester-linked lipid-AZT conjugates (lipid-AZT conjugates; CP-92), with selective and potent activity against human immunodeficiency virus type 1 (HIV-1). To extend these observations, we synthesized additional PC lipids and lipid-AZT conjugates (INK and INK-AZT conjugate) to evaluate their structure-activity relationships by testing for selectivity against infectious wild-type (wt) and drug-resistant HIV-1 replication, virus fusogenic activity and toxicity for mouse bone marrow cells. PC lipid compounds with medium chain lengths at positions 1 and 2 gave an improved selective index (SI). INK-3, with 12 and 8 carbons and INK-15, with 10 and 12 carbons were among the most selective when evaluated in CEM-SS cells. INK-14, a lipid-AZT conjugate where AZT replaced the choline in PC lipid INK-3, gave the highest SI of > 1250 against both infectious wt HIV-1 replication in CEM-SS cells and a clinical isolate in peripheral blood leukocytes. Notably, the PC lipid compounds INK-3 and INK-15, but not the lipid-AZT conjugate INK-14, were potent inhibitors of matched pairs of AZT-sensitive and AZT-resistant HIV-1 clinical isolates. INK-3 also inhibited replication of HIV-2 and TIBO-resistant HIV-1, and inhibited HIV-1-mediated fusogenic activity by 78, 41 and 9% in a dose-dependent manner. The TC50 for mouse bone marrow cells was > 100 micrograms/ml for INK-3 compared to 9.15-14.17 micrograms/ml for CP-51 and 0.142-0.259 microgram/ml for AZT. These data suggest that optimum PC lipid compounds are significantly less toxic than AZT and have high potential as novel therapeutic agents for AIDS
Athletic Training and Public Health Summit
To introduce athletic trainers to the benefits of using a population-based approach to injury and illness prevention and to explore opportunities for partnering with public health professionals on these initiatives
Temperature-dependent Faraday rotation and magnetization reorientation in cerium-substituted yttrium iron garnet thin films
We report on the temperature dependence of the magnetic and magneto-optical properties in cerium-substituted yttrium iron garnet (Ce: YIG) thin films. Measurements of the Faraday rotation as a function of temperature show that the magnetic easy axis of thin Ce: YIG films reorients from in-plane to out-of-plane on cooling below -100 degrees C. We argue that the temperature-dependence of the magnetostriction and magnetocrystalline anisotropy of Ce: YIG is the dominant factor contributing to the change in easy axis direction, and we describe the changes in the magneto-optical spectra with temperature.National Science Foundation (U.S.) (Award ECCS-1607865)United States. Defense Advanced Research Projects Agency (Award FA8650-16-1-7641
Optical, magneto-optical properties and fiber-drawing ability of tellurite glasses in the TeO2-ZnO-BaO ternary system
The presented work is focused on the optical and magneto-optical
characterization of TeO2-ZnO-BaO (TZB) tellurite glasses. We investigated the
refractive index and extinction coefficient dispersion by spectroscopic
ellipsometry from ultraviolet, 0.193 um, up to mid infrared, 25 um spectral
region. Studied glasses exhibited large values of linear (n632 = 1.91-2.09) and
non-linear refractive index (n2 = 1.20-2.67x10-11 esu), Verdet constant (V632 =
22-33 radT-1m-1) and optical band gap energy (Eg = 3.7-4.1 eV). The materials
characterization revealed that BaO substitution by ZnO leads (at constant
content of TeO2) to an increase in linear and nonlinear refractive index as
well as Verdet constant while the optical band gap energy decreases. Fiber
drawing ability of TeO2-ZnO-BaO glassy system has been demonstrated on
60TeO2-20ZnO-20BaO glass with presented mid infrared attenuation coefficient.
Specific parameters such as dispersion and single oscillator energy, Abbe
number, and first-/ third-order optical susceptibility are enclosed together
with the values of magneto-optic anomaly derived from the calculation of
measured dispersion of the refractive index
Precipitation from Space: Advancing Earth System Science
Of the three primary sources of spatially contiguous precipitation observations (surface networks, ground-based radar, and satellite-based radar/radiometers), only the last is a viable source over ocean and much of the Earth's land. As recently as 15 years ago, users needing quantitative detail of precipitation on anything under a monthly time scale relied upon products derived from geostationary satellite thermal infrared (IR) indices. The Special Sensor Microwave Imager (SSMI) passive microwave (PMW) imagers originated in 1987 and continue today with the SSMI sounder (SSMIS) sensor. The fortunate longevity of the joint National Aeronautics and Space Administration (NASA) and Japan Aerospace Exploration Agency (JAXA) Tropical Rainfall Measuring Mission (TRMM) is providing the environmental science community a nearly unbroken data record (as of April 2012, over 14 years) of tropical and sub-tropical precipitation processes. TRMM was originally conceived in the mid-1980s as a climate mission with relatively modest goals, including monthly averaged precipitation. TRMM data were quickly exploited for model data assimilation and, beginning in 1999 with the availability of near real time data, for tropical cyclone warnings. To overcome the intermittently spaced revisit from these and other low Earth-orbiting satellites, many methods to merge PMW-based precipitation data and geostationary satellite observations have been developed, such as the TRMM Multisatellite Precipitation Product and the Climate Prediction Center (CPC) morphing method (CMORPH. The purpose of this article is not to provide a survey or assessment of these and other satellite-based precipitation datasets, which are well summarized in several recent articles. Rather, the intent is to demonstrate how the availability and continuity of satellite-based precipitation data records is transforming the ways that scientific and societal issues related to precipitation are addressed, in ways that would not be otherwise possible. These developments have taken place in parallel with the growth of an increasingly interconnected scientific environment. Scientists from different disciplines can easily interact with each other via information and materials they encounter online, and collaborate remotely without ever meeting each other in person. Likewise, these precipitation datasets are quickly and easily available via various data portals and are widely used. Within the framework of the NASA/JAXA Global Precipitation Measurement (GPM mission, these applications will become increasingly interconnected. We emphasize that precipitation observations by themselves provide an incomplete picture of the state of the atmosphere. For example, it is unlikely that a richer understanding of the global water cycle will be possible by standalone missions and algorithms, but must also involve some component of data, where model analyses of the physical state are constrained alongside multiple observations (e.g., precipitation, evaporation, radiation). The next section provides examples extracted from the many applications that use various high-resolution precipitation products. The final section summarizes the future system for global precipitation processing
Prospects of Detecting Non-thermal Protons in Solar Flares via Lyman Line Spectroscopy: Revisiting the Orrall-Zirker Effect
Solar flares are efficient particle accelerators, with a substantial fraction
of the energy released manifesting as non-thermal particles. While the role
that non-thermal electrons play in transporting flare energy is well studied,
the properties and importance of non-thermal protons is rather less well
understood. This is in large part due to the paucity of diagnostics,
particularly at the lower-energy (deka-keV) range of non-thermal proton
distributions in flares. One means to identify the presence of deka-keV protons
is by an effect originally described by \cite{1976ApJ...208..618O}. In the
Orrall-Zirker effect, non-thermal protons interact with ambient neutral
hydrogen, and via charge exchange produce a population of energetic neutral
atoms (ENAs) in the chromosphere. These ENAs subsequently produce an extremely
redshifted photon in the red wings of hydrogen spectral lines. We revisit
predictions of the strength of this effect using modern interaction
cross-sections, and numerical models capable of self-consistently simulating
the flaring non-equilibrium ionization stratification, and the non-thermal
proton distribution (and, crucially, their feedback on each other). We
synthesize both the thermal and non-thermal emission from \lya\ and \lyb, the
most promising lines that may exhibit a detectable signal. These new
predictions are are weaker and more transient than prior estimates, but the
effects should be detectable in fortuitous circumstances. We degrade the \lyb\
emission to the resolution of the Spectral Imaging of the Coronal Environment
(SPICE) instrument on board Solar Orbiter, demonstrating that though likely
difficult, it should be possible to detect the presence of non-thermal protons
in flares observed by SPICE.Comment: Accepted for publication in The Astrophysical Journa
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