3,065 research outputs found

    A multichannel passive microwave atmospheric temperature sounding system

    Get PDF
    The development of a small, lightweight, low-power, seven channel passive microwave radiometer system for use on the Defense Meteorological Satellite Program (DMSP) was described. The 50-60 GHz sensor system operates in the region of an intense atmospheric oxygen absorption band to provide atmospheric temperature profiles to 30 kilometer altitudes on a global basis

    Annotation Studio: Multimedia Annotation for Students

    No full text
    Annotation Studio is a web-based annotation application that integrates a powerful set of textual interpretation tools behind an interface that makes using those tools intuitive for undergraduates. Building on students’ new media literacies, this Open-source application develops traditional humanistic skills including close reading, textual analysis, persuasive writing, and critical thinking. Initial features of the Annotation Studio prototype, supported by an NEH Start-Up Grant, include aligned multi-media annotation of written texts, user-defined sharing of annotations, and grouping of annotation by self-defined tags to support interpretation and argument development. The fully developed application will support annotation of image, video and audio documents; annotation visualization; export of texts with annotations; and a media repository. We will also identify best practices among faculty using Annotation Studio in a broad range of humanities classes across the country

    Noncontact technique for measuring surface tension and viscosity of molten materials using high temperature electrostatic levitation

    Get PDF
    A new, noncontact technique is described which entails simultaneous measurements of the surface tension and the dynamic viscosity of molten materials. In this technique, four steps were performed to achieve the results: (1) a small sample of material was levitated and melted in a high vacuum using a high temperature electrostatic levitator, (2) the resonant oscillation of the drop was induced by applying a low level ac electric field pulse at the drop of resonance frequency, (3) the transient signals which followed the pulses were recorded, and (4) both the surface tension and the viscosity were extracted from the signal. The validity of this technique was demonstrated using a molten tin and a zirconium sample. In zirconium, the measurements could be extended to undercooled states by as much as 300 K. This technique may be used for both molten metallic alloys and semiconductors

    Application of diffusion barriers to the refractory fibers of tungsten, columbium, carbon and aluminum oxide

    Get PDF
    A radio frequency powered ion-plating system was used to plate protective layers of refractory oxides and carbide onto high strength fiber substrates. Subsequent overplating of these combinations with nickel and titanium was made to determine the effectiveness of such barrier layers in preventing diffusion of the overcoat metal into the fibers with consequent loss of fiber strength. Four substrates, five coatings, and two metal matrix materials were employed for a total of forty material combinations. The substrates were tungsten, niobium, NASA-Hough carbon, and Tyco sapphire. The diffusion-barrier coatings were aluminum oxide, yttrium oxide, titanium carbide, tungsten carbide with 14% cobalt addition, and zirconium carbide. The metal matrix materials were IN 600 nickel and Ti 6/4 titanium. Adhesion of the coatings to all substrates was good except for the NASA-Hough carbon, where flaking off of the oxide coatings in particular was observed

    High-resolution antenna near-field imaging and sub-THz measurements with a small atomic vapor-cell sensing element

    Full text link
    Atomic sensing and measurement of millimeter-wave (mmW) and THz electric fields using quantum-optical EIT spectroscopy of Rydberg states in atomic vapors has garnered significant interest in recent years towards the development of atomic electric-field standards and sensor technologies. Here we describe recent work employing small atomic vapor cell sensing elements for near-field imaging of the radiation pattern of a Ku_u-band horn antenna at 13.49 GHz. We image fields at a spatial resolution of λ/10\lambda/10 and measure over a 72 to 240 V/m field range using off-resonance AC-Stark shifts of a Rydberg resonance. The same atomic sensing element is used to measure sub-THz electric fields at 255 GHz, an increase in mmW-frequency by more than one order of magnitude. The sub-THz field is measured over a continuous ±\pm100 MHz frequency band using a near-resonant mmW atomic transition

    DC Electric Fields in Electrode-Free Glass Vapor Cell by Photoillumination

    Full text link
    Rydberg-atom-enabled atomic vapor cell technologies show great potentials in developing devices for quantum enhanced sensors. In this paper, we demonstrate laser induced DC electric fields in an all-glass vapor cell without bulk or thin film electrodes. The spatial field distribution is mapped by Rydberg electromagnetically induced transparency spectroscopy. We explain the measured with a boundary-value electrostatic model. This work may inspire new ideas for DC electric field control in designing miniaturized atomic vapor cell devices. Limitations and other charge effects are also discussed

    Annotation Studio: multimedia text annotation for students

    Get PDF
    Annotation Studio will be a web-based application that actively engages students in interpreting literary texts and other humanities documents. While strengthening students' new media literacies, this open source web application will develop traditional humanistic skills including close reading, textual analysis, persuasive writing, and critical thinking. Initial features will include: 1) easy-to-use annotation tools that facilitate linking and comparing primary texts with multi-media source, variation, and adaptation documents; 2) sharable collections of multimedia materials prepared by faculty and student users; 3) multiple filtering and display mechanisms for texts, written annotations, and multimedia annotations; 4) collaboration functionality; and 5) multimedia composition tools. Products of the start-up phase will include a working prototype, feedback from students and instructors, and a white paper summarizing lessons learned

    Correlates of genetic monogamy in socially monogamous mammals: insights from Azara's owl monkeys

    Get PDF
    Understanding the evolution of mating systems, a central topic in evolutionary biology for more than 50 years, requires examining the genetic consequences of mating and the relationships between social systems and mating systems. Among pair-living mammals, where genetic monogamy is extremely rare, the extent of extra-group paternity rates has been associated withmale participation in infant care, strength of the pair bond and length of the breeding season. This study evaluated the relationship between two of those factors and the genetic mating system of socially monogamous mammals, testing predictions that male care and strength of pair bond would be negatively correlated with rates of extra-pair paternity (EPP). Autosomal microsatellite analyses provide evidence for genetic monogamy in a pair-living primate with bi-parental care, the Azara’s owl monkey (Aotus azarae). A phylogenetically corrected generalized least square analysis was used to relate male care and strength of the pair bond to their genetic mating system (i.e. proportions of EPP) in 15 socially monogamous mammalian species. The intensity of male care was correlated with EPP rates in mammals, while strength of pair bond failed to reach statistical significance. Our analyses showthat, once social monogamy has evolved, paternal care, and potentially also close bonds, may facilitate the evolution of genetic monogamy.German Science Foundation (HU 1746/2-1); Wenner-Gren Foundation; L.S.B. Leakey Foundation;National Geographic Society; National Science Foundation (BCS-0621020, 1219368, and 1232349); the University of Pennsylvania Research Foundation; the Zoological Society of San Dieg

    Profile of a Heterogeneous Grouping Plan for Reading

    Get PDF
    Grouping children by ability for reading instruction is common practice in many elementary schools today. By reducing heterogeneity, ability grouping presumably allows teachers to provide instruction at an appropriate level for students in a particular group. However, research has shown that grouping children by ability can have a negative impact on lower ability readers, especially when the grouping occurs over time

    Language control and parallel recovery of language in individuals with aphasia

    Get PDF
    Background: The causal basis of the different patterns of language recovery following stroke in bilingual speakers is not well understood. Our approach distinguishes the representation of language from the mechanisms involved in its control. Previous studies have suggested that difficulties in language control can explain selective aphasia in one language as well as pathological switching between languages. Here we test the hypothesis that difficulties in managing and resolving competition will also be observed in those who are equally impaired in both their languages even in the absence of pathological switching. Aims: To examine difficulties in language control in bilingual individuals with parallel recovery in aphasia and to compare their performance on different types of conflict task. Methods & procedures: Two right-handed, non-native English-speaking participants who showed parallel recovery of two languages after stroke and a group of non-native English-speaking, bilingual controls described a scene in English and in their first language and completed three explicit conflict tasks. Two of these were verbal conflict tasks: a lexical decision task in English, in which individuals distinguished English words from non-words, and a Stroop task, in English and in their first language. The third conflict task was a non-verbal flanker task. Outcomes & Results: Both participants with aphasia were impaired in the picture description task in English and in their first language but showed different patterns of impairment on the conflict tasks. For the participant with left subcortical damage, conflict was abnormally high during the verbal tasks (lexical decision and Stroop) but not during the non-verbal flanker task. In contrast, for the participant with extensive left parietal damage, conflict was less abnormal during the Stroop task than the flanker or lexical decision task. Conclusions: Our data reveal two distinct control impairments associated with parallel recovery. We stress the need to explore the precise nature of control problems and how control is implemented in order to develop fuller causal accounts of language recovery patterns in bilingual aphasia
    • 

    corecore