3,357 research outputs found
Representation and Intention: Wittgenstein on What Makes a Picture of a Target
Throughout his later philosophy, Wittgenstein repeatedly asks the following: âWhat makes my image of him into an image of him?â (LW1 308).â âWhat makes this picture his picture?â (LW1 309). He takes this same question to apply to linguistic utterances: âIsnât my question like this: âWhat makes this sentence a sentence that has to do with him?ââ (LW1 308). This is by no means a peripheral concern of Wittgensteinâs, and in Philosophical Grammar (62), where he first phrases this question, he pronounces: âThatâs him (this picture represents him --that contains the whole problem of representation.â
This essay will explore Wittgensteinâs evolving interest in this key problem of representation, his criticisms of certain tempting answers, and his own perspicuous solution
Laboratory studies, analysis, and interpretation of the spectra of hydrocarbons present in planetary atmospheres including cyanoacetylene, acetylene, propane, and ethane
Combining broadband Fourier transform spectrometers (FTS) from the McMath facility at NSO and from NRC in Ottawa and narrow band TDL data from the laboratories with computational physics techniques has produced a broad range of results for the study of planetary atmospheres. Motivation for the effort flows from the Voyager/IRIS observations and the needs of Voyager analysis for laboratory results. In addition, anticipation of the Cassini mission adds incentive to pursue studies of observed and potentially observable constituents of planetary atmospheres. Current studies include cyanoacetylene, acetylene, propane, and ethane. Particular attention is devoted to cyanoacetylen (H3CN) which is observed in the atmosphere of Titan. The results of a high resolution infrared laboratory study of the line positions of the 663, 449, and 22.5/cm fundamental bands are presented. Line position, reproducible to better than 5 MHz for the first two bands, are available for infrared astrophysical searches. Intensity and broadening studies are in progress. Acetylene is a nearly ubiquitous atmospheric constituent of the outer planets and Titan due to the nature of methane photochemistry. Results of ambient temperature absolute intensity measurements are presented for the fundamental and two two-quantum hotband in the 730/cm region. Low temperature hotband intensity and linewidth measurements are planned
Impact of tumor-specific targeting on the biodistribution and efficacy of siRNA nanoparticles measured by multimodality in vivo imaging
Targeted delivery represents a promising approach for the development of safer and more effective therapeutics for oncology applications. Although macromolecules accumulate nonspecifically in tumors through the enhanced permeability and retention (EPR) effect, previous studies using nanoparticles to deliver chemotherapeutics or siRNA demonstrated that attachment of cell-specific targeting ligands to the surface of nanoparticles leads to enhanced potency relative to nontargeted formulations. Here, we use positron emission tomography (PET) and bioluminescent imaging to quantify the in vivo biodistribution and function of nanoparticles formed with cyclodextrin-containing polycations and siRNA. Conjugation of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid to the 5' end of the siRNA molecules allows labeling with 64Cu for PET imaging. Bioluminescent imaging of mice bearing luciferase-expressing Neuro2A s.c. tumors before and after PET imaging enables correlation of functional efficacy with biodistribution data. Although both nontargeted and transferrin-targeted siRNA nanoparticles exhibit similar biodistribution and tumor localization by PET, transferrin-targeted siRNA nanoparticles reduce tumor luciferase activity by {approx}50% relative to nontargeted siRNA nanoparticles 1 d after injection. Compartmental modeling is used to show that the primary advantage of targeted nanoparticles is associated with processes involved in cellular uptake in tumor cells rather than overall tumor localization. Optimization of internalization may therefore be key for the development of effective nanoparticle-based targeted therapeutics
Heating Features of Interesting Supra-Arcade Downflows
Supra-arcade downflows (SADs) have been observed above flare loops during the decay phase of flare. They appear as tadpole-like dark plasma voids traveling towards the Sun. In areas surrounding where they appear, temperatures are often high. We aim to investigate temperature and heating mechanism of SADs. We apply our analysis to the M1.7 flare that occurred on 2012 July 12 and was observed by the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory. There are many obvious SADs above the arcade during this event in the AIA 131 channel. We calculate the differential emission measure and emission measure weighted temperature with AIA data in the region where SADs are concentrated. We find that the temperature in SADs region tends to be lower than the surrounding plasma. We also calculate velocities of SADs using the Fourier Local Correlation Tracking (FLCT, Fisher & Welsch, 2008) method to derive velocities in the supra-arcade region. Using corks to track the calculated velocities, we find our velocity results are consistent with the SAD motions in the AIA 131 intensity movie. We use the velocities to derive the adiabatic heating caused by the compression of plasma. Preliminary results indicate that there is adiabatic heating in front of the SADs
Thermal Structure of Supra-Arcade Plasma in Two Solar Flares
In this work, we use Hinode/XRT and SDO/AIA data to determine the thermal structure of supra-arcade plasma in two solar flares. The first flare is a Ml.2 flare that occurred on November 5, 2010 on the east limb. This flare was one of a series of flares from AR 11121, published in Reeves & Golub (2011). The second flare is an XI.7 flare that occurred on January 27, 2012 on the west limb. This flare exhibits visible supra-arcade downflows (SADs), where the November 2010 flare does not. For these two flares we combine XRT and AlA data to calculate DEMs of each pixel in the supra-arcade plasma, giving insight into the temperature and density structures in the fan of plasma above the post-flare arcade. We find in each case that the supra-arcade plasma is around 10 MK, and there is a marked decrease in the emission measure in the SADs. We also compare the DEMs calculated with the combined AIA/XRT dataset to those calculated using AIA alone
Morphology Of A Hot Prominence Cavity Observed with Hinode/XRT and SDO/AIA
Prominence cavities appear as circularly shaped voids in coronal emission over polarity inversion lines where a prominence channel is straddling the solar limb. The presence of chromospheric material suspended at coronal altitudes is a common but not necessary feature within these cavities. These voids are observed to change shape as a prominence feature rotates around the limb. We use a morphological model projected in cross-sections to fit the cavity emission in Hinode/XRT passbands, and then apply temperature diagnostics to XRT and SDO/AIA data to investigate the thermal structure. We find significant evidence that the prominence cavity is hotter than the corona immediately outside the cavity boundary. This investigation follows upon "Thermal Properties of A Solar Coronal Cavity Observed with the X-ray Telescope on Hinode" by Reeves et al., 2012, ApJ, in press
(No) Time for Change : When and Why Entrepreneurs Act During Underperforming Fundraising Attempts
Entrepreneurs need to mobilize funds, but they do so under considerable uncertainty about resource holdersâ preferences, leading often to fundraising attempts that perform below entrepreneursâ aspirations. Past research has offered contrasting theorizing and evidence for why entrepreneurs then make changes to their product offering during such attempts as well as for why entrepreneurs refrain from taking such action. This paper develops and tests behavioral theory to reconcile this tension, explicating when and why entrepreneurs change their product offering during underperforming fundraising attempts. Specifically, we argue that entrepreneurs draw on three sources of information that are inherent to fundraising attempts and that inform the extent of their actions to change their product offering: the degree to which they perform below their own fundraising aspirations, the degree to which they fall below peer fundraising performance, and the time that remains until the deadline for the fundraising attempt. Longitudinal data on 576 fundraising campaigns (6,758 observations) published on the crowdfunding platform Kickstarter support our theory. By developing novel behavioral theory on when and why entrepreneurs take action during resource mobilization, we offer contributions to research on entrepreneurial resource mobilization, the crowdfunding literature, and the Behavioral Theory of the Firm.© 2023 The Author(s). This work is licensed under a Creative Commons Attribution-NonCommercialNoDerivatives 4.0 International License. You are free to download this work and share with others, but cannot change in any way or use commercially without permission, and you must attribute this work as Organization Science. https://doi.org/10.1287/orsc.2020.13803, used under a Creative Commons Attribution License: https://creativecommons.org/licenses/by-nc-nd/4.0/.fi=vertaisarvioitu|en=peerReviewed
Growth and Performance of Nursery Pigs Fed Crude Glycerol
The growth and performance of 96 nursery pigs fed crude glycerol was evaluated in a 33 d trial. Pigs were weaned at 21 d of age and had an average start weight of 7.9±1.2 kg (17.4±2.6 lb). Pigs were provided ad libitum access to corn soybean diets containing three levels of crude glycerol, 0, 5, or 10%. Diets were formulated to be ioscaloric and isolysinic. There was no difference in pig performance based on dietary treatment. Crude glycerol can be fed to young pigs as an energy source without growth or performance effects
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