2,058 research outputs found
Microdosimetry radiation analysis method and device
Apparatus and method for qualitatively and quantitatively analyzing a complex radiation field are provided. A microdosimetry device is provided having an array of microstructure parallel p-n junctions. Each junction defines a predetermined sensitive volume within which a voltage pulse is produced responsive to incident radiation. Circuitry in communication with the detector array generates digital pulse signals representative of the voltage pulses induced within the sensitive volumes responsive to incident radiation, and further provides a summation of the digital pulses occurring at particular energies. The summations of digital pulses are compared to known energies generated by known ionizing particles in comparable sensitive volumes to generate an dose equivalent estimate. Apparatus and method for calculating the total dose from an incident radiation field may also be included
Mechano-responsive polymer solutions based on CO2 supersaturation: shaking-induced phase transitions and self-assembly or dissociation of polymeric nanoparticles
Mechanical stimulation of supersaturated aqueous CO2 solutions is accompanied by a pH increase within seconds. In solutions of tailored homo- and AB diblock copolymers this is exploited to induce micelle formation, or, taking advantage of an aqueous upper critical solution temperature transition, nanoparticle disassembly
ΠΠ½Π°Π»ΠΈΠ· ΠΈ ΠΈΠ½ΡΠ΅ΡΠΏΡΠ΅ΡΠ°ΡΠΈΡ Π³ΠΈΠ΄ΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ Π΄Π»Ρ Π΄Π²ΡΡ ΡΠ°Π·Π½ΠΎΠ³ΠΎ ΠΏΠΎΡΠΎΠΊΠ° (Π²ΠΎΠ΄Π°-Π½Π΅ΡΡΡ)
ΠΠΎΠΊΠ°Π·Π°Π½Ρ ΠΏΡΠΎΠ±Π»Π΅ΠΌΡ, Π²ΠΎΠ·Π½ΠΈΠΊΠ°ΡΡΠΈΠ΅ ΠΏΡΠΈ ΠΈΠ½ΡΠ΅ΡΠΏΡΠ΅ΡΠ°ΡΠΈΠΈ ΠΈ Π°Π½Π°Π»ΠΈΠ·Π΅ Π΄Π°Π½Π½ΡΡ
Π³ΠΈΠ΄ΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ, ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½Π½ΡΡ
Π½Π° ΡΠΊΠ²Π°ΠΆΠΈΠ½Π°Ρ
Ρ ΠΎΠ±Π²ΠΎΠ΄Π½Π΅Π½Π½ΠΎΡΡΡΡ, ΠΎΡΠ»ΠΈΡΠ½ΠΎΠΉ ΠΎΡ Π½ΡΠ»Ρ. Π Π°Π·ΠΎΠ±ΡΠ°Π½Ρ ΠΏΡΠ΅ΠΈΠΌΡΡΠ΅ΡΡΠ²Π° ΠΈ Π½Π΅Π΄ΠΎΡΡΠ°ΡΠΊΠΈ ΠΏΡΠΈΠΌΠ΅Π½ΡΠ΅ΠΌΡΡ
ΠΌΠ΅ΡΠΎΠ΄ΠΎΠ² ΠΈΠ½ΡΠ΅ΡΠΏΡΠ΅ΡΠ°ΡΠΈΠΈ ΠΈ Π°Π½Π°Π»ΠΈΠ·Π°. ΠΡΠ΅Π΄ΡΡΠ°Π²Π»Π΅Π½ Π½ΠΎΠ²ΡΠΉ ΠΌΠ΅ΡΠΎΠ΄ Π½ΠΎΡΠΌΠ°Π»ΠΈΠ·Π°ΡΠΈΠΈ ΠΏΠΎΠ΄Π²ΠΈΠΆΠ½ΠΎΡΡΠΈ Π΄Π»Ρ Π°Π½Π°Π»ΠΈΠ·Π° ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠΎΠ² Π³ΠΈΠ΄ΡΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ ΡΠΊΠ²Π°ΠΆΠΈΠ½
NDE Software Developed at NASA Glenn Research Center
NASA Glenn Research Center has developed several important Nondestructive Evaluation (NDE) related software packages for different projects in the last 10 years. Three of the software packages have been created with commercial-grade user interfaces and are available to United States entities for download on the NASA Technology Transfer and Partnership Office server (https://sr.grc.nasa.gov/). This article provides brief overviews of the software packages
Colloidal assembly of polydisperse particle blends during drying
In this work, we synthesize a polydisperse aqueous colloidal system composed of small and large zwitterionic particles, as well as medium sized standard acrylic particles. By assembling these dispersions into films by drying, we show using atomic force microscopy (AFM) how their top surfaces can be mostly covered by zwitterionic groups for a wide range of evaporation rates. We probe underneath the top film surface using Fourier-transform infrared (FTIR) spectroscopy β attenuated total reflection (ATR), observing that the content in zwitterionic particles of the film upper layer increases for faster evaporation rates. We show how polydisperse systems hold great potential to overcome the evaporation rate dependence of size segregation processes in drying colloidal blends, and we provide further insights into the assembly mechanisms involved. Polydisperse blends enhance the robustness of such processes for application in coatings and other soft products where evaporation rate can not be tuned.</p
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The Job Market for New Economists: A Market Design Perspective
This paper, written by the members of the American Economic Association (AEA) Ad Hoc Committee on the Job Market, provides an overview of the market for new Ph.D. economists. It describes the role of the AEA in the market and focuses in particular on two mechanisms adopted in recent years at the suggestion of our Committee. First, job market applicants now have a signaling service to send an expression of special interest to up to two employers prior to interviews at the January Allied Social Science Associations (ASSA) meetings. Second, the AEA now invites candidates who are still on the market, and employers whose positions are still vacant, to participate in a web-based "scramble" to reduce search costs and thicken the late part of the job market. We present statistics on the activity in these market mechanisms and present survey evidence that both mechanisms have facilitated matches. The paper concludes by discussing the emergence of platforms for transmitting job market information and other design issues that may arise in the market for new economists.Economic
Passive solid state microdosimeter with electronic readout
Apparatus and method for qualitatively and quantitatively analyzing a complex radiation field are provided. A passive microdosimetry detector device records the energy deposition of incident radiation using an array of microstructure non-volatile memory devices. Each microstructure non-volatile memory device is capable of storing a predetermined initial charge without requiring a power source. A radiation particle incident to a microstructure non-volatile memory device is termed an event . Each such event may generate a charge within a sensitive volume defined by the microstructure non-volatile memory device. The charge generated within the sensitive volume alters the stored initial charge by an amount falling within a range corresponding to the energy deposited by certain particle types. Data corresponding to such charge alterations for a plurality of microstructure non-volatile memory devices within an array of such devices are presented to a qualitative analyzing device. The qualitative analyzing device converts the data to a spectral analysis of the incident radiation field by applying ICRP-recommended weighting factors to individual events or approximations thereof
Biocompatibility and Physiological Thiolytic Degradability of Radically Made Thioester-Functional Copolymers: Opportunities for Drug Release
Being nondegradable, vinyl polymers have limited biomedical applicability. Unfortunately, backbone esters incorporated through conventional radical ring-opening methods do not undergo appreciable abiotic hydrolysis under physiologically relevant conditions. Here, PEG acrylate and di(ethylene glycol) acrylamide-based copolymers containing backbone thioesters were prepared through the radical ring-opening copolymerization of the thionolactone dibenzo[c,e]oxepin-5(7H)-thione. The thioesters degraded fully in the presence of 10 mM cysteine at pH 7.4, with the mechanism presumed to involve an irreversible SβN switch. Degradations with N-acetylcysteine and glutathione were reversible through the thiolβthioester exchange polycondensation of RβSC(βO)βpolymerβSH fragments with full degradation relying on an increased thiolate/thioester ratio. Treatment with 10 mM glutathione at pH 7.2 (mimicking intracellular conditions) triggered an insolubleβsoluble switch of a temperature-responsive copolymer at 37 Β°C and the release of encapsulated Nile Red (as a drug model) from core-degradable diblock copolymer micelles. Copolymers and their cysteinolytic degradation products were found to be noncytotoxic, making thioester backbone-functional polymers promising for drug delivery applications
Spectroscopic Discovery of the Broad-Lined Type Ic Supernova 2010bh Associated with the Low-Redshift GRB 100316D
We present the spectroscopic discovery of a broad-lined Type Ic supernova (SN
2010bh) associated with the nearby long-duration gamma-ray burst (GRB) 100316D.
At z = 0.0593, this is the third-nearest GRB-SN. Nightly optical spectra
obtained with the Magellan telescopes during the first week after explosion
reveal the gradual emergence of very broad spectral features superposed on a
blue continuum. The supernova features are typical of broad-lined SNe Ic and
are generally consistent with previous supernovae associated with low-redshift
GRBs. However, the inferred velocities of SN 2010bh at 21 days after explosion
are a factor of ~2 times larger than those of the prototypical SN 1998bw at
similar epochs, with v ~ 26,000 km/s, indicating a larger explosion energy or a
different ejecta structure. A near-infrared spectrum taken 13.8 days after
explosion shows no strong evidence for He I at 1.083 microns, implying that the
progenitor was largely stripped of its helium envelope. The host galaxy is of
low luminosity (M_R ~ -18.5 mag) and low metallicity (Z < 0.4 Z_solar), similar
to the hosts of other low-redshift GRB-SNe.Comment: 6 pages, 4 figures, 1 table, submitted to ApJ Letter
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