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80,066 Matching Results

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Fermi Discovery of Gamma-Ray Emission from NGC 1275 (open access)

Fermi Discovery of Gamma-Ray Emission from NGC 1275

We report the discovery of high-energy (E > 100 MeV) {gamma}-ray emission from NGC 1275, a giant elliptical galaxy lying at the center of the Perseus cluster of galaxies, based on observations made with the Large Area Telescope (LAT) of the Fermi Gamma-ray Space Telescope. The positional center of the {gamma}-ray source is only {approx}3{prime} away from the NGC 1275 nucleus, well within the 95% LAT error circle of {approx}5{prime}. The spatial distribution of {gamma}-ray photons is consistent with a point source. The average flux and power-law photon index measured with the LAT from 2008 August 4 to 2008 December 5 are F{sub {gamma}} = (2.10 {+-} 0.23) x 10{sup -7} ph (>100 MeV) cm{sup -2} s{sup -1} and {Gamma} = 2.17 {+-} 0.05, respectively. The measurements are statistically consistent with constant flux during the four-month LAT observing period. Previous EGRET observations gave an upper limit of F{sub {gamma}} < 3.72 x 10{sup -8} ph (>100 MeV) cm{sup -2} s{sup -1} to the {gamma}-ray flux from NGC 1275. This indicates that the source is variable on timescales of years to decades, and therefore restricts the fraction of emission that can be produced in extended regions of the galaxy cluster. Contemporaneous …
Date: May 15, 2009
Creator: Abdo, Aous A.; Ackermann, M.; Ajello, M.; Asano, K.; Baldini, L.; Ballet, J. et al.
Object Type: Article
System: The UNT Digital Library
Fermi Large Area Telescope Bright Gamma-ray Source List (open access)

Fermi Large Area Telescope Bright Gamma-ray Source List

Following its launch in 2008 June, the Fermi Gamma-ray Space Telescope (Fermi) began a sky survey in August. The Large Area Telescope (LAT) on Fermi in three months produced a deeper and better resolved map of the {gamma}-ray sky than any previous space mission. We present here initial results for energies above 100 MeV for the 205 most significant (statistical significance greater than {approx}10{sigma}) {gamma}-ray sources in these data. These are the best characterized and best localized point-like (i.e., spatially unresolved) {gamma}-ray sources in the early mission data.
Date: May 15, 2009
Creator: Abdo, Aous A.; Ackermann, M.; Ajello, M.; Atwood, W. B.; Axelsson, M.; Baldini, L. et al.
Object Type: Article
System: The UNT Digital Library
Bright AGN Source List from the First Three Months of the Fermi Large Area Telescope All-Sky Survey (open access)

Bright AGN Source List from the First Three Months of the Fermi Large Area Telescope All-Sky Survey

None
Date: May 15, 2009
Creator: Abdo, Aous A.; Ackermann, M.; Ajello, M.; Atwood, W.B.; Axelsson, M.; Baldini, L. et al.
Object Type: Article
System: The UNT Digital Library
Fermi/LAT Discovery of Gamma-Ray Emission From the Flat-Spectrum Radio Quasar PKS 1454-354 (open access)

Fermi/LAT Discovery of Gamma-Ray Emission From the Flat-Spectrum Radio Quasar PKS 1454-354

None
Date: May 15, 2009
Creator: Abdo, Aous A.; Ackermann, M.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J. et al.
Object Type: Article
System: The UNT Digital Library
The Fermi Gamma Ray Space Telescope discovers the Pulsar in the Young Galactic Supernova-Remnant CTA 1 (open access)

The Fermi Gamma Ray Space Telescope discovers the Pulsar in the Young Galactic Supernova-Remnant CTA 1

Energetic young pulsars and expanding blast waves (supernova remnants, SNRs) are the most visible remains after massive stars, ending their lives, explode in core-collapse supernovae. The Fermi Gamma-Ray Space Telescope has unveiled a radio quiet pulsar located near the center of the compact synchrotron nebula inside the supernova remnant CTA 1. The pulsar, discovered through its gamma-ray pulsations, has a period of 316.86 ms, a period derivative of 3.614 x 10{sup -13} s s{sup -1}. Its characteristic age of 10{sup 4} years is comparable to that estimated for the SNR. It is conjectured that most unidentified Galactic gamma ray sources associated with star-forming regions and SNRs are such young pulsars.
Date: May 15, 2009
Creator: Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, G. et al.
Object Type: Article
System: The UNT Digital Library
Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope (open access)

Discovery of Pulsed Gamma Rays from the Young Radio Pulsar PSR J1028-5819 with the Fermi Large Area Telescope

Radio pulsar PSR J1028-5819 was recently discovered in a high-frequency search (at 3.1 GHz) in the error circle of the Energetic Gamma-Ray Experiment Telescope (EGRET) source 3EG J1027-5817. The spin-down power of this young pulsar is great enough to make it very likely the counterpart for the EGRET source. We report here the discovery of {gamma}-ray pulsations from PSR J1028-5819 in early observations by the Large Area Telescope (LAT) on the Fermi Gamma-Ray Space Telescope. The {gamma}-ray light curve shows two sharp peaks having phase separation of 0.460 {+-} 0.004, trailing the very narrow radio pulse by 0.200 {+-} 0.003 in phase, very similar to that of other known {gamma}-ray pulsars. The measured {gamma}-ray flux gives an efficiency for the pulsar of {approx}10-20% (for outer magnetosphere beam models). No evidence of a surrounding pulsar wind nebula is seen in the current Fermi data but limits on associated emission are weak because the source lies in a crowded region with high background emission. However, the improved angular resolution afforded by the LAT enables the disentanglement of the previous COS-B and EGRET source detections into at least two distinct sources, one of which is now identified as PSR J1028-5819.
Date: May 15, 2009
Creator: Abdo, Aous A.; Ackermann, M.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, Guido et al.
Object Type: Article
System: The UNT Digital Library
MACK/MACKLIB System for Nuclear Response Functions (open access)

MACK/MACKLIB System for Nuclear Response Functions

The MACK computer program calculates energy pointwise and multigroup nuclear response functions from basic nuclear data in ENDF/B format. The new version of the program MACK-IV, incorporates major developments and improvements aimed at maximizing the utilization of available nuclear data and ensuring energy conservation in nuclear heating calculations. A new library, MACKLIB-IV, of nuclear response functions was generated in the CTR energy group structure of 171 neutron groups and 36 gamma groups. The library was prepared using MACK-IV and ENDF/B-IV and is suitable for fusion, fusion-fission hydrids, and fission applications.
Date: March 15, 1978
Creator: Abdou, M. A. & Gohar, Y. M.
Object Type: Report
System: The UNT Digital Library
A limit on {sigma} {center_dot} BR (B{sub c}{sup {+-}} {yields} J/{psi} + {pi}{sup {+-}})/{sigma} {center_dot} BR(B{sub u}{sup {+-}} {yields} J/{psi} + K{sup {+-}}) in {radical}s = 1.8 TeV proton-antiproton collisions (open access)

A limit on {sigma} {center_dot} BR (B{sub c}{sup {+-}} {yields} J/{psi} + {pi}{sup {+-}})/{sigma} {center_dot} BR(B{sub u}{sup {+-}} {yields} J/{psi} + K{sup {+-}}) in {radical}s = 1.8 TeV proton-antiproton collisions

We report on the results of a search for the B{sub c} (b{bar c}) meson in the decay B{sub c}{sup +-} {yields} J/{psi} + {pi}{sup +-}. This search is guided by a control sample of decays of B{sub u} mesons to J/{psi} + K and uses {approx_equal} 75pb{sup -1} of data collected at the Collider Detector Facility (CDF) at Fermilab. The lifetime of the B{sub c} meson is unknown, so the 95% confidence level limit on {sigma} {center_dot} BR(B{sub c} {yields} {psi} + {pi})/{sigma} {center_dot} BR(B{sub u} {yields} {psi} + K) is obtained as a function of the B{sub c} lifetime.
Date: July 15, 1995
Creator: Abe, F.
Object Type: Article
System: The UNT Digital Library
Measurement of the B{sup {minus}} and {bar B}{sup 0} meson lifetimes using semileptonic decays (open access)

Measurement of the B{sup {minus}} and {bar B}{sup 0} meson lifetimes using semileptonic decays

The lifetimes of the B{sup {minus}} and {bar B}{sup 0} mesons are measured using the partially reconstructed semileptonic decays in the CDF experiment.
Date: July 15, 1995
Creator: Abe, F.
Object Type: Report
System: The UNT Digital Library
Crustal Rock Fracture Mechanics for Design and Control of Artificial Subsurface Cracks in Geothermal Energy Extraction Engineering ({Gamma}-Project) (open access)

Crustal Rock Fracture Mechanics for Design and Control of Artificial Subsurface Cracks in Geothermal Energy Extraction Engineering ({Gamma}-Project)

Recently a significant role of artificial and/or natural cracks in the geothermal reservoir has been demonstrated in the literatures (Abe, H., et al., 1983, Nielson, D.L. and Hullen, J.B., 1983), where the cracks behave as fluid paths and/or heat exchanging surfaces. Until now, however, there are several problems such as a design procedure of hydraulic fracturing, and a quantitative estimate of fluid and heat transfer for reservoir design. In order to develop a design methodology of geothermal reservoir cracks, a special distinguished research project, named as ''{Lambda}-Project'', started at Tohoku University (5 years project, 1983-1988). In this project a basic fracture mechanics model of geothermal reservoir cracks is being demonstrated and its validation is being discussed both theoretically and experimentally. This paper descibes an outline of ''{Lambda}-Project''.
Date: December 15, 1983
Creator: Abe, Hiroyuki & Takahashi, Hideaki
Object Type: Article
System: The UNT Digital Library
Behaviors of Crack-Like Reservoirs by Means of Fracturing at Nigorikawa and Kakkonda Geothermal Fields (open access)

Behaviors of Crack-Like Reservoirs by Means of Fracturing at Nigorikawa and Kakkonda Geothermal Fields

A basic concept of the geothermal reservoir as a set of cracks is first presented. Extensions of subsurface cracks during well stimulation treatments at Nigorikawa(Mori) and closure operations of production well-head valves at Kakkonda are analysed and their behaviors are demonstrated based on results of long-distance AE Measurements.
Date: December 15, 1983
Creator: Abe, Hiroyuki; Takahashi, Hideaki; Nakatsuka, Katsuto; Niitsuma, Hiroaki & Takanohashi, Morihiko
Object Type: Article
System: The UNT Digital Library
Evaluate the Life History of Native Salmonids in the Malheur Subbasin, Fiscal Year 2008 Annual Report. (open access)

Evaluate the Life History of Native Salmonids in the Malheur Subbasin, Fiscal Year 2008 Annual Report.

This report has the following chapters: (1) Synopsis of 2000-2008 Stream Temperature Monitoring with Implications for Bull Trout Recovery in the Upper Malheur Logan Valley Wildlife Mitigation Property, 2008; (2) Bull Trout Spawning Survey Report, 2008; (3) 2008 Efforts to Trap and Haul Entrained Bull Trout Salvelinus confluentus over Agency Valley Dam on the North Fork Malheur River, Oregon; (4) Distribution and Abundance of Redband Trout Oncorhynchus mykiss in the Malheur River Basin, 2008; and (5) Spatial Patterns of Hybridization between Bull Trout, Salvelinus confluentus, and Brook Trout, Salvelinus fontinalis in an Oregon Stream Network.
Date: July 15, 2009
Creator: Abel, Chad; Brown, Daniel & Schwabe, Lawrence
Object Type: Report
System: The UNT Digital Library
[RE: State-Wide Impact of the Regional Institutes] (open access)

[RE: State-Wide Impact of the Regional Institutes]

A memo from Julie Abel, program associate at the Getty Center for Education in the Arts, to the Regional Institute Directors. The memo is in regards to updating the Center's survey they had asked the Directors to complete in the Summer of 1991 for the last year's Advisory Committee Notebook. In the memo, Abel has attached a chart showing the state-wide impact of the Regional Institutes that was complied form the information. Abel requests updated figures from 1992 by September 24, 1992.
Date: September 15, 1992
Creator: Abel, Julie
Object Type: Letter
System: The UNT Digital Library
[Account Statement for Abercrombie & Fitch, August 1956] (open access)

[Account Statement for Abercrombie & Fitch, August 1956]

Invoice for items sold to Mrs. D. W. Kempner by Abercrombie & Fitch including details of the previous balance, payments made, and balance due.
Date: August 15, 1956
Creator: Abercrombie & Fitch
Object Type: Text
System: The Portal to Texas History
[Account Statement for Abercrombie & Fitch Co., December 1952] (open access)

[Account Statement for Abercrombie & Fitch Co., December 1952]

Account statement for Abercrombie & Fitch Co. listing previous balance, returns, and balance due.
Date: December 15, 1952
Creator: Abercrombie & Fitch Co.
Object Type: Text
System: The Portal to Texas History
Simulated Passage Through A Modified Kaplan Turbine Pressure Regime: A Supplement to "Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish" (open access)

Simulated Passage Through A Modified Kaplan Turbine Pressure Regime: A Supplement to "Laboratory Studies of the Effects of Pressure and Dissolved Gas Supersaturation on Turbine-Passed Fish"

Migratory and resident fish in the Columbia River basin are exposed to stresses associated with hydroelectric power production, including pressure changes during turbine passage and dissolved gas supersaturation (resulting from the release of water from the spillway). The responses of fall Chinook salmon and bluegill sunfish to these two stresses, both singly and in combination, were investigated in the laboratory. A previous test series (Abernethy et al. 2001) evaluated the effects of passage through a Kaplan turbine under the ?worst case? pressure conditions. For this series of tests, pressure changes were modified to simulate passage through a Kaplan turbine under a more ?fish-friendly? mode of operation. The results were compared to results from Abernethy et al. (2001). Fish were exposed to total dissolved gas (TDG) levels of 100%, 120%, or 135% of saturation for 16-22 hours at either surface (101 kPa) or 30 ft (191 kPa) of pressure, then held at surface pressure at 100% saturation for a 48-hour observation period. Sensitivity of fall Chinook salmon to gas supersaturation was slightly higher than in the previous test series, with 15% mortality for surface-acclimated fish at 120% TDG, compared to 0% in the previous tests.
Date: March 15, 2002
Creator: Abernethy, Cary S.; Amidan, Brett G. & Cada, G. F.
Object Type: Report
System: The UNT Digital Library
Tales From the Big Thicket

Tales From the Big Thicket

Access: Use of this item is restricted to the UNT Community
Edited collection of writing about the Big Thicket area in Texas, including geographic descriptions, anecdotes, historical accounts, and other aspects of the people and features of the region. Index starts on page 235.
Date: February 15, 2002
Creator: Abernethy, Francis E.
Object Type: Book
System: The UNT Digital Library
Both Sides of the Border: A Scattering of Texas Folklore (open access)

Both Sides of the Border: A Scattering of Texas Folklore

Collection of Tex-Mex folklore and related essays, including papers presented at Texas Folklore Society meetings. The book is organized into four topical categories: I. Remembering Our Ancestors, II. Texas-Mexican Folklore, III. Miscellaneous Memorabilia, and IV. The Family Saga (Cont'd).
Date: November 15, 2004
Creator: Abernethy, Francis Edward & Untiedt, Kenneth L.
Object Type: Book
System: The UNT Digital Library
[Letter from Directors of the Abilene Central Railway Company to D. T. Bomar, March 15, 1910] (open access)

[Letter from Directors of the Abilene Central Railway Company to D. T. Bomar, March 15, 1910]

Letter from Directors of the Abilene Central Railway Company to D. T. Bomar giving notice to attend a Board of Directors meeting for the Abilene Central Railway Company.
Date: March 15, 1910
Creator: Abilene Central Railway Company
Object Type: Letter
System: The Portal to Texas History
[Letter from Directors of the Abilene Central Railway Company to D. T. Bomar, March 15, 1910] (open access)

[Letter from Directors of the Abilene Central Railway Company to D. T. Bomar, March 15, 1910]

Letter from Directors of the Abilene Central Railway Company to D. T. Bomar urging him to attend an upcoming meeting of the board of directors.
Date: March 15, 1910
Creator: Abilene Central Railway Company
Object Type: Letter
System: The Portal to Texas History
[Letter from Directors of the Abilene Central Railway Company to Morgan Jones, March 15,1910] (open access)

[Letter from Directors of the Abilene Central Railway Company to Morgan Jones, March 15,1910]

Letter from Directors of the Abilene Central Railway Company to Morgan Jones discussing Jones presence for a board of the directors for the company.
Date: March 15, 1910
Creator: Abilene Central Railway Company
Object Type: Letter
System: The Portal to Texas History
Diagnostic Examination of Generation 2 Lithium-Ion Cells and Assessment Ofperformance Degradation Mechanisms. (open access)

Diagnostic Examination of Generation 2 Lithium-Ion Cells and Assessment Ofperformance Degradation Mechanisms.

The Advanced Technology Development (ATD) Program is a multilaboratory effort to assist industrial developers of high-power lithium-ion batteries overcome the barriers of cost, calendar life, abuse tolerance, and low-temperature performance so that this technology may be rendered practical for use in hybrid electric vehicles (HEVs). Included in the ATD Program is a comprehensive diagnostics effort conducted by researchers at Argonne National Laboratory (ANL), Brookhaven National Laboratory (BNL), and Lawrence Berkeley National Laboratory (LBNL). The goals of this effort are to identify and characterize processes that limit lithium-ion battery performance and calendar life, and ultimately to describe the specific mechanisms that cause performance degradation. This report is a compilation of the diagnostics effort conducted since spring 2001 to characterize Generation 2 ATD cells and cell components. The report is divided into a main body and appendices. Information on the diagnostic approach, details from individual diagnostic techniques, and details on the phenomenological model used to link the diagnostic data to the loss of 18650-cell electrochemical performance are included in the appendices. The main body of the report includes an overview of the 18650-cell test data, summarizes diagnostic data and modeling information contained in the appendices, and provides an assessment of the various …
Date: July 15, 2005
Creator: Abraham, Daniel P.
Object Type: Report
System: The UNT Digital Library
Optimizing the Turbo-Roto-Compound (TRC) Engine. Final report (open access)

Optimizing the Turbo-Roto-Compound (TRC) Engine. Final report

Results of multidimensional computations of sprays in a very high pressure constant volume chamber are presented in two parts. Comparisons of computed and measured penetrations of non-vaporizing and vaporizing sprays are presented. A broad range of density ratios (0.005 to 0.243) is covered. It is shown that, provided sufficient numerical resolution is used, the model can adequately reproduce the measurements. Scaling laws for time and distance derived in a previous publication are found to apply also to the sprays over the broad range of density ratios considered. A combustion sub-model that has been used in spark-ignition engines, stratified-charge engines and Diesel engines is included in the model. The combustion sub-model represents low-temperature autoignition and high temperature heat release. Comparisons of computed and measured penetrations of combusting sprays and computed and measured chamber pressures are being made. In this report, only preliminary indicative comparisons of computed and measured chamber pressures for three cases are presented. Agreement of pressures within 5% is shown. The work is ongoing and a detailed report will be presented later.
Date: August 15, 1994
Creator: Abraham, J.
Object Type: Report
System: The UNT Digital Library
Expanded Scale Process Development of the Electrolytic Production of Thorium From ThCl$sub 4$ in Externally Heated Electrolytic Cells (open access)

Expanded Scale Process Development of the Electrolytic Production of Thorium From ThCl$sub 4$ in Externally Heated Electrolytic Cells

The commercial feasibility of the electrolytic process for Th production has been demonstrated. The cell produced 7 lb. of good quality metal per hour. A cathode cooling system was developed. The major construction materials, Ni and graphite, were satisfactory. The process yield was 86%. (T.R.H.)
Date: January 15, 1956
Creator: Abraham, L.; Merlub-Sobel, M.; Wyatt, J.L. & Wainer, E.
Object Type: Report
System: The UNT Digital Library