SGR-like behaviour of the repeating FRB 121102

NASA Astrophysics Data System (ADS)

Wang, F. Y.; Yu, H.

2017-03-01

Fast radio bursts (FRBs) are millisecond-duration radio signals occurring at cosmological distances. However the physical model of FRBs is mystery, many models have been proposed. Here we study the frequency distributions of peak flux, fluence, duration and waiting time for the repeating FRB 121102. The cumulative distributions of peak flux, fluence and duration show power-law forms. The waiting time distribution also shows power-law distribution, and is consistent with a non-stationary Poisson process. These distributions are similar as those of soft gamma repeaters (SGRs). We also use the statistical results to test the proposed models for FRBs. These distributions are consistent with the predictions from avalanche models of slowly driven nonlinear dissipative systems.

SGR-like behaviour of the repeating FRB 121102

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, F.Y.; Yu, H., E-mail: fayinwang@nju.edu.cn, E-mail: yuhai@smail.nju.edu.cn

2017-03-01

Fast radio bursts (FRBs) are millisecond-duration radio signals occurring at cosmological distances. However the physical model of FRBs is mystery, many models have been proposed. Here we study the frequency distributions of peak flux, fluence, duration and waiting time for the repeating FRB 121102. The cumulative distributions of peak flux, fluence and duration show power-law forms. The waiting time distribution also shows power-law distribution, and is consistent with a non-stationary Poisson process. These distributions are similar as those of soft gamma repeaters (SGRs). We also use the statistical results to test the proposed models for FRBs. These distributions are consistentmore » with the predictions from avalanche models of slowly driven nonlinear dissipative systems.« less

A Deep Near-Infrared Survey of the N 49 Region around the Soft Gamma-Ray Repeater 0526-66

NASA Technical Reports Server (NTRS)

Klose, S.; Henden, A. A.; Geppert, U.; Greiner, J.; Guetter, H. H.; Hartmann, D. H.; Kouveliotou, C.; Luginbuhl, C. B.; Stecklurn, B.; Vrba, F. J.

2004-01-01

We report the results of a deep near-infrared survey of the vicinity of supernova remnant N49 in the Large Magellanic Cloud (LMC), which contains the soft gamma-ray repeater (SGR) 0526-66. Two of the four confirmed SGRs are potentially associated with compact stellar clusters. We thus searched for a similar association of SGR0526-66, and find the unexplored young stellar cluster SL 463 at a projected distance of approx. 30 pc from the SGR. This constitutes the third cluster-SGR link, and lends support to scenarios in which SGR progenitors originate in young, embedded clusters. If real, the cluster-SGR association constrains the age and thus the initial mass of these stars. In addition, our high-resolution images of the super- nova remnant N49 reveal an area of excess K-band flux in the southeastern part of the SNR. This feature coincides with the maximum flux area at 8.28 microns as detected by the Midcourse Space Experiment (MSX satellite), which we identify with IRAS 052594607.

The rotation-powered nature of some soft gamma-ray repeaters and anomalous X-ray pulsars

NASA Astrophysics Data System (ADS)

Coelho, Jaziel G.; Cáceres, D. L.; de Lima, R. C. R.; Malheiro, M.; Rueda, J. A.; Ruffini, R.

2017-03-01

Context. Soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slow rotating isolated pulsars whose energy reservoir is still matter of debate. Adopting neutron star (NS) fiducial parameters; mass M = 1.4 M⊙, radius R = 10 km, and moment of inertia, I = 1045 g cm2, the rotational energy loss, Ėrot, is lower than the observed luminosity (dominated by the X-rays) LX for many of the sources. Aims: We investigate the possibility that some members of this family could be canonical rotation-powered pulsars using realistic NS structure parameters instead of fiducial values. Methods: We compute the NS mass, radius, moment of inertia and angular momentum from numerical integration of the axisymmetric general relativistic equations of equilibrium. We then compute the entire range of allowed values of the rotational energy loss, Ėrot, for the observed values of rotation period P and spin-down rate Ṗ. We also estimate the surface magnetic field using a general relativistic model of a rotating magnetic dipole. Results: We show that realistic NS parameters lowers the estimated value of the magnetic field and radiation efficiency, LX/Ėrot, with respect to estimates based on fiducial NS parameters. We show that nine SGRs/AXPs can be described as canonical pulsars driven by the NS rotational energy, for LX computed in the soft (2-10 keV) X-ray band. We compute the range of NS masses for which LX/Ėrot< 1. We discuss the observed hard X-ray emission in three sources of the group of nine potentially rotation-powered NSs. This additional hard X-ray component dominates over the soft one leading to LX/Ėrot > 1 in two of them. Conclusions: We show that 9 SGRs/AXPs can be rotation-powered NSs if we analyze their X-ray luminosity in the soft 2-10 keV band. Interestingly, four of them show radio emission and six have been associated with supernova remnants (including Swift J1834.9-0846 the first SGR observed with a surrounding wind nebula). These observations give

Reducing acetate excretion from E. coli K-12 by over-expressing the small RNA sgrS

PubMed Central

Negrete, Alejandro; Majdalani, Nadim; Phue, Je Nie; Shiloach, Joseph

2011-01-01

When exposed to the non-metabolized glucose derivative alpha methyl glucoside, both E. coli K-12 (JM109 and MG1655) and E. coli B (BL21) respond by reducing the concentration of the mRNA of the ptsG gene which is responsible for the biosynthesis of the glucose transporter EIICBglu. This occurs through the over-expression of the non-coding small RNA SgrS, which interacts specifically with the mRNA of the ptsG gene and prevents its translation. However, when these bacteria are exposed to a glucose concentration of 40 g/L, over-expression of SgrS is observed only in E. coli B (BL21). Unlike E. coli K-12 (JM109 and MG1655), which are affected by high glucose concentration and produce higher levels of acetate, E. coli B (BL21) is not affected. Based on this information, it was assumed that over-expression of SgrS enables E. coli B (BL21) to reduce its acetate excretion by controlling the glucose transport. When SgrS was over-expressed in both E. coli K-12 strains from a multicopy plasmid, it was possible to reduce their acetate excretion levels to those seen in E. coli B. This observation opens a new approach towards controlling bacterial metabolism through the use of non-coding RNA. PMID:22107968

Reducing acetate excretion from E. coli K-12 by over-expressing the small RNA SgrS.

PubMed

Negrete, Alejandro; Majdalani, Nadim; Phue, Je-Nie; Shiloach, Joseph

2013-01-25

When exposed to the nonmetabolized glucose derivative alpha methyl glucoside (αMG), both Escherichia coli K-12 (JM109 and MG1655) and E. coli B (BL21) respond by reducing the concentration of the mRNA of the ptsG gene which is responsible for the biosynthesis of the glucose transporter EIICB(glu). This occurs through the over-expression of the noncoding small RNA SgrS, which interacts specifically with the mRNA of the ptsG gene and prevents its translation. However, when these bacteria are exposed to a glucose concentration of 40 g/L, over-expression of SgrS is observed only in E. coli B (BL21). Unlike E. coli K-12 (JM109 and MG1655), which are affected by high glucose concentration and produce higher levels of acetate, E. coli B (BL21) is not affected. Based on this information, it was assumed that over-expression of SgrS enables E. coli B (BL21) to reduce its acetate excretion by controlling the glucose transport. When SgrS was over-expressed in both E. coli K-12 strains from a multicopy plasmid, it was possible to reduce their acetate excretion levels to those seen in E. coli B. This observation opens a new approach towards controlling bacterial metabolism through the use of noncoding RNA. Published by Elsevier B.V.

Observations of Soft Gamma Repeaters

NASA Technical Reports Server (NTRS)

Kouveliotou, Chryssa

2004-01-01

Magnetars (Soft Gamma Repeaters and Anomalous X-ray Pulsars) are a subclass of neutron stars characterized by their recurrent X-ray bursts. While in an active (bursting) state (lasting anywhere between days and years), they are emit&ng hundreds of predominantly soft (kT=30 kev), short (0.1-100 ms long) events. Their quiescent source x-ray light ewes exhibit puhlions rotational period rate changes (spin-down) indicate that their magnetic fields are extremely high, of the order of 10^14- 10^l5 G. Such high B-field objects, dubbed "magnetars", had been predicted to exist in 1992, but the first concrete observational evidence were obtained in 1998 for two of these sources. I will discuss here the history of Soft Gamma Repeaters, and their spectral, timing and flux characteristics both in the persistent and their burst emission.

Is magnetar a fact or fiction to us?

NASA Astrophysics Data System (ADS)

Tong, H.; Xu, R. X.

2013-03-01

The key point of studying AXPs/SGRs (anomalous X-ray pulsars/soft gamma-ray repeaters) is relevant to the energy budget. Historically, rotation was thought to be the only free energy of pulsar until the discovery of accretion power in X-ray binaries. AXPs/SGRs could be magnetars if they are magnetism-powered, but would alternatively be quark-star/fallback-disk systems if more and more observations would hardly be understood in the magnetar scenario.

The application of network synthesis to repeating classical gamma-ray bursts

NASA Technical Reports Server (NTRS)

Hurley, K.; Kouveliotou, C.; Fishman, J.; Meegan, C.; Laros, J.; Klebesadel, R.

1995-01-01

It has been suggested that the Burst and Transient Source Experiment (BATSE) gamma-ray burst catalog contains several groups of bursts clustered in space or in space and time, which provide evidence that a substantial fraction of the classical gamma-ray burst sources repeat. Because many of the bursts in these groups are weak, they are not directly detected by the Ulysses GRB experiment. We apply the network synthesis method to these events to test the repeating burst hypothesis. Although we find no evidence for repeating sources, the method must be applied under more general conditions before reaching any definite conclusions about the existence of classical gamma-ray burst repeating sources.

Do gamma-ray burst sources repeat?

NASA Technical Reports Server (NTRS)

Meegan, C. A.; Hartmann, D. H.; Brainerd, J. J.; Briggs, M.; Paciesas, W. S.; Pendleton, G.; Kouveliotou, C.; Fishman, G.; Blumenthal, G.; Brock, M.

1994-01-01

The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports of evidence for repetition in the first BATSE burst catalog have generated renewed interest in this issue. Here, we analyze the angular distribution of 585 bursts of the second BATSE catalog (Meegan et al. 1994). We search for evidence of burst recurrence using the nearest and farthest neighbor statistic ad the two-point angular correlation function. We find the data to be consistent with the hypothesis that burst sources do not repeat; however, a repeater fraction of up to about 20% of the bursts cannot be excluded.

Do gamma-ray burst sources repeat?

NASA Technical Reports Server (NTRS)

Meegan, Charles A.; Hartmann, Dieter H.; Brainerd, J. J.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey; Kouveliotou, Chryssa; Fishman, Gerald; Blumenthal, George; Brock, Martin

1995-01-01

The demonstration of repeated gamma-ray bursts from an individual source would severely constrain burst source models. Recent reports (Quashnock and Lamb, 1993; Wang and Lingenfelter, 1993) of evidence for repetition in the first BATSE burst catalog have generated renewed interest in this issue. Here, we analyze the angular distribution of 585 bursts of the second BATSE catalog (Meegan et al., 1994). We search for evidence of burst recurrence using the nearest and farthest neighbor statistic and the two-point angular correlation function. We find the data to be consistent with the hypothesis that burst sources do not repeat; however, a repeater fraction of up to about 20% of the observed bursts cannot be excluded.

Repeated irradiations with gamma-rays at a Dose of 0.5 Gy may exacerbate asthma.

PubMed

Fang, Su-ping; Tago, Fumitoshi; Tanaka, Takashi; Simura, Noriko; Muto, Yasuko; Goto, Resuke; Kojima, Shuji

2005-06-01

We previously showed that 0.5 Gy whole-body gamma-ray irradiation with a single or small number of repeated exposures inhibits tumor growth in mice, via elevation of the IFN-gamma/IL-4 ratio concomitantly with a decrease in the percentage of B cells. Here we examined whether repeated 0.5 Gy gamma-rays irradiation can improve asthma in an OVA-induced asthmatic mouse model. We found that repeated irradiation (10 times) with 0.5 Gy of gamma-rays significantly increased total IgE in comparison with the disease-control group. The levels of IL-4 and IL-5 were also significantly higher in the gamma-ray-irradiated group, while that of IFN-gamma was significantly lower, resulting in a further decrease of the IFN-gamma/IL-4 ratio from the normal value. These results indicate that the repeated irradiation with gamma-rays may exacerbate asthma, and may have opposite effects on different immune reactions unlike the irradiation with a single or small number of repeated exposures.

An exceptionally bright flare from SGR 1806-20 and the origins of short-duration gamma-ray bursts.

PubMed

Hurley, K; Boggs, S E; Smith, D M; Duncan, R C; Lin, R; Zoglauer, A; Krucker, S; Hurford, G; Hudson, H; Wigger, C; Hajdas, W; Thompson, C; Mitrofanov, I; Sanin, A; Boynton, W; Fellows, C; von Kienlin, A; Lichti, G; Rau, A; Cline, T

2005-04-28

Soft-gamma-ray repeaters (SGRs) are galactic X-ray stars that emit numerous short-duration (about 0.1 s) bursts of hard X-rays during sporadic active periods. They are thought to be magnetars: strongly magnetized neutron stars with emissions powered by the dissipation of magnetic energy. Here we report the detection of a long (380 s) giant flare from SGR 1806-20, which was much more luminous than any previous transient event observed in our Galaxy. (In the first 0.2 s, the flare released as much energy as the Sun radiates in a quarter of a million years.) Its power can be explained by a catastrophic instability involving global crust failure and magnetic reconnection on a magnetar, with possible large-scale untwisting of magnetic field lines outside the star. From a great distance this event would appear to be a short-duration, hard-spectrum cosmic gamma-ray burst. At least a significant fraction of the mysterious short-duration gamma-ray bursts may therefore come from extragalactic magnetars.

A New Type of Transient High-Energy Source in the Direction of the Galactic Centre

NASA Technical Reports Server (NTRS)

Kouveliotou, C.; VanParadijs, J.; Fishman, G. J.; Briggs, M. S.; Kommers, J.; Harmon, B. A.; Meegan, C. A.; Lewin, W. H. G.

1996-01-01

Sources of high-energy (greater than 20 keV) bursts fall into two distinct types: the non-repeating gamma-ray bursters, several thousand of which have been detected but whose origin remains unknown, and the soft gamma-ray repeaters (SGRs), of which there are only three. The SGRs are known to be associated with supernova remnants, suggesting that the burst events most probably originate from young neutron stars. Here we report the detection of a third type of transient high-energy source. On 2 December 1995, we observed the onset of a sequence of hard X-ray bursts from a direction close to that of the Galactic Center. The interval between bursts was initially several minutes, but after two days, the burst rate had dropped to about one per hour and has been largely unchanged since then. More than 1,000 bursts have now been detected, with remarkably similar light curves and intensities; this behaviour is unprecendented among transient X-ray and gamma-ray sources. We suggest that the origin of these bursts might be related to the spasmodic accretion of material onto a neutron star.

Universal statistics of soft gamma-ray repeating (SGR) bursts

NASA Astrophysics Data System (ADS)

Kondratyev, V. N.; Korovina, Yu. V.

2018-01-01

Soft gamma repeater (SGR) bursts are considered as a release of magnetic energy stored in the baryon degrees of freedom of the magnetar crust. It is shown that this interpretation allows all observations of these bursts to be systematized and universal statistical properties to be revealed and explained.

Ultra-high energy cosmic rays from white dwarf pulsars and the Hillas criterion

NASA Astrophysics Data System (ADS)

Lobato, Ronaldo V.; Coelho, Jaziel G.; Malheiro, M.

2017-06-01

The origins of ultra-high-energy cosmic rays (E ≳ 1019 eV) are a mystery and still under debate in astroparticle physics. In recent years some efforts were made to understand their nature. In this contribution we consider the possibility of Some Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs) beeing white dwarf pulsars, and show that these sources can achieve large electromagnetic potentials on their surface that accelerate particle almost at the speed of light, with energies E ~ 1020-21 eV. The sources SGRs/AXPs considered as highly magnetized white dwarfs are well described in the Hillas diagram, lying close to the AR Sorpii and AE Aquarii which are understood as white dwarf pulsars.

Repeat Gamma Knife Radiosurgery for Trigeminal Neuralgia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aubuchon, Adam C., E-mail: acaubuchon@gmail.com; Chan, Michael D.; Lovato, James F.

2011-11-15

Purpose: Repeat gamma knife stereotactic radiosurgery (GKRS) for recurrent or persistent trigeminal neuralgia induces an additional response but at the expense of an increased incidence of facial numbness. The present series summarized the results of a repeat treatment series at Wake Forest University Baptist Medical Center, including a multivariate analysis of the data to identify the prognostic factors for treatment success and toxicity. Methods and Materials: Between January 1999 and December 2007, 37 patients underwent a second GKRS application because of treatment failure after a first GKRS treatment. The mean initial dose in the series was 87.3 Gy (range, 80-90).more » The mean retreatment dose was 84.4 Gy (range, 60-90). The dosimetric variables recorded included the dorsal root entry zone dose, pons surface dose, and dose to the distal nerve. Results: Of the 37 patients, 81% achieved a >50% pain relief response to repeat GKRS, and 57% experienced some form of trigeminal dysfunction after repeat GKRS. Two patients (5%) experienced clinically significant toxicity: one with bothersome numbness and one with corneal dryness requiring tarsorraphy. A dorsal root entry zone dose at repeat treatment of >26.6 Gy predicted for treatment success (61% vs. 32%, p = .0716). A cumulative dorsal root entry zone dose of >84.3 Gy (72% vs. 44%, p = .091) and a cumulative pons surface dose of >108.5 Gy (78% vs. 44%, p = .018) predicted for post-GKRS numbness. The presence of any post-GKRS numbness predicted for a >50% decrease in pain intensity (100% vs. 60%, p = .0015). Conclusion: Repeat GKRS is a viable treatment option for recurrent trigeminal neuralgia, although the patient assumes a greater risk of nerve dysfunction to achieve maximal pain relief.« less

Large Torque Variations in Two Soft Gamma Repeaters

NASA Technical Reports Server (NTRS)

Woods, Peter M.; Kouveliotou, Chryssa; Gogus, Ersin; Finger, Mark H.; Swank, Jean; Markwardt, Craig B.; Hurley, Kevin; vanderKlis, Michiel

2002-01-01

We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-Ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor of approximately 4, which persist for several months. Using long-baseline phase-connected timing solutions as well as the overall frequency histories, we construct torque noise power spectra for each SGR (Soft Gamma Repeater). The power spectrum of each source is very red (power-law slope is approximately -3.5). The torque noise power levels are consistent with some accreting systems on timescales of approximately 1 yr, yet the full power spectrum is much steeper in frequency than any known accreting source. To the best of our knowledge, torque noise power spectra with a comparably steep frequency dependence have been seen only in young, glitching radio pulsars (e.g., Vela). The observed changes in spin-down rate do not correlate with burst activity; therefore, the physical mechanisms behind each phenomenon are also likely unrelated. Within the context of the magnetar model, seismic activity can not account for both the bursts and the long-term torque changes unless the seismically active regions are decoupled from one another.

Temporal and Spectral Analyses of SGRs Observed by HETE-2

NASA Astrophysics Data System (ADS)

Nakagawa, Y. E.; Yoshida, A.; Maetou, M.; Suzuki, M.; Tamagawa, T.; Sakamoto, T.; Kawai, N.; Shirasaki, Y.; Tanaka, K.; Matsuoka, M.; Fenimore, E. E.; Galassi, M.; Atteia, J.-L.; Hurley, K.; Ricker, G. R.

2006-05-01

HETE-2 localized 63 flares from SGR1806-20 and 6 flares from SGR1900+14 in the summer periods from June 18 2001 through August 7 2005. We report on the temporal and spectral analyses of short flares from those SGRs. The estimation of T90 durations in 2-30 keV and 30-100 keV revealed that there is no difference between them with a few exceptions. For these exceptional short flares, there seems softening or possibly hardening during flares, but these spectral evolution are not common. We also found a good linear correlation between the rise and decay time, and they do not depend on a peak flux. We also found that the spectra are well reproduced by a sum of two blackbody models for all short flares. The temperatures are lying around 4 keV and 11 keV which are consistent with previous studies. They are not depend on either the magnitude of flare, the event morphology or the source.

Rotational periods and other parameters of magnetars

NASA Astrophysics Data System (ADS)

Malov, I. F.

2006-05-01

The rotational periods P, period derivatives dP/dt, and magnetic fields B in the region where the emission of anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) is generated are calculated using a model that associates the emission of these objects with the existence of drift waves at the periphery of the magnetosphere of a neutron star. The values obtained for these parameters are P = 11-737 ms, dP/dt = 3.7 × 10-16-5.5 × 10-12, and log B (G) = 2.63-6.25. We find a dependence between the X-ray luminosity of AXPs and SGRs, L x, and the rate at which they lose rotational energy, dE/dt, which is similar to the L x(dE/dt) dependence for radio pulsars with detected X-ray emission. Within the errors, AXPs/SGRs and radio pulsars with short periods (P < 0.1 s) display the same slopes for their log(dP/dt)-log P relations and for the dependence of the efficiency of their transformation of rotational energy into radiation on their periods. A dipole model is used to calculate the surface magnetic fields of the neutron stars in AXPs and SGRs, which turn out to be, on average, comparable to the surface fields of normal radio pulsars ( = 11.90).

A search for non-triggered events in the BATSE data base

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kommers, J. M.; Lewin, W. H. G.; Kouveliotou, C.

1998-05-16

The archival data from BATSE permit a search for transients that did not activate the onboard burst trigger. Examples of such non-triggered events include faint gamma-ray bursts (GRBs), emission from soft gamma-ray repeaters (SGRs), and bursts and flares from X-ray binaries. A GRB may fail to trigger onboard because it is too faint, because it occurs while the onboard trigger is disabled, or because it biases the onboard background estimation. We describe a search of the BATSE archival data that is sensitive to GRBs with peak fluxes fainter by a factor of {approx}2 than those detected with the onboard burstmore » trigger (on the 1.024 s time scale)« less

Repeat Gamma Knife surgery for vestibular schwannomas

PubMed Central

Lonneville, Sarah; Delbrouck, Carine; Renier, Cécile; Devriendt, Daniel; Massager, Nicolas

2015-01-01

Background: Gamma Knife (GK) surgery is a recognized treatment option for the management of small to medium-sized vestibular schwannoma (VS) associated with high-tumor control and low morbidity. When a radiosurgical treatment fails to stop tumor growth, repeat GK surgery can be proposed in selected cases. Methods: A series of 27 GK retreatments was performed in 25 patients with VS; 2 patients underwent three procedures. The median time interval between GK treatments was 45 months. The median margin dose used for the first, second, and third GK treatments was 12 Gy, 12 Gy, and 14 Gy, respectively. Six patients (4 patients for the second irradiation and 2 patients for the third irradiation) with partial tumor regrowth were treated only on the growing part of the tumor using a median margin dose of 13 Gy. The median tumor volume was 0.9, 2.3, and 0.7 cc for the first, second, and third treatments, respectively. Stereotactic positron emission tomography (PET) guidance was used for dose planning in 6 cases. Results: Mean follow-up duration was 46 months (range 24–110). At the last follow-up, 85% of schwannomas were controlled. The tumor volume decreased, remained unchanged, or increased after retreatment in 15, 8, and 4 cases, respectively. Four patients had PET during follow-up, and all showed a significant metabolic decrease of the tumor. Hearing was not preserved after retreatment in any patients. New facial or trigeminal palsy did not occur after retreatment. Conclusions: Our results support the long-term efficacy and low morbidity of repeat GK treatment for selected patients with tumor growth after initial treatment. PMID:26500799

Repeat Gamma-Knife Radiosurgery for Refractory or Recurrent Trigeminal Neuralgia with Consideration About the Optimal Second Dose.

PubMed

Park, Seong-Cheol; Kwon, Do Hoon; Lee, Do Hee; Lee, Jung Kyo

2016-02-01

To investigate adequate radiation doses for repeat Gamma Knife radiosurgery (GKS) for trigeminal neuralgia in our series and meta-analysis. Fourteen patients treated by ipsilateral repeat GKS for trigeminal neuralgia were included. Median age of patients was 65 years (range, 28-78), the median target dose, 140-180). Patients were followed a median of 10.8 months (range, 1-151) after the second gamma-knife surgery. Brainstem dose analysis and vote-counting meta-analysis of 19 studies were performed. After the second gamma-knife radiosurgeries, pain was relieved effectively in 12 patients (86%; Barrow Neurological Institute Pain Intensity Score I-III). Post-gamma-knife radiosurgery trigeminal nerve deficits were mild in 5 patients. No serious anesthesia dolorosa was occurred. The second GKS radiation dose ≤ 60 Gy was significantly associated with worse pain control outcome (P = 0.018 in our series, permutation analysis of variance, and P = 0.009 in the meta-analysis, 2-tailed Fisher's exact test). Cumulative dose ≤ 140-150 Gy was significantly associated with poor pain control outcome (P = 0.033 in our series and P = 0.013 in the meta-analysis, 2-tailed Fisher's exact test). A cumulative brainstem edge dose >12 Gy tended to be associated with trigeminal nerve deficit (P = 0.077). Our study suggests that the second GKS dose is a potentially important factor. Copyright © 2016 Elsevier Inc. All rights reserved.

Search for soft gamma repeaters in the SMM/HXRBS data

NASA Technical Reports Server (NTRS)

Kouveliotou, C.; Norris, J. P.; Wood, K. S.; Cline, T. L.; Dennis, B. R.; Desal, U. D.; Orwig, L. E.

1992-01-01

The triggered fast memory of the hard X-ray burst spectrometer (HXRBS) on board the SMM is used to describe the results of a search for short transients resembling soft gamma repeater (SGR) bursts. Memory data for a total of about 4000 burst triggers, out of which only a very few could be considered as valid SGR candidate events, are analyzed. The search methodology is outlined, the HXRBS exposure and sensitivity to SGR bursts are calculated, and the criteria which constrain the number of candidate events are described. An upper limit is given for the SGR source number density. This limit, combined with results from other relevant observations and the assumption of a neutron star origin, are applied to obtain a constraint on SGR-active lifetimes.

Multiwavelength Observations of the Soft Gamma Repeater SGR 1900+14 During Its 2001 April Activation

NASA Technical Reports Server (NTRS)

Kouveliotou, C.; Tennant, A.; Woods, P. M.; Weisskopf, M. C.; Hurley, K.; Fender, R. P.; Garrington, S. T.; Patel, S. K.; Goegues, E.

2001-01-01

The soft gamma repeater SGR 1900+14 became active on 2001 April 18 after about two years of quiescence; it had remained at a very low state of activity since the fall of 1998, when it exhibited extraordinary flaring. We have observed the source in the gamma-rays and X-rays with Ulysses and Chandra and in the radio with MERLIN. We report here the confirmation of a two-component X-ray spectrum (power law and blackbody), indicating emission from the neutron star surface. We have determined that there is a dust halo, due to scattering in the interstellar medium, surrounding the source that extends up to approximately 100 arcsec from the center of SGR 1900+14.

Rotational and X-ray luminosity evolution of high-B radio pulsars

NASA Astrophysics Data System (ADS)

Benli, Onur; Ertan, Ünal

2018-05-01

In continuation of our earlier work on the long-term evolution of the so-called high-B radio pulsars (HBRPs) with measured braking indices, we have investigated the long-term evolution of the remaining five HBRPs for which braking indices have not been measured yet. This completes our source-by-source analyses of HBRPs in the fallback disc model that was also applied earlier to anomalous X-ray pulsars (AXPs), soft gamma repeaters (SGRs), and dim isolated neutron stars (XDINs). Our results show that the X-ray luminosities and the rotational properties of these rather different neutron star populations can be acquired by neutron stars with fallback discs as a result of differences in their initial conditions, namely the initial disc mass, initial period and the dipole field strength. For the five HBRPs, unlike for AXPs, SGRs and XDINs, our results do not constrain the dipole field strengths of the sources. We obtain evolutionary paths leading to the properties of HBRPs in the propeller phase with dipole fields sufficiently strong to produce pulsed radio emission.

Imprints of superfluidity on magnetoelastic quasiperiodic oscillations of soft gamma-ray repeaters.

PubMed

Gabler, Michael; Cerdá-Durán, Pablo; Stergioulas, Nikolaos; Font, José A; Müller, Ewald

2013-11-22

Our numerical simulations show that axisymmetric, torsional, magnetoelastic oscillations of magnetars with a superfluid core can explain the whole range of observed quasiperiodic oscillations (QPOs) in the giant flares of soft gamma-ray repeaters. There exist constant phase QPOs at f is < or approximately equal to 150 Hz and resonantly excited high-frequency QPOs (f>500 Hz), in good agreement with observations. The range of magnetic field strengths required to match the observed QPO frequencies agrees with that from spin-down estimates. These results suggest that there is at least one superfluid species in magnetar cores.

Evidence for a Sudden Magnetic Field Reconfiguration in Soft Gamma Repeater 1900+14

NASA Technical Reports Server (NTRS)

Woods, Peter M.; Kouveliotou, Chryssa; Gogus, Ersin; Finger, Mark H.; Swank, Jean; Smith, Don A.; Hurley, Kevin; Thompson, Christopher

2001-01-01

We report the detection of large flux changes in the persistent X-ray flux of soft gamma repeater (SGR) 1900 + 14 during its burst active episode in 1998. Most notably, we find a factor of approx. 700 increase in the nonburst X-ray flux following the August 27 flare, which decayed in time as a power law. Our measurements indicate that the pulse fraction remains constant throughout this decay. This suggests a global flux enhancement as a consequence of the August 27 flare rather than localized heating. While the persistent flux has since recovered to the preoutburst level, the pulse profile has not. The pulse shape changed to a near sinusoidal profile within the tail of the August 27 flare (in gamma-rays), and this effect has persisted for more than 1.5 years (in X-rays). The results presented here suggest that the magnetic field of the neutron star in SGR 1900 + 14 was significantly altered (perhaps globally) during the giant flare of August 27.

Multi-Wavelength Observations of the Soft Gamma Repeater SGR 1900+14 During its April 2001 Activation

NASA Technical Reports Server (NTRS)

Kouveliotou, C.; Tennant, A. F.; Woods, P.; Hurley, K.; Fender, R. P.; Garrington, S. T.; Patel, S. K.; Gogus, E.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

The soft-gamma repeater SGR became active on 18 April 2001 after about a year of quiescence; it had remained at a very low state of activity since the fall of 1998, when it exhibited extraordinary flaring. We have observed the source in the gamma and X-rays with \\ulysses and \\chandra, and in the radio with MERLIN. We report here the confirmation of a two component X-ray spectrum (power law $+$ blackbody), indicating emission from the neutron star surface. We have determined that there is a dust halo surrounding the source that extends up to $\\gtrsim100^{\\prime\\prime}$ from the SGR center, which is due to the scattering in the Interstellar Medium.

Background Information: Magnetars, Soft Gamma-Ray Repeaters and the Most Powerful Magnetic Fields in the Universe

NASA Astrophysics Data System (ADS)

1998-08-01

Near the end of its life, a star more massive than our Sun finds itself no longer able to support its own weight from the crush of gravity and so it collapses, producing an expanding shock wave that sweeps through the surrounding gas, creating what is called a supernova remnant. All that remains of the original star is a dense, compact object known as a neutron star. Magnetars are the latest addition to the "zoo" of neutron stars and they are truly exotic beasts with magnetic fields hundreds of millions of times stronger than have ever been seen on Earth. The story which led to the prediction of magnetars and then to their discovery is given elsewhere. Here we will focus on the other part of the story, the supernova remnants born at the same time as magnetars and the diffuse emission produced by the energetic outpourings of the magnetars. All four of the soft gamma-ray repeaters that we currently know are located in or near a supernova remnant. It was this discovery that led astronomers to determine that soft gamma-ray repeaters were in our Galaxy and the nearby galaxy known as the Large Magellanic Cloud. Through the study of these supernova remnants, astronomers were able to infer that soft gamma-ray repeaters were solitary young neutron stars speeding away from their birthplace at 3 million miles per hour. Theories predict that the same process which can produce the fantastic bursts of hard X-ray emission that give soft gamma-ray repeaters their name, can also accelerate particles (electrons, protons, etc) to speeds approaching the speed of light. As the saying goes, "where there's smoke there's fire" and this case is no exception. Most of the energy released by the burst event is carried away by these high energy particles and not the gamma-ray burst itself. As the particles spiral in the surrounding magnetic field, they too emit radiation, creating extended nebulae called "plerions". Provided there is some way to confine the outflow, these plerions act as "wind

Unveiling the Nature of Soft Gamma Repeaters and Magnetars: Scientists Measure the Most Powerful Magnet Known

NASA Technical Reports Server (NTRS)

Swank, Jean (Technical Monitor); Parke, William

2002-01-01

This newsletter from NASA Goddard Space Flight Center (GSFC) announces measurements of the magnetic field of a magnetar. The magnetic field was approx. 10(exp 15) gauss, up to 10 times more powerful than previous estimates. The newsletter also describes how the star's magnetic field slows its rotation, and how starquakes emit protons, which are trapped in this neutron star's magnetic field, and make it a soft gamma repeater (SGR).

Large Torque Variations in Two Soft Gamma Repeaters

NASA Technical Reports Server (NTRS)

Woods, Peter M.; Kouveliotou, Chryssa; Gogus, Ersin; Finger, Mark H.; Swank, Jean; Markwardt, Craig B.; Hurley, Kevin; vanderKlis, Michiel; Six, N. Frank (Technical Monitor)

2001-01-01

We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor of approximately 4, which persist for several months. Using long baseline phase-connected timing solutions as well as the overall frequency histories, we construct torque noise power spectra for each SGR. The power spectrum of each source is very red (power-law slope approximately -3.5). These power spectra are consistent in normalization with some accreting systems, yet much steeper in slope than any known accreting source. To the best of our knowledge, torque noise power spectra with a comparably steep frequency dependence have only been seen in young, glitching radio pulsars (e.g. Vela). The observed changes in spin-down rate do not correlate with burst activity, therefore, the physical mechanisms behind each phenomenon are also likely unrelated. Within the context of the magnetar model, seismic activity cannot account for both the bursts and the long-term torque changes unless the seismically active regions are decoupled from one another.

Repeated transsphenoidal surgery or gamma knife radiosurgery in recurrent cushing disease after transsphenoidal surgery.

PubMed

Bodaghabadi, Mohammad; Riazi, Hooman; Aran, Shima; Bitaraf, Mohammad Ali; Alikhani, Mazdak; Alahverdi, Mahmud; Mohamadi, Masoumeh; Shalileh, Keivan; Azar, Maziar

2014-03-01

This study compared Gamma knife radiosurgery (GKRS) and repeated transsphenoidal adenomectomy (TSA) to find the best approach for recurrence of Cushing disease (CD) after unsuccessful first TSA. Fifty-two patients with relapse of CD after TSA were enrolled and randomly underwent a second surgery or GKRS as the next therapeutic approach. They were followed for a mean period of 3.05 ± 0.8 years by physical examination and hormone measurement as well as magnetic resonance imaging. No significant difference was observed in sex ratio, mean age, adenoma type, follow-up duration, and initial hormone level between the two groups. No significant relationship was found between preoperative 24-hour free urine cortisol and disease-free months or tumor volume among both groups. Our statistical analysis showed higher recurrence-free interval in the GKRS group compared with TSA group. With longer recurrence-free interval, GKRS could be considered a good treatment alternative to repeated TSA in recurrent CD. Georg Thieme Verlag KG Stuttgart · New York.

No CAG repeat expansion of polymerase gamma is associated with male infertility in Tamil Nadu, South India

PubMed Central

Poongothai, J.

2013-01-01

Mitochondria contains a single deoxyribonucleic acid (DNA) polymerase, polymerase gamma (POLG) mapped to long arm of chromosome 15 (15q25), responsible for replication and repair of mitochondrial DNA. Exon 1 of the human POLG contains CAG trinucleotide repeat, which codes for polyglutamate. Ten copies of CAG repeat were found to be uniformly high (0.88) in different ethnic groups and considered as the common allele, whereas the mutant alleles (not -10/not -10 CAG repeats) were found to be associated with oligospermia/oligoasthenospermia in male infertility. Recent data suggested the implication of POLG CAG repeat expansion in infertility, but are debated. The aim of our study was to explore whether the not -10/not -10 variant is associated with spermatogenic failure. As few study on Indian population have been conducted so far to support this view, we investigated the distribution of the POLG CAG repeats in 61 infertile men and 60 normozoospermic control Indian men of Tamil Nadu, from the same ethnic background. This analysis interestingly revealed that the homozygous wild type genotype (10/-10) was common in infertile men (77% - 47/61) and in normozoospermic control men (71.7% - 43/60). Our study failed to confirm any influence of the POLG gene polymorphism on the efficiency of the spermatogenesis. PMID:24339545

On the evolution of high-B radio pulsars with measured braking indices

NASA Astrophysics Data System (ADS)

Benli, O.; Ertan, Ü.

2017-11-01

We have investigated the long-term evolutions of the high-magnetic field radio pulsars (HBRPs) with measured braking indices in the same model that was applied earlier to individual anomalous X-ray pulsars (AXPs), soft gamma repeaters (SGRs) and dim isolated neutron stars (XDINs). We have shown that the rotational properties (period, period derivative and braking index) and the X-ray luminosity of individual HBRPs can be acquired simultaneously by the neutron stars evolving with fallback discs. The model sources reach the observed properties of HBRPs in the propeller phases, when pulsed radio emission is allowed, at ages consistent with the estimated ages of the supernova remnants of the sources. Our results indicate that the strength of magnetic dipole fields of HBRPs are comparable to and even greater than those of AXP/SGRs and XDINs, but still one or two orders of magnitude smaller than the values inferred from the magnetic dipole torque formula. The possible evolutionary paths of the sources imply that they will lose their seemingly HBRP property after about a few 104 yr, because either their rapidly decreasing period derivatives will lead them into the normal radio pulsar population or they will evolve into the accretion phase switching off the radio pulses.

Unraveling the Cooling Trend of the Soft Gamma Repeater SGR 1627-41

NASA Technical Reports Server (NTRS)

Kouveliotou, C.; Eichler, D.; Woods, P. M.; Lyubarsky, Y.; Patel, S. K.; Gogus, E.; vanderKlis, M.; Tennant, A.; Wachter, S.; Hurley, K.

2003-01-01

SGR 1627-41 was discovered in 1998 after a single active episode that lasted approximately 6 weeks. We report here our monitoring results of the decay trend of the persistent X-ray luminosity of the source during the last 5 years. We find an initial temporal power-law decay with index 0.47, reaching a plateau that is followed by a sharp (factor of 10) flux decline approximately 800 days after the source activation. The source spectrum is best described during the entire period by a single power law with high absorption [N(sub H) = 9.0(7) x 10(exp 22) per square centimeter]; the spectral index, however, varies dramatically between 2.2 and 3.8 spanning the entire range for all known soft gamma repeater sources. We discuss the cooling behavior of the neutron star assuming a deep crustal heating initiated by the burst activity of the source during 1998.

The Short Bursts in SGR 1806-20, 1E 1048-5937, and SGR 0501+4516

NASA Astrophysics Data System (ADS)

Qu, Zhijie; Li, Zhaosheng; Chen, Yupeng; Dai, Shi; Ji, Long; Xu, Renxin; Zhang, Shu

2015-03-01

We analyzed temporal and spectral properties, focusing on the short bursts, for three anomalous X-ray pulsars (AXPs) and soft gamma repeaters (SGRs), including SGR 1806-20, 1E 1048-5937 and SGR 0501+4516. Using the data from XMM-Newton, we located the short bursts by Bayesian blocks algorithm. The short bursts' duration distributions for three sources were fitted by two lognormal functions. The spectra of shorter bursts ($< 0.2~\\rm s$) and longer bursts ($\\geq 0.2~\\rm s$) can be well fitted in two blackbody components model or optically thin thermal bremsstrahlung model for SGR 0501+4516. We also found that there is a positive correlation between the burst luminosity and the persistent luminosity with a power law index $\\gamma = 1.23 \\pm 0.18 $. The energy ratio of this persistent emission to the time averaged short bursts is in the range of $10 - 10^3$, being comparable to the case in Type I X-ray burst.

Rapid optical follow-up observations of SGR events with ROTSE-I

NASA Astrophysics Data System (ADS)

Balsano, R.; Akerlof, C.; Barthelmy, S.; Bloch, J.; Butterworth, P.; Casperson, D.; Cline, T.; Fletcher, S.; Gisler, G.; Hills, J.; Kehoe, R.; Lee, B.; Marshall, S.; McKay, T.; Pawl, A.; Priedhorsky, W.; Seldomridge, N.; Szymanski, J.; Wren, J.

2000-09-01

The primary mission of the Robotic Optical Transient Search Experiment (ROTSE) is to search for contemporaneous optical emission from GRBs. Among the triggers ROTSE receives via the GRB Coordinates Network (GCN), there are a number from Soft-Gamma Repeater (SGR) events. Since beginning operations in March 1998, ROTSE-I has triggered on 16 observable SGR events. Ten of these events had useful data, eight events from SGR 1900+14 and two events from SGR 1806-20. The error regions for these SGRs are a small fraction of the ROTSE 16°×16° field of view and have been searched for new or variable objects. Limits on optical transient counterparts are in the range mROTSE~12.5-15.5 during the period 10 seconds to 1 hour after the observed SGR events. .

Genomic sequences of murine gamma B- and gamma C-crystallin-encoding genes: promoter analysis and complete evolutionary pattern of mouse, rat and human gamma-crystallins.

PubMed

Graw, J; Liebstein, A; Pietrowski, D; Schmitt-John, T; Werner, T

1993-12-22

The murine genes, gamma B-cry and gamma C-cry, encoding the gamma B- and gamma C-crystallins, were isolated from a genomic DNA library. The complete nucleotide (nt) sequences of both genes were determined from 661 and 711 bp, respectively, upstream from the first exon to the corresponding polyadenylation sites, comprising more than 2650 and 2890 bp, respectively. The new sequences were compared to the partial cDNA sequences available for the murine gamma B-cry and gamma C-cry, as well as to the corresponding genomic sequences from rat and man, at both the nt and predicted amino acid (aa) sequence levels. In the gamma B-cry promoter region, a canonical CCAAT-box, a TATA-box, putative NF-I and C/EBP sites were detected. An R-repeat is inserted 366 bp upstream from the transcription start point. In contrast, the gamma C-cry promoter does not contain a CCAAT-box, but some other putative binding sites for transcription factors (AP-2, UBP-1, LBP-1) were located by computer analysis. The promoter regions of all six gamma-cry from mouse, rat and human, except human psi gamma F-cry, were analyzed for common sequence elements. A complex sequence element of about 70-80 bp was found in the proximal promoter, which contains a gamma-cry-specific and almost invariant sequence (crygpel) of 14 nt, and ends with the also invariant TATA-box. Within the complex sequence element, a minimum of three further features specific for the gamma A-, gamma B- and gamma D/E/F-cry genes can be defined, at least two of which were recently shown to be functional. In addition to these four sequence elements, a subtype-specific structure of inverted repeats with different-sized spacers can be deduced from the multiple sequence alignment. A phylogenetic analysis based on the promoter region, as well as the complete exon 3 of all gamma-cry from mouse, rat and man, suggests separation of only five gamma-cry subtypes (gamma A-, gamma B-, gamma C-, gamma D- and gamma E/F-cry) prior to species separation.

Fourth Workshop on Science with the New Generation of High Energy Gamma-ray Experiments

NASA Astrophysics Data System (ADS)

Massai, Marco Maria; Omodei, Nicola; Spandre, Gloria

I. Space-based telescope. Integral-4 years in orbit / P. Umbertini, P. Caraveo. The Suzaku mission / K. Yamaoka. The Swift mission: two years of operation / A. Moretti. Gamma-ray astrophysics with AGILE / F.Longo et al., The AGILE collaboration. The GLAST mission / J.E. McEnery -- II. Ground-based telescope. Recent results from CANGAROO / M. Mori for the CANGAROO team. The H.E.S.S. project / C. Masterson for the H.E.S.S. collaboration. The MAGIC experiment / N. Turini for the MAGIC collaboration. VERITAS: status and performance / J. Holder for the VERITAS collaboration -- III. Galactic variable sources. Galactic variable sky with EGRET and GLAST / S. Digel. Galactic variable sources observed with H.E.S.S. / N. Komin for the H.E.S.S collaboration. Gamma ray pulsars in the GLAST era / M. Razzano. Solving the riddle of unidentified high-energy gamma-ray sources / P. Caraveo. Supernovae and gamma-ray burst / M. Della Valle. First cycle of MAGIC galactic observations / J. Cortina for the MAGIC collaboration. Gamma-rays and neutrinos from a SNR in the galactic center / V. Cavasinni, D. Grasso, L. Maccione. Solving GRBs and SGRs puzzles by precessing jets / D. Fargion, O. Lanciano, P. Oliva -- IV. Extragalactic sources. Multiwavelength observations and theories of blazers / G. Tosti. AGN observations with the MAGIC telescope / C. Bigongiari for the MAGIC collaboration. Gamma ray bursts/ L. Amati. X-rays and GeV flares in GRB light curves / A. Galli ... [et al.]. The highest energy emission from gamma ray bursts: MILAGRO's constraints and HAWC's potential / B. Dingus for the MILAGRO and HAWC collaborations. Observation of GRB with the MAGIC telescope / N. Galante, P. Piccioli for the MAGIC collaboration. GRB 060218 and the outliers with respect to the E-E correlation / G. Ghirlanda, G. Ghibellini -- V. Poster session. Study of the performance and calibration of the GLAST-LAT silicon tracker / M. Brigida, N. Giglietto, P. Spinelli. The online monitor for the GLAST

Simultaneous X-Ray, Gamma-Ray, and Radio Observations of the Repeating Fast Radio Burst FRB 121102

NASA Astrophysics Data System (ADS)

Scholz, P.; Bogdanov, S.; Hessels, J. W. T.; Lynch, R. S.; Spitler, L. G.; Bassa, C. G.; Bower, G. C.; Burke-Spolaor, S.; Butler, B. J.; Chatterjee, S.; Cordes, J. M.; Gourdji, K.; Kaspi, V. M.; Law, C. J.; Marcote, B.; McLaughlin, M. A.; Michilli, D.; Paragi, Z.; Ransom, S. M.; Seymour, A.; Tendulkar, S. P.; Wharton, R. S.

2017-09-01

We undertook coordinated campaigns with the Green Bank, Effelsberg, and Arecibo radio telescopes during Chandra X-ray Observatory and XMM-Newton observations of the repeating fast radio burst FRB 121102 to search for simultaneous radio and X-ray bursts. We find 12 radio bursts from FRB 121102 during 70 ks total of X-ray observations. We detect no X-ray photons at the times of radio bursts from FRB 121102 and further detect no X-ray bursts above the measured background at any time. We place a 5σ upper limit of 3 × 10‑11 erg cm‑2 on the 0.5–10 keV fluence for X-ray bursts at the time of radio bursts for durations < 700 ms, which corresponds to a burst energy of 4 × 1045 erg at the measured distance of FRB 121102. We also place limits on the 0.5–10 keV fluence of 5 × 10‑10 and 1 × 10‑9 erg cm‑2 for bursts emitted at any time during the XMM-Newton and Chandra observations, respectively, assuming a typical X-ray burst duration of 5 ms. We analyze data from the Fermi Gamma-ray Space Telescope Gamma-ray Burst Monitor and place a 5σ upper limit on the 10–100 keV fluence of 4 × 10‑9 erg cm‑2 (5 × 1047 erg at the distance of FRB 121102) for gamma-ray bursts at the time of radio bursts. We also present a deep search for a persistent X-ray source using all of the X-ray observations taken to date and place a 5σ upper limit on the 0.5–10 keV flux of 4 × 10‑15 erg s‑1 cm‑2 (3 × 1041 erg s‑1 at the distance of FRB 121102). We discuss these non-detections in the context of the host environment of FRB 121102 and of possible sources of fast radio bursts in general.

An Expanding Radio Nebula Produced by a Giant Flare from the Magnetar SGR 1806-20

NASA Technical Reports Server (NTRS)

Gaensler, B. M.; Kouveliotou, C.; Gelfand, J. D.; Taylor, G. B.; Eichler, D.; Wijers, R. A. M. J.; Granot, J.; Ramirez-Ruiz, E.; Lyubarsky, Y. E.; Hunstead, R. W.

2005-01-01

Soft gamma repeaters (SGRs) are "magnetars", a small class of slowly spinning neutron stars with extreme surface magnetic fields, B approx. 10(sup 15) gauss. On 2004 December 27, a giant flare was detected from the magnetar SGR 1806-20, the third such event ever recorded. This burst of energy, which resulted in the highest flux of gamma-rays ever measured from a celestial object, was detected by a variety of instruments and even caused an ionospheric disturbance in the Earth's upper atmosphere recorded around the globe. Here we report the detection of a very bright but rapidly-fading radio source at the position of SGR 1806-20 following this outburst. From day 6 to day 19 after the flare, we see a resolved, linearly polarized, radio nebula, expanding at a velocity of approximately 0.3c. To create this nebula, at least 4 x 10(exp 43) ergs of energy must have been emitted by the giant flare in the form of magnetic fields and relativistic particles. The steep decline of the radio flux may indicate episodic particle acceleration followed by adiabatic expansion, as could occur if the ejecta have energized a thin shell surrounding a preexisting cavity.

Toxicokinetics of the flame retardant hexabromocyclododecane gamma: effect of dose, timing, route, repeated exposure, and metabolism.

PubMed

Szabo, David T; Diliberto, Janet J; Hakk, Heldur; Huwe, Janice K; Birnbaum, Linda S

2010-10-01

Hexabromocyclododecane-gamma (γ-HBCD) is the predominate diastereoisomer in the commercial HBCD mixture used as a flame retardant in a wide variety of consumer products. Three main diastereoisomers, alpha (α), beta (β), and gamma (γ), comprise the mixture. Despite the γ-diastereoisomer being the major diastereoisomer in the mixture and environmental samples, the α-diastereoisomer predominates human tissue and wildlife. This study was conducted to characterize absorption, distribution, metabolism, and excretion parameters of γ-HBCD with respect to dose and time following a single acute exposure and repeated exposure in adult female C57BL/6 mice. Results suggest that 85% of the administered dose (3 mg/kg) was absorbed after po exposure. Disposition was dose independent and did not significantly change after 10 days of exposure. Liver was the major depot (< 0.3% of dose) 4 days after treatment followed by blood, fat, and then brain. γ-HBCD was rapidly metabolized and eliminated in the urine and feces. For the first time, in vivo stereoisomerization was observed of the γ-diastereoisomer to the β-diastereoisomer in liver and brain tissues and to the α- and β-diastereoisomer in fat and feces. Polar metabolites in the blood and urine were a major factor in determining the initial whole-body half-life (1 day) after a single po exposure. Elimination, both whole-body and from individual tissues, was biphasic. Initial half-lives were approximately 1 day, whereas terminal half-lives were up to 4 days, suggesting limited potential for γ-diastereoisomer bioaccumulation. The toxicokinetic behavior reported here has important implications for the extrapolation of toxicological studies of the commercial HBCD mixture to the assessment of risk.

Feasibility of Multiple Repeat Gamma Knife Radiosurgeries for Trigeminal Neuralgia: A Case Report and Review of the Literature

PubMed Central

Jones, Guy C.; Elaimy, Ameer L.; Demakas, John J.; Jiang, Hansi; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Mackay, Alexander R.; Cooke, Barton S.; Lee, Christopher M.

2011-01-01

Treatment options for trigeminal neuralgia (TN) must be customized for the individual patient, and physicians must be aware of the medical, surgical, and radiation treatment modalities to prescribe optimal treatment courses for specific patients. The following case illustrates the potential for gamma knife radiosurgery (GKRS) to be repeated multiple times for the purpose of achieving facial pain control in cases of TN that have been refractory to other medical and surgical options, as well as prior GKRS. The patient described failed to achieve pain control with initial GKRS, as well as medical and surgical treatments, but experienced significant pain relief for a period of time with a second GKRS procedure and later underwent a third procedure. Only a small subset of patients have reportedly undergone more than two GKRS for TN; thus, further research and long-term clinical followup will be valuable in determining its usefulness in specific clinical situations. PMID:21904556

Gamma-ray burst constraints on the galactic frequency of extrasolar Oort Clouds

NASA Technical Reports Server (NTRS)

Shull, J. Michael; Stern, S. Alan

1995-01-01

With the strong Compton Gamma-Ray Observatory/Burst and Transient Source Experiment (CGRO/BATSE) evidence that most gamma-ray bursts do not come from galactic neutron stars, models involving the accretion of a comet onto a neutron star (NS) no longer appear to be strong contenders for explaining the majority of bursts. If this is the case, then it is worth asking whether the lack of an observed galactic gamma-ray burst population provides a useful constraint on the number of comets and comet clouds in the galaxy. Owing to the previously unrecognized structural weakness of cometary nuclei, we find the capture cross sections for comet-NS events to be much higher than previously published estimates, with tidal breakup at distances R(sub b) approx. equals 4 x 10(exp 10) cm from the NS. As a result, impacts of comets onto field NSs penetrating the Oort Clouds of other stars are found to dominate all other galactic NS-comet capture rates by a factor of 100. This in turn predicts that if comet clouds are common, there should be a significant population of repeater sources with (1) a galactic distribution, (2) space-correlated repetition, and (3) a wide range of peak luminosities and luminosity time histories. If all main sequence stars have Oort Clouds like our own, we predict approximately 4000 such repeater sources in the Milky Way at any time, each repeating on time scales of months to years. Based on estimates of the sensitivity of the CGRO/BATSE instrument and assuming isotropic gamma-ray beaming from such events, we estimate that a population of approximately 20-200 of these galactic NS-Oort Cloud gamma-ray repeater sources should be detectable by CGRO. In addition, if giant planet formation is common in the galaxy, we estimate that the accretion of isolated comets injected to the interstellar medium by giant planet formation should produce an additional source of galactic, nonrepeating, events. Comparing these estimates to the 3-4 soft gamma-ray repeater sources

New shield for gamma-ray spectrometry

NASA Technical Reports Server (NTRS)

Brar, S. S.; Gustafson, P. F.; Nelson, D. M.

1969-01-01

Gamma-ray shield that can be evacuated, refilled with a clean gas, and pressurized for exclusion of airborne radioactive contaminants effectively lowers background noise. Under working conditions, repeated evacuation and filling procedures have not adversely affected the sensitivity and resolution of the crystal detector.

Repeat Radiosurgery for Trigeminal Neuralgia.

PubMed

Helis, Corbin A; Lucas, John T; Bourland, J Daniel; Chan, Michael D; Tatter, Stephen B; Laxton, Adrian W

2015-11-01

Repeat Gamma Knife radiosurgery (GKRS) is an established option for patients whose pain has recurred after the initial procedure, with reported success rates varying from 68% to 95%. Predictive factors for response to the repeat GKRS are ill-defined. This cohort study aimed to report the outcomes and factors predictive of success for patients who have undergone repeated GKRS for trigeminal neuralgia at Wake Forest University Baptist Medical Center. Between 1999 and 2013, 152 patients underwent repeat GKRS at Wake Forest, 125 of whom were available for long-term follow-up. A retrospective chart review and telephone interviews were conducted to determine background medical history, dosimetric data, outcomes, and adverse effects of the procedure. Eighty-four percent of patients achieved at least Barrow Neurological Institute (BNI) IIIb pain relief, with 46% achieving BNI I. The 1-, 3-, and 5-year rates of BNI I pain relief were 63%, 50%, and 37%, respectively. The 1-, 3-, and 5-year rates of BNI IIIb or better pain relief were 74%, 59%, and 46%, respectively. One patient experienced bothersome numbness and 2 patients developed anesthesia dolorosa. The dominant predictive factors for pain relief were facial numbness after the first GKRS and a positive pain response to the first GKRS. Repeat GKRS is an effective method of treating recurrent trigeminal neuralgia. Patients who have facial numbness after the first treatment and a positive pain response to the first GKRS are significantly more likely to respond well to the second treatment.

An expanding radio nebula produced by a giant flare from the magnetar SGR 1806-20.

PubMed

Gaensler, B M; Kouveliotou, C; Gelfand, J D; Taylor, G B; Eichler, D; Wijers, R A M J; Granot, J; Ramirez-Ruiz, E; Lyubarsky, Y E; Hunstead, R W; Campbell-Wilson, D; van der Horst, A J; McLaughlin, M A; Fender, R P; Garrett, M A; Newton-McGee, K J; Palmer, D M; Gehrels, N; Woods, P M

2005-04-28

Soft gamma-ray repeaters (SGRs) are 'magnetars', a small class of slowly spinning neutron stars with extreme surface magnetic fields, B approximately 10(15) gauss (refs 1 , 2 -3). On 27 December 2004, a giant flare was detected from the magnetar SGR 1806-20 (ref. 2), only the third such event recorded. This burst of energy was detected by a variety of instruments and even caused an ionospheric disturbance in the Earth's upper atmosphere that was recorded around the globe. Here we report the detection of a fading radio afterglow produced by this outburst, with a luminosity 500 times larger than the only other detection of a similar source. From day 6 to day 19 after the flare from SGR 1806-20, a resolved, linearly polarized, radio nebula was seen, expanding at approximately a quarter of the speed of light. To create this nebula, at least 4 x 10(43) ergs of energy must have been emitted by the giant flare in the form of magnetic fields and relativistic particles.

Improved Limits on Gamma-Ray Burst Repetition from BATSE

NASA Technical Reports Server (NTRS)

Tegmark, Max; Hartmann, Dieter H.; Briggs, Michael S.; Hakkila, Jon; Meegan, Charles A.

1996-01-01

We tighten previous upper limits on gamma-ray burst repetition by analyzing the angular power spectrum of the BATSE 3B catalog of 1122 bursts. At 95% confidence, we find that no more than 2% of all observed bursts can be labeled as repeaters, even if no sources are observed to repeat more than once. If a fraction f of all observed bursts can be labeled as repeaters that are observed to burst upsilon times each, then all models with (upsilon - 1)f greater than or equal to 0.05 are ruled out at 99% confidence, as compared to the best previous 99% limit (upsilon - 1)f greater than or equal to 0.27. At 95% confidence, our new limit is (upsilon - 1)f greater than or equal to 0.02. Thus, even a cluster of six events from a single source would have caused excess power above that present in the 3B catalog. We conclude that the current BATSE data are consistent with no repetition of classical gamma-ray bursts and that any repeater model is severely constrained by the near-perfect isotropy of their angular distribution.

Improved Limits on Gamma-Ray Burst Repetition from BATSE

NASA Technical Reports Server (NTRS)

Tegmark, Max; Hartmann, Dieter H.; Briggs, Michael S.; Meegan, Charles A.; Hakkila, Jon

1996-01-01

We tighten previous upper limits on gamma-ray burst repetition by analyzing the angular power spectrum of the BATSE 3B catalog of 1122 bursts. At 95% confidence, we find that no more than 2% of all observed bursts can be labeled as repeaters, even if no sources are observed to repeat more than once. If a fraction f of all observed bursts can be labeled as repeaters that are observed to burst nu times each, then all models with (nu - 1)f greater than or equal to 0.05 are ruled out at 99% confidence, as compared to the best previous 99% limit (nu - 1)f greater than or equal to 0.27. At 95% confidence, our new limit is (nu - 1)f greater than or equal to 0.02. Thus, even a cluster of six events from a single source would have caused excess power above that present in the 3B catalog. We conclude that the current BATSE data are consistent with no repetition of classical gamma-ray bursts and that any repeater model is severely constrained by the near-perfect isotropy of their angular dis- tribution.

Gamma-ray burst constraints on the galactic frequency of extra-solar Oort clouds

NASA Technical Reports Server (NTRS)

Shull, J. Michael; Stern, S. Alan

1994-01-01

With the strong CGRO/BATSE evidence that most gamma-ray bursts do not come from galactic neutron stars, models involving the accretion of a comet onto a neutron star (NS) no longer appear to be strong contenders for explaining the majority of bursts. If this is the case, then it is worth asking whether the lack of an observed galactic gamma-ray burst population provides a useful constraint on the number of comets and comet clouds in the galaxy. Owing to the previously unrecognized structural weakness of cometary nuclei, we find the capture cross sections for comet-NS events to be much higher than previously published estimates, with tidal breakup at distances R(sub b) approximately equals to 4 x 10(exp 10) cm from the NS. As a result, impacts of comets onto field NS's penetrating the Oort Clouds of other stars are found to dominate all other galactic NS-comet capture rates by a factor of 100. This in turn predicts that if comet clouds are common, there should be a significant population of repeater sources with (1) a galactic distribution, (2) space-correlated repetition, and (3) a wide range of peak luminosities and luminosity time histories. If all main sequences stars have Oort Clouds like our own, we predict approximately 4000 such repeater sources in the Milky Way at any time, each repeating on timescales of months to years. Based on estimates of the sensitivity of the CGRO/BATSE instrument and assuming isotropic gamma-ray beaming from such events, we estimate that a population of approximately 20-200 of these galactic NS-Oort Cloud gamma-ray repeater sources should be detectable by CGRO. In addition, if giant planet formation is common in the galaxy, we estimate that the accretion of isolated comets injected to the interstellar medium by giant planet formation should produce an additional source of galactic, nonrepeating events. Comparing these estimates to the three to four soft gamma-ray repeater sources detected by BATSE, one is forced to conclude that (1

Swift Gamma-Ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

NASA Technical Reports Server (NTRS)

Bundas, David J.

2004-01-01

The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up with narrow field instruments capable of multi-wavelength (UV, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space-based observatories drive the end-to-end data analysis and distribution requirements.

Swift Gamma-ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

NASA Technical Reports Server (NTRS)

Bundas, David J.

2005-01-01

The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up with narrow field instruments capable of multi-wavelength (UT, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space-based observatories drive the end-to-end data analysis and distribution requirements.

Characterization of non-CG genomic hypomethylation associated with gamma-ray-induced suppression of CMT3 transcription in Arabidopsis thaliana.

PubMed

Kim, Ji Eun; Lee, Min Hee; Cho, Eun Ju; Kim, Ji Hong; Chung, Byung Yeoup; Kim, Jin-Hong

2013-12-01

Ionizing radiation causes various epigenetic changes, as well as a variety of DNA lesions such as strand breaks, cross-links, oxidative damages, etc., in genomes. However, radiation-induced epigenetic changes have rarely been substantiated in plant genomes. The current study investigates whether DNA methylation of Arabidopsis thaliana genome is altered by gamma rays. We found that genomic DNA methylation decreased in wild-type plants with increasing doses of gamma rays (5, 50 and 200 Gy). Irradiation with 200 Gy significantly increased the expression of transcriptionally inactive centromeric 180-bp (CEN) and transcriptionally silent information (TSI) repeats. This increase suggested that there was a substantial release of transcriptional gene silencing by gamma rays, probably by induction of DNA hypomethylation. High expression of the DNA demethylase ROS1 and low expression of the DNA methyltransferase CMT3 supported this hypothesis. Moreover, Southern blot analysis following digestion of genomic DNA with methylation-sensitive enzymes revealed that the DNA hypomethylation occured preferentially at CHG or CHH sites rather than CG sites, depending on the radiation dose. Unlike CEN and TSI repeats, the number of Ta3, AtSN1 and FWA repeats decreased in transcription but increased in non-CG methylation. In addition, the cmt3-11 mutant showed neither DNA hypomethylation nor transcriptional activation of silenced repeats upon gamma irradiation. Furthermore, profiles of genome-wide transcriptomes in response to gamma rays differed between the wild-type and cmt3-11 mutant. These results suggest that gamma irradiation induced DNA hypomethylation preferentially at non-CG sites of transcriptionally inactive repeats in a locus-specific manner, which depends on CMT3 activity.

The physicochemical properties of a spray dried glutinous rice starch biopolymer.

PubMed

Laovachirasuwan, Pornpun; Peerapattana, Jomjai; Srijesdaruk, Voranuch; Chitropas, Padungkwan; Otsuka, Makoto

2010-06-15

Glutinous rice starch (GRS) is a biopolymer used widely in the food industry but not at all in the pharmaceutical industry. There are several ways to modify this biopolymer. Physical modification is simple and cheap because it requires no chemicals or biological agents. The aim of this study was to characterize the physicochemical properties of a spray dried glutinous rice starch (SGRS) produced from pregelatinized GRS. The surface morphology changed from an irregular to concave spherical shape as revealed by Scanning Electron Microscopy (SEM). SGRS was almost amorphous as determined by X-ray Diffraction (XRD) spectroscopy. The water molecules became linked through hydrogen bonds to the exposed hydroxyl group of amorphous SGRS as determined by Near Infrared (NIR) spectroscopy. Then, SGRS formed a colloid gel matrix with water and developed a highly viscous gelatinous form as determined using Differential Scanning Calorimetry (DSC) and a stress control type rheometer. In addition, SGRS can swell and produce a gelatinous surface barrier like a hydrophilic matrix biopolymer which controls drug release. Therefore, a novel application of SGRS is as a sustained release modifier for direct compression tablets in the pharmaceutical industry. Copyright 2010 Elsevier B.V. All rights reserved.

TOXICOKINETICS OF THE FLAME RETARDANT HEXABROMOCYCLODODECANE GAMMA: EFFECT OF DOSE, TIMING, ROUTE, REPEATED EXPOSURE AND METABOLISM

EPA Science Inventory

1,2,5,6,9,10-Hexabromocyc1ododecane-gamma (y-HBCD) is the predominate diastereoisomer in the commercial HBCD mixture used as a flame retardant in a wide variety of consumer products. Three main diastereoisomers, alpha (a), beta (B) and gamma (y) comprise the commercial mixture. D...

"Magnetar-like Emission from the Young Pulsar in Kes 75"

NASA Technical Reports Server (NTRS)

Gavrill, R.; Gonzalez, M.; Livingstone, M.; Gotthelf, E.; Kaspi, V.; Woods, P.

2008-01-01

Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs) are thought to be magnetars - isolated neutron stars with ultra-high magnetic fields. These sources exhibit X-ray and gamma-ray bursts, and week to month-long flux enhancements, all too bright to be accounted for by their spindown luminosity. A mystery in neutron star astrophysics is why such emission has never been seen from rotation-powered pulsars with magnetar-like fields. Here we report the first detection of magnetar-like X-ray bursts from what has been long thought to be a rotation-powered pulsar, PSR 51846-0258, at the center of the supernova remnant Kes 75. PSR J1846-0258 has an inferred surface dipolar magnetic field of 4.9 X 1103 G, which is sixth highest among the > 1700 known rotation-powered pulsars, but less than those of the approximately 12 confirmed magnetars. The bursts coincided with a sudden flux increase and an unprecedented change in timing behavior, f m l y establishing PSR 51 846-0258 as a rotation-powered pulsar/magnetar transition object. These observations demonstrate that magnetar-like emission can be seen from sources with fields lower than the magnetars, and suggest that the intensity of magnetar-like activity in neutron stars depends on magnetic field strength in a more continuous way than previously thought.

Search for Gravitational Wave Bursts from Six Magnetars

NASA Astrophysics Data System (ADS)

Abadie, J.; Abbott, B. P.; Abbott, R.; Abernathy, M.; Accadia, T.; Acernese, F.; Adams, C.; Adhikari, R.; Affeldt, C.; Allen, B.; Allen, G. S.; Amador Ceron, E.; Amariutei, D.; Amin, R. S.; Anderson, S. B.; Anderson, W. G.; Antonucci, F.; Arai, K.; Arain, M. A.; Araya, M. C.; Aston, S. M.; Astone, P.; Atkinson, D.; Aufmuth, P.; Aulbert, C.; Aylott, B. E.; Babak, S.; Baker, P.; Ballardin, G.; Ballmer, S.; Barker, D.; Barnum, S.; Barone, F.; Barr, B.; Barriga, P.; Barsotti, L.; Barsuglia, M.; Barton, M. A.; Bartos, I.; Bassiri, R.; Bastarrika, M.; Basti, A.; Bauchrowitz, J.; Bauer, Th. S.; Behnke, B.; Beker, M. G.; Bell, A. S.; Belletoile, A.; Belopolski, I.; Benacquista, M.; Bertolini, A.; Betzwieser, J.; Beveridge, N.; Beyersdorf, P. T.; Bilenko, I. A.; Billingsley, G.; Birch, J.; Birindelli, S.; Biswas, R.; Bitossi, M.; Bizouard, M. A.; Black, E.; Blackburn, J. K.; Blackburn, L.; Blair, D.; Bland, B.; Blom, M.; Bock, O.; Bodiya, T. P.; Bogan, C.; Bondarescu, R.; Bondu, F.; Bonelli, L.; Bonnand, R.; Bork, R.; Born, M.; Boschi, V.; Bose, S.; Bosi, L.; Bouhou, B.; Boyle, M.; Braccini, S.; Bradaschia, C.; Brady, P. R.; Braginsky, V. B.; Brau, J. E.; Breyer, J.; Bridges, D. O.; Brillet, A.; Brinkmann, M.; Brisson, V.; Britzger, M.; Brooks, A. F.; Brown, D. A.; Brummit, A.; Budzyński, R.; Bulik, T.; Bulten, H. J.; Buonanno, A.; Burguet-Castell, J.; Burmeister, O.; Buskulic, D.; Buy, C.; Byer, R. L.; Cadonati, L.; Cagnoli, G.; Cain, J.; Calloni, E.; Camp, J. B.; Campagna, E.; Campsie, P.; Cannizzo, J.; Cannon, K.; Canuel, B.; Cao, J.; Capano, C.; Carbognani, F.; Caride, S.; Caudill, S.; Cavaglià, M.; Cavalier, F.; Cavalieri, R.; Cella, G.; Cepeda, C.; Cesarini, E.; Chaibi, O.; Chalermsongsak, T.; Chalkley, E.; Charlton, P.; Chassande-Mottin, E.; Chelkowski, S.; Chen, Y.; Chincarini, A.; Christensen, N.; Chua, S. S. Y.; Chung, C. T. Y.; Chung, S.; Clara, F.; Clark, D.; Clark, J.; Clayton, J. H.; Cleva, F.; Coccia, E.; Colacino, C. N.; Colas, J.; Colla, A.; Colombini, M.; Conte, R.; Cook, D.; Corbitt, T. R.; Cornish, N.; Corsi, A.; Costa, C. A.; Coughlin, M.; Coulon, J.-P.; Coward, D. M.; Coyne, D. C.; Creighton, J. D. E.; Creighton, T. D.; Cruise, A. M.; Culter, R. M.; Cumming, A.; Cunningham, L.; Cuoco, E.; Dahl, K.; Danilishin, S. L.; Dannenberg, R.; D'Antonio, S.; Danzmann, K.; Das, K.; Dattilo, V.; Daudert, B.; Daveloza, H.; Davier, M.; Davies, G.; Daw, E. J.; Day, R.; Dayanga, T.; De Rosa, R.; DeBra, D.; Debreczeni, G.; Degallaix, J.; del Prete, M.; Dent, T.; Dergachev, V.; DeRosa, R.; DeSalvo, R.; Dhurandhar, S.; Di Fiore, L.; Di Lieto, A.; Di Palma, I.; Emilio, M. Di Paolo; Di Virgilio, A.; Díaz, M.; Dietz, A.; Donovan, F.; Dooley, K. L.; Dorsher, S.; Douglas, E. S. D.; Drago, M.; Drever, R. W. P.; Driggers, J. C.; Dumas, J.-C.; Dwyer, S.; Eberle, T.; Edgar, M.; Edwards, M.; Effler, A.; Ehrens, P.; Engel, R.; Etzel, T.; Evans, M.; Evans, T.; Factourovich, M.; Fafone, V.; Fairhurst, S.; Fan, Y.; Farr, B. F.; Fazi, D.; Fehrmann, H.; Feldbaum, D.; Ferrante, I.; Fidecaro, F.; Finn, L. S.; Fiori, I.; Flaminio, R.; Flanigan, M.; Foley, S.; Forsi, E.; Forte, L. A.; Fotopoulos, N.; Fournier, J.-D.; Franc, J.; Frasca, S.; Frasconi, F.; Frede, M.; Frei, M.; Frei, Z.; Freise, A.; Frey, R.; Fricke, T. T.; Friedrich, D.; Fritschel, P.; Frolov, V. V.; Fulda, P.; Fyffe, M.; Galimberti, M.; Gammaitoni, L.; Garcia, J.; Garofoli, J. A.; Garufi, F.; Gáspár, M. E.; Gemme, G.; Genin, E.; Gennai, A.; Ghosh, S.; Giaime, J. A.; Giampanis, S.; Giardina, K. D.; Giazotto, A.; Gill, C.; Goetz, E.; Goggin, L. M.; González, G.; Gorodetsky, M. L.; Goßler, S.; Gouaty, R.; Graef, C.; Granata, M.; Grant, A.; Gras, S.; Gray, C.; Greenhalgh, R. J. S.; Gretarsson, A. M.; Greverie, C.; Grosso, R.; Grote, H.; Grunewald, S.; Guidi, G. M.; Guido, C.; Gupta, R.; Gustafson, E. K.; Gustafson, R.; Hage, B.; Hallam, J. M.; Hammer, D.; Hammond, G.; Hanks, J.; Hanna, C.; Hanson, J.; Harms, J.; Harry, G. M.; Harry, I. W.; Harstad, E. D.; Hartman, M. T.; Haughian, K.; Hayama, K.; Hayau, J.-F.; Hayler, T.; Heefner, J.; Heitmann, H.; Hello, P.; Hendry, M. A.; Heng, I. S.; Heptonstall, A. W.; Herrera, V.; Hewitson, M.; Hild, S.; Hoak, D.; Hodge, K. A.; Holt, K.; Hong, T.; Hooper, S.; Hosken, D. J.; Hough, J.; Howell, E. J.; Huet, D.; Hughey, B.; Husa, S.; Huttner, S. H.; Ingram, D. R.; Inta, R.; Isogai, T.; Ivanov, A.; Jaranowski, P.; Johnson, W. W.; Jones, D. I.; Jones, G.; Jones, R.; Ju, L.; Kalmus, P.; Kalogera, V.; Kandhasamy, S.; Kanner, J. B.; Katsavounidis, E.; Katzman, W.; Kawabe, K.; Kawamura, S.; Kawazoe, F.; Kells, W.; Kelner, M.; Keppel, D. G.; Khalaidovski, A.; Khalili, F. Y.; Khazanov, E. A.; Kim, H.; Kim, N.; King, P. J.; Kinzel, D. L.; Kissel, J. S.; Klimenko, S.; Kondrashov, V.; Kopparapu, R.; Koranda, S.; Korth, W. Z.; Kowalska, I.; Kozak, D.; Kringel, V.; Krishnamurthy, S.; Krishnan, B.; Królak, A.; Kuehn, G.; Kumar, R.; Kwee, P.; Landry, M.; Lantz, B.; Lastzka, N.; Lazzarini, A.; Leaci, P.; Leong, J.; Leonor, I.; Leroy, N.; Letendre, N.; Li, J.; Li, T. G. F.; Liguori, N.; Lindquist, P. E.; Lockerbie, N. A.; Lodhia, D.; Lorenzini, M.; Loriette, V.; Lormand, M.; Losurdo, G.; Lu, P.; Luan, J.; Lubiński, M.; Lück, H.; Lundgren, A. P.; Macdonald, E.; Machenschalk, B.; MacInnis, M.; Mageswaran, M.; Mailand, K.; Majorana, E.; Maksimovic, I.; Man, N.; Mandel, I.; Mandic, V.; Mantovani, M.; Marandi, A.; Marchesoni, F.; Marion, F.; Márka, S.; Márka, Z.; Maros, E.; Marque, J.; Martelli, F.; Martin, I. W.; Martin, R. M.; Marx, J. N.; Mason, K.; Masserot, A.; Matichard, F.; Matone, L.; Matzner, R. A.; Mavalvala, N.; McCarthy, R.; McClelland, D. E.; McGuire, S. C.; McIntyre, G.; McKechan, D. J. A.; Meadors, G.; Mehmet, M.; Meier, T.; Melatos, A.; Melissinos, A. C.; Mendell, G.; Mercer, R. A.; Merill, L.; Meshkov, S.; Messenger, C.; Meyer, M. S.; Miao, H.; Michel, C.; Milano, L.; Miller, J.; Minenkov, Y.; Mino, Y.; Mitrofanov, V. P.; Mitselmakher, G.; Mittleman, R.; Miyakawa, O.; Moe, B.; Moesta, P.; Mohan, M.; Mohanty, S. D.; Mohapatra, S. R. P.; Moraru, D.; Moreno, G.; Morgado, N.; Morgia, A.; Mosca, S.; Moscatelli, V.; Mossavi, K.; Mours, B.; Mow-Lowry, C. M.; Mueller, G.; Mukherjee, S.; Mullavey, A.; Müller-Ebhardt, H.; Munch, J.; Murray, P. G.; Nash, T.; Nawrodt, R.; Nelson, J.; Neri, I.; Newton, G.; Nishida, E.; Nishizawa, A.; Nocera, F.; Nolting, D.; Ochsner, E.; O'Dell, J.; Ogin, G. H.; Oldenburg, R. G.; O'Reilly, B.; O'Shaughnessy, R.; Osthelder, C.; Ott, C. D.; Ottaway, D. J.; Ottens, R. S.; Overmier, H.; Owen, B. J.; Page, A.; Pagliaroli, G.; Palladino, L.; Palomba, C.; Pan, Y.; Pankow, C.; Paoletti, F.; Papa, M. A.; Parameswaran, A.; Pardi, S.; Parisi, M.; Pasqualetti, A.; Passaquieti, R.; Passuello, D.; Patel, P.; Pathak, D.; Pedraza, M.; Pekowsky, L.; Penn, S.; Peralta, C.; Perreca, A.; Persichetti, G.; Phelps, M.; Pichot, M.; Pickenpack, M.; Piergiovanni, F.; Pietka, M.; Pinard, L.; Pinto, I. M.; Pitkin, M.; Pletsch, H. J.; Plissi, M. V.; Podkaminer, J.; Poggiani, R.; Pöld, J.; Postiglione, F.; Prato, M.; Predoi, V.; Price, L. R.; Prijatelj, M.; Principe, M.; Privitera, S.; Prix, R.; Prodi, G. A.; Prokhorov, L.; Puncken, O.; Punturo, M.; Puppo, P.; Quetschke, V.; Raab, F. J.; Rabeling, D. S.; Rácz, I.; Radkins, H.; Raffai, P.; Rakhmanov, M.; Ramet, C. R.; Rankins, B.; Rapagnani, P.; Raymond, V.; Re, V.; Redwine, K.; Reed, C. M.; Reed, T.; Regimbau, T.; Reid, S.; Reitze, D. H.; Ricci, F.; Riesen, R.; Riles, K.; Roberts, P.; Robertson, N. A.; Robinet, F.; Robinson, C.; Robinson, E. L.; Rocchi, A.; Roddy, S.; Rolland, L.; Rollins, J.; Romano, J. D.; Romano, R.; Romie, J. H.; Rosińska, D.; Röver, C.; Rowan, S.; Rüdiger, A.; Ruggi, P.; Ryan, K.; Sakata, S.; Sakosky, M.; Salemi, F.; Salit, M.; Sammut, L.; Sancho de la Jordana, L.; Sandberg, V.; Sannibale, V.; Santamaría, L.; Santiago-Prieto, I.; Santostasi, G.; Saraf, S.; Sassolas, B.; Sathyaprakash, B. S.; Sato, S.; Satterthwaite, M.; Saulson, P. R.; Savage, R.; Schilling, R.; Schlamminger, S.; Schnabel, R.; Schofield, R. M. S.; Schulz, B.; Schutz, B. F.; Schwinberg, P.; Scott, J.; Scott, S. M.; Searle, A. C.; Seifert, F.; Sellers, D.; Sengupta, A. S.; Sentenac, D.; Sergeev, A.; Shaddock, D. A.; Shaltev, M.; Shapiro, B.; Shawhan, P.; Shihan Weerathunga, T.; Shoemaker, D. H.; Sibley, A.; Siemens, X.; Sigg, D.; Singer, A.; Singer, L.; Sintes, A. M.; Skelton, G.; Slagmolen, B. J. J.; Slutsky, J.; Smith, J. R.; Smith, M. R.; Smith, N. D.; Smith, R.; Somiya, K.; Sorazu, B.; Soto, J.; Speirits, F. C.; Sperandio, L.; Stefszky, M.; Stein, A. J.; Steinlechner, J.; Steinlechner, S.; Steplewski, S.; Stochino, A.; Stone, R.; Strain, K. A.; Strigin, S.; Stroeer, A. S.; Sturani, R.; Stuver, A. L.; Summerscales, T. Z.; Sung, M.; Susmithan, S.; Sutton, P. J.; Swinkels, B.; Szokoly, G. P.; Tacca, M.; Talukder, D.; Tanner, D. B.; Tarabrin, S. P.; Taylor, J. R.; Taylor, R.; Thomas, P.; Thorne, K. A.; Thorne, K. S.; Thrane, E.; Thüring, A.; Titsler, C.; Tokmakov, K. V.; Toncelli, A.; Tonelli, M.; Torre, O.; Torres, C.; Torrie, C. I.; Tournefier, E.; Travasso, F.; Traylor, G.; Trias, M.; Tseng, K.; Turner, L.; Ugolini, D.; Urbanek, K.; Vahlbruch, H.; Vaishnav, B.; Vajente, G.; Vallisneri, M.; van den Brand, J. F. J.; Van Den Broeck, C.; van der Putten, S.; van der Sluys, M. V.; van Veggel, A. A.; Vass, S.; Vasuth, M.; Vaulin, R.; Vavoulidis, M.; Vecchio, A.; Vedovato, G.; Veitch, J.; Veitch, P. J.; Veltkamp, C.; Verkindt, D.; Vetrano, F.; Viceré, A.; Villar, A. E.; Vinet, J.-Y.; Vocca, H.; Vorvick, C.; Vyachanin, S. P.; Waldman, S. J.; Wallace, L.; Wanner, A.; Ward, R. L.; Was, M.; Wei, P.; Weinert, M.; Weinstein, A. J.; Weiss, R.; Wen, L.; Wen, S.; Wessels, P.; West, M.; Westphal, T.; Wette, K.; Whelan, J. T.; Whitcomb, S. E.; White, D.; Whiting, B. F.; Wilkinson, C.; Willems, P. A.; Williams, H. R.; Williams, L.; Willke, B.; Winkelmann, L.; Winkler, W.; Wipf, C. C.; Wiseman, A. G.; Woan, G.; Wooley, R.; Worden, J.; Yablon, J.; Yakushin, I.; Yamamoto, H.; Yamamoto, K.; Yang, H.; Yeaton-Massey, D.; Yoshida, S.; Yu, P.; Yvert, M.; Zanolin, M.; Zhang, L.; Zhang, Z.; Zhao, C.; Zotov, N.; Zucker, M. E.; Zweizig, J.; LIGO Scientific Collaboration; Virgo Collaboration; Aptekar, R. L.; Boynton, W. V.; Briggs, M. S.; Cline, T. L.; Connaughton, V.; Frederiks, D. D.; Gehrels, N.; Goldsten, J. O.; Golovin, D.; van der Horst, A. J.; Hurley, K. C.; Kaneko, Y.; von Kienlin, A.; Kouveliotou, C.; Krimm, H. A.; Lin, L.; Mitrofanov, I.; Ohno, M.; Pal'shin, V. D.; Rau, A.; Sanin, A.; Tashiro, M. S.; Terada, Y.; Yamaoka, K.

2011-06-01

Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely ~1 kpc from Earth, an order of magnitude closer than magnetars targeted in previous GW searches. A second, AXP 1E 1547.0-5408, gave a burst with an estimated isotropic energy >1044 erg which is comparable to the giant flares. We find no evidence of GWs associated with a sample of 1279 electromagnetic triggers from six magnetars occurring between 2006 November and 2009 June, in GW data from the LIGO, Virgo, and GEO600 detectors. Our lowest model-dependent GW emission energy upper limits for band- and time-limited white noise bursts in the detector sensitive band, and for f-mode ringdowns (at 1090 Hz), are 3.0 × 1044 d 2 1 erg and 1.4 × 1047 d 2 1 erg, respectively, where d_{1} = \\frac{d_{{0501}}}{1\\,{kpc}} and d 0501 is the distance to SGR 0501+4516. These limits on GW emission from f-modes are an order of magnitude lower than any previous, and approach the range of electromagnetic energies seen in SGR giant flares for the first time.

Collaborative work on evaluation of ovarian toxicity. 13) Two- or four-week repeated dose studies and fertility study of PPAR alpha/gamma dual agonist in female rats.

PubMed

Sato, Norihiro; Uchida, Keisuke; Nakajima, Mikio; Watanabe, Atsushi; Kohira, Terutomo

2009-01-01

The main focus of this study was to determine the optimal dosing period in a repeated dose toxicity study based on toxic effects as assessed by ovarian morphological changes. To assess morphological and functional changes induced in the ovary by a peroxisome proliferator-activated receptor (PPAR) alpha/gamma dual agonist, the compound was administered to female rats at dose levels of 0, 4, 20, and 100 mg/kg/day in a repeated dose toxicity study for 2 or 4 weeks, and from 2 weeks prior to mating to Day 7 of pregnancy in a female fertility study. In the repeated dose toxicity study, an increase in atresia of large follicles, a decrease in corpora lutea, and an increase in stromal cells were observed in the treated groups. In addition, the granulosa cell exfoliations into antrum of large follicles and corpora lutea with retained oocyte are morphological characteristics induced by this compound, and they might be related with abnormal condition of ovulation. In the female fertility study, the pregnancy rate tended to decrease in the 100 mg/kg/day group. At necropsy, decreases in the number of corpora lutea, implantations and live embryos were noted in the 20 and 100 mg/kg/day group. No changes were observed in animals given 4 mg/kg/day. These findings indicated that histopathological changes in the ovary are important endpoints for evaluation of drugs inducing ovarian damage. In conclusion, a 2-week administration period is sufficient to detect ovarian toxicity of this test compound in the repeated dose toxicity study.

Effects of Inoculated Bacillus subtilis on Geosmin and 2-Methylisoborneol Removal in Suspended Growth Reactors Using Aquacultural Waste for Biofloc Production.

PubMed

Luo, Guozhi; Wang, Jiao; Ma, Niannian; Liu, Zefeng; Tan, Hongxin

2016-08-28

Geosmin and 2-methylisoborneol (2-MIB) are two of the most common taint compounds that adversely affect the quality of aquacultural animals. In the present study, 94% of geosmin and 97% of 2-MIB in suspended growth reactors producing bioflocs (SGRs) with aquaculture waste were removed after inoculation with Bacillus subtilis, significantly higher than that of control SGRs (70% of geosmin and 86.4% of 2-MIB). The lowest concentrations of geosmin and 2-MIB achieved in the effluent of the SGRs were 2.43 ± 0.42 ng/l and 2.23 ± 0.15 ng/l, respectively. The crude protein content of the bioflocs produced in the SGRs was 35 ± 4%. The NH4(+)-N and NO2(-)-N concentrations in the effluent of the reactors were 1.13 ± 0.21 mg/l and 0.42 ± 0.04 mg/l, respectively. These results suggest that inoculated with Bacillus subtilis, SGRs have a better performance to reuse the nitrogen in fish waste and to remove geosmin and 2-MIB from the culture water efficiently.

Changes in the X-Ray Emission from the Magnetar Candidate 1E 2259+586 During its 2002 Outburst

NASA Technical Reports Server (NTRS)

Woods, P. M.; Kaspi, V. M.; Thompson, C.; Gavrill, F. P.; Marshall, H. L.; Chakrabarty, D.; Flanagan, K.; Heyl, J.; Hernquist, L.

2004-01-01

An outburst of more than 80 individual bursts, similar to those seen from Soft Gamma Repeaters (SGRs), was detected from the anomalous X-ray pulsar (AXP) 1E 2259+586 in 2002 June. Coincident with this burst activity were gross changes in the pulsed flux, persistent flux, energy spectrum, pulse profile, and spin-down of the underlying X-ray source. We present Rossi X-Ray Timing Explorer and X-Ray Multi-Mirror Mission observations of 1E 2259+586 that show the evolution of the aforementioned source parameters during and following this episode and identify recovery timescales for each. Specifically, we observe an X-ray flux increase (pulsed and phase-averaged) by more than an order of magnitude having two distinct components. The first component is linked to the burst activity and decays within approx. 2 days, during which the energy spectrum is considerably harder than during the quiescent state of the source. The second component decays over the year following the glitch according to a power law in time with an exponent -0.22 +/- 0.01. The pulsed fraction decreased initially to approx. 15% rms but recovered rapidly to the preoutburst level of approx. 23% within the first 3 days. The pulse profile changed significantly during the outburst and recovered almost fully within 2 months of the outburst. A glitch of size Delta(sib (nu)max) = (4.24 +/- 0.11) x 10(exp -6) was observed in 1E 2259+586, which preceded the observed burst activity. The glitch could not be well fitted with a simple partial exponential recovery. An exponential rise of approx. 20% of the frequency jump with a timescale of approx. 14 days results in a significantly better fit to the data; however, contamination from a systematic drift in the phase of the pulse profile cannot be excluded. A fraction of the glitch (approx. 19%) was recovered in a quasi-exponential manner having a recovery timescale of approx. 16 days. The long-term postglitch spin-down rate decreased in magnitude relative to the

Dust Radiative Transfer Modeling of the Infrared Ring around the Magnetar SGR 1900+14

DOE Office of Scientific and Technical Information (OSTI.GOV)

Natale, G.; Rea, N.; Torres, D. F.

2017-03-01

A peculiar infrared ring-like structure was discovered by Spitzer around the strongly magnetized neutron star SGR 1900+14. This infrared (IR) structure was suggested to be due to a dust-free cavity, produced by the Soft Gamma-ray Repeaters (SGRs) Giant Flare occurring in 1998, and kept illuminated by surrounding stars. Using a 3D dust radiative transfer code, we aimed to reproduce the emission morphology and the integrated emission flux of this structure assuming different spatial distributions and densities for the dust, and different positions for the illuminating stars. We found that a dust-free ellipsoidal cavity can reproduce the shape, flux, and spectrummore » of the ring-like IR emission, provided that the illuminating stars are inside the cavity and that the interstellar medium has high gas density ( n {sub H} ∼ 1000 cm{sup −3}). We further constrain the emitting region to have a sharp inner boundary and to be significantly extended in the radial direction, possibly even just a cavity in a smooth molecular cloud. We discuss possible scenarios for the formation of the dustless cavity and the particular geometry that allows it to be IR-bright.« less

SGR J1745-29: Swift Discovery and Monitoring of a New SGR Near Sgr A*

NASA Technical Reports Server (NTRS)

Kennea, Jamie A.; Burrows, David N.; Kouveliotou, Chryssa; Palmer, David; Kaneko, Yuki; Evans, Phil; Degenaar, Nathalie; Reynolds, Mark; Miller, Jon M.; Wijnands, Rudy;

Compositions containing poly (.gamma.-glutamylcysteinyl)glycines

DOEpatents

Jackson, Paul J.; Delhaize, Emmanuel; Robinson, Nigel J.; Unkefer, Clifford J.; Furlong, Clement

1992-01-01

A method of removing heavy metals from aqueous solution, a composition of matter used in effecting said removal, and apparatus used in effecting said removal. One or more of the polypeptides, poly (.gamma.-glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly (.gamma.-glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form.

The 2001 April Burst Activation of SGR 1900-14: Pulse Properties and Torque

NASA Technical Reports Server (NTRS)

Woods, P. M.; Kouveliotou, C.; Goegues, E.; Finger, M. H.; Feroci, M.; Mereghetti, S.; Swank, J. H.; Hurley, K.; Heise, J.; Smith D.

2003-01-01

We report on observations of SGR 1900+14 made with the Rossi X-Ray Timing Explorer (RXTE) and BeppoSAXduring the 2001 April burst activation of the source. Using these data, we measure the spin-down torque on the star and confirm earlier findings that the torque and burst activity are not directly correlated. We compare the X-ray pulse profile to the gamma-ray profile during the April 18 intermediate flare and show that (1) their shapes are similar and (1) the gamma-ray profile aligns closely in phase with the X-ray pulsations. The good phase alignment of the gamma-ray and X-ray profiles suggests that there was no rapid spin-down following this flare of the magnitude inferred for the August 27 giant flare. We discuss how these observations further constrain magnetic field reconfiguration models for the large flares of SGRs.

Decrease in gamma-band activity tracks sequence learning

PubMed Central

Madhavan, Radhika; Millman, Daniel; Tang, Hanlin; Crone, Nathan E.; Lenz, Fredrick A.; Tierney, Travis S.; Madsen, Joseph R.; Kreiman, Gabriel; Anderson, William S.

2015-01-01

Learning novel sequences constitutes an example of declarative memory formation, involving conscious recall of temporal events. Performance in sequence learning tasks improves with repetition and involves forming temporal associations over scales of seconds to minutes. To further understand the neural circuits underlying declarative sequence learning over trials, we tracked changes in intracranial field potentials (IFPs) recorded from 1142 electrodes implanted throughout temporal and frontal cortical areas in 14 human subjects, while they learned the temporal-order of multiple sequences of images over trials through repeated recall. We observed an increase in power in the gamma frequency band (30–100 Hz) in the recall phase, particularly in areas within the temporal lobe including the parahippocampal gyrus. The degree of this gamma power enhancement decreased over trials with improved sequence recall. Modulation of gamma power was directly correlated with the improvement in recall performance. When presenting new sequences, gamma power was reset to high values and decreased again after learning. These observations suggest that signals in the gamma frequency band may play a more prominent role during the early steps of the learning process rather than during the maintenance of memory traces. PMID:25653598

Compositions containing poly ([gamma]glutamylcysteinyl)glycines

DOEpatents

Jackson, P.J.; Delhaize, E.; Robinson, N.J.; Unkefer, C.J.; Furlong, C.

1992-02-18

A method of removing heavy metals from aqueous solution, a composition of matter used in effecting the removal, and the apparatus used in effecting the removal are described. One or more of the polypeptides, poly ([gamma]glutamylcysteinyl)glycines, is immobilized on an inert material in particulate form. Upon contact with an aqueous solution containing heavy metals, the polypeptides sequester the metals, removing them from the solution. There is selectivity of poly ([gamma]glutamylcysteinyl)glycines having a particular number of monomer repeat units for particular metals. The polypeptides are easily regenerated by contact with a small amount of an organic acid, so that they can be used again to remove heavy metals from solution. This also results in the removal of the metals from the column in a concentrated form. 1 figs.

The GAMMA Ray Sky as Seen by Fermi: Opening a New Window on the High Energy Space Environment

DTIC Science & Technology

2009-01-01

pulsars , stars whose repeating emissions can be used as ultra-precise chronometers. Measurement of gamma radiation provides unique insight...diffuse glow are a number of bright point sources, mostly gamma ray pulsars — rotating, magnetized neutron stars — as discussed below. The bright sources...important early discoveries of Fermi have been from objects in our galaxy. The LAT has discovered 12 new pulsars that seem to be visible only in gamma

Rapid Optical Follow-up Observations of SGR Events with ROTSE-I

NASA Astrophysics Data System (ADS)

Akerlof, C.; Balsano, R.; Barthelmy, S.; Bloch, J.; Butterworth, P.; Casperson, D.; Cline, T.; Fletcher, S.; Gisler, G.; Hills, J.; Kehoe, R.; Lee, B.; Marshall, S.; McKay, T.; Pawl, A.; Priedhorsky, W.; Seldomridge, N.; Szymanski, J.; Wren, J.

2000-10-01

In order to observe nearly simultaneous emission from gamma-ray bursts (GRBs), the Robotic Optical Transient Search Experiment (ROTSE) receives triggers via the GRB Coordinates Network (GCN). Since beginning operations in 1998 March, ROTSE has also taken useful data for 10 SGR events: eight from SGR 1900+14 and two from SGR 1806-20. We have searched for new or variable sources in the error regions of these SGRs, and no optical counterparts were observed. Limits are in the range mROTSE~12.5-15.5 during the period 20 s to 1 hr after the observed SGR events.

Z{gamma}{gamma}{gamma} {yields} 0 Processes in SANC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bardin, D. Yu., E-mail: bardin@nu.jinr.ru; Kalinovskaya, L. V., E-mail: kalinov@nu.jinr.ru; Uglov, E. D., E-mail: corner@nu.jinr.ru

2013-11-15

We describe the analytic and numerical evaluation of the {gamma}{gamma} {yields} {gamma}Z process cross section and the Z {yields} {gamma}{gamma}{gamma} decay rate within the SANC system multi-channel approach at the one-loop accuracy level with all masses taken into account. The corresponding package for numeric calculations is presented. For checking of the results' correctness we make a comparison with the other independent calculations.

Sneaky Gamma-Rays: Using Gravitational Lensing to Avoid Gamma-Gamma-Absorption

NASA Astrophysics Data System (ADS)

Boettcher, Markus; Barnacka, Anna

2014-08-01

It has recently been suggested that gravitational lensing studies of gamma-ray blazars might be a promising avenue to probe the location of the gamma-ray emitting region in blazars. Motivated by these prospects, we have investigated potential gamma-gamma absorption signatures of intervening lenses in the very-high-energy gamma-ray emission from lensedblazars. We considered intervening galaxies and individual stars within these galaxies. We find that the collective radiation field of galaxies acting as sources of macrolensing are not expected to lead to significant gamma-gamma absorption. Individual stars within intervening galaxies could, in principle, cause a significant opacity to gamma-gamma absorption for VHE gamma-rays if the impact parameter (the distance of closest approach of the gamma-ray to the center of the star) is small enough. However, we find that the curvature of the photon path due to gravitational lensing will cause gamma-ray photons to maintain a sufficiently large distance from such stars to avoid significant gamma-gamma absorption. This re-inforces the prospect of gravitational-lensing studies of gamma-ray blazars without interference due to gamma-gamma absorption due to the lensing objects.

Real time method and computer system for identifying radioactive materials from HPGe gamma-ray spectroscopy

DOEpatents

Rowland, Mark S.; Howard, Douglas E.; Wong, James L.; Jessup, James L.; Bianchini, Greg M.; Miller, Wayne O.

2007-10-23

A real-time method and computer system for identifying radioactive materials which collects gamma count rates from a HPGe gamma-radiation detector to produce a high-resolution gamma-ray energy spectrum. A library of nuclear material definitions ("library definitions") is provided, with each uniquely associated with a nuclide or isotope material and each comprising at least one logic condition associated with a spectral parameter of a gamma-ray energy spectrum. The method determines whether the spectral parameters of said high-resolution gamma-ray energy spectrum satisfy all the logic conditions of any one of the library definitions, and subsequently uniquely identifies the material type as that nuclide or isotope material associated with the satisfied library definition. The method is iteratively repeated to update the spectrum and identification in real time.

The Z {yields} cc-bar {yields} {gamma}{gamma}*, Z {yields} bb-bar {yields} {gamma}{gamma}* triangle diagrams and the Z {yields} {gamma}{psi}, Z {yields} {gamma}Y decays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Achasov, N. N., E-mail: achasov@math.nsc.ru

2011-03-15

The approach to the Z {yields} {gamma}{psi} and Z {yields} {gamma}Y decay study is presented in detail, based on the sum rules for the Z {yields} cc-bar {yields} {gamma}{gamma}* and Z {yields} bb-bar {yields} {gamma}{gamma}* amplitudes and their derivatives. The branching ratios of the Z {yields} {gamma}{psi} and Z {yields} {gamma}Y decays are calculated for different hypotheses on saturation of the sum rules. The lower bounds of {Sigma}{sub {psi}} BR(Z {yields} {gamma}{psi}) = 1.95 Multiplication-Sign 10{sup -7} and {Sigma}{sub {upsilon}} BR(Z {yields} {gamma}Y) = 7.23 Multiplication-Sign 10{sup -7} are found. Deviations from the lower bounds are discussed, including the possibilitymore » of BR(Z {yields} {gamma}J/{psi}(1S)) {approx} BR(Z {yields} {gamma}Y(1S)) {approx} 10{sup -6}, that could be probably measured in LHC. The angular distributions in the Z {yields} {gamma}{psi} and Z {yields} {gamma}Y decays are also calculated.« less

Embolization with Gamma Knife Radiosurgery of Giant Intracranial Arteriovenous Malformations.

PubMed

Chun, Dong Hyun; Kim, Moo Seong; Kim, Sung Tae; Paeng, Sung Hwa; Jeong, Hae Woong; Lee, Won Hee

2016-01-01

Giant arteriovenous malformations (i.e., those greater than 6 cm maximum diameter or volume > 33 cc) are difficult to treat and often carry higher treatment morbidity and mortality rates. In our study, we reviewed the angiographic results and clinical outcomes for 11 patients with giant arteriovenous malformations who were treated between 1994 and 2012. The patients selected included 9 males (82%) and 2 females (18%). Their presenting symptoms were hemorrhage (n=2; 18%), seizure (n=7; 64%), and headache (n=2; 12%). Nine patients were Spetzler-Martin Grade III, 2 were Spetzler-Martin Grade IV. The mean arteriovenous malformation volume was 41 cc (33-52 cc). The mean age of the patients was 45.1 years (24-57 years) and the mean radiation dose delivered to the margin of the nidus was 14.2 Gy. Ten patients received pre-Gamma Knife radiosurgery embolization and Gamma Knife radiosurgery, 1 patient received pre-Gamma Knife radiosurgery embolization and Gamma Knife radiosurgery twice and the interval between Gamma Knife radiosurgeries was 3 months. The complete obliteration rate following Gamma Knife radiosurgery was 36%, subtotal obliteration ( > 70% decreased size of nidus) was 36%, and partial obliteration was 28%. One patient experienced a small hemorrhage after embolization. Combined embolization and Gamma Knife radiosurgery showed successful obliteration of the arteriovenous malformation nidus. The use of embolization to initially reduce nidus size followed by Gamma Knife radiosurgery improves the treatment results. Repeated Gamma Knife radiosurgery should be a treatment option when there is a small nidus remnant.

Repeated Nrf2 stimulation using sulforaphane protects fibroblasts from ionizing radiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathew, Sherin T.; Bergström, Petra; Hammarsten, Ola, E-mail: ola.hammarsten@clinchem.gu.se

2014-05-01

Most of the cytotoxicity induced by ionizing radiation is mediated by radical-induced DNA double-strand breaks. Cellular protection from free radicals can be stimulated several fold by sulforaphane-mediated activation of the transcription factor Nrf2 that regulates more than 50 genes involved in the detoxification of reactive substances and radicals. Here, we report that repeated sulforaphane treatment increases radioresistance in primary human skin fibroblasts. Cells were either treated with sulforaphane for four hours once or with four-hour treatments repeatedly for three consecutive days prior to radiation exposure. Fibroblasts exposed to repeated-sulforaphane treatment showed a more pronounced dose-dependent induction of Nrf2-regulated mRNA andmore » reduced amount of radiation-induced free radicals compared with cells treated once with sulforaphane. In addition, radiation- induced DNA double-strand breaks measured by gamma-H2AX foci were attenuated following repeated sulforaphane treatment. As a result, cellular protection from ionizing radiation measured by the 5-ethynyl-2′-deoxyuridine (EdU) assay was increased, specifically in cells exposed to repeated sulforaphane treatment. Sulforaphane treatment was unable to protect Nrf2 knockout mouse embryonic fibroblasts, indicating that the sulforaphane-induced radioprotection was Nrf2-dependent. Moreover, radioprotection by repeated sulforaphane treatment was dose-dependent with an optimal effect at 10 uM, whereas both lower and higher concentrations resulted in lower levels of radioprotection. Our data indicate that the Nrf2 system can be trained to provide further protection from radical damage. - Highlights: • Repeated treatment with sulforaphane protects fibroblasts from ionizing radiation • Repeated sulforaphane treatment attenuates radiation induced ROS and DNA damage • Sulforaphane mediated protection is Nrf2 dependent.« less

Repeat tuberculin skin testing leads to desensitisation in naturally infected tuberculous cattle which is associated with elevated interleukin-10 and decreased interleukin-1 beta responses.

PubMed

Coad, Michael; Clifford, Derek; Rhodes, Shelley G; Hewinson, R Glyn; Vordermeier, H Martin; Whelan, Adam O

2010-01-01

The principal surveillance tool used to control bovine tuberculosis in cattle is the removal of animals that provide a positive response to the tuberculin skin-test. In this study we performed a longitudinal investigation of the immunological and diagnostic consequences of repeated short-interval skin-tests in cattle naturally infected with Mycobacterium bovis. Tuberculin skin-test positive cattle were subjected to up to four further intradermal comparative cervical skin-tests at approximately 60-day intervals. A significant progressive reduction in the strength of the skin-test was observed after successive tests. In contrast, the magnitude of interferon-gamma (IFN-gamma) responses was not influenced by repeat skin-testing either transiently around the time of each skin-test or longitudinally following repeated tests. A significant boost in blood interleukin-10 (IL-10) production was observed within 3 days following each skin-test although the magnitude of this boosted response returned to lower levels by day 10 post-test. The application of a novel multiplex assay to simultaneously measure seven cytokines and chemokines also identified that skin-testing resulted in a significant and progressive reduction in antigen specific interleukin-1beta (IL-1beta) whilst confirming stable IFN-gamma and elevated IL-10 responses in the blood. Therefore, we have demonstrated that in cattle naturally infected with M. bovis, repeat short-interval skin-testing can lead to a progressive reduction in skin-test responsiveness which has potential negative consequences for the detection of infected animals with marginal or inconclusive skin-test responses. The desensitising effect is associated with decreased IL-1beta and elevated IL-10 responses, but importantly, does not influence antigen specific IFN-gamma responses. INRA, EDP Sciences, 2009

Dosimetric evaluation of lithium carbonate (Li2CO3) as a dosemeter for gamma-radiation dose measurements.

PubMed

Popoca, R; Ureña-Núñez, F

2009-06-01

This work reports the possibility of using lithium carbonate as a dosimetric material for gamma-radiation measurements. Carboxi-radical ions, CO(2)(-) and CO(3)(-), arise from the gamma irradiation of Li(2)CO(3), and these radical ions can be quantified by electron paramagnetic resonance (EPR) spectrometry. The EPR-signal response of gamma-irradiated lithium carbonate has been investigated to determine some dosimetric characteristics such as: peak-to-peak signal intensity versus gamma dose received, zero-dose response, signal fading, signal repeatability, batch homogeneity, dose rate effect and stability at different environmental conditions. Using the conventional peak-to-peak method of stable ion radicals, it is concluded that lithium carbonate could be used as a gamma dosemeter in the range of 3-100 Gy.

Limits to the Cassiopeia A 44Ti Line Flux and Constraints on the Ejecta Energy and the Compact Source

NASA Astrophysics Data System (ADS)

Rothschild, R. E.; Lingenfelter, R. E.

2003-01-01

Two long observations of the Cas A supernova remnant were made by the Rossi X-Ray Timing Explorer in 1996 and 1997 to search for hard X-ray line emission at 67.9 and 78.4 keV from the decay of 44Ti formed during the supernova event. Continuum flux was detected up to 100 keV, but the 44Ti lines were not detected. The 90% confidence upper limit to the line flux is 3.6×10-5 photons cm-2 s-1. This is consistent with the recent BeppoSAX detection and with the Compton Gamma Ray Observatory/Imaging Compton Telescope (CGRO/COMPTEL) detection of the companion transition line flux for 44Sc decay. The mean BeppoSAX-COMPTEL flux indicates that 1.5+/-0.3×10-4 Msolar of 44Ti was produced in the supernova explosion. On the basis of recent theoretical calculations and optical observations suggesting a WN Wolf-Rayet progenitor with an initial mass of >=25 Msolar, the observed 44Ti yield implies that the Cas A supernova ejecta energy was ~2×1051 ergs, and as a result a neutron star was formed, rather than a black hole. We suggest that Cas A is possibly in the early stages of the anomalous X-ray pulsar/soft gamma-ray repeater (AXP/SGR) scenario in which the pushback disk has yet to form, and when the disk does form, the accretion will increase the luminosity to that of present-day AXP/SGRs, and pulsed emission will commence.

Fermi/GBM Observations of SGRJ0501 + 4516 Bursts

NASA Technical Reports Server (NTRS)

Lin, Lin; Kouveliotou, Chryssa; Baring, Matthew G.; van der Horst, Alexander J.; Guiriec, Sylvain; Woods, Peter M.; Goegues, Ersin; Kaneko, Yuki; Scargle, Jeffrey; Granot, Jonathan;

The High Energy Transient Explorer (HETE): Mission and Science Overview

NASA Astrophysics Data System (ADS)

Ricker, G. R.; Atteia, J.-L.; Crew, G. B.; Doty, J. P.; Fenimore, E. E.; Galassi, M.; Graziani, C.; Hurley, K.; Jernigan, J. G.; Kawai, N.; Lamb, D. Q.; Matsuoka, M.; Pizzichini, G.; Shirasaki, Y.; Tamagawa, T.; Vanderspek, R.; Vedrenne, G.; Villasenor, J.; Woosley, S. E.; Yoshida, A.

2003-04-01

The High Energy Transient Explorer (HETE ) mission is devoted to the study of gamma-ray bursts (GRBs) using soft X-ray, medium X-ray, and gamma-ray instruments mounted on a compact spacecraft. The HETE satellite was launched into equatorial orbit on 9 October 2000. A science team from France, Japan, Brazil, India, Italy, and the US is responsible for the HETE mission, which was completed for ~ 1/3 the cost of a NASA Small Explorer (SMEX). The HETE mission is unique in that it is entirely ``self-contained,'' insofar as it relies upon dedicated tracking, data acquisition, mission operations, and data analysis facilities run by members of its international Science Team. A powerful feature of HETE is its potential for localizing GRBs within seconds of the trigger with good precision (~ 10') using medium energy X-rays and, for a subset of bright GRBs, improving the localization to ~ 30''accuracy using low energy X-rays. Real-time GRB localizations are transmitted to ground observers within seconds via a dedicated network of 14 automated ``Burst Alert Stations,'' thereby allowing prompt optical, IR, and radio follow-up, leading to the identification of counterparts for a large fraction of HETE -localized GRBs. HETE is the only satellite that can provide near-real time localizations of GRBs, and that can localize GRBs that do not have X-ray, optical, and radio afterglows, during the next two years. These capabilities are the key to allowing HETE to probe further the unique physics that produces the brightest known photon sources in the universe. To date (December 2002), HETE has produced 31 GRB localizations. Localization accuracies are routinely in the 4'- 20' range; for the five GRBs with SXC localization, accuracies are ~1-2'. In addition, HETE has detected ~ 25 bursts from soft gamma repeaters (SGRs), and >600 X-ray bursts (XRBs).

Adeno-associated virus inverted terminal repeats stimulate gene editing.

PubMed

Hirsch, M L

2015-02-01

Advancements in genome editing have relied on technologies to specifically damage DNA which, in turn, stimulates DNA repair including homologous recombination (HR). As off-target concerns complicate the therapeutic translation of site-specific DNA endonucleases, an alternative strategy to stimulate gene editing based on fragile DNA was investigated. To do this, an episomal gene-editing reporter was generated by a disruptive insertion of the adeno-associated virus (AAV) inverted terminal repeat (ITR) into the egfp gene. Compared with a non-structured DNA control sequence, the ITR induced DNA damage as evidenced by increased gamma-H2AX and Mre11 foci formation. As local DNA damage stimulates HR, ITR-mediated gene editing was investigated using DNA oligonucleotides as repair substrates. The AAV ITR stimulated gene editing >1000-fold in a replication-independent manner and was not biased by the polarity of the repair oligonucleotide. Analysis of additional human DNA sequences demonstrated stimulation of gene editing to varying degrees. In particular, inverted yet not direct, Alu repeats induced gene editing, suggesting a role for DNA structure in the repair event. Collectively, the results demonstrate that inverted DNA repeats stimulate gene editing via double-strand break repair in an episomal context and allude to efficient gene editing of the human chromosome using fragile DNA sequences.

Spontaneous Gamma Activity in Schizophrenia.

PubMed

Hirano, Yoji; Oribe, Naoya; Kanba, Shigenobu; Onitsuka, Toshiaki; Nestor, Paul G; Spencer, Kevin M

2015-08-01

A major goal of translational neuroscience is to identify neural circuit abnormalities in neuropsychiatric disorders that can be studied in animal models to facilitate the development of new treatments. Oscillations in the gamma band (30-100 Hz) of the electroencephalogram have received considerable interest as the basic mechanisms underlying these oscillations are understood, and gamma abnormalities have been found in schizophrenia (SZ). Animal models of SZ based on hypofunction of the N-methyl-d-aspartate receptor (NMDAR) demonstrate increased spontaneous broadband gamma power, but this phenomenon has not been identified clearly in patients with SZ. To examine spontaneous gamma power and its relationship to evoked gamma oscillations in the auditory cortex of patients with SZ. We performed a cross-sectional study including 24 patients with chronic SZ and 24 matched healthy control participants at the Veterans Affairs Boston Healthcare System from January 1, 2009, through December 31, 2012. Electroencephalograms were obtained during auditory steady-state stimulation at multiple frequencies (20, 30, and 40 Hz) and during a resting state in 18 participants in each group. Electroencephalographic activity in the auditory cortex was estimated using dipole source localization. Auditory steady-state response (ASSR) measures included the phase-locking factor and evoked power. Spontaneous gamma power was measured as induced (non-phase-locked) gamma power in the ASSR data and as total gamma power in the resting-state data. The ASSR phase-locking factor was reduced significantly in patients with SZ compared with controls for the 40-Hz stimulation (mean [SD], 0.075 [0.028] vs 0.113 [0.065]; F1,46 = 6.79 [P = .012]) but not the 20- or the 30-Hz stimulation (0.042 [0.038] vs 0.043 [0.034]; F1,46 = 0.006 [P = .938] and 0.084 [0.040] vs 0.098 [0.050]; F1,46 = 1.605 [P = .212], respectively), repeating previous findings. The mean [SD] broadband-induced (30

Repeated Nrf2 stimulation using sulforaphane protects fibroblasts from ionizing radiation.

PubMed

Mathew, Sherin T; Bergström, Petra; Hammarsten, Ola

2014-05-01

Most of the cytotoxicity induced by ionizing radiation is mediated by radical-induced DNA double-strand breaks. Cellular protection from free radicals can be stimulated several fold by sulforaphane-mediated activation of the transcription factor Nrf2 that regulates more than 50 genes involved in the detoxification of reactive substances and radicals. Here, we report that repeated sulforaphane treatment increases radioresistance in primary human skin fibroblasts. Cells were either treated with sulforaphane for four hours once or with four-hour treatments repeatedly for three consecutive days prior to radiation exposure. Fibroblasts exposed to repeated-sulforaphane treatment showed a more pronounced dose-dependent induction of Nrf2-regulated mRNA and reduced amount of radiation-induced free radicals compared with cells treated once with sulforaphane. In addition, radiation- induced DNA double-strand breaks measured by gamma-H2AX foci were attenuated following repeated sulforaphane treatment. As a result, cellular protection from ionizing radiation measured by the 5-ethynyl-2'-deoxyuridine (EdU) assay was increased, specifically in cells exposed to repeated sulforaphane treatment. Sulforaphane treatment was unable to protect Nrf2 knockout mouse embryonic fibroblasts, indicating that the sulforaphane-induced radioprotection was Nrf2-dependent. Moreover, radioprotection by repeated sulforaphane treatment was dose-dependent with an optimal effect at 10 uM, whereas both lower and higher concentrations resulted in lower levels of radioprotection. Our data indicate that the Nrf2 system can be trained to provide further protection from radical damage. Copyright © 2014 Elsevier Inc. All rights reserved.

A NEW RESULT ON THE ORIGIN OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou Ming; Wang Jiancheng, E-mail: mzhou@ynao.ac.cn

2013-06-01

In this paper, we repeatedly use the method of image stacking to study the origin of the extragalactic gamma-ray background (EGB) at GeV bands, and find that the Faint Images of the Radio Sky at Twenty centimeters (FIRST) sources undetected by the Large Area Telescope on the Fermi Gamma-ray Space Telescope can contribute about (56 {+-} 6)% of the EGB. Because FIRST is a flux-limited sample of radio sources with incompleteness at the faint limit, we consider that point sources, including blazars, non-blazar active galactic nuclei, and starburst galaxies, could produce a much larger fraction of the EGB.

Study of gas production from shale reservoirs with multi-stage hydraulic fracturing horizontal well considering multiple transport mechanisms.

PubMed

Guo, Chaohua; Wei, Mingzhen; Liu, Hong

2018-01-01

Development of unconventional shale gas reservoirs (SGRs) has been boosted by the advancements in two key technologies: horizontal drilling and multi-stage hydraulic fracturing. A large number of multi-stage fractured horizontal wells (MsFHW) have been drilled to enhance reservoir production performance. Gas flow in SGRs is a multi-mechanism process, including: desorption, diffusion, and non-Darcy flow. The productivity of the SGRs with MsFHW is influenced by both reservoir conditions and hydraulic fracture properties. However, rare simulation work has been conducted for multi-stage hydraulic fractured SGRs. Most of them use well testing methods, which have too many unrealistic simplifications and assumptions. Also, no systematical work has been conducted considering all reasonable transport mechanisms. And there are very few works on sensitivity studies of uncertain parameters using real parameter ranges. Hence, a detailed and systematic study of reservoir simulation with MsFHW is still necessary. In this paper, a dual porosity model was constructed to estimate the effect of parameters on shale gas production with MsFHW. The simulation model was verified with the available field data from the Barnett Shale. The following mechanisms have been considered in this model: viscous flow, slip flow, Knudsen diffusion, and gas desorption. Langmuir isotherm was used to simulate the gas desorption process. Sensitivity analysis on SGRs' production performance with MsFHW has been conducted. Parameters influencing shale gas production were classified into two categories: reservoir parameters including matrix permeability, matrix porosity; and hydraulic fracture parameters including hydraulic fracture spacing, and fracture half-length. Typical ranges of matrix parameters have been reviewed. Sensitivity analysis have been conducted to analyze the effect of the above factors on the production performance of SGRs. Through comparison, it can be found that hydraulic fracture

The 2001 April Burst Activation of SGR 1900+14: Pulse Properties and Torque

NASA Technical Reports Server (NTRS)

Woods, P. M.; Kouveliotou, C.; Goegues, E.; Finger, M. H.; Feroci, M.; Mereghetti, S.; Swank, J. H.; Hurley, K.; Heise, J.; Smith, D.;

HCP to FCT + precipitate transformations in lamellar gamma-titanium aluminide alloys

NASA Astrophysics Data System (ADS)

Karadge, Mallikarjun Baburao

Fully lamellar gamma-TiAl [alpha2(HCP) + gamma(FCT)] based alloys are potential structural materials for aerospace engine applications. Lamellar structure stabilization and additional strengthening mechanisms are major issues in the ongoing development of titanium aluminides due to the microstructural instability resulting from decomposition of the strengthening alpha 2 phase. This work addresses characterization of multi-component TiAl systems to identify the mechanism of lamellar structure refinement and assess the effects of light element additions (C and Si) on creep deformation behavior. Transmission electron microscopy studies directly confirmed for the first time that, fine lamellar structure is formed by the nucleation and growth of a large number of basal stacking faults on the 1/6<112¯0> dislocations cross slipping repeatedly into and out of basal planes. This lamellar structure can be tailored by modifying jog heights through chemistry and thermal processing. alpha 2 → gamma transformation during heating (investigated by differential scanning calorimetry and X-ray diffraction) is a two step process involving the formation of a novel disordered FCC gamma' TiAl [with a(gamma') = c(gamma)] as an intermediate phase followed by ordering. Addition of carbon and silicon induced Ti2AlC H-type carbide precipitation inside the alpha2 lath and Ti 5(Al,Si)3 zeta-type silicide precipitation at the alpha 2/gamma interface. The H-carbides preserve alpha2/gamma type interfaces, while zeta-silicide precipitates restrict ledge growth and interfacial sliding enabling strong resistance to creep deformation.

The effect of gamma-enhancing binaural beats on the control of feature bindings.

PubMed

Colzato, Lorenza S; Steenbergen, Laura; Sellaro, Roberta

2017-07-01

Binaural beats represent the auditory experience of an oscillating sound that occurs when two sounds with neighboring frequencies are presented to one's left and right ear separately. Binaural beats have been shown to impact information processing via their putative role in increasing neural synchronization. Recent studies of feature-repetition effects demonstrated interactions between perceptual features and action-related features: repeating only some, but not all features of a perception-action episode hinders performance. These partial-repetition (or binding) costs point to the existence of temporary episodic bindings (event files) that are automatically retrieved by repeating at least one of their features. Given that neural synchronization in the gamma band has been associated with visual feature bindings, we investigated whether the impact of binaural beats extends to the top-down control of feature bindings. Healthy adults listened to gamma-frequency (40 Hz) binaural beats or to a constant tone of 340 Hz (control condition) for ten minutes before and during a feature-repetition task. While the size of visuomotor binding costs (indicating the binding of visual and action features) was unaffected by the binaural beats, the size of visual feature binding costs (which refer to the binding between the two visual features) was considerably smaller during gamma-frequency binaural beats exposure than during the control condition. Our results suggest that binaural beats enhance selectivity in updating episodic memory traces and further strengthen the hypothesis that neural activity in the gamma band is critically associated with the control of feature binding.

Anticonvulsant properties of alpha, gamma, and alpha, gamma-substituted gamma-butyrolactones.

PubMed

Klunk, W E; Covey, D F; Ferrendelli, J A

1982-09-01

Derivatives of gamma-butyrolactone (GBL) substituted on the alpha- and/or gamma-positions were synthesized and tested for their effects on behavior in mice, on the electroencephalographs and blood pressure of paralyzed-ventilated guinea pigs, and on electrical activity of incubated hippocampal slices. Several compounds, including alpha-ethyl-alpha-methyl GBL (alpha-EMGBL), alpha, alpha-dimethyl GBL, alpha, gamma-diethyl-alpha, gamma-dimethyl GBL, and gamma-ethyl-gamma-methyl GBL, prevented seizures induced by pentylenetetrazol, beta-ethyl-beta-methyl-gamma-butyrolactone (beta-EMGBL), picrotoxin, or all three compounds in mice and guinea pigs but had no effect on seizures induced by maximal electroshock or bicuculline. Neither gamma-hydroxybutyrate (GHB) nor alpha-isopropylidine GBL had any anticonvulsant activity. The anticonvulsant alpha-substituted compounds had a potent hypotensive effect and antagonized the hypertensive effect of beta-EMGBL, alpha-EMGBL was tested in incubated hippocampal slices and was found to depress basal activity and antagonize excitation induced by beta-EMGBL. These results demonstrate that alpha-alkyl-substituted GBL and, to a lesser extent, gamma-substituted derivatives are anticonvulsant agents and that their effects are strikingly different from those of GHB or beta-alkyl-substituted GBLs, which are epileptogenic. Possibly beta- and alpha-substituted GBLs act at the same site as agonists and antagonists, respectively.

GABAB receptor-mediated, layer-specific synaptic plasticity reorganizes gamma-frequency neocortical response to stimulation

PubMed Central

Ainsworth, Matthew; Lee, Shane; Kaiser, Marcus; Simonotto, Jennifer; Kopell, Nancy J.

2016-01-01

Repeated presentations of sensory stimuli generate transient gamma-frequency (30–80 Hz) responses in neocortex that show plasticity in a task-dependent manner. Complex relationships between individual neuronal outputs and the mean, local field potential (population activity) accompany these changes, but little is known about the underlying mechanisms responsible. Here we show that transient stimulation of input layer 4 sufficient to generate gamma oscillations induced two different, lamina-specific plastic processes that correlated with lamina-specific changes in responses to further, repeated stimulation: Unit rates and recruitment showed overall enhancement in supragranular layers and suppression in infragranular layers associated with excitatory or inhibitory synaptic potentiation onto principal cells, respectively. Both synaptic processes were critically dependent on activation of GABAB receptors and, together, appeared to temporally segregate the cortical representation. These data suggest that adaptation to repetitive sensory input dramatically alters the spatiotemporal properties of the neocortical response in a manner that may both refine and minimize cortical output simultaneously. PMID:27118845

GABAB receptor-mediated, layer-specific synaptic plasticity reorganizes gamma-frequency neocortical response to stimulation.

PubMed

Ainsworth, Matthew; Lee, Shane; Kaiser, Marcus; Simonotto, Jennifer; Kopell, Nancy J; Whittington, Miles A

2016-05-10

Repeated presentations of sensory stimuli generate transient gamma-frequency (30-80 Hz) responses in neocortex that show plasticity in a task-dependent manner. Complex relationships between individual neuronal outputs and the mean, local field potential (population activity) accompany these changes, but little is known about the underlying mechanisms responsible. Here we show that transient stimulation of input layer 4 sufficient to generate gamma oscillations induced two different, lamina-specific plastic processes that correlated with lamina-specific changes in responses to further, repeated stimulation: Unit rates and recruitment showed overall enhancement in supragranular layers and suppression in infragranular layers associated with excitatory or inhibitory synaptic potentiation onto principal cells, respectively. Both synaptic processes were critically dependent on activation of GABAB receptors and, together, appeared to temporally segregate the cortical representation. These data suggest that adaptation to repetitive sensory input dramatically alters the spatiotemporal properties of the neocortical response in a manner that may both refine and minimize cortical output simultaneously.

Toxicokinetics of the Sterioisomer Specific Flame Retardant Hexabromocyclododecane (HBCD) Gamma: Effect of Dose, Time, and Repeated Exposure

EPA Science Inventory

Hexabromocyclododecanes (HBCDs) are high production volume brominated aliphatic cyclic hydrocarbons used as flame-retardants in foams, plastics and textiles. Commercial HBCD is a mixture of three main stereoisomers, alpha (α), beta (β) and gamma (γ). A shift from the high percent...

Identified Cellular Correlates of Neocortical Ripple and High-Gamma Oscillations during Spindles of Natural Sleep.

PubMed

Averkin, Robert G; Szemenyei, Viktor; Bordé, Sándor; Tamás, Gábor

2016-11-23

Ultra-high-frequency network events in the hippocampus are instrumental in a dialogue with the neocortex during memory formation, but the existence of transient ∼200 Hz network events in the neocortex is not clear. Our recordings from neocortical layer II/III of freely behaving rats revealed field potential events at ripple and high-gamma frequencies repeatedly occurring at troughs of spindle oscillations during sleep. Juxtacellular recordings identified subpopulations of fast-spiking, parvalbumin-containing basket cells with epochs of firing at ripple (∼200 Hz) and high-gamma (∼120 Hz) frequencies detected during spindles and centered with millisecond precision at the trough of spindle waves in phase with field potential events but phase shifted relative to pyramidal cell firing. The results suggest that basket cell subpopulations are involved in spindle-nested, high-frequency network events that hypothetically provide repeatedly occurring neocortical temporal reference states potentially involved in mnemonic processes. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Limits on the High-Energy Gamma and Neutrino Fluxes from the SGR 1806-20 Giant Flare of 27 December 2004 with the AMANDA-II Detector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Achterberg, A.; Duvoort, M. R.; Heise, J.

2006-12-01

On 27 December 2004, a giant {gamma} flare from the Soft Gamma-Ray Repeater 1806-20 saturated many satellite gamma-ray detectors, being the brightest transient event ever observed in the Galaxy. AMANDA-II was used to search for down-going muons indicative of high-energy gammas and/or neutrinos from this object. The data revealed no significant signal, so upper limits (at 90% C.L.) on the normalization constant were set: 0.05(0.5) TeV{sup -1} m{sup -2} s{sup -1} for {gamma}=-1.47 (-2) in the gamma flux and 0.4(6.1) TeV{sup -1} m{sup -2} s{sup -1} for {gamma}=-1.47 (-2) in the high-energy neutrino flux.

X-ray studies of highly magnetized neutron stars and their environs

NASA Astrophysics Data System (ADS)

Kumar, Harsha Sanjeev

Supernova explosions are among the most energetic events known in the universe, leaving supernova remnants (SNRs) as their relics. The cores of massive stars collapse to form neutron stars, among the most compact and strongest magnets in the cosmos. The thesis studies a sample of such magnetic "beauties" in X-rays, the magnetars and high-magnetic field pulsars (HBPs), with the motivation to understand their evolutionary links. We also address the connection between these sources by investigating their environs through their securely associated SNRs. Magnetars have ultra-high magnetic fields B ~ 1014 -- 1015 Gauss (G) and include the soft-gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs). The HBPs have magnetic fields B ~ 1013 -- 10 14 G, intermediate between the classical rotation-powered pulsars (B ~ 1012 G) and magnetars. We focussed on two HBPs: J1119-6127 and J1846-0258, with similar spin-properties and associated with the SNRs G292.2-0.5 and Kes 75, respectively. In our studies, magnetar-like behavior was discovered from the Crab-like pulsar J1846-0258, clearly establishing a connection between the HBPs and magnetars for the first time, while no such behavior has been observed from PSR J1119-6127 so far. J1119-6127's overall X-ray properties together with its compact pulsar wind nebula resemble more the classical rotation-powered pulsars. We studied two magnetars, one from each sub-class: SGR 0501+4516 and AXP 1E 1841-045. The spectral and statistical analysis of the bursts and the persistent X-ray emission properties observed from them were found consistent with the magnetar model predictions as well as those seen in other SGRs. Finally, we probed the environment of these stellar magnets by performing a detailed X-ray imaging and spatially resolved spectroscopic study of two SNRs: G292.2-0.5 and Kes 73 associated with J1119-6127 and 1E 1841-045, respectively. We found that both SNRs point to very massive progenitors ( ≳ 25 solar masses), further

Impaired intracortical transmission in G2019S leucine rich-repeat kinase Parkinson patients.

PubMed

Ponzo, Viviana; Di Lorenzo, Francesco; Brusa, Livia; Schirinzi, Tommaso; Battistini, Stefania; Ricci, Claudia; Sambucci, Manolo; Caltagirone, Carlo; Koch, Giacomo

2017-05-01

A mutation in leucine-rich repeat kinase 2 is the most common cause of hereditary Parkinson's disease (PD), yet the neural mechanisms and the circuitry potentially involved are poorly understood. We used different transcranial magnetic stimulation protocols to explore in the primary motor cortex the activity of intracortical circuits and cortical plasticity (long-term potentiation) in patients with the G2019S leucine-rich repeat kinase 2 gene mutation when compared with idiopathic PD patients and age-matched healthy subjects. Paired pulse transcranial magnetic stimulation was used to investigate short intracortical inhibition and facilitation and short afferent inhibition. Intermittent theta burst stimulation, a form of repetitive transcranial magnetic stimulation, was used to test long-term potentiation-like cortical plasticity. Leucine-rich repeat kinase 2 and idiopathic PD were tested both in ON and in OFF l-dopa therapy. When compared with idiopathic PD and healthy subjects, leucine-rich repeat kinase 2 PD patients showed a remarkable reduction of short intracortical inhibition in both ON and in OFF l-dopa therapy. This reduction was paralleled by an increase of intracortical facilitation in OFF l-dopa therapy. Leucine-rich repeat kinase 2 PD showed abnormal long-term potentiation-like cortical plasticity in ON l-dopa therapy. The motor cortex in leucine-rich repeat kinase 2 mutated PD patients is strongly disinhibited and hyperexcitable. These abnormalities could be a result of an impairment of inhibitory (gamma-Aminobutyric acid) transmission eventually related to altered neurotransmitter release. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.

Gamma oscillations distinguish mere exposure from other likability effects.

PubMed

Kongthong, Nutchakan; Minami, Tetsuto; Nakauchi, Shigeki

2014-02-01

Repeated exposure to neutral stimuli enhances liking for those, which is called mere exposure effect (MEE) (Zajonc, 1968). Its behavioral effects have been extensively investigated. However, the mechanism by which it is generated remains unclear. To elucidate the neural mechanism of the MEE, we recorded electroencephalograms while subjects indicated their preferences for face stimuli with and without MEE induction. According to behavioral data, participants were divided into two groups, one with, and one without MEE tendency. In participants with an MEE tendency, gamma activity (40-60 [Hz]) in the parieto-occipital area was significantly weaker for exposed faces than unexposed ones, indicating a repetition-suppression effect. Gamma activity from sites exhibiting peak repetition-suppression effects was significantly weaker in theoretically genuine MEE trials than non-MEE trials, indicating that emotion processing might influence the MEE. These results suggest that existing theories regarding mechanisms underlying the MEE, namely, fluency misattribution and apprehensiveness reduction might not be mutually exclusive. Moreover, gamma activity might be a potential indicator to distinguish the MEE from other likability effects, at least in the case of human face stimuli. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Repeat Look at Repeating Patterns

ERIC Educational Resources Information Center

Markworth, Kimberly A.

2016-01-01

A "repeating pattern" is a cyclical repetition of an identifiable core. Children in the primary grades usually begin pattern work with fairly simple patterns, such as AB, ABC, or ABB patterns. The unique letters represent unique elements, whereas the sequence of letters represents the core that is repeated. Based on color, shape,…

Validation of a track repeating algorithm for intensity modulated proton therapy: clinical cases study

NASA Astrophysics Data System (ADS)

Yepes, Pablo P.; Eley, John G.; Liu, Amy; Mirkovic, Dragan; Randeniya, Sharmalee; Titt, Uwe; Mohan, Radhe

2016-04-01

Monte Carlo (MC) methods are acknowledged as the most accurate technique to calculate dose distributions. However, due its lengthy calculation times, they are difficult to utilize in the clinic or for large retrospective studies. Track-repeating algorithms, based on MC-generated particle track data in water, accelerate dose calculations substantially, while essentially preserving the accuracy of MC. In this study, we present the validation of an efficient dose calculation algorithm for intensity modulated proton therapy, the fast dose calculator (FDC), based on a track-repeating technique. We validated the FDC algorithm for 23 patients, which included 7 brain, 6 head-and-neck, 5 lung, 1 spine, 1 pelvis and 3 prostate cases. For validation, we compared FDC-generated dose distributions with those from a full-fledged Monte Carlo based on GEANT4 (G4). We compared dose-volume-histograms, 3D-gamma-indices and analyzed a series of dosimetric indices. More than 99% of the voxels in the voxelized phantoms describing the patients have a gamma-index smaller than unity for the 2%/2 mm criteria. In addition the difference relative to the prescribed dose between the dosimetric indices calculated with FDC and G4 is less than 1%. FDC reduces the calculation times from 5 ms per proton to around 5 μs.

Field gamma-ray spectrometer GS256: measurements stability

NASA Astrophysics Data System (ADS)

Mojzeš, Andrej

2009-01-01

The stability of in situ readings of the portable gamma-ray spectrometer GS256 during the field season of 2006 was studied. The instrument is an impulse detector of gamma rays based on NaI(Tl) 3" × 3" scintillation unit and 256-channel spectral analyzer which allows simultaneous assessment of up to 8 radioisotopes in rocks. It is commonly used in surface geophysical survey for the measurement of natural 40K, 238U and 232Th but also artificial 137Cs quantities. The statistical evaluation is given of both repeated measurements - in the laboratory and at several field control points in different survey areas. The variability of values shows both the instrument stability and also the relative influence of some meteorological factors, mainly rainfalls. The analysis shows an acceptable level of instrument measurements stability, the necessity to avoid measurement under unfavourable meteorological conditions and to keep detailed field book information about time, position and work conditions.

Intrasteric control of AMPK via the gamma1 subunit AMP allosteric regulatory site.

PubMed

Adams, Julian; Chen, Zhi-Ping; Van Denderen, Bryce J W; Morton, Craig J; Parker, Michael W; Witters, Lee A; Stapleton, David; Kemp, Bruce E

2004-01-01

AMP-activated protein kinase (AMPK) is a alphabetagamma heterotrimer that is activated in response to both hormones and intracellular metabolic stress signals. AMPK is regulated by phosphorylation on the alpha subunit and by AMP allosteric control previously thought to be mediated by both alpha and gamma subunits. Here we present evidence that adjacent gamma subunit pairs of CBS repeat sequences (after Cystathionine Beta Synthase) form an AMP binding site related to, but distinct from the classical AMP binding site in phosphorylase, that can also bind ATP. The AMP binding site of the gamma(1) CBS1/CBS2 pair, modeled on the structures of the CBS sequences present in the inosine monophosphate dehydrogenase crystal structure, contains three arginine residues 70, 152, and 171 and His151. The yeast gamma homolog, snf4 contains a His151Gly substitution, and when this is introduced into gamma(1), AMP allosteric control is substantially lost and explains why the yeast snf1p/snf4p complex is insensitive to AMP. Arg70 in gamma(1) corresponds to the site of mutation in human gamma(2) and pig gamma(3) genes previously identified to cause an unusual cardiac phenotype and glycogen storage disease, respectively. Mutation of any of AMP binding site Arg residues to Gln substantially abolishes AMP allosteric control in expressed AMPK holoenzyme. The Arg/Gln mutations also suppress the previously described inhibitory properties of ATP and render the enzyme constitutively active. We propose that ATP acts as an intrasteric inhibitor by bridging the alpha and gamma subunits and that AMP functions to derepress AMPK activity.

gamma-Hexachlorocyclohexane (gamma-HCH)

Integrated Risk Information System (IRIS)

gamma - Hexachlorocyclohexane ( gamma - HCH ) ; CASRN 58 - 89 - 9 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Asse

Reward modulation of contextual cueing: Repeated context overshadows repeated target location.

PubMed

Sharifian, Fariba; Contier, Oliver; Preuschhof, Claudia; Pollmann, Stefan

2017-10-01

Contextual cueing can be enhanced by reward. However, there is a debate if reward is associated with the repeated target-distractor configurations or with the repeated target locations that occur in both repeated and new displays. Based on neuroimaging evidence, we hypothesized that reward becomes associated with the target location only in new displays, but not in repeated displays, where the repeated target location is overshadowed by the more salient repeated target-distractor configuration. To test this hypothesis, we varied the reward value associated with the same target location in repeated and new displays. The results confirmed the overshadowing hypothesis in that search facilitation in repeated target-distractor configurations was modulated by the variable value associated with the target location. This effect was observed mainly in early learning.

Unidentified Gamma-Ray Sources: Hunting Gamma-Ray Blazars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Massaro, F.; D'Abrusco, R.; Tosti, G.

2012-04-02

One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of the unidentified {gamma}-ray sources (UGSs). Despite the large improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one third of the Fermi-detected objects are still not associated to low energy counterparts. Recently, using the Wide-field Infrared Survey Explorer (WISE) survey, we discovered that blazars, the rarest class of Active Galactic Nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Basedmore » on this result, we designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated to the UGS sample of the second Fermi {gamma}-ray catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated to {gamma}-ray sources in the 2FGL catalog.« less

UNIDENTIFIED {gamma}-RAY SOURCES: HUNTING {gamma}-RAY BLAZARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Massaro, F.; Ajello, M.; D'Abrusco, R.

2012-06-10

One of the main scientific objectives of the ongoing Fermi mission is unveiling the nature of unidentified {gamma}-ray sources (UGSs). Despite the major improvements of Fermi in the localization of {gamma}-ray sources with respect to the past {gamma}-ray missions, about one-third of the Fermi-detected objects are still not associated with low-energy counterparts. Recently, using the Wide-field Infrared Survey Explorer survey, we discovered that blazars, the rarest class of active galactic nuclei and the largest population of {gamma}-ray sources, can be recognized and separated from other extragalactic sources on the basis of their infrared (IR) colors. Based on this result, wemore » designed an association method for the {gamma}-ray sources to recognize if there is a blazar candidate within the positional uncertainty region of a generic {gamma}-ray source. With this new IR diagnostic tool, we searched for {gamma}-ray blazar candidates associated with the UGS sample of the second Fermi {gamma}-ray LAT catalog (2FGL). We found that our method associates at least one {gamma}-ray blazar candidate as a counterpart to each of 156 out of 313 UGSs analyzed. These new low-energy candidates have the same IR properties as the blazars associated with {gamma}-ray sources in the 2FGL catalog.« less

Search for gamma-ray emission from Galactic novae with the Fermi -LAT

NASA Astrophysics Data System (ADS)

Franckowiak, A.; Jean, P.; Wood, M.; Cheung, C. C.; Buson, S.

2018-02-01

Context. A number of novae have been found to emit high-energy gamma rays (>100 MeV). However, the origin of this emission is not yet understood. We report on the search for gamma-ray emission from 75 optically detected Galactic novae in the first 7.4 years of operation of the Fermi Large Area Telescope using the Pass 8 data set. Aims: We compile an optical nova catalog including light curves from various resources and estimate the optical peak time and optical peak magnitude in order to search for gamma-ray emission to determine whether all novae are gamma-ray emitters. Methods: We repeated the analysis of the six novae previously identified as gamma-ray sources and developed a unified analysis strategy that we then applied to all novae in our catalog. We searched for emission in a 15 day time window in two-day steps ranging from 20 days before to 20 days after the optical peak time. We performed a population study with Monte Carlo simulations to set constraints on the properties of the gamma-ray emission of novae. Results: Two new novae candidates have been found at 2σ global significance. Although these two novae candidates were not detected at a significant level individually, taking them together with the other non-detected novae, we found a sub-threshold nova population with a cumulative 3σ significance. We report the measured gamma-ray flux for detected sources and flux upper limits for novae without significant detection. Our results can be reproduced by several gamma-ray emissivity models (e.g., a power-law distribution with a slope of 2), while a constant emissivity model (i.e., assuming novae are standard candles) can be rejected.

Search for gamma-ray emission from Galactic novae with the Fermi-LAT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Franckowiak, A.; Jean, P.; Wood, M.

Context. A number of novae have been found to emit high-energy gamma rays (>100 MeV). However, the origin of this emission is not yet understood. We report on the search for gamma-ray emission from 75 optically detected Galactic novae in the first 7.4 years of operation of the Fermi Large Area Telescope using the Pass 8 data set. Aims. We compile an optical nova catalog including light curves from various resources and estimate the optical peak time and optical peak magnitude in order to search for gamma-ray emission to determine whether all novae are gamma-ray emitters. Methods. We repeated themore » analysis of the six novae previously identified as gamma-ray sources and developed a unified analysis strategy that we then applied to all novae in our catalog. We searched for emission in a 15 day time window in two-day steps ranging from 20 days before to 20 days after the optical peak time. We performed a population study with Monte Carlo simulations to set constraints on the properties of the gamma-ray emission of novae. Results. Two new novae candidates have been found at ~ 2σ global significance. Although these two novae candidates were not detected at a significant level individually, taking them together with the other non-detected novae, we found a sub-threshold nova population with a cumulative 3σ significance. We report the measured gamma-ray flux for detected sources and flux upper limits for novae without significant detection. Lastly, our results can be reproduced by several gamma-ray emissivity models (e.g., a power-law distribution with a slope of 2), while a constant emissivity model (i.e., assuming novae are standard candles) can be rejected.« less

Search for gamma-ray emission from Galactic novae with the Fermi-LAT

DOE PAGES

Franckowiak, A.; Jean, P.; Wood, M.; ...

2018-02-05

Context. A number of novae have been found to emit high-energy gamma rays (>100 MeV). However, the origin of this emission is not yet understood. We report on the search for gamma-ray emission from 75 optically detected Galactic novae in the first 7.4 years of operation of the Fermi Large Area Telescope using the Pass 8 data set. Aims. We compile an optical nova catalog including light curves from various resources and estimate the optical peak time and optical peak magnitude in order to search for gamma-ray emission to determine whether all novae are gamma-ray emitters. Methods. We repeated themore » analysis of the six novae previously identified as gamma-ray sources and developed a unified analysis strategy that we then applied to all novae in our catalog. We searched for emission in a 15 day time window in two-day steps ranging from 20 days before to 20 days after the optical peak time. We performed a population study with Monte Carlo simulations to set constraints on the properties of the gamma-ray emission of novae. Results. Two new novae candidates have been found at ~ 2σ global significance. Although these two novae candidates were not detected at a significant level individually, taking them together with the other non-detected novae, we found a sub-threshold nova population with a cumulative 3σ significance. We report the measured gamma-ray flux for detected sources and flux upper limits for novae without significant detection. Lastly, our results can be reproduced by several gamma-ray emissivity models (e.g., a power-law distribution with a slope of 2), while a constant emissivity model (i.e., assuming novae are standard candles) can be rejected.« less

Growth kinetics of gamma-prime precipitates in a directionally solidified eutectic, gamma/gamma-prime-delta

NASA Technical Reports Server (NTRS)

Tewari, S. N.

1976-01-01

A directionally solidified eutectic alloy (DSEA), of those viewed as potential candidates for the next generation of aircraft gas turbine blade materials, is studied for the gamma-prime growth kinetics, in the system Ni-Nb-Cr-Al, specifically: Ni-20 w/o Nb-6 w/o Cr-2.5 w/o Al gamma/gamma-prime-delta DSEA. Heat treatment, polishing and etching, and preparation for electron micrography are described, and the size distribution of gamma-prime phase following various anneals is plotted, along with gamma-prime growth kinetics in this specific DSEA, and the cube of gamma-prime particle size vs anneal time. Activation energies and coarsening kinetics are studied.

The neutron-gamma Feynman variance to mean approach: Gamma detection and total neutron-gamma detection (theory and practice)

NASA Astrophysics Data System (ADS)

Chernikova, Dina; Axell, Kåre; Avdic, Senada; Pázsit, Imre; Nordlund, Anders; Allard, Stefan

2015-05-01

Two versions of the neutron-gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron-gamma detection, respectively, are derived and compared in this paper. The new formulas have particular importance for detectors of either gamma photons or detectors sensitive to both neutron and gamma radiation. If applied to a plastic or liquid scintillation detector, the total neutron-gamma detection Feynman-Y expression corresponds to a situation where no discrimination is made between neutrons and gamma particles. The gamma variance to mean formulas are useful when a detector of only gamma radiation is used or when working with a combined neutron-gamma detector at high count rates. The theoretical derivation is based on the Chapman-Kolmogorov equation with the inclusion of general reactions and corresponding intensities for neutrons and gammas, but with the inclusion of prompt reactions only. A one energy group approximation is considered. The comparison of the two different theories is made by using reaction intensities obtained in MCNPX simulations with a simplified geometry for two scintillation detectors and a 252Cf-source. In addition, the variance to mean ratios, neutron, gamma and total neutron-gamma are evaluated experimentally for a weak 252Cf neutron-gamma source, a 137Cs random gamma source and a 22Na correlated gamma source. Due to the focus being on the possibility of using neutron-gamma variance to mean theories for both reactor and safeguards applications, we limited the present study to the general analytical expressions for Feynman-alpha formulas.

Study of gas production from shale reservoirs with multi-stage hydraulic fracturing horizontal well considering multiple transport mechanisms

PubMed Central

Wei, Mingzhen; Liu, Hong

2018-01-01

Development of unconventional shale gas reservoirs (SGRs) has been boosted by the advancements in two key technologies: horizontal drilling and multi-stage hydraulic fracturing. A large number of multi-stage fractured horizontal wells (MsFHW) have been drilled to enhance reservoir production performance. Gas flow in SGRs is a multi-mechanism process, including: desorption, diffusion, and non-Darcy flow. The productivity of the SGRs with MsFHW is influenced by both reservoir conditions and hydraulic fracture properties. However, rare simulation work has been conducted for multi-stage hydraulic fractured SGRs. Most of them use well testing methods, which have too many unrealistic simplifications and assumptions. Also, no systematical work has been conducted considering all reasonable transport mechanisms. And there are very few works on sensitivity studies of uncertain parameters using real parameter ranges. Hence, a detailed and systematic study of reservoir simulation with MsFHW is still necessary. In this paper, a dual porosity model was constructed to estimate the effect of parameters on shale gas production with MsFHW. The simulation model was verified with the available field data from the Barnett Shale. The following mechanisms have been considered in this model: viscous flow, slip flow, Knudsen diffusion, and gas desorption. Langmuir isotherm was used to simulate the gas desorption process. Sensitivity analysis on SGRs’ production performance with MsFHW has been conducted. Parameters influencing shale gas production were classified into two categories: reservoir parameters including matrix permeability, matrix porosity; and hydraulic fracture parameters including hydraulic fracture spacing, and fracture half-length. Typical ranges of matrix parameters have been reviewed. Sensitivity analysis have been conducted to analyze the effect of the above factors on the production performance of SGRs. Through comparison, it can be found that hydraulic fracture

[The "light" water effect on lenticular opacity development in mice after repeated low dose gamma-irradiation].

PubMed

Abrosimova, A N; Rakov, D V; Siniak, Iu E

2009-01-01

Action of "light" water with reduced quantities of heavy stable hydrogen and 18O ions on incidence and progress of lenticular opacity was studied in gamma-irradiated mice (60Co, 1.0 Gy). The animals were subjected to electroophthalmoscopy regularly till end of life time. The observation showed that chronic intake of "light" water safeguarded the irradiated mice against lenticular opacity. The experimental data indicate that "light" water strengthens the general body resistance as well as slows down aging of mammals.

Very high-energy gamma rays from gamma-ray bursts.

PubMed

Chadwick, Paula M

2007-05-15

Very high-energy (VHE) gamma-ray astronomy has undergone a transformation in the last few years, with telescopes of unprecedented sensitivity having greatly expanded the source catalogue. Such progress makes the detection of a gamma-ray burst at the highest energies much more likely than previously. This paper describes the facilities currently operating and their chances for detecting gamma-ray bursts, and reviews predictions for VHE gamma-ray emission from gamma-ray bursts. Results to date are summarized.

Remote sensing studies of immature soils on the Moon (Reiner-gamma formation)

NASA Technical Reports Server (NTRS)

Shevchenko, V. V.; Pinet, P.; Chevrel, S.

1993-01-01

On the base of laboratory results and telescopic data it is shown that the spectropolarization ratio P(sub max(sup B))/P(sub max(sup R)) for blue and red spectral regions is a remote sensing parameter of lunar soil maturity. It correlates with value of maturity index derived from morphological or ferromagnetic methods of exposure age determination. This parameter is equal to 0.315 for Reiner-gamma formation. So Reiner-gamma area is covered by immature soil. An extensive spectral mapping of the Reiner-gamma formation with high spatial resolution (0.2 km/pixel) was produced. This result was obtained at the 2-meter aperture telescope of Pic-du-Midi (France). The data sets consist in repeated runs comprising 10 selected narrow-band images (from 0.4 to 1.05 micron). The analysis of these data suggests that such a type of immature material includes not more than 28% of agglutinattes. We find the model grain size of fine fraction to be 40 micrometers grain size, of more immature soil 400-500 micrometers, and of the formation soil 120-150 micrometers. The exposure age of the Reiner-gamma immature soil is equal about 10 x 10(exp 6) years.

Successful use of Gamma Knife surgery in a distal lenticulostriate artery aneurysm intervention.

PubMed

Lan, ZhiGang; Li, Jin; You, Chao; Chen, Jing

2012-02-01

We report a case of a 21-year-old woman who underwent radiosurgical treatment of a distal lenticulostriate artery (LSA) aneurysm. Twenty-two months after treatment, repeat angiography demonstrated patency of the parent vessel and complete obliteration of the aneurysm. Our case implies that Gamma Knife surgery (GKS) might serve as an alternative microinvasive technique in the treatment of LSA aneurysms, making this procedure a potential addition to present methods.

Gamma knife surgery for brainstem arteriovenous malformations.

PubMed

Yen, Chun-Po; Steiner, Ladislau

2011-01-01

To evaluate the long-term imaging and clinical outcomes of patients with brainstem arteriovenous malformations (AVMs) treated with Gamma Knife surgery (GKS). The study included 85 patients with brainstem AVMs undergoing GKS during the period 1989-2007. The locations of the nidi were the midbrain in 42 patients, pons in 31 patients, and medulla oblongata in 12 patients. The volume of the nidi ranged from 0.1-8.9 mL (median 1.4 mL, mean 1.9 mL), and the prescription dose ranged from 5-32 Gy (median 20 Gy, mean 19.9 Gy). After the initial Gamma procedure, 18 patients had repeat GKS for AVM residuals that were still patent. Two patients had a third GKS 7 years and 16 years after a failed repeat GKS. Clinical follow-up ranged from 24-252 months with a mean of 100 months (median 102 months) after the initial GKS. GKS yielded a total angiographic obliteration in 50 (58.8%) patients and subtotal obliteration in 4 (4.7%) patients. In 22 (25.9%) patients, the AVMs remained patent. In 9 patients (10.6%), no flow voids were observed on magnetic resonance imaging (MRI), but angiographic confirmation was unavailable. A small nidus volume and a high prescription dose were significantly associated with increased AVM obliteration rate. Radiation-induced changes developed in 34 patients (40%); 24 were asymptomatic, 1 patient had only headache, and 9 patients developed neurologic deficits. One patient developed a large cyst 6 years after GKS. Given the poor surgical outcome of brainstem AVMs, the results of 59% nidus obliteration and 6% permanent neurologic deficits make GKS a reasonable management of these difficult lesions. Copyright © 2011 Elsevier Inc. All rights reserved.

Swift Gamma-Ray Burst Explorer: Mission Design for Rapid, Accurate Location of Gamma-ray Bursts

NASA Technical Reports Server (NTRS)

Bundas, David J.

2004-01-01

The Swift Gamma-ray Burst Explorer is a NASA Mid-sized Explorer (MIDEX) with the primary mission of determining the origins of Gamma-Ray Bursts (GRBs). It will be the first mission to autonomously respond to newly-discovered GRBs and provide immediate follow-up narrow field instruments capable of multi-wavelength (UV, Optical, X-ray) observations. The characteristics of GRBs that are the key mission design drivers, are their non-repeating and brief duration bursts of multi-wavelength photons. In addition, rapid notification of the location and characteristics of the GRBs to ground-and-space- based observatories drive the end-to-end data analysis and distribution requirements. The Swift mission is managed by the GSFC, and includes an international team of contributors that each bring their unique perspective that have proven invaluable to the mission. The spacecraft bus, provided by Spectrum Astro, Inc. was procured through a Rapid Spacecraft Development Office (RSDO) contract by the GSFC. There are three instruments: the Burst Alert Telescope (BAT) provided by the GSFC; the X-Ray Telescope (XRT) provided by a team led by the Pennsylvania State University (PSU); and the Ultra-Violet Optical Telescope (UVOT), again managed by PSU. The Mission Operations Center (MOC) was developed by and is located at PSU. Science archiving and data analysis centers are located at the GSFC, in the UK and in Italy.

The Effects of Theta and Gamma tACS on Working Memory and Electrophysiology

PubMed Central

Pahor, Anja; Jaušovec, Norbert

2018-01-01

A single blind sham-controlled study was conducted to explore the effects of theta and gamma transcranial alternating current stimulation (tACS) on offline performance on working memory tasks. In order to systematically investigate how specific parameters of tACS affect working memory, we manipulated the frequency of stimulation (theta frequency vs. gamma frequency), the type of task (n-back vs. change detection task) and the content of the tasks (verbal vs. figural stimuli). A repeated measures design was used that consisted of three sessions: theta tACS, gamma tACS and sham tACS. In total, four experiments were conducted which differed only with respect to placement of tACS electrodes (bilateral frontal, bilateral parietal, left fronto-parietal and right-fronto parietal). Healthy female students (N = 72) were randomly assigned to one of these groups, hence we were able to assess the efficacy of theta and gamma tACS applied over different brain areas, contrasted against sham stimulation. The pre-post/sham resting electroencephalogram (EEG) analysis showed that theta tACS significantly affected theta amplitude, whereas gamma tACS had no significant effect on EEG amplitude in any of the frequency bands of interest. Gamma tACS did not significantly affect working memory performance compared to sham, and theta tACS led to inconsistent changes in performance on the n-back tasks. Active theta tACS significantly affected P3 amplitude and latency during performance on the n-back tasks in the bilateral parietal and right-fronto parietal protocols. PMID:29375347

Gamma-sky.net: Portal to the gamma-ray sky

NASA Astrophysics Data System (ADS)

Voruganti, Arjun; Deil, Christoph; Donath, Axel; King, Johannes

2017-01-01

http://gamma-sky.net is a novel interactive website designed for exploring the gamma-ray sky. The Map View portion of the site is powered by the Aladin Lite sky atlas, providing a scalable survey image tesselated onto a three-dimensional sphere. The map allows for interactive pan and zoom navigation as well as search queries by sky position or object name. The default image overlay shows the gamma-ray sky observed by the Fermi-LAT gamma-ray space telescope. Other survey images (e.g. Planck microwave images in low/high frequency bands, ROSAT X-ray image) are available for comparison with the gamma-ray data. Sources from major gamma-ray source catalogs of interest (Fermi-LAT 2FHL, 3FGL and a TeV source catalog) are overlaid over the sky map as markers. Clicking on a given source shows basic information in a popup, and detailed pages for every source are available via the Catalog View component of the website, including information such as source classification, spectrum and light-curve plots, and literature references. We intend for gamma-sky.net to be applicable for both professional astronomers as well as the general public. The website started in early June 2016 and is being developed as an open-source, open data project on GitHub (https://github.com/gammapy/gamma-sky). We plan to extend it to display more gamma-ray and multi-wavelength data. Feedback and contributions are very welcome!

To Repeat or Not to Repeat a Course

ERIC Educational Resources Information Center

Armstrong, Michael J.; Biktimirov, Ernest N.

2013-01-01

The difficult transition from high school to university means that many students need to repeat (retake) 1 or more of their university courses. The authors examine the performance of students repeating first-year core courses in an undergraduate business program. They used data from university records for 116 students who took a total of 232…

Resonance production in. gamma gamma. collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renard, F.M.

1983-04-01

The processes ..gamma gamma.. ..-->.. hadrons can be depicted as follows. One photon creates a q anti q pair which starts to evolve; the other photon can either (A) make its own q anti q pair and the (q anti q q anti q) system continue to evolve or (B) interact with the quarks of the first pair and lead to a modified (q anti q) system in interaction with C = +1 quantum numbers. A review of the recent theoretical activity concerning resonance production and related problems is given under the following headings: hadronic C = +1 spectroscopy (qmore » anti q, qq anti q anti q, q anti q g, gg, ggg bound states and mixing effects); exclusive ..gamma gamma.. processes (generalities, unitarized Born method, VDM and QCD); total cross section (soft and hard contributions); q/sup 2/ dependence of soft processes (soft/hard separation, 1/sup +- +/ resonances); and polarization effects. (WHK)« less

Theta-Gamma Coding Meets Communication-through-Coherence: Neuronal Oscillatory Multiplexing Theories Reconciled.

PubMed

McLelland, Douglas; VanRullen, Rufin

2016-10-01

Several theories have been advanced to explain how cross-frequency coupling, the interaction of neuronal oscillations at different frequencies, could enable item multiplexing in neural systems. The communication-through-coherence theory proposes that phase-matching of gamma oscillations between areas enables selective processing of a single item at a time, and a later refinement of the theory includes a theta-frequency oscillation that provides a periodic reset of the system. Alternatively, the theta-gamma neural code theory proposes that a sequence of items is processed, one per gamma cycle, and that this sequence is repeated or updated across theta cycles. In short, both theories serve to segregate representations via the temporal domain, but differ on the number of objects concurrently represented. In this study, we set out to test whether each of these theories is actually physiologically plausible, by implementing them within a single model inspired by physiological data. Using a spiking network model of visual processing, we show that each of these theories is physiologically plausible and computationally useful. Both theories were implemented within a single network architecture, with two areas connected in a feedforward manner, and gamma oscillations generated by feedback inhibition within areas. Simply increasing the amplitude of global inhibition in the lower area, equivalent to an increase in the spatial scope of the gamma oscillation, yielded a switch from one mode to the other. Thus, these different processing modes may co-exist in the brain, enabling dynamic switching between exploratory and selective modes of attention.

Repeating and non-repeating fast radio bursts from binary neutron star mergers

NASA Astrophysics Data System (ADS)

Yamasaki, Shotaro; Totani, Tomonori; Kiuchi, Kenta

2018-04-01

Most fast radio bursts (FRB) do not show evidence of repetition, and such non-repeating FRBs may be produced at the time of a merger of binary neutron stars (BNS), provided that the BNS merger rate is close to the high end of the currently possible range. However, the merger environment is polluted by dynamical ejecta, which may prohibit the radio signal from propagating. We examine this by using a general-relativistic simulation of a BNS merger, and show that the ejecta appears about 1 ms after the rotation speed of the merged star becomes the maximum. Therefore there is a time window in which an FRB signal can reach outside, and the short duration of non-repeating FRBs can be explained by screening after ejecta formation. A fraction of BNS mergers may leave a rapidly rotating and stable neutron star, and such objects may be the origin of repeating FRBs like FRB 121102. We show that a merger remnant would appear as a repeating FRB on a time scale of ˜1-10 yr, and expected properties are consistent with the observations of FRB 121102. We construct an FRB rate evolution model that includes these two populations of repeating and non-repeating FRBs from BNS mergers, and show that the detection rate of repeating FRBs relative to non-repeating ones rapidly increases with improving search sensitivity. This may explain why only the repeating FRB 121102 was discovered by the most sensitive FRB search with Arecibo. Several predictions are made, including the appearance of a repeating FRB 1-10 yr after a BNS merger that is localized by gravitational waves and subsequent electromagnetic radiation.

Repeating and non-repeating fast radio bursts from binary neutron star mergers

NASA Astrophysics Data System (ADS)

Yamasaki, Shotaro; Totani, Tomonori; Kiuchi, Kenta

2018-06-01

Most fast radio bursts (FRB) do not show evidence of repetition, and such non-repeating FRBs may be produced at the time of a merger of binary neutron stars (BNS), provided that the BNS merger rate is close to the high end of the currently possible range. However, the merger environment is polluted by dynamical ejecta, which may prohibit the radio signal from propagating. We examine this by using a general-relativistic simulation of a BNS merger, and show that the ejecta appears about 1 ms after the rotation speed of the merged star becomes the maximum. Therefore there is a time window in which an FRB signal can reach outside, and the short duration of non-repeating FRBs can be explained by screening after ejecta formation. A fraction of BNS mergers may leave a rapidly rotating and stable neutron star, and such objects may be the origin of repeating FRBs like FRB 121102. We show that a merger remnant would appear as a repeating FRB on a time scale of ˜1-10 yr, and expected properties are consistent with the observations of FRB 121102. We construct an FRB rate evolution model that includes these two populations of repeating and non-repeating FRBs from BNS mergers, and show that the detection rate of repeating FRBs relative to non-repeating ones rapidly increases with improving search sensitivity. This may explain why only the repeating FRB 121102 was discovered by the most sensitive FRB search with Arecibo. Several predictions are made, including the appearance of a repeating FRB 1-10 yr after a BNS merger that is localized by gravitational waves and subsequent electromagnetic radiation.

Amphetamine regulation of acetylcholine and gamma-aminobutyric acid in nucleus accumbens.

PubMed

Lindefors, N; Hurd, Y L; O'Connor, W T; Brené, S; Persson, H; Ungerstedt, U

1992-01-01

In situ hybridization histochemistry and in vivo microdialysis were combined to study the effect of amphetamine on the expression of choline acetyltransferase and glutamate decarboxylase67 mRNA and in vivo release of acetylcholine and GABA in rat medial nucleus accumbens. Differential effects on acetylcholine and GABA neurons by a single challenge injection of amphetamine (1.5 mg/kg, s.c.) were apparent in saline-pretreated and amphetamine-pretreated (same dose, twice daily for the previous seven days) rats. Extracellular acetylcholine levels were increased up to 50% over a prolonged period following both single and repeated amphetamine. In contrast, extracellular concentrations of GABA were gradually decreased to half the control values, but only in rats receiving repeated amphetamine. Although the increase of acetylcholine release was not associated with any change in choline acetyltransferase mRNA levels, the number of neurons expressing high levels of glutamate decarboxylase67 mRNA was decreased (28%) following repeated injections. Thus we suggest that amphetamine decreases extracellular GABA levels by a slow mechanism, associated with the decreased expression of glutamate decarboxylase67 mRNA in a subpopulation of densely labeled neurons in the medial nucleus accumbens. The delayed response by GABA to amphetamine may reflect supersensitivity in the activity of postsynaptic gamma-aminobutyric acid-containing neurons in nucleus accumbens as a consequence of the repeated amphetamine treatment.

Method of incident low-energy gamma-ray direction reconstruction in the GAMMA-400 gamma-ray space telescope

NASA Astrophysics Data System (ADS)

Kheymits, M. D.; Leonov, A. A.; Zverev, V. G.; Galper, A. M.; Arkhangelskaya, I. V.; Arkhangelskiy, A. I.; Suchkov, S. I.; Topchiev, N. P.; Yurkin, Yu T.; Bakaldin, A. V.; Dalkarov, O. D.

2016-02-01

The GAMMA-400 gamma-ray space-based telescope has as its main goals to measure cosmic γ-ray fluxes and the electron-positron cosmic-ray component produced, theoretically, in dark-matter-particles decay or annihilation processes, to search for discrete γ-ray sources and study them in detail, to examine the energy spectra of diffuse γ-rays — both galactic and extragalactic — and to study gamma-ray bursts (GRBs) and γ-rays from the active Sun. Scientific goals of GAMMA-400 telescope require fine angular resolution. The telescope is of a pair-production type. In the converter-tracker, the incident gamma-ray photon converts into electron-positron pair in the tungsten layer and then the tracks are detected by silicon- strip position-sensitive detectors. Multiple scattering processes become a significant obstacle in the incident-gamma direction reconstruction for energies below several gigaelectronvolts. The method of utilising this process to improve the resolution is proposed in the presented work.

A Unified Model for Repeating and Non-repeating Fast Radio Bursts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagchi, Manjari, E-mail: manjari@imsc.res.in

The model that fast radio bursts (FRBs) are caused by plunges of asteroids onto neutron stars can explain both repeating and non-repeating bursts. If a neutron star passes through an asteroid belt around another star, there would be a series of bursts caused by a series of asteroid impacts. Moreover, the neutron star would cross the same belt repetitively if it were in a binary with the star hosting the asteroid belt, leading to a repeated series of bursts. I explore the properties of neutron star binaries that could lead to the only known repeating FRB so far (FRB121102). Inmore » this model, the next two epochs of bursts are expected around 2017 February 27 and 2017 December 18. On the other hand, if the asteroid belt is located around the neutron star itself, then a chance fall of an asteroid from that belt onto the neutron star would lead to a non-repeating burst. Even a neutron star grazing an asteroid belt can lead to a non-repeating burst caused by just one asteroid plunge during the grazing. This is possible even when the neutron star is in a binary with the asteroid-hosting star, if the belt and the neutron star orbit are non-coplanar.« less

Repeatability of Cryogenic Multilayer Insulation

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-01-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between multiple identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five GRC provided coupons with 25 layers was shown to be +/- 8.4 whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0. A second group of 10 coupons have been fabricated by Yetispace and tested by Florida State University, through the first 4 tests, the repeatability has been shown to be +/- 16. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Repeatability of Cryogenic Multilayer Insulation

NASA Technical Reports Server (NTRS)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-01-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between multiple identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five GRC provided coupons with 25 layers was shown to be +/- 8.4% whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0%. A second group of 10 coupons have been fabricated by Yetispace and tested by Florida State University, through the first 4 tests, the repeatability has been shown to be +/- 15-25%. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Repeatability of Cryogenic Multilayer Insulation

NASA Astrophysics Data System (ADS)

Johnson, W. L.; Vanderlaan, M.; Wood, J. J.; Rhys, N. O.; Guo, W.; Van Sciver, S.; Chato, D. J.

2017-12-01

Due to the variety of requirements across aerospace platforms, and one off projects, the repeatability of cryogenic multilayer insulation (MLI) has never been fully established. The objective of this test program is to provide a more basic understanding of the thermal performance repeatability of MLI systems that are applicable to large scale tanks. There are several different types of repeatability that can be accounted for: these include repeatability between identical blankets, repeatability of installation of the same blanket, and repeatability of a test apparatus. The focus of the work in this report is on the first two types of repeatability. Statistically, repeatability can mean many different things. In simplest form, it refers to the range of performance that a population exhibits and the average of the population. However, as more and more identical components are made (i.e. the population of concern grows), the simple range morphs into a standard deviation from an average performance. Initial repeatability testing on MLI blankets has been completed at Florida State University. Repeatability of five Glenn Research Center (GRC) provided coupons with 25 layers was shown to be +/- 8.4% whereas repeatability of repeatedly installing a single coupon was shown to be +/- 8.0%. A second group of 10 coupons has been fabricated by Yetispace and tested by Florida State University, the repeatability between coupons has been shown to be +/- 15-25%. Based on detailed statistical analysis, the data has been shown to be statistically significant.

Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

NASA Technical Reports Server (NTRS)

Galper, A.M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A.I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu. V.;

Cosmic Gamma-Rays

Science.gov Websites

[Argonne Logo] [DOE Logo] Cosmic Gamma-Rays Home Publications Talks People Students Argonne > ; HEP > Cosmic Gamma-Rays Projects VERITAS Past Projects TrICE What's New CTA Cosmic Gamma-Rays The

Design and Performance of the GAMMA-400 Gamma-Ray Telescope for Dark Matter Searches

NASA Technical Reports Server (NTRS)

Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu V.;

Optically stimulated luminescence of natural NaCl mineral from Dead Sea exposed to gamma radiation.

PubMed

Roman-Lopez, J; Piña López, Y I; Cruz-Zaragoza, E; Marcazzó, J

2018-08-01

In this work, the continuous wave - optically stimulated luminescence (CW-OSL) emissions of natural salt minerals, collected from Dead Sea in summer of 2015, were studied. The CW-OSL dose response of natural salt showed a linear range between 0.5Gy and 10Gy of gamma radiation of 60 Co. Samples exposed at 3Gy exhibited good repeatability with a variation coefficient of 4.6%. The CW-OSL response as function of the preheating temperature (50-250°C) was analyzed. An increase of 15% of the CW-OSL response was observed in NaCl samples during storage period of 336h. The results showed that the natural Dead Sea salt minerals could be applied as natural dosimeter of gamma radiation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Reconfigurable multiport EPON repeater

NASA Astrophysics Data System (ADS)

Oishi, Masayuki; Inohara, Ryo; Agata, Akira; Horiuchi, Yukio

2009-11-01

An extended reach EPON repeater is one of the solutions to effectively expand FTTH service areas. In this paper, we propose a reconfigurable multi-port EPON repeater for effective accommodation of multiple ODNs with a single OLT line card. The proposed repeater, which has multi-ports in both OLT and ODN sides, consists of TRs, BTRs with the CDR function and a reconfigurable electrical matrix switch, can accommodate multiple ODNs to a single OLT line card by controlling the connection of the matrix switch. Although conventional EPON repeaters require full OLT line cards to accommodate subscribers from the initial installation stage, the proposed repeater can dramatically reduce the number of required line cards especially when the number of subscribers is less than a half of the maximum registerable users per OLT. Numerical calculation results show that the extended reach EPON system with the proposed EPON repeater can save 17.5% of the initial installation cost compared with a conventional repeater, and can be less expensive than conventional systems up to the maximum subscribers especially when the percentage of ODNs in lightly-populated areas is higher.

Analysis and recent advances in gamma heating measurements in MINERVE facility by using TLD and OSLD techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amharrak, H.; Di Salvo, J.; Lyoussi, A.

2011-07-01

The objective of this study is to develop nuclear heating measurement methods in Zero Power experimental reactors. This paper presents the analysis of Thermo-Luminescent Detector (TLD) and Optically Stimulated Luminescent Detectors (OSLD) experiments in the UO{sub 2} core of the MINERVE research reactor at the CEA Cadarache. The experimental sources of uncertainties on the gamma dose have been reduced by improving the conditions, as well as the repeatability, of the calibration step for each individual TLD. The interpretation of these measurements needs to take into account calculation of cavity correction factors, related to calibration and irradiation configurations, as well asmore » neutron corrections calculations. These calculations are based on Monte Carlo simulations of neutron-gamma and gamma-electron transport coupled particles. TLD and OSLD are positioned inside aluminum pillboxes. The comparison between calculated and measured integral gamma-ray absorbed doses using TLD, shows that calculation slightly overestimates the measurement with a C/E value equal to 1.05 {+-} 5.3 % (k = 2). By using OSLD, the calculation slightly underestimates the measurement with a C/E value equal to 0.96 {+-} 7.0% (k = 2. (authors)« less

Single isotope evaluation of pulmonary capillary protein leak (ARDS model) using computerized gamma scintigraphy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tatum, J.L.; Strash, A.M.; Sugerman, H.J.

Using a canine oleic acid model, a computerized gamma scintigraphic technique was evaluated to determine 1) ability to detect pulmonary capillary protein leak in a model temporally consistent with clinical adult respiratory distress syndrome (ARDS), 2) the possibility of providing a quantitative index of leak, and 3) the feasibility of closely spaced repeat evaluations. Study animals received oleic acid (controls, n . 10; 0.05 ml/kg, n . 10; 0.10 ml/kg, n . 12; 0.15 ml/kg, n . 6) 3 hours prior to a tracer dose of technetium-99m (/sup 99/mTc) HSA. One animal in each dose group also received two repeatmore » tracer injections spaced a minimum of 45 minutes apart. Digital images were obtained with a conventional gamma camera interfaced to a dedicated medical computer. Lung: heart ratio versus time curves were generated, and a slope index was calculated for each curve. Slope index values for all doses were significantly greater than control values (P(t) less than 0.0001). Each incremental dose increase was also significantly greater than the previous dose level. Oleic acid dose versus slope index fitted a linear regression model with r . 0.94. Repeat dosing produced index values with standard deviations less than the group sample standard deviations. We feel this technique may have application in the clinical study of pulmonary permeability edema.« less

Optical gamma thermometer

DOEpatents

Koster, Glen Peter; Xia, Hua; Lee, Boon Kwee

2013-08-06

An optical gamma thermometer includes a metal mass having a temperature proportional to a gamma flux within a core of a nuclear reactor, and an optical fiber cable for measuring the temperature of the heated metal mass. The temperature of the heated mass may be measured by using one or more fiber grating structures and/or by using scattering techniques, such as Raman, Brillouin, and the like. The optical gamma thermometer may be used in conjunction with a conventional reactor heat balance to calibrate the local power range monitors over their useful in-service life. The optical gamma thermometer occupies much less space within the in-core instrument tube and costs much less than the conventional gamma thermometer.

Repeated isoflurane exposure and neuroapoptosis in the midgestation fetal sheep brain.

PubMed

Olutoye, Olutoyin A; Sheikh, Fariha; Zamora, Irving J; Yu, Ling; Akinkuotu, Adesola C; Adesina, Adekunle M; Olutoye, Oluyinka O

2016-04-01

Advances in surgery and technology have resulted in increased in-utero procedures. However, the effect of anesthesia on the fetal brain is not fully known. The inhalational anesthetic agent, isoflurane, other gamma amino butyric acid agonists (benzodiazepines, barbiturates, propofol, other inhalation anesthetics), and N-methyl D aspartate antagonists, eg, ketamine, have been shown to induce neuroapoptosis. The ovine model has been used extensively to study maternal-fetal physiologic interactions and to investigate different surgical interventions on the fetus. The purpose of this study was to determine effects of different doses and duration of isoflurane on neuroapoptosis in midgestation fetal sheep. We hypothesized that repeated anesthetic exposure and high concentrations of isoflurane would result in increased neuroapoptosis. Time-dated, pregnant sheep at 70 days gestation (term 145 days) received either isoflurane 2% × 1 hour, 4% × 3 hours, or 2% × 1 hour every other day for 3 exposures (repeated exposure group). Euthanasia occurred following anesthetic exposure and fetal brains were processed. Neuroapoptosis was detected by immunohistochemistry using anticaspase-3 antibodies. Fetuses unexposed to anesthesia served as controls. Another midgestation group with repeated 2% isoflurane exposure was examined at day 130 (long-term group) and neuronal cell density compared to age-matched controls. Representative sections of the brain were analyzed using Aperio Digital imaging (Leica Microsystems Inc, Buffalo Grove, IL). Data, reported by number of neurons per cubic millimeter of brain tissue are presented as means and SEM. Data were analyzed using the Mann-Whitney U and Kruskal-Wallis tests as appropriate. A total of 34 fetuses were studied. There was no significant difference in neuroapoptosis observed in fetuses exposed to 2% isoflurane for 1 hour or 4% isoflurane for 3 hours. Increased neuroapoptosis was observed in the frontal cortex following repeated 2

PolyQ repeat expansions in ATXN2 associated with ALS are CAA interrupted repeats.

PubMed

Yu, Zhenming; Zhu, Yongqing; Chen-Plotkin, Alice S; Clay-Falcone, Dana; McCluskey, Leo; Elman, Lauren; Kalb, Robert G; Trojanowski, John Q; Lee, Virginia M-Y; Van Deerlin, Vivianna M; Gitler, Aaron D; Bonini, Nancy M

2011-03-29

Amyotrophic lateral sclerosis (ALS) is a devastating, rapidly progressive disease leading to paralysis and death. Recently, intermediate length polyglutamine (polyQ) repeats of 27-33 in ATAXIN-2 (ATXN2), encoding the ATXN2 protein, were found to increase risk for ALS. In ATXN2, polyQ expansions of ≥ 34, which are pure CAG repeat expansions, cause spinocerebellar ataxia type 2. However, similar length expansions that are interrupted with other codons, can present atypically with parkinsonism, suggesting that configuration of the repeat sequence plays an important role in disease manifestation in ATXN2 polyQ expansion diseases. Here we determined whether the expansions in ATXN2 associated with ALS were pure or interrupted CAG repeats, and defined single nucleotide polymorphisms (SNPs) rs695871 and rs695872 in exon 1 of the gene, to assess haplotype association. We found that the expanded repeat alleles of 40 ALS patients and 9 long-repeat length controls were all interrupted, bearing 1-3 CAA codons within the CAG repeat. 21/21 expanded ALS chromosomes with 3CAA interruptions arose from one haplotype (GT), while 18/19 expanded ALS chromosomes with <3CAA interruptions arose from a different haplotype (CC). Moreover, age of disease onset was significantly earlier in patients bearing 3 interruptions vs fewer, and was distinct between haplotypes. These results indicate that CAG repeat expansions in ATXN2 associated with ALS are uniformly interrupted repeats and that the nature of the repeat sequence and haplotype, as well as length of polyQ repeat, may play a role in the neurological effect conferred by expansions in ATXN2.

Implications of Gamma-Ray Transparency Constraints in Blazars: Minimum Distances and Gamma-Ray Collimation

NASA Technical Reports Server (NTRS)

Becker, Peter A.; Kafatos, Menas

1995-01-01

We develop a general expression for the gamma - gamma absorption coefficient, alpha(sub gamma(gamma)) for gamma-rays propagating in an arbitrary direction at an arbitrary point in space above an X-ray-emitting accretion disk. The X-ray intensity is assumed to vary as a power law in energy and radius between the outer disk radius, R(sub 0), and the inner radius, R(sub ms) which is the radius of marginal stability for a Schwarzschild black hole. We use our result for alpha(sub gamma(gamma)) to calculate the gamma - gamma optical depth, tau(sub gamma(gamma)) for gamma - rays created at height z and propagating at angle Phi relative to the disk axis, and we show that for Phi = 0 and z greater than or approx equal to R(sub 0), tau(sub gamma(gamma)) proportional to Epsilon(sup alpha)z(sup -2(alpha) - 3), where alpha is the X-ray spectral index and Epsilon is the gamma - ray energy. As an application, we use our formalism to compute the minimum distance between the central black hole and the site of production of the gamma-rays detected by EGRET during the 1991 June flare of 3C 279. In order to obtain an upper limit, we assume that all of the X-rays observed contemporaneously by Ginga were emitted by the disk. Our results suggest that the observed gamma - rays may have originated within less than or approx equal to 45 GM/sq c from a black hole of mass greater than or approx equal to 10(exp 9) solar mass, perhaps in active plasma located above the central funnel of the accretion disk. This raises the possibility of establishing a direct connection between the production of the observed gamma - rays and the accretion of material onto the black hole. We also consider the variation of the optical depth as a function of the angle of propagation Phi. Our results indicate that the "focusing" of the gamma - rays along the disk axis due to pair production is strong enough to explain the observed degree of alignment in blazar sources. If the gamma - rays are produced isotropically

Design and performance of the GAMMA-400 gamma-ray telescope for dark matter searches

NASA Astrophysics Data System (ADS)

Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Fradkin, M. I.; Gusakov, Yu. V.; Kaplin, V. A.; Kachanov, V. A.; Kheymits, M. D.; Leonov, A. A.; Longo, F.; Mazets, E. P.; Maestro, P.; Marrocchesi, P.; Mereminskiy, I. A.; Mikhailov, V. V.; Moiseev, A. A.; Mocchiutti, E.; Mori, N.; Moskalenko, I. V.; Naumov, P. Yu.; Papini, P.; Picozza, P.; Rodin, V. G.; Runtso, M. F.; Sparvoli, R.; Spillantini, P.; Suchkov, S. I.; Tavani, M.; Topchiev, N. P.; Vacchi, A.; Vannuccini, E.; Yurkin, Yu. T.; Zampa, N.; Zverev, V. G.; Zirakashvili, V. N.

2013-02-01

The GAMMA-400 gamma-ray telescope is designed to measure the fluxes of gamma-rays and cosmic-ray electrons + positrons, which can be produced by annihilation or decay of the dark matter particles, as well as to survey the celestial sphere in order to study point and extended sources of gamma-rays, measure energy spectra of Galactic and extragalactic diffuse gamma-ray emission, gamma-ray bursts, and gamma-ray emission from the Sun. GAMMA-400 covers the energy range from 100 MeV to 3000 GeV. Its angular resolution is ~0.01° (Eγ > 100 GeV), the energy resolution ~1% (Eγ > 10 GeV), and the proton rejection factor ~106. GAMMA-400 will be installed on the Russian space platform Navigator. The beginning of observations is planned for 2018.

Superconducting High Energy Resolution Gamma-ray Spectrometers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, D T

2002-02-22

We have demonstrated that a bulk absorber coupled to a TES can serve as a good gamma-ray spectrometer. Our measured energy resolution of 70 eV at 60 keV is among the best measurements in this field. We have also shown excellent agreement between the noise predictions and measured noise. Despite this good result, we noted that our detector design has shortcomings with a low count rate and vulnerabilities with the linearity of energy response. We addressed these issues by implementation of an active negative feedback bias. We demonstrated the effects of active bias such as additional pulse shortening, reduction ofmore » TES change in temperature during a pulse, and linearization of energy response at low energy. Linearization at higher energy is possible with optimized heat capacities and thermal conductivities of the microcalorimeter. However, the current fabrication process has low control and repeatability over the thermal properties. Thus, optimization of the detector performance is difficult until the fabrication process is improved. Currently, several efforts are underway to better control the fabrication of our gamma-ray spectrometers. We are developing a full-wafer process to produce TES films. We are investigating the thermal conductivity and surface roughness of thicker SiN membranes. We are exploring alternative methods to couple the absorber to the TES film for reproducibility. We are also optimizing the thermal conductivities within the detector to minimize two-element phonon noise. We are experimenting with different absorber materials to optimize absorption efficiency and heat capacity. We are also working on minimizing Johnson noise from the E S shunt and SQUID amplifier noise. We have shown that our performance, noise, and active bias models agree very well with measured data from several microcalorimeters. Once the fabrication improvements have been implemented, we have no doubt that our gamma-ray spectrometer will achieve even more spectacular

Increase in neutrophil Fc gamma receptor I expression following interferon gamma treatment in rheumatoid arthritis.

PubMed Central

Goulding, N J; Knight, S M; Godolphin, J L; Guyre, P M

1992-01-01

The therapeutic potential of interferon gamma (IFN gamma) in a number of disease states is still being explored, but progress is hampered by the lack of a suitable measure of in vivo biological activity. To assess the in vivo biological effects of recombinant human IFN gamma (rhIFN gamma), 14 patients were studied in a randomised, prospective, double blind, placebo controlled trial of this cytokine for the treatment of rheumatoid arthritis. The levels of Fc gamma receptors on peripheral blood neutrophils were measured at baseline and after 21 days of once daily, subcutaneous injections of rhIFN gamma or placebo. An induction of neutrophil Fc gamma receptor type I (Fc gamma RI) was seen in the group of patients receiving recombinant human rhIFN gamma but not in those receiving placebo. No change in the expression of Fc gamma RII or Fc gamma RIII was detected. The amount of induction of Fc gamma RI detected on the neutrophils of patients receiving rhIFN gamma did not correlate with clinical measures of response at either 21 days or at the end of the study (24 weeks). No significant clinical responses were observed in the rhIFN gamma group at these times. These data confirm that the reported in vitro effect of IFN gamma on human neutrophil Fc receptor expression can be reproduced in vivo. PMID:1534001

Increase in neutrophil Fc gamma receptor I expression following interferon gamma treatment in rheumatoid arthritis.

PubMed

Goulding, N J; Knight, S M; Godolphin, J L; Guyre, P M

1992-04-01

The therapeutic potential of interferon gamma (IFN gamma) in a number of disease states is still being explored, but progress is hampered by the lack of a suitable measure of in vivo biological activity. To assess the in vivo biological effects of recombinant human IFN gamma (rhIFN gamma), 14 patients were studied in a randomised, prospective, double blind, placebo controlled trial of this cytokine for the treatment of rheumatoid arthritis. The levels of Fc gamma receptors on peripheral blood neutrophils were measured at baseline and after 21 days of once daily, subcutaneous injections of rhIFN gamma or placebo. An induction of neutrophil Fc gamma receptor type I (Fc gamma RI) was seen in the group of patients receiving recombinant human rhIFN gamma but not in those receiving placebo. No change in the expression of Fc gamma RII or Fc gamma RIII was detected. The amount of induction of Fc gamma RI detected on the neutrophils of patients receiving rhIFN gamma did not correlate with clinical measures of response at either 21 days or at the end of the study (24 weeks). No significant clinical responses were observed in the rhIFN gamma group at these times. These data confirm that the reported in vitro effect of IFN gamma on human neutrophil Fc receptor expression can be reproduced in vivo.

SU-F-T-370: A Fast Monte Carlo Dose Engine for Gamma Knife

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, T; Zhou, L; Li, Y

2016-06-15

Purpose: To develop a fast Monte Carlo dose calculation algorithm for Gamma Knife. Methods: To make the simulation more efficient, we implemented the track repeating technique on GPU. We first use EGSnrc to pre-calculate the photon and secondary electron tracks in water from two mono-energy photons of 60Co. The total photon mean free paths for different materials and energies are obtained from NIST. During simulation, each entire photon track was first loaded to shared memory for each block, the incident original photon was then splitted to Nthread sub-photons, each thread transport one sub-photon, the Russian roulette technique was applied formore » scattered and bremsstrahlung photons. The resultant electrons from photon interactions are simulated by repeating the recorded electron tracks. The electron step length is stretched/shrunk proportionally based on the local density and stopping power ratios of the local material. Energy deposition in a voxel is proportional to the fraction of the equivalent step length in that voxel. To evaluate its accuracy, dose deposition in a 300mm*300mm*300mm water phantom is calculated, and compared to EGSnrc results. Results: Both PDD and OAR showed great agreements (within 0.5%) between our dose engine result and the EGSnrc result. It only takes less than 1 min for every simulation, being reduced up to ∼40 times compared to EGSnrc simulations. Conclusion: We have successfully developed a fast Monte Carlo dose engine for Gamma Knife.« less

Leksell Gamma Knife radiosurgery of the jugulotympanic glomus tumor: long-term results.

PubMed

Liscak, Roman; Urgosik, Dusan; Chytka, Tomas; Simonova, Gabriela; Novotny, Josef; Vymazal, Josef; Guseynova, Khumar; Vladyka, Vilibald

2014-12-01

Glomus tumors usually display indolent behavior, and the effectiveness of radiation in stopping their growth can be assessed after long-term follow-up. Currently only midterm results of radiosurgery are available, so the authors included patients treated by Gamma Knife at least 10 years ago in this study to obtain a perspective of long-term results. During the period from 1992 to 2003, the Gamma Knife was used to treat 46 patients with glomus tumors. The age of the patients ranged from 21 to 79 years (median 56 years). Gamma Knife radiosurgery was the primary treatment in 17 patients (37%). Open surgery preceded radiosurgery in 46% of cases, embolization in 17%, and fractionated radiotherapy in 4%. The volume of the tumor ranged from 0.2 to 24.3 cm(3) (median 3.6 cm(3)). The minimal dose to the tumor margin ranged between 10 and 30 Gy (median 20 Gy). One patient was lost for follow-up after radiosurgery. Clinical follow-up was available in 45 patients and 44 patients were followed with MRI in a follow-up period that ranged from 12 to 217 months (median 118 months). Neurological deficits improved in 19 (42%) of 45 patients and deteriorated in 2 patients (4%). Tumor size decreased in 34 (77%) of 44 patients with imaging follow-up, while an increase in volume was observed in 1 patient (2%) 182 months after radiosurgery and Gamma Knife treatment was repeated. One patient underwent another Gamma Knife treatment for secondary induced meningioma close to the glomus tumor 98 months after initial radiosurgical treatment. Seven patients died 22-96 months after radiosurgery (median 48 months), all for unrelated reasons. Radiosurgery has proved to be a safe treatment with a low morbidity rate and a reliable long-term antiproliferative effect.

Gamma Knife

MedlinePlus

... equipment? How is safety ensured? What is this equipment used for? The Gamma Knife® and its associated ... in size. top of page How does the equipment work? The Gamma Knife® utilizes a technique called ...

Gamma-400 Science Objectives Built on the Current HE Gamma-Ray and CR Results

NASA Technical Reports Server (NTRS)

Moiseev, Alexander; Mitchell, John; Thompson, David

2012-01-01

The main scientific interest of the Russian Gamma-400 team: Observe gamma-rays above approximately 50 GeV with excellent energy and angular resolution with the goals of: (1) Studying the fine spectral structure of the isotropic high-energy gamma-radiation, (2) Attempting to identify the many still-unidentified Fermi-LAT gamma-ray sources. Gamma-400 will likely be the only space-based gamma-ray observatory operating at the end of the decade. In our proposed Gamma-400-LE version, it will substantially improve upon the capabilities of Fermi LAT and AGILE in both LE and HE energy range. Measuring gamma-rays from approx 20 MeV to approx 1 TeV for at least 7 years, Gamma-400-LE will address the topics of dark matter, cosmic ray origin and propagation, neutron stars, flaring pulsars, black holes, AGNs, GRBs, and actively participate in multiwavelength campaigns.

Risks of repeated miscarriage.

PubMed

George, Lena; Granath, Fredrik; Johansson, Anna L V; Olander, Bodil; Cnattingius, Sven

2006-03-01

There is a lack of well-designed epidemiological studies of possible risk factors for repeated miscarriage. In this Swedish population-based case-control study, we investigated the association between sociodemographic and anthropometric factors, obstetric history and life-style factors, with respect to the risks of first-trimester repeated miscarriage. Information on maternal characteristics was collected through in-person interviews. Plasma blood samples were analysed for cotinine and folate concentrations. Adjusted odds ratios (OR) with 95% confidence interval [CI] were used to estimate the relative risk of repeated miscarriage. The risks of repeated miscarriage were increased for women aged > or = 35 years (adjusted OR 2.9 [95% CI 1.4, 5.8]), as well as for women aged < or = 24 years (OR 2.8 [95% CI 1.1, 6.8]). Women with a history of at least one preceding miscarriage prior to the two index pregnancies, women reporting prolonged time to conceive, and women with a history of myoma, faced a more than fourfold increased risk of repeated miscarriage. Smokers were at an increased risk of repeated miscarriage (OR 2.1 [95% CI 1.1, 4.1]). Among non-smoking women with high caffeine intake, there was an increased risk of repeated miscarriage, whereas there was no such association among smokers. Low plasma folate levels were not associated with increased risks.

Predicting diffusion paths and interface motion in gamma/gamma + beta, Ni-Cr-Al diffusion couples

NASA Technical Reports Server (NTRS)

Nesbitt, J. A.; Heckel, R. W.

1987-01-01

A simplified model has been developed to predict Beta recession and diffusion paths in ternary gamma/gamma + beta diffusion couples (gamma:fcc, beta: NiAl structure). The model was tested by predicting beta recession and diffusion paths for four gamma/gamma + beta, Ni-Cr-Al couples annealed for 100 hours at 1200 C. The model predicted beta recession within 20 percent of that measured for each of the couples. The model also predicted shifts in the concentration of the gamma phase at the gamma/gamma + beta interface within 2 at. pct Al and 6 at. pct Cr of that measured in each of the couples. A qualitative explanation based on simple kinetic and mass balance arguments has been given which demonstrates the necessity for diffusion in the two-phase region of certain gamma/gamma + beta, Ni-Cr-Al couples.

Comparison of gamma-gamma Phase Coarsening Responses of Three Powder Metal Disk Superalloys

NASA Technical Reports Server (NTRS)

Gabb, T. P.; Gayda, J.; Johnson, D. F.; MacKay, R. A.; Rogers, R. B.; Sudbrack, C. K.; Garg, A.; Locci, I. E.; Semiatin, S. L.; Kang, E.

2016-01-01

The phase microstructures of several powder metal (PM) disk superalloys were quantitatively evaluated. Contents, chemistries, and lattice parameters of gamma and gamma strengthening phase were determined for conventionally heat treated Alloy 10, LSHR, and ME3 superalloys, after electrolytic phase extractions. Several of long term heat treatments were then performed, to allow quantification of the precipitation, content, and size distribution of gamma at a long time interval to approximate equilibrium conditions. Additional coarsening heat treatments were performed at multiple temperatures and shorter time intervals, to allow quantification of the precipitation, contents and size distributions of gamma at conditions diverging from equilibrium. Modest differences in gamma and gamma lattice parameters and their mismatch were observed among the alloys, which varied with heat treatment. Yet, gamma coarsening rates were very similar for all three alloys in the heat treatment conditions examined. Alloy 10 had higher gamma dissolution and formation temperatures than LSHR and ME3, but a lower lattice mismatch, which was slightly positive for all three alloys at room temperature. The gamma precipitates of Alloy 10 appeared to remain coherent at higher temperatures than for LSHR and ME3. Higher coarsening rates were observed for gamma precipitates residing along grain boundaries than for those within grains in all three alloys, during slow-moderate quenching from supersolvus solution heat treatments, and during aging at temperatures of 843 C and higher.

Revisiting the TALE repeat.

PubMed

Deng, Dong; Yan, Chuangye; Wu, Jianping; Pan, Xiaojing; Yan, Nieng

2014-04-01

Transcription activator-like (TAL) effectors specifically bind to double stranded (ds) DNA through a central domain of tandem repeats. Each TAL effector (TALE) repeat comprises 33-35 amino acids and recognizes one specific DNA base through a highly variable residue at a fixed position in the repeat. Structural studies have revealed the molecular basis of DNA recognition by TALE repeats. Examination of the overall structure reveals that the basic building block of TALE protein, namely a helical hairpin, is one-helix shifted from the previously defined TALE motif. Here we wish to suggest a structure-based re-demarcation of the TALE repeat which starts with the residues that bind to the DNA backbone phosphate and concludes with the base-recognition hyper-variable residue. This new numbering system is consistent with the α-solenoid superfamily to which TALE belongs, and reflects the structural integrity of TAL effectors. In addition, it confers integral number of TALE repeats that matches the number of bound DNA bases. We then present fifteen crystal structures of engineered dHax3 variants in complex with target DNA molecules, which elucidate the structural basis for the recognition of bases adenine (A) and guanine (G) by reported or uncharacterized TALE codes. Finally, we analyzed the sequence-structure correlation of the amino acid residues within a TALE repeat. The structural analyses reported here may advance the mechanistic understanding of TALE proteins and facilitate the design of TALEN with improved affinity and specificity.

The gamma-ray observatory

NASA Technical Reports Server (NTRS)

1991-01-01

An overview is given of the Gamma Ray Observatory (GRO) mission. Detection of gamma rays and gamma ray sources, operations using the Space Shuttle, and instruments aboard the GRO, including the Burst and Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (COMPTEL), and the Energetic Gamma Ray Experiment Telescope (EGRET) are among the topics surveyed.

High-frequency gamma oscillations coexist with low-frequency gamma oscillations in the rat visual cortex in vitro.

PubMed

Oke, Olaleke O; Magony, Andor; Anver, Himashi; Ward, Peter D; Jiruska, Premysl; Jefferys, John G R; Vreugdenhil, Martin

2010-04-01

Synchronization of neuronal activity in the visual cortex at low (30-70 Hz) and high gamma band frequencies (> 70 Hz) has been associated with distinct visual processes, but mechanisms underlying high-frequency gamma oscillations remain unknown. In rat visual cortex slices, kainate and carbachol induce high-frequency gamma oscillations (fast-gamma; peak frequency approximately 80 Hz at 37 degrees C) that can coexist with low-frequency gamma oscillations (slow-gamma; peak frequency approximately 50 Hz at 37 degrees C) in the same column. Current-source density analysis showed that fast-gamma was associated with rhythmic current sink-source sequences in layer III and slow-gamma with rhythmic current sink-source sequences in layer V. Fast-gamma and slow-gamma were not phase-locked. Slow-gamma power fluctuations were unrelated to fast-gamma power fluctuations, but were modulated by the phase of theta (3-8 Hz) oscillations generated in the deep layers. Fast-gamma was spatially less coherent than slow-gamma. Fast-gamma and slow-gamma were dependent on gamma-aminobutyric acid (GABA)(A) receptors, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors and gap-junctions, their frequencies were reduced by thiopental and were weakly dependent on cycle amplitude. Fast-gamma and slow-gamma power were differentially modulated by thiopental and adenosine A(1) receptor blockade, and their frequencies were differentially modulated by N-methyl-D-aspartate (NMDA) receptors, GluK1 subunit-containing receptors and persistent sodium currents. Our data indicate that fast-gamma and slow-gamma both depend on and are paced by recurrent inhibition, but have distinct pharmacological modulation profiles. The independent co-existence of fast-gamma and slow-gamma allows parallel processing of distinct aspects of vision and visual perception. The visual cortex slice provides a novel in vitro model to study cortical high-frequency gamma oscillations.

A method to describe inelastic gamma field distribution in neutron gamma density logging.

PubMed

Zhang, Feng; Zhang, Quanying; Liu, Juntao; Wang, Xinguang; Wu, He; Jia, Wenbao; Ti, Yongzhou; Qiu, Fei; Zhang, Xiaoyang

2017-11-01

Pulsed neutron gamma density logging (NGD) is of great significance for radioprotection and density measurement in LWD, however, the current methods have difficulty in quantitative calculation and single factor analysis for the inelastic gamma field distribution. In order to clarify the NGD mechanism, a new method is developed to describe the inelastic gamma field distribution. Based on the fast-neutron scattering and gamma attenuation, the inelastic gamma field distribution is characterized by the inelastic scattering cross section, fast-neutron scattering free path, formation density and other parameters. And the contribution of formation parameters on the field distribution is quantitatively analyzed. The results shows the contribution of density attenuation is opposite to that of inelastic scattering cross section and fast-neutron scattering free path. And as the detector-spacing increases, the density attenuation gradually plays a dominant role in the gamma field distribution, which means large detector-spacing is more favorable for the density measurement. Besides, the relationship of density sensitivity and detector spacing was studied according to this gamma field distribution, therefore, the spacing of near and far gamma ray detector is determined. The research provides theoretical guidance for the tool parameter design and density determination of pulsed neutron gamma density logging technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

All-photonic quantum repeaters

PubMed Central

Azuma, Koji; Tamaki, Kiyoshi; Lo, Hoi-Kwong

2015-01-01

Quantum communication holds promise for unconditionally secure transmission of secret messages and faithful transfer of unknown quantum states. Photons appear to be the medium of choice for quantum communication. Owing to photon losses, robust quantum communication over long lossy channels requires quantum repeaters. It is widely believed that a necessary and highly demanding requirement for quantum repeaters is the existence of matter quantum memories. Here we show that such a requirement is, in fact, unnecessary by introducing the concept of all-photonic quantum repeaters based on flying qubits. In particular, we present a protocol based on photonic cluster-state machine guns and a loss-tolerant measurement equipped with local high-speed active feedforwards. We show that, with such all-photonic quantum repeaters, the communication efficiency scales polynomially with the channel distance. Our result paves a new route towards quantum repeaters with efficient single-photon sources rather than matter quantum memories. PMID:25873153

The gamma cycle.

PubMed

Fries, Pascal; Nikolić, Danko; Singer, Wolf

2007-07-01

Activated neuronal groups typically engage in rhythmic synchronization in the gamma-frequency range (30-100 Hz). Experimental and modeling studies demonstrate that each gamma cycle is framed by synchronized spiking of inhibitory interneurons. Here, we review evidence suggesting that the resulting rhythmic network inhibition interacts with excitatory input to pyramidal cells such that the more excited cells fire earlier in the gamma cycle. Thus, the amplitude of excitatory drive is recoded into phase values of discharges relative to the gamma cycle. This recoding enables transmission and read out of amplitude information within a single gamma cycle without requiring rate integration. Furthermore, variation of phase relations can be exploited to facilitate or inhibit exchange of information between oscillating cell assemblies. The gamma cycle could thus serve as a fundamental computational mechanism for the implementation of a temporal coding scheme that enables fast processing and flexible routing of activity, supporting fast selection and binding of distributed responses. This review is part of the INMED/TINS special issue Physiogenic and pathogenic oscillations: the beauty and the beast, based on presentations at the annual INMED/TINS symposium (http://inmednet.com).

RepeatsDB-lite: a web server for unit annotation of tandem repeat proteins.

PubMed

Hirsh, Layla; Paladin, Lisanna; Piovesan, Damiano; Tosatto, Silvio C E

2018-05-09

RepeatsDB-lite (http://protein.bio.unipd.it/repeatsdb-lite) is a web server for the prediction of repetitive structural elements and units in tandem repeat (TR) proteins. TRs are a widespread but poorly annotated class of non-globular proteins carrying heterogeneous functions. RepeatsDB-lite extends the prediction to all TR types and strongly improves the performance both in terms of computational time and accuracy over previous methods, with precision above 95% for solenoid structures. The algorithm exploits an improved TR unit library derived from the RepeatsDB database to perform an iterative structural search and assignment. The web interface provides tools for analyzing the evolutionary relationships between units and manually refine the prediction by changing unit positions and protein classification. An all-against-all structure-based sequence similarity matrix is calculated and visualized in real-time for every user edit. Reviewed predictions can be submitted to RepeatsDB for review and inclusion.

Measurement of gamma' precipitates in a nickel-based superalloy using energy-filtered transmission electron microscopy coupled with automated segmenting techniques.

PubMed

Tiley, J S; Viswanathan, G B; Shiveley, A; Tschopp, M; Srinivasan, R; Banerjee, R; Fraser, H L

2010-08-01

Precipitates of the ordered L1(2) gamma' phase (dispersed in the face-centered cubic or FCC gamma matrix) were imaged in Rene 88 DT, a commercial multicomponent Ni-based superalloy, using energy-filtered transmission electron microscopy (EFTEM). Imaging was performed using the Cr, Co, Ni, Ti and Al elemental L-absorption edges in the energy loss spectrum. Manual and automated segmentation procedures were utilized for identification of precipitate boundaries and measurement of precipitate sizes. The automated region growing technique for precipitate identification in images was determined to measure accurately precipitate diameters. In addition, the region growing technique provided a repeatable method for optimizing segmentation techniques for varying EFTEM conditions. (c) 2010 Elsevier Ltd. All rights reserved.

Gamma response characterizations of optically stimulated luminescence (OSL) affects personal dosimetry

NASA Astrophysics Data System (ADS)

Monthonwattana, S.; Esor, J.; Rungseesumran, T.; Intang, A.

2017-06-01

Optically Stimulated Luminescence (OSL) is the current technique of personal dosimetry changed by Nuclear Technology Service Center instead of Thermoluminescence dosimetry (TLD) because OSL has more advantages, such as repeat reading and elimination of heating process. In this study, OSL was used to test the gamma response characterizations. Detailed OSL investigation on personal dosimetry was carried out in the dose range of 0.2 - 3.0 mSv. The batch homogeneity was 7.66%. R2 value of the linear regression was 0.9997. The difference ratio of angular dependence at ± 60° was 8.7%. Fading of the reading was about 3%.

A Platinum-Enriched gamma+gamma' Two-Phase Bond Coat on Ni-Base Superalloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ying; Pint, Bruce A; Haynes, James A

2005-01-01

Pt-enriched {gamma} + {gamma}{prime} two-phase coating was applied to directionally-solidified Ni-based superalloy Ren{acute e} 142 substrates with three different Hf levels (0.02, 0.76, and 1.37 wt.%). The coating was prepared by electroplating a thin layer of Pt on the superalloy followed by a diffusion treatment. The as-deposited coating exhibited a {gamma} + {gamma}{prime} two-phase microstructure with a major composition of Ni-16Al-18Pt-7Cr-9Co (in at.%) along with some incorporation of refractory elements from the substrates. Cyclic oxidation testing at 1100 C in air indicated improved oxidation resistance of the Ren{acute e} 142 alloys with the Pt-enriched {gamma} + {gamma}{prime} coatings. In addition,more » the oxidation resistance of both uncoated and coated alloys was proportional to the Hf content in the substrate. Compared with the single-phase {beta}-(Ni,Pt)Al coating, slightly higher mass gains and localized spallation were observed on the {gamma} + {gamma}{prime} two-phase coating, which might be due to the segregation of refractory elements and high sulfur levels in these superalloy substrates.« less

Gamma ray transients

NASA Technical Reports Server (NTRS)

Cline, Thomas L.

1987-01-01

The discovery of cosmic gamma ray bursts was made with systems designed at Los Alamos Laboratory for the detection of nuclear explosions beyond the atmosphere. HELIOS-2 was the first gamma ray burst instrument launched; its initial results in 1976, seemed to deepen the mystery around gamma ray transients. Interplanetary spacecraft data were reviewed in terms of explaining the behavior and source of the transients.

Expression of peroxisome proliferator-activated receptor gamma (PPAR-gamma) in canine nasal carcinomas.

PubMed

Paciello, O; Borzacchiello, G; Varricchio, E; Papparella, S

2007-10-01

Peroxisome proliferator-activated receptor gamma (PPAR-gamma) is a ligand-activated transcriptional factor belonging to the steroid receptor superfamily. PPAR-gamma is expressed in multiple normal and neoplastic tissues, such as the breast, colon, lung, ovary and placenta. In addition to adipogenic and anti-inflammatory effects, PPAR-gamma activation has been shown to be anti-proliferative by its differentiation-promoting effect, suggesting that activation of PPAR-gamma may be useful in slowing or arresting the proliferation of de-differentiated tumour cells. In this study, we investigated the expression of PPAR-gamma in normal and neoplastic canine nasal epithelium. Twenty-five samples composed of five normal nasal epithelia and 20 canine nasal carcinomas, were immunohistochemically stained for PPAR-gamma. The specificity of the antibody was verified by Western Blot analysis. Confocal laser scanning microscopical investigation was also performed. In normal epithelium, the staining pattern was cytoplasmic and polarized at the cellular free edge. In carcinomas, the neoplastic cells showed mainly strong cytoplasmatic PPAR-gamma expression; moreover, perinuclear immunoreactivity was also detected and few neoplastic cells exhibited a nuclear positivity. Our results demonstrate different patterns of PPAR-gamma expression in normal canine nasal epithelium when compared with canine nasal carcinoma. The importance of this transcription factor in the pathophysiology of several different tumours has stimulated much research in this field and has opened new opportunities for the treatment of the tumours.

Cloning, sequencing and expression of white rhinoceros (Ceratotherium simum) interferon-gamma (IFN-gamma) and the production of rhinoceros IFN-gamma specific antibodies.

PubMed

Morar, D; Tijhaar, E; Negrea, A; Hendriks, J; van Haarlem, D; Godfroid, J; Michel, A L; Rutten, V P M G

2007-01-15

Bovine tuberculosis (BTB) is endemic in African buffalo (Syncerus caffer) in the Kruger National Park (KNP). In addition to buffalo, Mycobacterium bovis has been found in at least 14 other mammalian species in South Africa, including kudu (Tragelaphus strepsiceros), Chacma baboon (Papio ursinus) and lion (Panthera leo). This has raised concern about the spillover into other potentially susceptible species like rhinoceros, thus jeopardising breeding and relocation projects aiming at the conservation of biodiversity. Hence, procedures to screen for and diagnose BTB in black rhinoceros (Diceros bicornis) and white rhinoceros (Ceratotherium simum) need to be in place. The Interferon-gamma (IFN-gamma) assay is used as a routine diagnostic tool to determine infection of cattle and recently African buffalo, with M. bovis and other mycobacteria. The aim of the present work was to develop reagents to set up a rhinoceros IFN-gamma (RhIFN-gamma) assay. The white rhinoceros IFN-gamma gene was cloned, sequenced and expressed as a mature protein. Amino acid (aa) sequence analysis revealed that RhIFN-gamma shares a homology of 90% with equine IFN-gamma. Monoclonal antibodies, as well as polyclonal chicken antibodies (Yolk Immunoglobulin-IgY) with specificity for recombinant RhIFN-gamma were produced. Using the monoclonals as capture antibodies and the polyclonal IgY for detection, it was shown that recombinant as well as native white rhinoceros IFN-gamma was recognised. This preliminary IFN-gamma enzyme-linked immunosorbent assay (ELISA), has the potential to be developed into a diagnostic assay for M. bovis infection in rhinoceros.

Measurements of the $$\\mathrm{ pp \\to W \\gamma\\gamma }$$ and $$\\mathrm{ pp \\to Z \\gamma\\gamma }$$ cross sections and limits on anomalous quartic gauge couplings at $$\\sqrt{s} =$$ 8 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.

Here, measurements are presented ofmore » $$ \\mathrm{ W \\gamma\\gamma } $$ and $$ \\mathrm{ Z \\gamma\\gamma } $$ production in proton-proton collisions. Fiducial cross sections are reported based on a data sample corresponding to an integrated luminosity of 19.4 fb$$^{-1}$$ collected with the CMS detector at a center-of-mass energy of 8 TeV. Signal is identified through the $$\\mathrm{ W } \\to \\ell\

Measurements of the $$\\mathrm{ pp \\to W \\gamma\\gamma }$$ and $$\\mathrm{ pp \\to Z \\gamma\\gamma }$$ cross sections and limits on anomalous quartic gauge couplings at $$\\sqrt{s} =$$ 8 TeV

DOE PAGES

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; ...

2017-10-11

Here, measurements are presented ofmore » $$ \\mathrm{ W \\gamma\\gamma } $$ and $$ \\mathrm{ Z \\gamma\\gamma } $$ production in proton-proton collisions. Fiducial cross sections are reported based on a data sample corresponding to an integrated luminosity of 19.4 fb$$^{-1}$$ collected with the CMS detector at a center-of-mass energy of 8 TeV. Signal is identified through the $$\\mathrm{ W } \\to \\ell\

Repeatability of paired counts.

PubMed

Alexander, Neal; Bethony, Jeff; Corrêa-Oliveira, Rodrigo; Rodrigues, Laura C; Hotez, Peter; Brooker, Simon

2007-08-30

The Bland and Altman technique is widely used to assess the variation between replicates of a method of clinical measurement. It yields the repeatability, i.e. the value within which 95 per cent of repeat measurements lie. The valid use of the technique requires that the variance is constant over the data range. This is not usually the case for counts of items such as CD4 cells or parasites, nor is the log transformation applicable to zero counts. We investigate the properties of generalized differences based on Box-Cox transformations. For an example, in a data set of hookworm eggs counted by the Kato-Katz method, the square root transformation is found to stabilize the variance. We show how to back-transform the repeatability on the square root scale to the repeatability of the counts themselves, as an increasing function of the square mean root egg count, i.e. the square of the average of square roots. As well as being more easily interpretable, the back-transformed results highlight the dependence of the repeatability on the sample volume used.

Structural relationships between human erythrocyte sialoglycoproteins beta and gamma and abnormal sialoglycoproteins found in certain rare human erythrocyte variants lacking the Gerbich blood-group antigen(s).

PubMed Central

Reid, M E; Anstee, D J; Tanner, M J; Ridgwell, K; Nurse, G T

1987-01-01

The human erythrocyte membrane sialoglycoproteins beta and gamma are important for the maintenance of the discoid shape of the normal erythrocyte. In this paper we show that the human erythrocyte sialoglycoproteins beta and gamma (hereafter called beta and gamma) are structurally related. Rabbit antisera produced against purified beta and beta 1 and rendered specific to the cytoplasmic portion of these proteins also react with the cytoplasmic portion of gamma. Some human anti-Gerbich (Ge) sera react with the extracellular portion of both beta and gamma. This reactivity is shown to be directed towards a common epitope on beta and gamma. However, most anti-Ge sera do not react with beta, but react with an extracellular epitope only present on gamma. All individuals who lack the Ge antigens lack beta and gamma. In some cases abnormal sialoglycoproteins are present in the erythrocytes, and these are shown to be structurally related to beta and gamma. Rabbit antisera raised against the purified abnormal sialoglycoprotein from a Ge-negative erythrocyte type reacted with the cytoplasmic portion of both beta and gamma. Unlike normal beta and gamma, the abnormal sialoglycoproteins found in Ge-negative erythrocytes migrate as a diffuse band on SDS/polyacrylamide-gel electrophoresis. Studies using endoglycosidases suggest that the diffuse nature of these bands results from carbohydrate heterogeneity and that the abnormal sialoglycoproteins contain N-glycosidically linked oligosaccharides with repeating lactosamine units. Such polylactosamine chains are not present on normal beta or gamma. Images Fig. 1. Fig. 2. Fig. 3. PMID:2444210

Folding control in cyclic peptides through N-methylation pattern selection: formation of antiparallel beta-sheet dimers, double reverse turns and supramolecular helices by 3alpha,gamma cyclic peptides.

PubMed

Amorín, Manuel; Castedo, Luis; Granja, Juan R

2008-01-01

Peptide foldamers constitute a growing class of nanomaterials with potential applications in a wide variety of chemical, medical and technological fields. Here we describe the preparation and structural characteristics of a new class of cyclic peptide foldamers (3alpha,gamma-CPs) that, depending on their backbone N-methylation patterns and the medium, can either remain as flat rings that dimerize through arrays of hydrogen bonds of antiparallel beta-sheet type, or can fold into twisted double reverse turns that, in the case of double gamma-turns, associate in nonpolar solvents to form helical supramolecular structures. A 3alpha,gamma-CP consists of a number of multiples of a repeat unit made up of four amino acid residues of alternating chirality: three corresponding to alpha-amino acids and one to a gamma-amino acid (a cis-3-aminocycloalkanecarboxylic acid).

Basics of Gamma Ray Detection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stinnett, Jacob; Venkataraman, Ram

The objective of this training is to explain the origin of x-rays and gamma rays, gamma ray interactions with matter, detectors and electronics used in gamma ray-spectrometry, and features of a gamma-ray spectrum for nuclear material that is safeguarded.

Dynamic gamma knife radiosurgery

NASA Astrophysics Data System (ADS)

Luan, Shuang; Swanson, Nathan; Chen, Zhe; Ma, Lijun

2009-03-01

Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C™ and Perfexion™ units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can obtain a family of plans representing a tradeoff between the delivery time and the

Gamma knife radiosurgery for typical trigeminal neuralgia: An institutional review of 108 patients

PubMed Central

Elaimy, Ameer L.; Lamm, Andrew F.; Demakas, John J.; Mackay, Alexander R.; Lamoreaux, Wayne T.; Fairbanks, Robert K.; Pfeffer, Robert D.; Cooke, Barton S.; Peressini, Benjamin J.; Lee, Christopher M.

2013-01-01

Background: In this study, we present the previously unreported pain relief outcomes of 108 patients treated at Gamma Knife of Spokane for typical trigeminal neuralgia (TN) between 2002 and 2011. Methods: Pain relief outcomes were measured using the Barrow Neurological Institute (BNI) pain intensity scale. In addition, the effects gender, age at treatment, pain laterality, previous surgical treatment, repeat Gamma Knife radiosurgery (GKRS), and maximum radiosurgery dose have on patient pain relief outcomes were retrospectively analyzed. Statistical analysis was performed using Andersen 95% confidence intervals, approximate confidence intervals for log hazard ratios, and multivariate Cox proportional hazard models. Results: All 108 patients included in this study were grouped into BNI class IV or V prior to GKRS. The median clinical follow-up time was determined to be 15 months. Following the first GKRS procedure, 71% of patients were grouped into BNI class I-IIIb (I = 31%; II = 3%; IIIa = 19%; IIIb = 18%) and the median duration of pain relief for those patients was determined to be 11.8 months. New facial numbness was reported in 19% of patients and new facial paresthesias were reported in 7% of patients after the first GKRS procedure. A total of 19 repeat procedures were performed on the 108 patients included in this study. Following the second GKRS procedure, 73% of patients were grouped into BNI class I-IIIb (I = 44%; II = 6%; IIIa = 17%, IIIb = 6%) and the median duration of pain relief for those patients was determined to be 4.9 months. For repeat procedures, new facial numbness was reported in 22% of patients and new facial paresthesias were reported in 6% of patients. Conclusions: GKRS is a safe and effective management approach for patients diagnosed with typical TN. However, further studies and supporting research is needed on the effects previous surgical treatment, number of radiosurgery procedures, and maximum radiosurgery dose have on GKRS clinical

Sequence repeats and protein structure

NASA Astrophysics Data System (ADS)

Hoang, Trinh X.; Trovato, Antonio; Seno, Flavio; Banavar, Jayanth R.; Maritan, Amos

2012-11-01

Repeats are frequently found in known protein sequences. The level of sequence conservation in tandem repeats correlates with their propensities to be intrinsically disordered. We employ a coarse-grained model of a protein with a two-letter amino acid alphabet, hydrophobic (H) and polar (P), to examine the sequence-structure relationship in the realm of repeated sequences. A fraction of repeated sequences comprises a distinct class of bad folders, whose folding temperatures are much lower than those of random sequences. Imperfection in sequence repetition improves the folding properties of the bad folders while deteriorating those of the good folders. Our results may explain why nature has utilized repeated sequences for their versatility and especially to design functional proteins that are intrinsically unstructured at physiological temperatures.

Galactic plane gamma-radiation

NASA Technical Reports Server (NTRS)

Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tumer, T.; Ozel, M. E.

1979-01-01

Analysis of the SAS 2 data together with the COS B results shows that the distribution of galactic gamma-radiation has several similarities to that of other large-scale tracers of galactic structure. The radiation is primarily confined to a thin disc which exhibits offsets from b = 0 degrees similar to warping at radio frequencies. The principal distinction of the gamma-radiation is a stronger contrast in intensity between the region from 310 to 45 degrees in longitude and the regions away from the center that can be attributed to a variation in cosmic-ray density as a function of position in Galaxy. The diffuse galactic gamma-ray energy spectrum shows no significant variation in direction, and the spectrum seen along the plane is the same as that for the galactic component of the gamma-radiation at high altitudes. The uniformity of the galactic gamma-ray spectrum, the smooth decrease in intensity as a function of altitude, and the absence of any galactic gamma-ray sources at high altitudes indicate a diffuse origin for bulk of the galactic gamma-radiation rather than a collection of localized sources.

Gamma-ray burster recurrence timescales

NASA Technical Reports Server (NTRS)

Schaefer, B. E.; Cline, T. L.

1984-01-01

Three optical transients have been found which are associated with gamma-ray bursters (GRBs). The deduced recurrence timescale for these optical transients (tau sub opt) will depend on the minimum brightness for which a flash would be detected. A detailed analysis using all available data of tau sub opt as a function of E(gamma)/E(opt) is given. For flashes similar to those found in the Harvard archives, the best estimate of tau sub opt is 0.74 years, with a 99% confidence interval from 0.23 years to 4.7 years. It is currently unclear whether the optical transients from GRBs also give rise to gamma-ray events. One way to test this association is to measure the recurrence timescale of gamma-ray events tau sub gamma. A total of 210 gamma-ray error boxes were examined and it was found that the number of observed overlaps is not significantly different from the number expected from chance coincidence. This observation can be used to place limits on tau sub gamma for an assumed luminosity function. It was found that tau sub gamma is approx. 10 yr if bursts are monoenergetic. However, if GRBs have a power law luminosity function with a wide dynamic range, then the limit is tau sub gamma 0.5 yr. Hence, the gamma-ray data do not require tau sub gamma and tau sub opt to be different.

Repeat Customer Success in Extension

ERIC Educational Resources Information Center

Bess, Melissa M.; Traub, Sarah M.

2013-01-01

Four multi-session research-based programs were offered by two Extension specialist in one rural Missouri county. Eleven participants who came to multiple Extension programs could be called "repeat customers." Based on the total number of participants for all four programs, 25% could be deemed as repeat customers. Repeat customers had…

Repeat migration and disappointment.

PubMed

Grant, E K; Vanderkamp, J

1986-01-01

This article investigates the determinants of repeat migration among the 44 regions of Canada, using information from a large micro-database which spans the period 1968 to 1971. The explanation of repeat migration probabilities is a difficult task, and this attempt is only partly successful. May of the explanatory variables are not significant, and the overall explanatory power of the equations is not high. In the area of personal characteristics, the variables related to age, sex, and marital status are generally significant and with expected signs. The distance variable has a strongly positive effect on onward move probabilities. Variables related to prior migration experience have an important impact that differs between return and onward probabilities. In particular, the occurrence of prior moves has a striking effect on the probability of onward migration. The variable representing disappointment, or relative success of the initial move, plays a significant role in explaining repeat migration probabilities. The disappointment variable represents the ratio of actural versus expected wage income in the year after the initial move, and its effect on both repeat migration probabilities is always negative and almost always highly significant. The repeat probabilities diminish after a year's stay in the destination region, but disappointment in the most recent year still has a bearing on the delayed repeat probabilities. While the quantitative impact of the disappointment variable is not large, it is difficult to draw comparisons since similar estimates are not available elsewhere.

Gamma watermarking

DOEpatents

Ishikawa, Muriel Y.; Wood, Lowell L.; Lougheed, Ronald W.; Moody, Kenton J.; Wang, Tzu-Fang

2004-05-25

A covert, gamma-ray "signature" is used as a "watermark" for property identification. This new watermarking technology is based on a unique steganographic or "hidden writing" digital signature, implemented in tiny quantities of gamma-ray-emitting radioisotopic material combinations, generally covertly emplaced on or within an object. This digital signature may be readily recovered at distant future times, by placing a sensitive, high energy-resolution gamma-ray detecting instrument reasonably precisely over the location of the watermark, which location may be known only to the object's owner; however, the signature is concealed from all ordinary detection means because its exceedingly low level of activity is obscured by the natural radiation background (including the gamma radiation naturally emanating from the object itself, from cosmic radiation and material surroundings, from human bodies, etc.). The "watermark" is used in object-tagging for establishing object identity, history or ownership. It thus may serve as an aid to law enforcement officials in identifying stolen property and prosecuting theft thereof. Highly effective, potentially very low cost identification-on demand of items of most all types is thus made possible.

The Gamma-ray Sky with Fermi

NASA Technical Reports Server (NTRS)

Thompson, David

2012-01-01

Gamma rays reveal extreme, nonthermal conditions in the Universe. The Fermi Gamma-ray Space Telescope has been exploring the gamma-ray sky for more than four years, enabling a search for powerful transients like gamma-ray bursts, novae, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge gamma-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

Gamma Ray Astronomy

NASA Technical Reports Server (NTRS)

Wu, S. T.

2000-01-01

The project has progressed successfully during this period of performance. The highlights of the Gamma Ray Astronomy teams efforts are: (1) Support daily BATSE data operations, including receipt, archival and dissemination of data, quick-look science analysis, rapid gamma-ray burst and transient monitoring and response efforts, instrument state-of-health monitoring, and instrument commanding and configuration; (2) On-going scientific analysis, including production and maintenance of gamma-ray burst, pulsed source and occultation source catalogs, gamma-ray burst spectroscopy, studies of the properties of pulsars and black holes, and long-term monitoring of hard x-ray sources; (3) Maintenance and continuous improvement of BATSE instrument response and calibration data bases; (4) Investigation of the use of solid state detectors for eventual application and instrument to perform all sky monitoring of X-Ray and Gamma sources with high sensitivity; and (5) Support of BATSE outreach activities, including seminars, colloquia and World Wide Web pages. The highlights of this efforts can be summarized in the publications and presentation list.

Magnetar Observations in the Swift-Fermi/GBM Era

NASA Technical Reports Server (NTRS)

Kouveliotou, Chryssa

2010-01-01

NASA's Fermi Observatory was launched June 11, 2008; the Fermi Gamma Ray Burst Monitor (GBM) began normal operations on July 14, about a month after launch, when the trigger algorithms were enabled. Since then, and against all odds, GBM recorded over 600 bursts from 4 SGRs. Of these four sources, only one was an old magnetar: SGR J1806+20. SGR J0501+4516, was discovered with Swift and extensively monitored with GBM. A source originally classified as AXP 1E1547.0-5408 exhibited SGR-like bursting behavior and we reclassified it as SGR J1550-5418. Finally, GBM discovered SGR J0418+5729 on 2009 June. Finally, on March 2010, a third new magnetar was discovered with Swift, SGR J1833-0832. I report below on the current status of the field and on several results combining multi-satellite and ground-based data

Gamma ray detector shield

DOEpatents

Ohlinger, R.D.; Humphrey, H.W.

1985-08-26

A gamma ray detector shield comprised of a rigid, lead, cylindrical-shaped vessel having upper and lower portions with an pneumatically driven, sliding top assembly. Disposed inside the lead shield is a gamma ray scintillation crystal detector. Access to the gamma detector is through the sliding top assembly.

A TIGHT CONNECTION BETWEEN GAMMA-RAY OUTBURSTS AND PARSEC-SCALE JET ACTIVITY IN THE QUASAR 3C 454.3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jorstad, Svetlana G.; Marscher, Alan P.; Agudo, Ivan

2013-08-20

We analyze the multi-frequency behavior of the quasar 3C 454.3 during three prominent {gamma}-ray outbursts: 2009 Autumn, 2010 Spring, and 2010 Autumn. The data reveal a repeating pattern, including a triple flare structure, in the properties of each {gamma}-ray outburst, which implies similar mechanism(s) and location for all three events. The multi-frequency behavior indicates that the lower frequency events are co-spatial with the {gamma}-ray outbursts, although the {gamma}-ray emission varies on the shortest timescales. We determine that the variability from UV to IR wavelengths during an outburst results from a single synchrotron component whose properties do not change significantly overmore » the different outbursts. Despite a general increase in the degree of optical linear polarization during an outburst, the polarization drops significantly at the peak of the {gamma}-ray event, which suggests that both shocks and turbulent processes are involved. We detect two disturbances (knots) with superluminal apparent speeds in the parsec-scale jet associated with the outbursts in 2009 Autumn and 2010 Autumn. The kinematic properties of the knots can explain the difference in amplitudes of the {gamma}-ray events, while their millimeter-wave polarization is related to the optical polarization during the outbursts. We interpret the multi-frequency behavior within models involving either a system of standing conical shocks or magnetic reconnection events located in the parsec-scale millimeter-wave core of the jet. We argue that {gamma}-ray outbursts with variability timescales as short as {approx}3 hr can occur on parsec scales if flares take place in localized regions such as turbulent cells.« less

Wetting characteristics and blood clotting on surfaces of copoly(gamma-Benzyl-L-glutamate, gamma-hydroxyethyl-L-glutamine).

PubMed

Yano, E; Komai, T; Kawasaki, T; Kaifu, K; Atsuta, T; Kubo, Y; Fujiwara, Y

1985-09-01

The film surface of poly(gamma-benzyl-L-glutamate) (PBLG) was modified with 2-aminoethanol to enhance its hydrophilicity. Controlling the reaction conditions of PBLG and 2-aminoethanol, various types of copoly(gamma-benzyl-L-glutamate, gamma-hydroxyethyl-L-glutamine) film surfaces were obtained. Surface free energy (gamma sv), the dispersive component of gamma sv (gamma dsv), the nondispersive component of gamma sv (gamma psv), and the interfacial free energy of polymer surface with water (gamma sw), which were obtained by using the contact angle measurement and calculation method proposed by Andrade et al., were changed remarkably by the aminolysis. The gamma sv value increased after 2 h of aminolysis from 48.2 (PBLG) to 65.3 dyn/cm and gradually increased to around 70 dyn/cm after 12 h reaction. (gamma dsv) and (gamma psv) changed from 31.0 and 17.2 dyn/cm (PBLG) to 26.5 and 44.3 dyn/cm, respectively. These parameters of the material surfaces, modified over 12 h reaction, were found to be similar to those of the surfaces of canine aorta, vein, and human fibrin membrane. Blood clotting times on these polymer surfaces were comparatively longer than on siliconized glass surfaces.

Nucleotide sequence and genetic organization of barley stripe mosaic virus RNA gamma.

PubMed

Gustafson, G; Hunter, B; Hanau, R; Armour, S L; Jackson, A O

1987-06-01

The complete nucleotide sequences of RNA gamma from the Type and ND18 strains of barley stripe mosaic virus (BSMV) have been determined. The sequences are 3164 (Type) and 2791 (ND18) nucleotides in length. Both sequences contain a 5'-noncoding region (87 or 88 nucleotides) which is followed by a long open reading frame (ORF1). A 42-nucleotide intercistronic region separates ORF1 from a second, shorter open reading frame (ORF2) located near the 3'-end of the RNA. There is a high degree of homology between the Type and ND18 strains in the nucleotide sequence of ORF1. However, the Type strain contains a 366 nucleotide direct tandem repeat within ORF1 which is absent in the ND18 strain. Consequently, the predicted translation product of Type RNA gamma ORF1 (mol wt 87,312) is significantly larger than that of ND18 RNA gamma ORF1 (mol wt 74,011). The amino acid sequence of the ORF1 polypeptide contains homologies with putative RNA polymerases from other RNA viruses, suggesting that this protein may function in replication of the BSMV genome. The nucleotide sequence of RNA gamma ORF2 is nearly identical in the Type and ND18 strains. ORF2 codes for a polypeptide with a predicted molecular weight of 17,209 (Type) or 17,074 (ND18) which is known to be translated from a subgenomic (sg) RNA. The initiation point of this sgRNA has been mapped to a location 27 nucleotides upstream of the ORF2 initiation codon in the intercistronic region between ORF1 and ORF2. The sgRNA is not coterminal with the 3'-end of the genomic RNA, but instead contains heterogeneous poly(A) termini up to 150 nucleotides long (J. Stanley, R. Hanau, and A. O. Jackson, 1984, Virology 139, 375-383). In the genomic RNA gamma, ORF2 is followed by a short poly(A) tract and a 238-nucleotide tRNA-like structure.

Expanded complexity of unstable repeat diseases

PubMed Central

Polak, Urszula; McIvor, Elizabeth; Dent, Sharon Y.R.; Wells, Robert D.; Napierala, Marek

2015-01-01

Unstable Repeat Diseases (URDs) share a common mutational phenomenon of changes in the copy number of short, tandemly repeated DNA sequences. More than 20 human neurological diseases are caused by instability, predominantly expansion, of microsatellite sequences. Changes in the repeat size initiate a cascade of pathological processes, frequently characteristic of a unique disease or a small subgroup of the URDs. Understanding of both the mechanism of repeat instability and molecular consequences of the repeat expansions is critical to developing successful therapies for these diseases. Recent technological breakthroughs in whole genome, transcriptome and proteome analyses will almost certainly lead to new discoveries regarding the mechanisms of repeat instability, the pathogenesis of URDs, and will facilitate development of novel therapeutic approaches. The aim of this review is to give a general overview of unstable repeats diseases, highlight the complexities of these diseases, and feature the emerging discoveries in the field. PMID:23233240

Analyzing repeated measures semi-continuous data, with application to an alcohol dependence study.

PubMed

Liu, Lei; Strawderman, Robert L; Johnson, Bankole A; O'Quigley, John M

2016-02-01

Two-part random effects models (Olsen and Schafer,(1) Tooze et al.(2)) have been applied to repeated measures of semi-continuous data, characterized by a mixture of a substantial proportion of zero values and a skewed distribution of positive values. In the original formulation of this model, the natural logarithm of the positive values is assumed to follow a normal distribution with a constant variance parameter. In this article, we review and consider three extensions of this model, allowing the positive values to follow (a) a generalized gamma distribution, (b) a log-skew-normal distribution, and (c) a normal distribution after the Box-Cox transformation. We allow for the possibility of heteroscedasticity. Maximum likelihood estimation is shown to be conveniently implemented in SAS Proc NLMIXED. The performance of the methods is compared through applications to daily drinking records in a secondary data analysis from a randomized controlled trial of topiramate for alcohol dependence treatment. We find that all three models provide a significantly better fit than the log-normal model, and there exists strong evidence for heteroscedasticity. We also compare the three models by the likelihood ratio tests for non-nested hypotheses (Vuong(3)). The results suggest that the generalized gamma distribution provides the best fit, though no statistically significant differences are found in pairwise model comparisons. © The Author(s) 2012.

Fostering repeat donations in Ghana.

PubMed

Owusu-Ofori, S; Asenso-Mensah, K; Boateng, P; Sarkodie, F; Allain, J-P

2010-01-01

Most African countries are challenged in recruiting and retaining voluntary blood donors by cost and other complexities and in establishing and implementing national blood policies. The availability of replacement donors who are a cheaper source of blood has not enhanced repeat voluntary donor initiatives. An overview of activities for recruiting and retaining voluntary blood donors was carried out. Donor records from mobile sessions were reviewed from 2002 to 2008. A total of 71,701 blood donations; 45,515 (63.5%) being voluntary donations with 11,680 (25%) repeat donations were collected during the study period. Donations from schools and colleges contributed a steady 60% of total voluntary whilst radio station blood drives increased contribution from 10 to 27%. Though Muslim population is less than 20%, blood collection was above the 30-donation cost-effectiveness threshold with a repeat donation trend reaching 60%. In contrast Christian worshippers provided <25 unit/session and 30% repeat donations. Repeat donation trends amongst school donors and radio blood drives were 20% and 70% respectively. Repeat donations rates have been variable amongst different blood donor groups in Kumasi, Ghana. The impact of community leaders in propagating altruism cannot be overemphasized. Programs aiming at motivating replacement donors to be repeat donors should be developed and assessed. Copyright 2009 The International Association for Biologicals. All rights reserved.

Identification and characterization of novel peroxisome proliferator-activated receptor-gamma (PPAR-gamma) transcriptional variants in pig and human.

PubMed

Omi, T; Brenig, B; Spilar Kramer, S; Iwamoto, S; Stranzinger, G; Neuenschwander, S

2005-04-01

The peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a member of the steroid/thyroid/retinoid receptor superfamily, and is primarily expressed in fat tissue. To date, two major PPAR-gamma isoforms have been identified in pig, PPAR-gamma1 and PPAR-gamma2. Porcine PPAR-gamma1a consists of two leader exons, designated A1 and A2, followed by six exons containing the open reading frame. Here, we report the isolation and characterization of three novel PPAR-gamma1 transcripts. PPAR-gamma1b is derived from exon A1, with exon A2 spliced out. PPAR-gamma1c and PPAR-gamma1d are derived from the new exon, A', containing exon A2 (gamma1c) or without exon A2 (gamma1d). Based on PCR analysis of PAC clones that included sequences from the 5'-untranslated region of the PPAR-gamma gene, the new A' exon is located between the known exons A1 and A2. We also isolated the human homologue to exon A', as well as the two new PPAR-gamma1c and -gamma1d splice variants, from human adipose tissue. Studies of the expression of porcine PPAR-gamma by real time reverse transcription-polymerase chain reaction analysis show that transcripts derived from exon A1 were not expressed at significantly different levels in visceral fat (lamina subserosa) or subcutaneous fat (back fat, inner and outer layer). In contrast, exon A'-derived transcripts were expressed at progressively higher levels in the inner and outer layers of subcutaneous fat than in visceral fat. The same expression pattern was also observed for PPAR-gamma2. We hypothesize that there are three promoters, which differentially regulate PPAR-gamma1 and PPAR-gamma2 gene expression, depending on the specific localization of the fat tissue.

Terrestrial Gamma-Ray Flashes (TGFs)

NASA Technical Reports Server (NTRS)

Fishman, Gerald J.

2010-01-01

This slide presentation reviews the observation of Terrestrial Gamma Ray Flashes (TGFs) by Gamma-Ray Telescopes. These were: (1) BATSE /Compton Observatory, (2) Solar Spectroscopic Imager, (3) AGILE Gamma-ray Telescope, and (4) Gamma-ray Burst Monitor (GBM) on the Fermi Gamma-ray Space Telescope. It contains charts which display the counts over time, a map or the TGFs observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI). and a map showing the latitude and longitude of 85 of the TGFs observed by the Fermi GBM.

Gamma ray camera

DOEpatents

Perez-Mendez, Victor

1997-01-01

A gamma ray camera for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array.

Evolution of Protein Domain Repeats in Metazoa

PubMed Central

Schüler, Andreas; Bornberg-Bauer, Erich

2016-01-01

Repeats are ubiquitous elements of proteins and they play important roles for cellular function and during evolution. Repeats are, however, also notoriously difficult to capture computationally and large scale studies so far had difficulties in linking genetic causes, structural properties and evolutionary trajectories of protein repeats. Here we apply recently developed methods for repeat detection and analysis to a large dataset comprising over hundred metazoan genomes. We find that repeats in larger protein families experience generally very few insertions or deletions (indels) of repeat units but there is also a significant fraction of noteworthy volatile outliers with very high indel rates. Analysis of structural data indicates that repeats with an open structure and independently folding units are more volatile and more likely to be intrinsically disordered. Such disordered repeats are also significantly enriched in sites with a high functional potential such as linear motifs. Furthermore, the most volatile repeats have a high sequence similarity between their units. Since many volatile repeats also show signs of recombination, we conclude they are often shaped by concerted evolution. Intriguingly, many of these conserved yet volatile repeats are involved in host-pathogen interactions where they might foster fast but subtle adaptation in biological arms races. Key Words: protein evolution, domain rearrangements, protein repeats, concerted evolution. PMID:27671125

Topological characteristics of helical repeat proteins.

PubMed

Groves, M R; Barford, D

1999-06-01

The recent elucidation of protein structures based upon repeating amino acid motifs, including the armadillo motif, the HEAT motif and tetratricopeptide repeats, reveals that they belong to the class of helical repeat proteins. These proteins share the common property of being assembled from tandem repeats of an alpha-helical structural unit, creating extended superhelical structures that are ideally suited to create a protein recognition interface.

Formation of gamma'-Ni3Al via the Peritectoid Reaction: gamma plus beta (+Al2O3) equals gamma'(+Al2O3)

NASA Technical Reports Server (NTRS)

Copland, Evan

2008-01-01

The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8 - 32 at.%Al and temperature range T = 1400 - 1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma'-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3) = gamma + beta (+ Al2O3), at 1640 plus or minus 1 K and a liquid composition of 24.8 plus or minus 0.2 at.%Al (at an unknown oxygen content). The {gamma + beta + Al2O3} phase field is stable over the temperature range 1633 - 1640 K, and gamma'-Ni3Al forms via the peritectiod, gamma + beta (+ Al2O3) = gamma'(+ Al2O3), at 1633 plus or minus 1 K. This behavior is inconsistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma'-Ni3Al phase field.

Gamma-ray astrophysics

NASA Technical Reports Server (NTRS)

Stecker, F. W. (Editor); Trombka, J. I. (Editor)

1973-01-01

Conference papers on gamma ray astrophysics are summarized. Data cover the energy region from about 0.3 MeV to a few hundred GeV and theoretical models of production mechanisms that give rise to both galactic and extragalactic gamma rays.

The Gamma-ray Universe through Fermi

NASA Technical Reports Server (NTRS)

Thompson, David J.

2012-01-01

Gamma rays, the most powerful form of light, reveal extreme conditions in the Universe. The Fermi Gamma-ray Space Telescope and its smaller cousin AGILE have been exploring the gamma-ray sky for several years, enabling a search for powerful transients like gamma-ray bursts, novae, solar flares, and flaring active galactic nuclei, as well as long-term studies including pulsars, binary systems, supernova remnants, and searches for predicted sources of gamma rays such as dark matter annihilation. Some results include a stringent limit on Lorentz invariance derived from a gamma-ray burst, unexpected gamma-ray variability from the Crab Nebula, a huge ga.nuna-ray structure associated with the center of our galaxy, surprising behavior from some gamma-ray binary systems, and a possible constraint on some WIMP models for dark matter.

Topics in gamma ray astronomy

NASA Technical Reports Server (NTRS)

Ramaty, R.; Lingenfelter, R. E.

1986-01-01

Observations of gamma rays from solar flares, gamma ray bursts, the Galactic center, galactic nucleosynthesis, SS433, and Cygnus X-3, and their effects on astrophysical problems are discussed. It is observed that gamma ray spectra from solar flares are applicable to the study of particle acceleration and confinement and the determination of chemical abundances in the solar atmosphere. The gamma ray lines from the compact galactic object SS433 are utilized to examine the acceleration of jets, and analysis of the gamma ray lines of Cygnus X-3 reveal that particles can be accelerated in compact sources to ultrahigh energies.

A study of interdiffusion in beta + gamma/gamma + gamma prime Ni-Cr-Al. M.S. Thesis. Final Report

NASA Technical Reports Server (NTRS)

Carol, L. A.

1985-01-01

Ternary diffusion in the NiCrAl system at 1200 C was studied with beta + gamma/gamma + gamma prime infinite diffusion couples. Interdiffusion resulted in the formation of complex, multiphase diffusion zones. Concentration/distance profiles for Cr and Al in the phases present in the diffusion zone were measured after 200 hr. The Ni-rich portion of the NiCrAl phase diagram (1200 C) was also determined. From these data, bulk Cr and Al profiles were calculated and translated to diffusion paths on the ternary isotherm. Growth layer kinetics of the layers present in the diffusion zone were also measured.

Neutron monitoring systems including gamma thermometers and methods of calibrating nuclear instruments using gamma thermometers

DOEpatents

Moen, Stephan Craig; Meyers, Craig Glenn; Petzen, John Alexander; Foard, Adam Muhling

2012-08-07

A method of calibrating a nuclear instrument using a gamma thermometer may include: measuring, in the instrument, local neutron flux; generating, from the instrument, a first signal proportional to the neutron flux; measuring, in the gamma thermometer, local gamma flux; generating, from the gamma thermometer, a second signal proportional to the gamma flux; compensating the second signal; and calibrating a gain of the instrument based on the compensated second signal. Compensating the second signal may include: calculating selected yield fractions for specific groups of delayed gamma sources; calculating time constants for the specific groups; calculating a third signal that corresponds to delayed local gamma flux based on the selected yield fractions and time constants; and calculating the compensated second signal by subtracting the third signal from the second signal. The specific groups may have decay time constants greater than 5.times.10.sup.-1 seconds and less than 5.times.10.sup.5 seconds.

On the correlation of angular position with time of occurrence of gamma-ray bursts

NASA Technical Reports Server (NTRS)

Petrosian, Vahe; Efron, Bradley

1995-01-01

Evidence indicating that a large fraction of gamma-ray bursts are repeaters would provide strong support for noncosmological origin of these sources. Wang & Lingenfelter have claimed existance of a correlation between angular position and time of occurrence of bursts. We perform statistical tests and find a marginal evidence for nearby bursts occurring within 4 to 5 days of each other in the BATSE 1B catalog. This evidence is present also in the 2B catalogs, which in addition, shows some marginal evidence for bursts repetition at longer time delays up to the total length of the observations.

Gamma-ray astronomy

NASA Technical Reports Server (NTRS)

Ramaty, R.; Lingenfelter, R. E.

1982-01-01

Cosmic gamma rays, the physical processes responsible for their production and the astrophysical sites from which they were seen are reported. The bulk of the observed gamma ray emission is in the photon energy range from about 0.1 MeV to 1 GeV, where observations are carried out above the atmosphere. There are also, however, gamma ray observations at higher energies obtained by detecting the Cerenkov light produced by the high energy photons in the atmosphere. Gamma ray emission was observed from sources as close as the Sun and the Moon and as distant as the quasar 3C273, as well as from various other galactic and extragalactic sites. The radiation processes also range from the well understood, e.g. energetic particle interactions with matter, to the still incompletely researched, such as radiation transfer in optically thick electron positron plasmas in intense neutron star magnetic fields.

Functional Haplotypes of Fc gamma (Fcγ) receptor (FcγRIIA and FcγRIIIB) predict risk to repeated episodes of severe malarial anemia and mortality in Kenyan children

PubMed Central

Ouma, Collins; Davenport, Gregory C.; Garcia, Steven; Kempaiah, Prakasha; Chaudhary, Ateefa; Were, Tom; Anyona, Samuel B.; Raballah, Evans; Konah, Stephen N.; Hittner, James B.; Vulule, John M.; Ong’echa, John M.; Perkins, Douglas J.

2011-01-01

Development of protective immunity against Plasmodium falciparum is partially mediated through binding of malaria-specific IgG to Fc gamma (γ) receptors. Variation in human FcγRIIA-H/R-131 and FcγRIIIB-NA1/NA2 affect differential binding of IgG sub-classes. Since variability in FcγR may play an important role in severe malarial anemia (SMA) pathogenesis by mediating phagocytosis of red blood cells and triggering cytokine production, the relationship between FcγRIIA-H/R131 and FcγRIIIB-NA1/NA2 haplotypes and susceptibility to SMA (Hb<6.0g/dL) was investigated in Kenyan children (n=528) with acute malaria residing in a holoendemic P. falciparum transmission region. In addition, the association between carriage of the haplotypes and repeated episodes of SMA and all-cause mortality were investigated over a three-year follow-up period. Since variability in FcγR can alter interferon (IFN)-γ production, a mediator of innate and adaptive immune responses, functional associations between the haplotypes and IFN-γ were also explored. During acute malaria, children with SMA had elevated peripheral IFN-γ levels (P=0.006). Although multivariate logistic regression analyses (controlling for covariates) revealed no associations between the FcγR haplotypes and susceptibility to SMA during acute infection, the FcγRIIA-131H/FcγRIIIB-NA1 haplotype was associated with decreased peripheral IFN-γ (P=0.046). Longitudinal analyses showed that carriage of the FcγRIIA-131H/FcγRIIIB-NA1 haplotype was associated with reduced risk of SMA (RR; 0.65, 95%CI, 0.46-0.90; P=0.012) and all-cause mortality (P=0.002). In contrast, carriers of the FcγRIIA-131H/FcγRIIIB-NA2 haplotype had increased susceptibility to SMA (RR; 1.47, 95%CI, 1.06-2.04; P=0.020). Results here demonstrate that variation in the FcγR gene alters susceptibility to repeated episodes of SMA and mortality, as well as functional changes in IFN-γ production. PMID:21818580

Simulated and measured neutron/gamma light output distribution for poly-energetic neutron/gamma sources

NASA Astrophysics Data System (ADS)

Hosseini, S. A.; Zangian, M.; Aghabozorgi, S.

2018-03-01

In the present paper, the light output distribution due to poly-energetic neutron/gamma (neutron or gamma) source was calculated using the developed MCNPX-ESUT-PE (MCNPX-Energy engineering of Sharif University of Technology-Poly Energetic version) computational code. The simulation of light output distribution includes the modeling of the particle transport, the calculation of scintillation photons induced by charged particles, simulation of the scintillation photon transport and considering the light resolution obtained from the experiment. The developed computational code is able to simulate the light output distribution due to any neutron/gamma source. In the experimental step of the present study, the neutron-gamma discrimination based on the light output distribution was performed using the zero crossing method. As a case study, 241Am-9Be source was considered and the simulated and measured neutron/gamma light output distributions were compared. There is an acceptable agreement between the discriminated neutron/gamma light output distributions obtained from the simulation and experiment.

Induction conductivity and natural gamma logs collected in 15 wells at Camp Stanley Storage Activity, Bexar County, Texas

USGS Publications Warehouse

Stanton, Gregory P.

2005-01-01

The U.S. Geological Survey, in cooperation with the Camp Stanley Storage Activity conducted electromagnetic induction conductivity and natural gamma logging of 15 selected wells on the Camp Stanley Storage Activity, located in northern Bexar County, Texas, during March 28–30, 2005. In late 2004, a helicopter electromagnetic survey was flown of the Camp Stanley Storage Activity as part of a U.S. Geological Survey project to better define subsurface geologic units, the structure, and the catchment area of the Trinity aquifer. The electromagnetic induction conductivity and natural gamma log data in this report were collected to constrain the calculation of resistivity depth sections and to provide subsurface controls for interpretation of the helicopter electromagnetic data collected for the Camp Stanley Storage Activity. Logs were recorded digitally while moving the probe in an upward direction to maintain proper depth control. Logging speed was no greater than 30 feet per minute. During logging, a repeat section of at least 100 feet was recorded to check repeatability of log responses. Several of the wells logged were completed with polyvinyl chloride casing that can be penetrated by electromagnetic induction fields and allows conductivity measurement. However, some wells were constructed with steel centralizers and stainless steel screen that caused spikes on both conductivity and resulting resistivity log curves. These responses are easily recognizable and appear at regular intervals on several logs.

Measuring the charged pion polarizability in the gamma gamma -> pi+pi- reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lawrence, David W.; Miskimen, Rory A.; Mushkarenkov, Alexander Nikolaevich

2013-08-01

Development has begun of a new experiment to measure the charged pion polarizabilitymore » $$\\alpha_{\\pi}-\\beta_{\\pi}$$. The charged pion polarizability ranks among the most important tests of low-energy QCD presently unresolved by experiment. Analogous to precision measurements of $$\\pi^{\\circ}\\rightarrow\\gamma\\gamma$$ that test the intrinsic odd-parity (anomalous) sector of QCD, the pion polarizability tests the intrinsic even-parity sector of QCD. The measurement will be performed using the $$\\gamma\\gamma\\rightarrow\\pi^{+{}}\\pi^{-{}}$$ cross section accessed via the Primakoff mechanism on nuclear targets using the GlueX detector in Hall D at Jefferson Lab. The linearly polarized photon source in Hall-D will be utilized to separate the Primakoff cross-section from coherent $$\\rho^{\\circ}$$ production.« less

Future prospects for gamma-ray

NASA Technical Reports Server (NTRS)

Fichtel, C.

1980-01-01

Astrophysical phenomena discussed are: the very energetic and nuclear processes associated with compact objects; astrophysical nucleo-synthesis; solar particle acceleration; the chemical composition of the planets and other bodies of the solar system; the structure of our galaxy; the origin and dynamic pressure effects of the cosmic rays; the high energy particles and energetic processes in other galaxies, especially active ones; and the degree of matter antimater symmetry of the universe. The gamma ray results of GAMMA-I, the gamma ray observatory, the gamma ray burst network, solar polar, and very high energy gamma ray telescopes on the ground provide justification for more sophisticated telescopes.

Gamma ray camera

DOEpatents

Perez-Mendez, V.

1997-01-21

A gamma ray camera is disclosed for detecting rays emanating from a radiation source such as an isotope. The gamma ray camera includes a sensor array formed of a visible light crystal for converting incident gamma rays to a plurality of corresponding visible light photons, and a photosensor array responsive to the visible light photons in order to form an electronic image of the radiation therefrom. The photosensor array is adapted to record an integrated amount of charge proportional to the incident gamma rays closest to it, and includes a transparent metallic layer, photodiode consisting of a p-i-n structure formed on one side of the transparent metallic layer, and comprising an upper p-type layer, an intermediate layer and a lower n-type layer. In the preferred mode, the scintillator crystal is composed essentially of a cesium iodide (CsI) crystal preferably doped with a predetermined amount impurity, and the p-type upper intermediate layers and said n-type layer are essentially composed of hydrogenated amorphous silicon (a-Si:H). The gamma ray camera further includes a collimator interposed between the radiation source and the sensor array, and a readout circuit formed on one side of the photosensor array. 6 figs.

Repeated nightmares

MedlinePlus

Nightmares - repeated; Dream anxiety disorder ... Arnulf I, Nightmares and dream disturbances. In: Kryger M, Roth T, Dement WC, eds. Principles and Practice of Sleep Medicine . 6th ed. Philadelphia, PA: Elsevier; ...

Histaminergic regulation of interferon-gamma (IFN-gamma) production by human natural killer (NK) cells.

PubMed

Asea, A; Hansson, M; Czerkinsky, C; Houze, T; Hermodsson, S; Strannegård, O; Hellstrand, K

1996-08-01

Monocytes, recovered from human peripheral blood by counter-current centrifugal elutriation, effectively inhibit the production of IFN-gamma by CD3-/56+ NK cells in response to IL-2. This study aimed at defining the nature of the inhibitory signal, particularly the importance of monocyte-derived reactive metabolites of oxygen. It was found that monocytes recovered from patients with chronic granulomatous disease (CGD), a condition characterized by deficient NADPH-oxidase activity of phagocytes, did not inhibit IFN-gamma production by NK cells. Further, catalase, a scavenger of hydrogen peroxide, completely reversed the inhibitory signal whereas scavengers of the superoxide anion, hypohalous acids, the hydroxyl radical, or nitric oxide synthesis inhibitors such as L-NMMA were ineffective. Inhibition of IFN-gamma production was operating on a pretranslational level, as indicated by the inability of enriched NK cells to accumulate IFN-gamma mRNA in the presence of elutriated monocytes. Hydrogen peroxide, at micromolar concentrations, reconstituted the inhibition of IFN-gamma production when added to enriched NK cells. Histamine, a biogenic amine which inhibits the generation of reactive oxygen metabolites in monocytes, abrogated the inhibition of IFN-gamma production in NK cells; by this mechanism, histamine strongly synergized with IL-2 to induce IFN-gamma in mixtures of NK cells and monocytes. The synergizing effect of histamine was specifically mediated by H2-type histamine receptors. We conclude that: (i) the induction of IFN-gamma mRNA in NK cells is effectively down-regulated by products of the oxidative metabolism of monocytes; and (ii) histamine effectively enhances IFN-gamma production by preventing monocyte-induced oxidative damage to NK cells.

Swarms of repeating stick-slip glacierquakes triggered by snow loading at Mount Rainier volcano

NASA Astrophysics Data System (ADS)

Allstadt, K.; Malone, S. D.; Shean, D. E.; Fahnestock, M. A.; Vidale, J. E.

2013-12-01

We have detected over 150,000 low-frequency (~1-5 Hz) repeating earthquakes over the past decade at Mount Rainier volcano by scanning continuous seismic data from the permanent seismic network. Most of these were previously undetected due to their small size (M<1), shallow locations, and emergent waveforms. The earthquakes are located high (>3000 m) on the glacier-covered part of the edifice. They occur primarily in week- to month-long swarms of activity that strongly correlate with precipitation, namely snowfall, with a lag of about 1-2 days. Furthermore, there is a linear relationship between inter-event repeat time and the size of the subsequent event - consistent with slip-predictable stick-slip behavior. This pattern suggests that the additional load imparted by the sudden added weight of snow during winter storms triggers a temporary change from smooth aseismic sliding to seismic stick-slip basal sliding in locations where basal conditions are close to frictional instability. This sensitivity is analogous to the triggering of repeating earthquakes due to tiny overall stress changes in more traditional tectonic environments (e.g., tremor modulated by tides, dynamic triggering of repeating earthquakes). Using codawave interferometry on stacks of the repeating waveforms of the families with the most events, we found that the sources move at speeds of ~1 m/day. Using a GAMMA ground based radar interferometer, we collected spatially continuous line-of-sight velocities of several glaciers at Mount Rainier in both summer and late fall. We found that the faster parts of the glaciers also move at ~1 m/day or faster, even in late fall. Movement of the sources of these repeating earthquakes at glacial speeds indicates that the asperities are dirty patches that move with the ice rather than stationary bedrock bumps. The reappearance of some event families up to several years apart suggests that certain areas at the base of certain glaciers are prodigious producers of

Gamma ray astrophysics to the year 2000. Report of the NASA Gamma Ray Program Working Group

NASA Technical Reports Server (NTRS)

1988-01-01

Important developments in gamma-ray astrophysics up to energies of 100 GeV during the last decade are reviewed. Also, the report seeks to define the major current scientific goals of the field and proposes a vigorous program to pursue them, extending to the year 2000. The goals of gamma-ray astronomy include the study of gamma rays which provide the most direct means of studying many important problems in high energy astrophysics including explosive nucleosynthesis, accelerated particle interactions and sources, and high-energy processes around compact objects. The current research program in gamma-ray astronomy in the U.S. including the space program, balloon program and foreign programs in gamma-ray astronomy is described. The high priority recommendations for future study include an Explorer-class high resolution gamma-ray spectroscopy mission and a Get Away Special cannister (GAS-can) or Scout class multiwavelength experiment for the study of gamma-ray bursts. Continuing programs include an extended Gamma Ray Observatory mission, continuation of the vigorous program of balloon observations of the nearby Supernova 1987A, augmentation of the balloon program to provide for new instruments and rapid scientific results, and continuation of support for theoretical research. Long term recommendations include new space missions using advanced detectors to better study gamma-ray sources, the development of these detectors, continued study for the assembly of large detectors in space, collaboration with the gamma-ray astronomy missions initiated by other countries, and consideration of the Space Station attached payloads for gamma-ray experiments.

The effect of alloying on gamma and gamma prime in nickel-base superalloys

NASA Technical Reports Server (NTRS)

Dreshfield, R. L.; Wallace, J. F.

1972-01-01

An investigation was conducted to determine the compositional limits of gamma and gamma prime phases in nickel-base superalloys. Fifty-one nickel-base alloys were melted under vacuum and heat treated for 4 hours at 1190 C followed by 1008 hours at 850 C. The alloys had the following composition ranges: A1 4.0 to 13 atomic percent, Cr 6.5 to 20.5 percent, Ti 0.25 to 4.75 percent, Mo 0.0 to 6.0 percent, and W 0.0 to 4.0 percent. The residues from the ammonium sulfate electrolytic extraction for the two-phase alloys were analyzed chemically and by X-ray diffraction. The results of the investigation were used to assemble a mathematical model of the gamma-gamma prime region of the Ni-Al-Cr-Ti-Mo-W system. A computer program was written to analyze the model of the phase diagram. Some of these results are also presented graphically. The resulting model is capable of satisfactorily predicting the compositions of conjugate gamma-gamma prime phases in the alloys investigated and twelve of fifteen commercial superalloys studied.

Phenotypic characterization of individuals with 30-40 CAG repeats in the Huntington disease (HD) gene reveals HD cases with 36 repeats and apparently normal elderly individuals with 36-39 repeats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rubinsztein, D.C.; Leggo, J.; Whittaker, J.L.

1996-07-01

Abnormal CAG expansions in the IT-15 gene are associated with Huntington disease (HD). In the diagnostic setting it is necessary to define the limits of the CAG size ranges on normal and HD-associated chromosomes. Most large analyses that defined the limits of the normal and pathological size ranges employed PCR assays, which included the CAG repeats and a CCG repeat tract that was thought to be invariant. Many of these experiments found an overlap between the normal and disease size ranges. Subsequent findings that the CCG repeats vary by 9 trinucleotide lengths suggested that the limits of the normal andmore » disease size ranges should be reevaluated with assays that exclude the CCG polymorphism. Since patients with between 30 and 40 repeats are rare, a consortium was assembled to collect such individuals. All 178 samples were reanalyzed in Cambridge by using assays specific for the CAG repeats. We have optimized methods for reliable sizing of CAG repeats and show cases that demonstrate the dangers of using PCR assays that include both the CAG and CCG polymorphisms. Seven HD patients had 36 repeats, which confirms that this allele is associated with disease. Individuals without apparent symptoms or signs of HD were found at 36 repeats (aged 74, 78, 79, and 87 years), 37 repeats (aged 69 years), 38 repeats (aged 69 and 90 years), and 39 repeats (aged 67, 90, and 95 years). The detailed case histories of an exceptional case from this series will be presented: a 95-year-old man with 39 repeats who did not have classical features of HD. The apparently healthy survival into old age of some individuals with 36-39 repeats suggests that the HD mutation may not always be fully penetrant. 26 refs., 3 figs., 1 tab.« less

Status of the GAMMA-400 Project

NASA Technical Reports Server (NTRS)

Galper, A. M.; Adriani, O.; Aptekar, R. L.; Arkhangelskaja, I. V.; Arkhangelskiy, A. I.; Boezio, M.; Bonvicini, V.; Boyarchuk, K. A.; Gusakov, Yu. V.; Farber, M. O.;

Formation of fine {gamma} grain structure through fine {alpha}{sub 2}/{gamma} lamellar structure in Ti-rich TiAl alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kumagai, T.; Abe, E.; Nakamura, M.

1997-12-31

Microstructural development of an extremely fine {alpha}{sub 2}-Ti{sub 32}Al/{gamma}-TiAl lamellar structure, which was formed by ice water quenching after solution-treatment in a high-temperature {alpha}-Ti phase field for a long period of time, was examined during isothermal treatment. In an as-quenched Ti-48at.%Al alloy, the massively transformed {gamma} ({gamma}{sub m}) and untransformed (meaning massively untransformed) fine {alpha}{sub 2}/{gamma} lamellar regions were observed. Fine {gamma} grains, which were similar to {gamma}{sub m}, were generated both within the fine {alpha}{sub 2}/{gamma} lamellae and at the boundary area between the {gamma}{sub m} and the fine {alpha}{sub 2}/{gamma} lamellar regions by aging at low-temperature (1,173 K)more » for a short time (180s). Further aging (1.8ks) caused the coarsening of these newly generated fine {gamma} grains. On the other hand, the coarsening of the {gamma} grains occurred by a high-temperature (1,323 K) aging treatment even for 180s. Fine {alpha}{sub 2} plates and particles, which were aligned to a particular direction, were observed in the {gamma} grain interiors, indicating that the newly generated {gamma} grains grew at the expense of the fine {alpha}{sub 2}/{gamma} lamellae. It can be considered that the {gamma} grain formation through the fine {alpha}{sub 2}/{gamma} lamellae is closely related to the {alpha}{sub 2}{yields}{gamma} reaction of the {alpha}{sub 2} plates sandwiched by the {gamma} plates, and needs the fast heating rate enough to overcome the {alpha}{sub 2}/{gamma}{yields}{gamma}/{gamma} lamellae reaction.« less

Fusion gamma diagnostics

NASA Astrophysics Data System (ADS)

Medley, S. S.; Cecil, F. E.; Cole, D.; Conway, M. A.; Wilkinson, F. J., III

1985-05-01

Nuclear reactions of interest in fusion research often possess a branch yielding prompt emission of gamma radiation in excess of 15 MeV which can be exploited to provide a new fusion reaction diagnostic having applications similar to conventional neutron emission measurements. Conceptual aspects of fusion gamma diagnostics are discussed with emphasis on application to the Tokamak Fusion Test Reactor (TFTR) during deuterium neutral beam heating of D-T and D-3He plasmas. Recent measurements of the D (T, γ)5He, D(3He, γ)5Li, and D(D, γ)4He branching ratios at low center-of-mass energy (30-100 keV) and of the response of a large volume Ne226 detector for gamma detection in high neutron backgrounds are presented. Using a well-shielded Ne226 detector during 20 MW-120 kV deuterium beam heating of a tritium plasma in TFTR, the D(T, γ)5He gamma signal level is estimated to be 3.5×105 cps.

A gamma beam profile imager for ELI-NP Gamma Beam System

NASA Astrophysics Data System (ADS)

Cardarelli, P.; Paternò, G.; Di Domenico, G.; Consoli, E.; Marziani, M.; Andreotti, M.; Evangelisti, F.; Squerzanti, S.; Gambaccini, M.; Albergo, S.; Cappello, G.; Tricomi, A.; Veltri, M.; Adriani, O.; Borgheresi, R.; Graziani, G.; Passaleva, G.; Serban, A.; Starodubtsev, O.; Variola, A.; Palumbo, L.

2018-06-01

The Gamma Beam System of ELI-Nuclear Physics is a high brilliance monochromatic gamma source based on the inverse Compton interaction between an intense high power laser and a bright electron beam with tunable energy. The source, currently being assembled in Magurele (Romania), is designed to provide a beam with tunable average energy ranging from 0.2 to 19.5 MeV, rms energy bandwidth down to 0.5% and flux of about 108 photons/s. The system includes a set of detectors for the diagnostic and complete characterization of the gamma beam. To evaluate the spatial distribution of the beam a gamma beam profile imager is required. For this purpose, a detector based on a scintillator target coupled to a CCD camera was designed and a prototype was tested at INFN-Ferrara laboratories. A set of analytical calculations and Monte Carlo simulations were carried out to optimize the imager design and evaluate the performance expected with ELI-NP gamma beam. In this work the design of the imager is described in detail, as well as the simulation tools used and the results obtained. The simulation parameters were tuned and cross-checked with the experimental measurements carried out on the assembled prototype using the beam from an x-ray tube.

Gamma-Ray Bursts: An Overview

NASA Technical Reports Server (NTRS)

Fishman, Gerald J.

1995-01-01

A history and overview of the observed properties of gamma-ray bursts are presented. The phenomenon of gamma-ray bursts is without precedent in astronomy, having no observed property that would be a direct indicator of their distance and no counterpart object in another wavelength region. Their brief, random appearance only in the gamma-ray region has made their study difficult. The observed time profiles, spectral properties, and durations of gamma-ray bursts cover a wide range. All proposed models for their origin must be considered speculative. It is humbling to think that even after 25 years since their discovery, the distance scale of gamma-ray bursts is still very much debatable.

47 CFR 97.205 - Repeater station.

Code of Federal Regulations, 2013 CFR

2013-10-01

... case, the licensee of the non-coordinated repeater has primary responsibility to resolve the interference. (d) A repeater may be automatically controlled. (e) Ancillary functions of a repeater that are available to users on the input channel are not considered remotely controlled functions of the station...

47 CFR 97.205 - Repeater station.

Code of Federal Regulations, 2014 CFR

2014-10-01

... case, the licensee of the non-coordinated repeater has primary responsibility to resolve the interference. (d) A repeater may be automatically controlled. (e) Ancillary functions of a repeater that are available to users on the input channel are not considered remotely controlled functions of the station...

47 CFR 97.205 - Repeater station.

Code of Federal Regulations, 2012 CFR

2012-10-01

... case, the licensee of the non-coordinated repeater has primary responsibility to resolve the interference. (d) A repeater may be automatically controlled. (e) Ancillary functions of a repeater that are available to users on the input channel are not considered remotely controlled functions of the station...

47 CFR 97.205 - Repeater station.

Code of Federal Regulations, 2011 CFR

2011-10-01

... case, the licensee of the non-coordinated repeater has primary responsibility to resolve the interference. (d) A repeater may be automatically controlled. (e) Ancillary functions of a repeater that are available to users on the input channel are not considered remotely controlled functions of the station...

47 CFR 97.205 - Repeater station.

Code of Federal Regulations, 2010 CFR

2010-10-01

... case, the licensee of the non-coordinated repeater has primary responsibility to resolve the interference. (d) A repeater may be automatically controlled. (e) Ancillary functions of a repeater that are available to users on the input channel are not considered remotely controlled functions of the station...

High energy gamma ray astronomy

NASA Technical Reports Server (NTRS)

Fichtel, Carl E.

1987-01-01

High energy gamma ray astronomy has evolved with the space age. Nonexistent twenty-five years ago, there is now a general sketch of the gamma ray sky which should develop into a detailed picture with the results expected to be forthcoming over the next decade. The galactic plane is the dominant feature of the gamma ray sky, the longitude and latitude distribution being generally correlated with galactic structural features including the spiral arms. Two molecular clouds were already seen. Two of the three strongest gamma ray sources are pulsars. The highly variable X-ray source Cygnus X-3 was seen at one time, but not another in the 100 MeV region, and it was also observed at very high energies. Beyond the Milky Way Galaxy, there is seen a diffuse radiation, whose origin remains uncertain, as well as at least one quasar, 3C 273. Looking to the future, the satellite opportunities for high energy gamma ray astronomy in the near term are the GAMMA-I planned to be launched in late 1987 and the Gamma Ray Observatory, scheduled for launch in 1990. The Gamma Ray Observatory will carry a total of four instruments covering the entire energy range from 30,000 eV to 3 x 10 to the 10th eV with over an order of magnitude increase in sensitivity relative to previous satellite instruments.

GammaM23K, gammaM232K, and gammaL77K single substitutions in the TF1-ATPase lower ATPase activity by disrupting a cluster of hydrophobic side chains.

PubMed

Bandyopadhyay, Sanjay; Allison, William S

2004-07-27

In crystal structures of the bovine F(1)-ATPase (MF(1)), the side chains of gammaMet(23), gammaMet(232), and gammaLeu(77) interact in a cluster. Substitution of the corresponding residues in the alpha(3)beta(3)gamma subcomplex of TF(1) with lysine lowers the ATPase activity to 2.3, 11, and 15%, respectively, of that displayed by wild-type. In contrast, TF(1) subcomplexes containing the gammaM(23)C, gammaM(232)C, and gammaL(77)C substitutions display 36, 36, and 130%, respectively, of the wild-type ATPase activity. The ATPase activity of the gammaM(23)C/gammaM(232)C double mutant subcomplex is 36% that of the wild-type subcomplex before and after cross-linking the introduced cysteines, whereas the ATPase activity of the gammaM(23)C/L(77)C double mutant increased from 50 to 85% that of wild-type after cross-linking the introduced cysteines. Only beta-beta cross-links formed when the alpha(3)(betaE(395)C)(3)gammaM(23)C double mutant was inactivated with CuCl(2). The overall results suggest that the attenuated ATPase of the mutant subcomplexes containing the gammaM(23)K, gammaL(77)K, and gammaM(232)K substitutions is caused by disruption of the cluster of hydrophobic amino acid side chains and that the midregion of the coiled-coil comprised of the amino- and carboxyl-terminal alpha helices of the gamma subunit does not undergo unwinding or major displacement from the side chain of gammaLeu(77) during ATP-driven rotation of the gamma subunit.

Compton Gamma-Ray Observatory

NASA Technical Reports Server (NTRS)

1991-01-01

This photograph shows the Compton Gamma-Ray Observatory (GRO) being deployed by the Remote Manipulator System (RMS) arm aboard the Space Shuttle Atlantis during the STS-37 mission in April 1991. The GRO reentered Earth atmosphere and ended its successful mission in June 2000. For nearly 9 years, the GRO Burst and Transient Source Experiment (BATSE), designed and built by the Marshall Space Flight Center (MSFC), kept an unblinking watch on the universe to alert scientists to the invisible, mysterious gamma-ray bursts that had puzzled them for decades. By studying gamma-rays from objects like black holes, pulsars, quasars, neutron stars, and other exotic objects, scientists could discover clues to the birth, evolution, and death of stars, galaxies, and the universe. The gamma-ray instrument was one of four major science instruments aboard the Compton. It consisted of eight detectors, or modules, located at each corner of the rectangular satellite to simultaneously scan the entire universe for bursts of gamma-rays ranging in duration from fractions of a second to minutes. In January 1999, the instrument, via the Internet, cued a computer-controlled telescope at Las Alamos National Laboratory in Los Alamos, New Mexico, within 20 seconds of registering a burst. With this capability, the gamma-ray experiment came to serve as a gamma-ray burst alert for the Hubble Space Telescope, the Chandra X-Ray Observatory, and major gound-based observatories around the world. Thirty-seven universities, observatories, and NASA centers in 19 states, and 11 more institutions in Europe and Russia, participated in the BATSE science program.

Compton Gamma-Ray Observatory

NASA Technical Reports Server (NTRS)

1991-01-01

This photograph shows the Compton Gamma-Ray Observatory being released from the Remote Manipulator System (RMS) arm aboard the Space Shuttle Atlantis during the STS-35 mission in April 1991. The GRO reentered the Earth's atmosphere and ended its successful mission in June 2000. For nearly 9 years, GRO's Burst and Transient Source Experiment (BATSE), designed and built by the Marshall Space Flight Center, kept an unblinking watch on the universe to alert scientist to the invisible, mysterious gamma-ray bursts that had puzzled them for decades. By studying gamma-rays from objects like black holes, pulsars, quasars, neutron stars, and other exotic objects, scientists could discover clues to the birth, evolution, and death of star, galaxies, and the universe. The gamma-ray instrument was one of four major science instruments aboard the Compton. It consisted of eight detectors, or modules, located at each corner of the rectangular satellite to simultaneously scan the entire universe for bursts of gamma-rays ranging in duration from fractions of a second to minutes. In January 1999, the instrument, via the Internet, cued a computer-controlled telescope at Las Alamos National Laboratory in Los Alamos, New Mexico, within 20 seconds of registering a burst. With this capability, the gamma-ray experiment came to serve as a gamma-ray burst alert for the Hubble Space Telescope, the Chandra X-Ray Observatory, and major gound-based observatories around the world. Thirty-seven universities, observatories, and NASA centers in 19 states, and 11 more institutions in Europe and Russia, participated in BATSE's science program.

Gamma Oscillations and Visual Binding

NASA Astrophysics Data System (ADS)

Robinson, Peter A.; Kim, Jong Won

2006-03-01

At the root of visual perception is the mechanism the brain uses to analyze features in a scene and bind related ones together. Experiments show this process is linked to oscillations of brain activity in the 30-100 Hz gamma band. Oscillations at different sites have correlation functions (CFs) that often peak at zero lag, implying simultaneous firing, even when conduction delays are large. CFs are strongest between cells stimulated by related features. Gamma oscillations are studied here by modeling mm-scale patchy interconnections in the visual cortex. Resulting predictions for gamma responses to stimuli account for numerous experimental findings, including why oscillations and zero-lag synchrony are associated, observed connections with feature preferences, the shape of the zero-lag peak, and variations of CFs with attention. Gamma waves are found to obey the Schroedinger equation, opening the possibility of cortical analogs of quantum phenomena. Gamma instabilities are tied to observations of gamma activity linked to seizures and hallucinations.

Space instrumentation for gamma-ray astronomy

NASA Astrophysics Data System (ADS)

Teegarden, B. J.

1999-02-01

The decade of the 1990s has witnessed a renaissance in the field of gamma-ray astronomy. The seminal event was the launch of the Compton Gamma-Ray Observatory (CGRO) in April 1991. There have been a flood of major discoveries from CGRO including breakthroughs in gamma-ray bursts, annihilation radiation, and blazars. The Italian SAX satellite was launched in April 1996. Although not primarily a gamma-ray mission, it has added a new dimension to our understanding of gamma-ray bursts. Along with these new discoveries a firm groundwork has been laid for missions and new technology development that should maintain a healthy and vigorous field throughout most of the next decade. These include the ESA INTEGRAL mission (INTErnational Gamma-Ray Astrophysics Laboratory, to be launched in mid-2001) and the NASA GLAST mission (Gamma-Ray Large Area Space Telescope) with a likely launch in the middle of the next decade. These two missions will extend the observational capabilities well beyond those of CGRO. New technologies (to gamma-ray astronomy), such as cooled germanium detectors, silicon strip detectors, and CdTe detectors are planned for these new missions. Additional promising new technologies such as CdZnTe strip detectors, scintillator fibers, and a gamma-ray lens for future gamma-ray astronomy missions are under development in laboratories around the world.

The fast detection of rare auditory feature conjunctions in the human brain as revealed by cortical gamma-band electroencephalogram.

PubMed

Ruusuvirta, T; Huotilainen, M

2005-01-01

Natural environments typically contain temporal scatters of sounds emitted from multiple sources. The sounds may often physically stand out from one another in their conjoined rather than simple features. This poses a particular challenge for the brain to detect which of these sounds are rare and, therefore, potentially important for survival. We recorded gamma-band (32-40 Hz) electroencephalographic (EEG) oscillations from the scalp of adult humans who passively listened to a repeated tone carrying frequent and rare conjunctions of its frequency and intensity. EEG oscillations that this tone induced, rather than evoked, differed in amplitude between the two conjunction types within the 56-ms analysis window from tone onset. Our finding suggests that, perhaps with the support of its non-phase-locked synchrony in the gamma band, the human brain is able to detect rare sounds as feature conjunctions very rapidly.

A new measurement of the rare decay eta -> pi^0 gamma gamma with the Crystal Ball/TAPS detectors at the Mainz Microtron

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nefkens, B M; Prakhov, S; Aguar-Bartolom��, P

2014-08-01

A new measurement of the rare, doubly radiative decay eta->pi^0 gamma gamma was conducted with the Crystal Ball and TAPS multiphoton spectrometers together with the photon tagging facility at the Mainz Microtron MAMI. New data on the dependence of the partial decay width, Gamma(eta->pi^0 gamma gamma), on the two-photon invariant mass squared, m^2(gamma gamma), as well as a new, more precise value for the decay width, Gamma(eta->pi^0 gamma gamma) = (0.33+/-0.03_tot) eV, are based on analysis of 1.2 x 10^3 eta->pi^0 gamma gamma decays from a total of 6 x 10^7 eta mesons produced in the gamma p -> etamore » p reaction. The present results for dGamma(eta->pi^0 gamma gamma)/dm^2(gamma gamma) are in good agreement with previous measurements and recent theoretical calculations for this dependence.« less

Formation of gamma(sup prime)-Ni3Al via the Peritectoid Reaction: gamma + beta (+ Al2O3)=gamma(sup prime)(+ Al2O3)

NASA Technical Reports Server (NTRS)

Copeland, Evan

2008-01-01

The activities of Al and Ni were measured using multi-cell Knudsen effusion-cell mass spectrometry (multi-cell KEMS), over the composition range 8-32 at.%Al and temperature range T=1400-1750 K in the Ni-Al-O system. These measurements establish that equilibrium solidification of gamma(sup prime)-Ni3Al-containing alloys occurs by the eutectic reaction, L (+ Al2O3)=gamma + Beta(+ Al2O3), at 1640 +/- 1 K and a liquid composition of 24.8 +/- 0.2 at.%al (at an unknown oxygen content). The {gamma + Beta (+Al2O3} phase field is stable over the temperature range 1633-1640 K, and gamma(sup prime)-Ni3Al forms via the peritectoid, gamma + Beta (+ Al2O3)=gamma(sup prime) (+ Al2O3), at 1633 +/- 1 K. This behavior is consistent with the current Ni-Al phase diagram and a new diagram is proposed. This new Ni-Al phase diagram explains a number of unusual steady-state solidification structures reported previously and provides a much simpler reaction scheme in the vicinity of the gamma(sup prime)-Ni2Al phase field.

Evaluation of gamma interferon (IFN-gamma)-induced protein 10 (IP-10) responses for detection of cattle infected with Mycobacterium bovis: comparisons to IFN-gamma responses

USDA-ARS?s Scientific Manuscript database

Gamma interferon (IFN-gamma)-induced protein 10 (IP-10) has recently shown promise as a diagnostic biomarker of Mycobacterium tuberculosis infection of humans. The aim of the current study was to compare IP-10 and IFN-gamma responses upon Mycobacterium bovis infection in cattle using archived sample...

Cell death is induced by ciglitazone, a peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) agonist, independently of PPAR{gamma} in human glioma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Myoung Woo; Kim, Dae Seong; Kim, Hye Ryung

Highlights: Black-Right-Pointing-Pointer Greater than 30 {mu}M ciglitazone induces cell death in glioma cells. Black-Right-Pointing-Pointer Cell death by ciglitazone is independent of PPAR{gamma} in glioma cells. Black-Right-Pointing-Pointer CGZ induces cell death by the loss of MMP via decreased Akt. -- Abstract: Peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) regulates multiple signaling pathways, and its agonists induce apoptosis in various cancer cells. However, their role in cell death is unclear. In this study, the relationship between ciglitazone (CGZ) and PPAR{gamma} in CGZ-induced cell death was examined. At concentrations of greater than 30 {mu}M, CGZ, a synthetic PPAR{gamma} agonist, activated caspase-3 and induced apoptosis inmore » T98G cells. Treatment of T98G cells with less than 30 {mu}M CGZ effectively induced cell death after pretreatment with 30 {mu}M of the PPAR{gamma} antagonist GW9662, although GW9662 alone did not induce cell death. This cell death was also observed when cells were co-treated with CGZ and GW9662, but was not observed when cells were treated with CGZ prior to GW9662. In cells in which PPAR{gamma} was down-regulated cells by siRNA, lower concentrations of CGZ (<30 {mu}M) were sufficient to induce cell death, although higher concentrations of CGZ ( Greater-Than-Or-Slanted-Equal-To 30 {mu}M) were required to induce cell death in control T98G cells, indicating that CGZ effectively induces cell death in T98G cells independently of PPAR{gamma}. Treatment with GW9662 followed by CGZ resulted in a down-regulation of Akt activity and the loss of mitochondrial membrane potential (MMP), which was accompanied by a decrease in Bcl-2 expression and an increase in Bid cleavage. These data suggest that CGZ is capable of inducing apoptotic cell death independently of PPAR{gamma} in glioma cells, by down-regulating Akt activity and inducing MMP collapse.« less

Mechanical unfolding of an ankyrin repeat protein.

PubMed

Serquera, David; Lee, Whasil; Settanni, Giovanni; Marszalek, Piotr E; Paci, Emanuele; Itzhaki, Laura S

2010-04-07

Ankryin repeat proteins comprise tandem arrays of a 33-residue, predominantly alpha-helical motif that stacks roughly linearly to produce elongated and superhelical structures. They function as scaffolds mediating a diverse range of protein-protein interactions, and some have been proposed to play a role in mechanical signal transduction processes in the cell. Here we use atomic force microscopy and molecular-dynamics simulations to investigate the natural 7-ankyrin repeat protein gankyrin. We find that gankyrin unfolds under force via multiple distinct pathways. The reactions do not proceed in a cooperative manner, nor do they always involve fully stepwise unfolding of one repeat at a time. The peeling away of half an ankyrin repeat, or one or more ankyrin repeats, occurs at low forces; however, intermediate species are formed that are resistant to high forces, and the simulations indicate that in some instances they are stabilized by nonnative interactions. The unfolding of individual ankyrin repeats generates a refolding force, a feature that may be more easily detected in these proteins than in globular proteins because the refolding of a repeat involves a short contraction distance and incurs a low entropic cost. We discuss the origins of the differences between the force- and chemical-induced unfolding pathways of ankyrin repeat proteins, as well as the differences between the mechanics of natural occurring ankyrin repeat proteins and those of designed consensus ankyin repeat and globular proteins. Copyright (c) 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Comparative gene expression profiles induced by PPAR{gamma} and PPAR{alpha}/{gamma} agonists in rat hepatocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogue, Alexandra; Universite de Rennes 1, 35065 Rennes Cedex; Biologie Servier, 45520 Gidy

2011-07-01

Species-differential toxic effects have been described with PPAR{alpha} and PPAR{gamma} agonists between rodent and human liver. PPAR{alpha} agonists (fibrates) are potent hypocholesterolemic agents in humans while they induce peroxisome proliferation and tumors in rodent liver. By contrast, PPAR{gamma} agonists (glitazones) and even dual PPAR{alpha}/{gamma} agonists (glitazars) have caused idiosyncratic hepatic and nonhepatic toxicities in human without evidence of any damage in rodent during preclinical studies. The mechanisms involved in such differences remain largely unknown. Several studies have identified the major target genes of PPAR{alpha} agonists in rodent liver while no comprehensive analysis has been performed on gene expression changes inducedmore » by PPAR{gamma} and dual PPAR{alpha}/{gamma} agonists. Here, we investigated transcriptomes of rat hepatocytes after 24 h treatment with two PPAR{gamma} (troglitazone and rosiglitazone) and two PPAR{alpha}/{gamma} (muraglitazar and tesaglitazar) agonists. Although, hierarchical clustering revealed a gene expression profile characteristic of each PPAR agonist class, only a limited number of genes was specifically deregulated by glitazars. Functional analyses showed that many genes known as PPAR{alpha} targets were also modulated by both PPAR{gamma} and PPAR{alpha}/{gamma} agonists and quantitative differences in gene expression profiles were observed between these two classes. Moreover, most major genes modulated in rat hepatocytes were also found to be deregulated in rat liver after tesaglitazar treatment. Taken altogether, these results support the conclusion that differential toxic effects of PPAR{alpha} and PPAR{gamma} agonists in rodent liver do not result from transcriptional deregulation of major PPAR target genes but rather from qualitative and/or quantitative differential responses of a small subset of genes.« less

Gamma Ray Pulsars: Multiwavelength Observations

NASA Technical Reports Server (NTRS)

Thompson, David J.

2004-01-01

High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The seven or more pulsars seen by instruments on the Compton Gamma Ray Observatory (CGRO) show that: the light curves usually have double-peak structures (suggesting a broad cone of emission); gamma rays are frequently the dominant component of the radiated power; and all the spectra show evidence of a high-energy turnover. For all the known gamma-ray pulsars, multiwavelength observations and theoretical models based on such observations offer the prospect of gaining a broad understanding of these rotating neutron stars. The Gamma-ray Large Area Space Telescope (GLAST), now in planning for a launch in 2006, will provide a major advance in sensitivity, energy range, and sky coverage.

Chromosomal localization and partial genomic structure of the human peroxisome proliferator activated receptor-gamma (hPPAR gamma) gene.

PubMed

Beamer, B A; Negri, C; Yen, C J; Gavrilova, O; Rumberger, J M; Durcan, M J; Yarnall, D P; Hawkins, A L; Griffin, C A; Burns, D K; Roth, J; Reitman, M; Shuldiner, A R

1997-04-28

We determined the chromosomal localization and partial genomic structure of the coding region of the human PPAR gamma gene (hPPAR gamma), a nuclear receptor important for adipocyte differentiation and function. Sequence analysis and long PCR of human genomic DNA with primers that span putative introns revealed that intron positions and sizes of hPPAR gamma are similar to those previously determined for the mouse PPAR gamma gene[13]. Fluorescent in situ hybridization localized hPPAR gamma to chromosome 3, band 3p25. Radiation hybrid mapping with two independent primer pairs was consistent with hPPAR gamma being within 1.5 Mb of marker D3S1263 on 3p25-p24.2. These sequences of the intron/exon junctions of the 6 coding exons shared by hPPAR gamma 1 and hPPAR gamma 2 will facilitate screening for possible mutations. Furthermore, D3S1263 is a suitable polymorphic marker for linkage analysis to evaluate PPAR gamma's potential contribution to genetic susceptibility to obesity, lipoatrophy, insulin resistance, and diabetes.

Structure and creep rupture properties of directionally solidified eutectic gamma/gamma-prime-alpha alloy

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.; Wirth, G.

1982-01-01

A simple ternary gamma/gamma-prime-alpha alloy of nominal composition (wt-%) Ni-32Mo-6Al has been directionally solidified at 17 mm/h and tested in creep rupture at 1073, 1173, and 1273 K. A uniform microstructure consisting of square-shaped Mo fibers in a gamma + gamma-prime matrix was found despite some variation in the molybdenum and aluminum concentrations along the growth direction. Although the steady-state creep rate is well described by the normal stress temperature equation, the stress exponent (12) and the activation energy (580 kJ/mol) are high. The rupture behavior is best characterized by the Larson-Miller parameter where the constant equals 20.

The development of gamma-gamma-prime lamellar structures in a nickel-base superalloy during elevated temperature mechanical testing

NASA Technical Reports Server (NTRS)

Mackay, R. A.; Ebert, L. J.

1985-01-01

The kinetics of the formation and subsequent development of the directional coarsening of the gamma-prime precipitate in model Ni-Al-Mo-Ta superalloy single crystals are examined during tensile creep under various stress levels at 982 and 1038 C. Special attention is given to the gamma and gamma-prime relation to creep time and strain in order to trace the changing gamma-gamma-prime morphology. Directional coarsening of gamma-prime is found to begin during primary creep and its rate is shown to increase with an increase in temperature or stress level. The length of gamma-prime thickness increased linearly with time up to a plateau reached after the onset of steady state creep. The raft thickness, equal to the gamma-prime size, remained constant at this initial value up through the onset of the tertiary creep. The interlaminar spacing indicates the stability of directionally coarsened structure.

A Comprehensive Study of Short Bursts from SGR1806-20 and SGR1900+14 Detected by HETE-2

NASA Astrophysics Data System (ADS)

Nakagawa, Yujin E.; Yoshida, Atsumasa; Hurley, Kevin; Atteia, Jean-Luc; Maetou, Miki; Tamagawa, Toru; Suzuki, Motoko; Yamazaki, Tohru; Tanaka, Kaoru; Kawai, Nobuyuki; Shirasaki, Yuji; Pelangeon, Alexandre; Matsuoka, Masaru; Vanderspek, Roland; Crew, Geoff B.; Villasenor, Joel S.; Sato, Rie; Sugita, Satoshi; Kotoku, Jun'ichi; Arimoto, Makoto; Pizzichini, Graziella; Doty, John P.; Ricker, George R.

2007-06-01

Temporal and spectral studies of short bursts (≲ a few hundred milliseconds) are presented for the soft gamma repeaters (SGRs) 1806-20 and 1900+14 using the HETE-2 samples. In five years from 2001 to 2005, HETE-2 localized 50 bursts from SGR1806-20 and 5 bursts from SGR1900+14. The cumulative number-intensity distribution of SGR1806-20 in the active year 2004 is well described by a power-law model with an index of -1.1±0.6. It is consistent with previous studies, but burst data taken in other years clearly give a steeper distribution. This may suggest that more energetic bursts could occur more frequently in periods of greater activity. From the data, the spectral evolution during bursts with a time scale of ≳ 20ms does not seem to be common in the HETE-2 sample. The spectra of all short bursts are well reproduced by a two blackbody function with temperatures of ˜ 4 and ˜ 11keV. From a timing analysis to the SGR1806-20 data, a time lag of 2.2±0.4ms is found between the 30-100keV and 2-10keV radiation bands. This may imply (1) a very rapid spectral softening and energy reinjection, (2) diffused (elongated) emission plasma along the magnetic field lines in pseudo-equilibrium with multi-temperatures, or (3) a separate (located at ≲ 700km) emission region of a softer component (say, ˜ 4keV), which could be reprocessed X-rays by higher energy (≳ 11keV) photons from an emission region near the stellar surface.

Magnetars: the physics behind observations. A review.

PubMed

Turolla, R; Zane, S; Watts, A L

2015-11-01

Magnetars are the strongest magnets in the present universe and the combination of extreme magnetic field, gravity and density makes them unique laboratories to probe current physical theories (from quantum electrodynamics to general relativity) in the strong field limit. Magnetars are observed as peculiar, burst-active x-ray pulsars, the anomalous x-ray pulsars (AXPs) and the soft gamma repeaters (SGRs); the latter emitted also three 'giant flares', extremely powerful events during which luminosities can reach up to 10(47) erg s(-1) for about one second. The last five years have witnessed an explosion in magnetar research which has led, among other things, to the discovery of transient, or 'outbursting', and 'low-field' magnetars. Substantial progress has been made also on the theoretical side. Quite detailed models for explaining the magnetars' persistent x-ray emission, the properties of the bursts, the flux evolution in transient sources have been developed and confronted with observations. New insight on neutron star asteroseismology has been gained through improved models of magnetar oscillations. The long-debated issue of magnetic field decay in neutron stars has been addressed, and its importance recognized in relation to the evolution of magnetars and to the links among magnetars and other families of isolated neutron stars. The aim of this paper is to present a comprehensive overview in which the observational results are discussed in the light of the most up-to-date theoretical models and their implications. This addresses not only the particular case of magnetar sources, but the more fundamental issue of how physics in strong magnetic fields can be constrained by the observations of these unique sources.

Magnetars: the physics behind observations. A review

NASA Astrophysics Data System (ADS)

Turolla, R.; Zane, S.; Watts, A. L.

2015-11-01

Magnetars are the strongest magnets in the present universe and the combination of extreme magnetic field, gravity and density makes them unique laboratories to probe current physical theories (from quantum electrodynamics to general relativity) in the strong field limit. Magnetars are observed as peculiar, burst-active x-ray pulsars, the anomalous x-ray pulsars (AXPs) and the soft gamma repeaters (SGRs); the latter emitted also three ‘giant flares’, extremely powerful events during which luminosities can reach up to 1047erg s-1 for about one second. The last five years have witnessed an explosion in magnetar research which has led, among other things, to the discovery of transient, or ‘outbursting’, and ‘low-field’ magnetars. Substantial progress has been made also on the theoretical side. Quite detailed models for explaining the magnetars’ persistent x-ray emission, the properties of the bursts, the flux evolution in transient sources have been developed and confronted with observations. New insight on neutron star asteroseismology has been gained through improved models of magnetar oscillations. The long-debated issue of magnetic field decay in neutron stars has been addressed, and its importance recognized in relation to the evolution of magnetars and to the links among magnetars and other families of isolated neutron stars. The aim of this paper is to present a comprehensive overview in which the observational results are discussed in the light of the most up-to-date theoretical models and their implications. This addresses not only the particular case of magnetar sources, but the more fundamental issue of how physics in strong magnetic fields can be constrained by the observations of these unique sources.

The gamma-aminobutyric acid type B (GABAB) receptor agonist baclofen inhibits morphine sensitization by decreasing the dopamine level in rat nucleus accumbens

PubMed Central

2012-01-01

Background Repeated morphine exposure can induce behavioral sensitization. There are evidences have shown that central gamma-aminobutyric acid (GABA) system is involved in morphine dependence. However, the effect of a GABAB receptor agonist baclofen on morphine-induced behavioral sensitization in rats is unclear. Methods We used morphine-induced behavioral sensitization model in rat to investigate the effects of baclofen on behavioral sensitization. Moreover, dopamine release in the shell of the nucleus accumbens was evaluated using microdialysis assay in vivo. Results The present study demonstrated that morphine challenge (3 mg/kg, s.c.) obviously enhanced the locomotor activity following 4-day consecutive morphine administration and 3-day withdrawal period, which indicated the expression of morphine sensitization. In addition, chronic treatment with baclofen (2.5, 5 mg/kg) significantly inhibited the development of morphine sensitization. It was also found that morphine challenge 3 days after repeated morphine administration produced a significant increase of extracellular dopamine release in nucleus accumbens. Furthermore, chronic treatment with baclofen decreased the dopamine release induced by morphine challenge. Conclusions Our results indicated that gamma-aminobutyric acid system plays an important role in the morphine sensitization in rat and suggested that behavioral sensitization is a promising model to study the mechanism underlying drug abuse. PMID:22559224

Gamma-hadron families and scaling violation

NASA Technical Reports Server (NTRS)

Gaisser, T. K.; Stanev, T.; Wrotniak, J. A.

1985-01-01

For three different interaction models we have simulated gamma-hadron families, including the detector (Pamir emulsion chamber) response. Rates of gamma families, hadrons, and hadron-gamma ratios were compared with experiments.

Repeated vitrification/warming of human sperm gives better results than repeated slow programmable freezing

PubMed Central

Vutyavanich, Teraporn; Lattiwongsakorn, Worashorn; Piromlertamorn, Waraporn; Samchimchom, Sudarat

2012-01-01

In this study, we compared the effects of repeated freezing/thawing of human sperm by our in-house method of rapid freezing with slow programmable freezing. Sperm samples from 11 normozoospermic subjects were processed through density gradients and divided into three aliquots: non-frozen, rapid freezing and slow programmable freezing. Sperm in the rapid freezing group had better motility and viability than those in the slow freezing group (P<0.01) after the first, second and third cycles of freezing/thawing, but there was no difference in morphology. In the second experiment, rapid freezing was repeated three times in 20 subjects. The samples from each thawing cycle were evaluated for DNA fragmentation using the alkaline comet assay. DNA fragmentation began to increase considerably after the second cycle of freezing/thawing, but to a level that was not clinically important. In the third experiment, rapid freezing was done repeatedly in 10 subjects, until no motile sperm were observed after thawing. The median number of repeated freezing/thawing that yielded no motile sperm was seven (range: 5–8, mean: 6.8). In conclusion, we demonstrated that repeated freezing/thawing of processed semen using our rapid freezing method gave better results than standard slow programmable freezing. This method can help maximize the usage of precious cryopreserved sperm samples in assisted reproduction technology. PMID:23064685

The Gamma-Ray Imager GRI

NASA Astrophysics Data System (ADS)

Wunderer, Cornelia B.; GRI Collaboration

2006-09-01

Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe. While at lower wavebands the observed emission is generally dominated by thermal processes, the gamma-ray sky provides us with a view on the non-thermal Universe. Here particles are accelerated to extreme relativistic energies by mechanisms which are still poorly understood, and nuclear reactions are synthesizing the basic constituents of our world. Cosmic accelerators and cosmic explosions are the major science themes that are addressed in the gamma-ray regime. With the INTEGRAL observatory, ESA has provided a unique tool to the astronomical community revealing hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes. While INTEGRAL provides the global overview over the soft gamma-ray sky, there is a growing need to perform deeper, more focused investigations of gamma-ray sources. In soft X-rays a comparable step was taken going from the Einstein and the EXOSAT satellites to the Chandra and XMM/Newton observatories. Technological advances in the past years in the domain of gamma-ray focusing using Laue diffraction and multilayer coated mirror techniques have paved the way towards a gamma-ray mission, providing major improvements compared to past missions regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow to study particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.

The Andromeda galaxy in gamma-rays

NASA Technical Reports Server (NTRS)

Oezel, M. E.; Berkhuijsen, E. M.

1987-01-01

Implications of high-energy gamma-ray observations of the Andromeda galaxy with the next generation of satellites Gamma-1 and GRO are discussed in the context of the origin of cosmic rays and gamma-ray processes. The present estimate of the total gamma-ray flux of this galaxy at energies above 100 MeV is a factor of about three less than previous estimates.

Directional gamma detector

DOEpatents

LeVert, Francis E.; Cox, Samson A.

1981-01-01

An improved directional gamma radiation detector has a collector sandwiched etween two layers of insulation of varying thicknesses. The collector and insulation layers are contained within an evacuated casing, or emitter, which releases electrons upon exposure to gamma radiation. Delayed electrons and electrons entering the collector at oblique angles are attenuated as they pass through the insulation layers on route to the collector.

Gamma ray pulsars

NASA Technical Reports Server (NTRS)

Oegelman, H.; Ayasli, S.; Hacinliyan, A.

1976-01-01

Recent data from the high energy gamma ray experiment have revealed the existence of four pulsars emitting photons above 35 MeV. An attempt is made to explain the gamma ray emission from these pulsars in terms of an electron-photon cascade that develops in the magnetosphere of the pulsar. Although there is very little material above the surface of the pulsar, the very intense magnetic fields correspond to many radiation lengths which cause electrons to emit photons via magnetic bremsstrahlung and these photons to pair produce. The cascade develops until the mean photon energy drops below the pair production threshold which happens to be in the gamma ray range; at this stage the photons break out from the source.

Highlights of GeV Gamma-Ray Astronomy

NASA Technical Reports Server (NTRS)

Thompson, David J.

2010-01-01

Because high-energy gamma rays are primarily produced by high-energy particle interactions, the gamma-ray survey of the sky by the Fermi Gamma-ray Space Telescope offers a view of sites of cosmic ray production and interactions. Gamma-ray bursts, pulsars, pulsar wind nebulae, binary sources, and Active Galactic Nuclei are all phenomena that reveal particle acceleration through their gamma-ray emission. Diffuse Galactic gamma radiation, Solar System gamma-ray sources, and energetic radiation from supernova remnants are likely tracers of high-energy particle interactions with matter and photon fields. This paper will present a broad overview of the constantly changing sky seen with the Large Area Telescope (LAT) on the Fermi spacecraft.

Hard gamma radiation background from coding collimator of gamma telescope under space experiment conditions

NASA Astrophysics Data System (ADS)

Aleksandrov, A. P.; Berezovoy, A. N.; Galper, A. M.; Grachev, V. M.; Dmitrenko, V. V.; Kirillov-Ugryumov, V. G.; Lebedev, V. V.; Lyakhov, V. A.; Moiseyev, A. A.; Ulin, S. Y.

1985-09-01

Coding collimators are used to improve the angular resolution of gamma-ray telescopes at energies above 50 MeV. However, the interaction of cosmic rays with the collimation material can lead to the appearance of a gamma-ray background flux which can have a deleterious effect on measurement efficiency. An experiment was performed on the Salyut-6-Soyuz spacecraft system with the Elena-F small-scale gamma-ray telescope in order to measure the magnitude of this background. It is shown that, even at a zenith angle of approximately zero degrees (the angle at which the gamma-ray observations are made), the coding collimator has only an insignificant effect on the background conditions.

Comparative viability of unirradiated and gamma irradiated bacterial cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxcy, R.B.

1977-01-01

Gamma radiation injured Escherichia coli, Salmonella typhimurium, and Moraxella sp. were studied under various environmental stresses to determine their fate relative to the parent population. Irradiated cultures formed smaller colonies on surface plates with fewer cells per colony. Unirradiated cultures had a shorter lag phase than irradiated cultures in broth and duration of lag increased as a result of increasing the radiation dose. Repeated irradiation and subculture progressively retarded growth rate. Multiple radiation of highly resistant Moraxella sp. showed radiation injured cells to be more sensitive than uninjured cells. With the three species studied, irradiation raised the lower limits ofmore » growth temperature, increased the sensitivity to freezing and thawing, and increased the susceptibility to lowered water activity. This work indicated that the production of a bizarre, resistant strain of bacteria through recycling in a food processing operation is highly unlikely.« less

Near-infrared and gamma-ray monitoring of TANAMI gamma-ray bright sources

DOE PAGES

Nesci, R.; Tosti, G.; Pursimo, T.; ...

2013-06-18

Context. We present that spectral energy distribution and its variability are basic tools for understanding the physical processes operating in active galactic nuclei (AGN). Aims. In this paper we report the results of a one-year near-infrared (NIR) and optical monitoring of a sample of 22 AGN known to be gamma-ray emitters, aimed at discovering correlations between optical and gamma-ray emission. Methods. We observed our objects with the Rapid Eye Mount (REM) telescope in J,H,K, and R bands nearly twice every month during their visibility window and derived light curves and spectral indexes. We also analyzed the gamma-ray data from themore » Fermi gamma-ray Space Telescope, making weekly averages. Results. Six sources were never detected during our monitoring, proving to be fainter than their historical Two micron all sky survey (2MASS) level. All of the sixteen detected sources showed marked flux density variability, while the spectral indexes remained unchanged within our sensitivity limits. Steeper sources showed, on average, a larger variability. From the NIR light curves we also computed a variability speed index for each detected source. Only one source (PKS 0208-512) underwent an NIR flare during our monitoring. Half of the sources showed a regular flux density trend on a one-year time scale, but do not show any other peculiar characteristic. The broadband spectral index α ro appears to be a good proxy of the NIR spectral index only for BL Lac objects. No clear correlation between NIR and gamma-ray data is evident in our data, save for PKS 0537-441, PKS 0521-360, PKS 2155-304, and PKS 1424-418. In conclusion, the gamma-ray/NIR flux ratio showed a large spread, QSO being generally gamma-louder than BL Lac, with a marked correlation with the estimated peak frequency (ν peak) of the synchrotron emission.« less

Digital gamma-gamma coincidence HPGe system for environmental analysis.

PubMed

Marković, Nikola; Roos, Per; Nielsen, Sven Poul

2017-08-01

The performance of a new gamma-gamma coincidence spectrometer system for environmental samples analysis at the Center for Nuclear Technologies of the Technical University of Denmark (DTU) is reported. Nutech Coincidence Low Energy Germanium Sandwich (NUCLeGeS) system consists of two HPGe detectors in a surface laboratory with a digital acquisition system used to collect the data in time-stamped list mode with 10ns time resolution. The spectrometer is used in both anticoincidence and coincidence modes. Copyright © 2017 Elsevier Ltd. All rights reserved.

High resolution mapping of the binding site on human IgG1 for Fc gamma RI, Fc gamma RII, Fc gamma RIII, and FcRn and design of IgG1 variants with improved binding to the Fc gamma R.

PubMed

Shields, R L; Namenuk, A K; Hong, K; Meng, Y G; Rae, J; Briggs, J; Xie, D; Lai, J; Stadlen, A; Li, B; Fox, J A; Presta, L G

2001-03-02

Immunoglobulin G (IgG) Fc receptors play a critical role in linking IgG antibody-mediated immune responses with cellular effector functions. A high resolution map of the binding site on human IgG1 for human Fc gamma RI, Fc gamma RIIA, Fc gamma RIIB, Fc gamma RIIIA, and FcRn receptors has been determined. A common set of IgG1 residues is involved in binding to all Fc gamma R; Fc gamma RII and Fc gamma RIII also utilize residues outside this common set. In addition to residues which, when altered, abrogated binding to one or more of the receptors, several residues were found that improved binding only to specific receptors or simultaneously improved binding to one type of receptor and reduced binding to another type. Select IgG1 variants with improved binding to Fc gamma RIIIA exhibited up to 100% enhancement in antibody-dependent cell cytotoxicity using human effector cells; these variants included changes at residues not found at the binding interface in the IgG/Fc gamma RIIIA co-crystal structure (Sondermann, P., Huber, R., Oosthuizen, V., and Jacob, U. (2000) Nature 406, 267-273). These engineered antibodies may have important implications for improving antibody therapeutic efficacy.

Gamma-ray line astrophysics

NASA Technical Reports Server (NTRS)

Lingenfelter, R. E.; Ramaty, R.

1986-01-01

Recent observations of gamma-ray line emission from solar flares, gamma-ray bursts, the galactic center, the interstellar medium and the jets of SS433 are reviewed. The implications of these observations on high energy processes in these sources are discussed.

Registered particles onboard identification in the various apertures of GAMMA-400 space gamma-telescope

NASA Astrophysics Data System (ADS)

Arkhangelskaja, Irene

2016-07-01

GAMMA-400 (Gamma Astronomical Multifunctional Modular Apparatus) will be the gamma-telescope onboard international satellite gamma-observatory designed for particle registration in the wide energy band. Its parameters are optimized for detection of gamma-quanta with the energy ˜ 100 GeV in the main aperture. The main scientific goals of GAMMA-400 are to investigate fluxes of γ-rays and the electron-positron cosmic ray component possibly generated by dark matter particles decay or annihilation and to search for and study in detail discrete γ-ray sources, to investigate the energy spectra of Galactic and extragalactic diffuse γ-rays, and to study γ-ray bursts and γ-emission from the active Sun. This article presents analysis of detected events identification procedures and energy resolution in three apertures provide particles registration both from upper and lateral directions based on GAMMA-400 modeling due special designed software. Time and segmentation methods are used to reject backsplash (backscattering particles created when high energy γ-rays interact with the calorimeter's matter and move in the opposite direction) in the main aperture while only energy deposition analysis allows to reject this effect in the additional and lateral ones. The main aperture provides the best angular (all strip layers information analysis) and energy (energy deposition in the all detectors studying) resolution in the energy range 0.1 - 3 × 10^{3} GeV. The energy resolution in this band is 1%. Triggers in the main aperture will be formed using information about particle direction provided by time of flight system and presence of charged particle or backsplash signal formed according to analysis of energy deposition in combination of all two-layers anticoincidence systems individual detectors. In the additional aperture gamma-telescope allows to register events in the energy band 10 × 10^{-3} - 3 × 10^{3} GeV. The additional aperture energy resolution provides due to

GRI: The Gamma-Ray Imager mission

NASA Astrophysics Data System (ADS)

Knödlseder, J.; Gri Consortium

Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe While at lower wavebands the observed emission is generally dominated by thermal processes the gamma-ray sky provides us with a view on the non-thermal Universe Here particles are accelerated to extreme relativistic energies by mechanisms which are still poorly understood and nuclear reactions are synthesizing the basic constituents of our world Cosmic accelerators and cosmic explosions are the major science themes that are addressed in the gamma-ray regime With the INTEGRAL observatory ESA has provided a unique tool to the astronomical community and has put Europe in the lead in the field of gamma-ray astronomy INTEGRAL provides an unprecedented survey of the soft gamma-ray sky revealing hundreds of sources new classes of objects extraordinary views of antimatter annihilation in our Galaxy and fingerprints of recent nucleosynthesis processes While INTEGRAL has provided the global overview over the soft gamma-ray sky there is a growing need to perform deeper more focused investigations of gamma-ray sources In soft X-rays a comparable step was taken going from the Einstein satellite to the XMM Newton observatory Technological advances in the past years in the domain of gamma-ray focusing using Laue diffraction and multilayer-coated mirror techniques have paved the way towards a gamma-ray mission providing major improvements compared to past missions regarding sensitivity and angular resolution Such a

SCA8 Repeat Expansion: Large CTA/CTG Repeat Alleles Are More Common in Ataxic Patients, Including Those with SCA6

PubMed Central

Izumi, Yuishin; Maruyama, Hirofumi; Oda, Masaya; Morino, Hiroyuki; Okada, Takayuki; Ito, Hidefumi; Sasaki, Iwao; Tanaka, Hiroyasu; Komure, Osamu; Udaka, Fukashi; Nakamura, Shigenobu; Kawakami, Hideshi

2003-01-01

We analyzed the SCA8 CTA/CTG repeat in a large group of Japanese subjects. The frequency of large alleles (85–399 CTA/CTG repeats) was 1.9% in spinocerebellar ataxia (SCA), 0.4% in Parkinson disease, 0.3% in Alzheimer disease, and 0% in a healthy control group; the frequency was significantly higher in the group with SCA than in the control group. Homozygotes for large alleles were observed only in the group with SCA. In five patients with SCA from two families, a large SCA8 CTA/CTG repeat and a large SCA6 CAG repeat coexisted. Age at onset was correlated with SCA8 repeats rather than SCA6 repeats in these five patients. In one of these families, at least one patient showed only a large SCA8 CTA/CTG repeat allele, with no large SCA6 CAG repeat allele. We speculate that the presence of a large SCA8 CTA/CTG repeat allele influences the function of channels such as α1A-voltage–dependent calcium channel through changing or aberrant splicing, resulting in the development of cerebellar ataxia, especially in homozygous patients. PMID:12545428

SCA8 repeat expansion: large CTA/CTG repeat alleles are more common in ataxic patients, including those with SCA6.

PubMed

Izumi, Yuishin; Maruyama, Hirofumi; Oda, Masaya; Morino, Hiroyuki; Okada, Takayuki; Ito, Hidefumi; Sasaki, Iwao; Tanaka, Hiroyasu; Komure, Osamu; Udaka, Fukashi; Nakamura, Shigenobu; Kawakami, Hideshi

2003-03-01

We analyzed the SCA8 CTA/CTG repeat in a large group of Japanese subjects. The frequency of large alleles (85-399 CTA/CTG repeats) was 1.9% in spinocerebellar ataxia (SCA), 0.4% in Parkinson disease, 0.3% in Alzheimer disease, and 0% in a healthy control group; the frequency was significantly higher in the group with SCA than in the control group. Homozygotes for large alleles were observed only in the group with SCA. In five patients with SCA from two families, a large SCA8 CTA/CTG repeat and a large SCA6 CAG repeat coexisted. Age at onset was correlated with SCA8 repeats rather than SCA6 repeats in these five patients. In one of these families, at least one patient showed only a large SCA8 CTA/CTG repeat allele, with no large SCA6 CAG repeat allele. We speculate that the presence of a large SCA8 CTA/CTG repeat allele influences the function of channels such as alpha(1A)-voltage-dependent calcium channel through changing or aberrant splicing, resulting in the development of cerebellar ataxia, especially in homozygous patients.

Gamma rays from Centaurus A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gupta, Nayantara, E-mail: nayan@phy.iitb.ac.in

2008-06-15

Centaurus A, the cosmic ray accelerator a few Mpc away from us, is possibly one of the nearest sources of extremely high energy cosmic rays. We investigate whether the gamma ray data currently available from Centaurus A in the GeV-TeV energy band can be explained with only proton-proton interactions. We show that for a single power law proton spectrum, mechanisms of {gamma}-ray production other than proton-proton interactions are needed inside this radio-galaxy to explain the gamma ray flux observed by EGRET, upper limits from HESS/CANGAROO-III and the correlated extremely energetic cosmic ray events observed by the Pierre Auger experiment. Inmore » future, with better {gamma}-ray data, and simultaneous observation with {gamma}-ray and cosmic ray detectors, it will be possible to carry out such studies on different sources in more detail.« less

Application of gamma imaging techniques for the characterisation of position sensitive gamma detectors

NASA Astrophysics Data System (ADS)

Habermann, T.; Didierjean, F.; Duchêne, G.; Filliger, M.; Gerl, J.; Kojouharov, I.; Li, G.; Pietralla, N.; Schaffner, H.; Sigward, M.-H.

2017-11-01

A device to characterize position-sensitive germanium detectors has been implemented at GSI. The main component of this so called scanning table is a gamma camera that is capable of producing online 2D images of the scanned detector by means of a PET technique. To calibrate the gamma camera Compton imaging is employed. The 2D data can be processed further offline to obtain depth information. Of main interest is the response of the scanned detector in terms of the digitized pulse shapes from the preamplifier. This is an important input for pulse-shape analysis algorithms as they are in use for gamma tracking arrays in gamma spectroscopy. To validate the scanning table, a comparison of its results with a second scanning table implemented at the IPHC Strasbourg is envisaged. For this purpose a pixelated germanium detector has been scanned.

Simultaneous beta and gamma spectroscopy

DOEpatents

Farsoni, Abdollah T.; Hamby, David M.

2010-03-23

A phoswich radiation detector for simultaneous spectroscopy of beta rays and gamma rays includes three scintillators with different decay time characteristics. Two of the three scintillators are used for beta detection and the third scintillator is used for gamma detection. A pulse induced by an interaction of radiation with the detector is digitally analyzed to classify the type of event as beta, gamma, or unknown. A pulse is classified as a beta event if the pulse originated from just the first scintillator alone or from just the first and the second scintillator. A pulse from just the third scintillator is recorded as gamma event. Other pulses are rejected as unknown events.

Comparison of simple sequence repeats in 19 Archaea.

PubMed

Trivedi, S

2006-12-05

All organisms that have been studied until now have been found to have differential distribution of simple sequence repeats (SSRs), with more SSRs in intergenic than in coding sequences. SSR distribution was investigated in Archaea genomes where complete chromosome sequences of 19 Archaea were analyzed with the program SPUTNIK to find di- to penta-nucleotide repeats. The number of repeats was determined for the complete chromosome sequences and for the coding and non-coding sequences. Different from what has been found for other groups of organisms, there is an abundance of SSRs in coding regions of the genome of some Archaea. Dinucleotide repeats were rare and CG repeats were found in only two Archaea. In general, trinucleotide repeats are the most abundant SSR motifs; however, pentanucleotide repeats are abundant in some Archaea. Some of the tetranucleotide and pentanucleotide repeat motifs are organism specific. In general, repeats are short and CG-rich repeats are present in Archaea having a CG-rich genome. Among the 19 Archaea, SSR density was not correlated with genome size or with optimum growth temperature. Pentanucleotide density had an inverse correlation with the CG content of the genome.

[Induction of glutathione and activation of immune functions by low-dose, whole-body irradiation with gamma-rays].

PubMed

Kojima, Shuji

2006-10-01

We first examined the relation between the induction of glutathione and immune functions in mice after low-dose gamma-ray irradiation. Thereafter, inhibition of tumor growth by radiation was confirmed in Ehrlich solid tumor (EST)-bearing mice. The total glutathione level of the splenocytes transiently increased soon after irradiation and reached a maximum at around 4 h postirradiation. Thereafter, the level reverted to the 0 h value by 24 h postirradiation. A significantly high splenocyte proliferative response was also recognized 4 h postirradiation. Natural killer (NK) activity was also increased significantly in a similar manner. The time at which the response reached the maximum coincided well with that of maximum total glutathione levels of the splenocytes in the gamma-ray-irradiated mice. Reduced glutathione exogenously added to splenocytes obtained from normal mice enhanced the proliferative response and NK activity in a dose-dependent manner. The inhibitory effects of radiation on tumor growth was then examined in EST-bearing mice. Repeated low-dose irradiation (0.5 Gy, four times, before and within an early time after inoculation) significantly delayed the tumor growth. Finally, the effect of single low-dose (0.5 Gy), whole-body gamma-ray irradiation on immune balance was examined to elucidate the mechanism underlying the antitumor immunity. The percentage of B cells in blood lymphocytes was selectively decreased after radiation, concomitant with an increase in that of the helper T cell population. The IFN-gamma level in splenocyte culture prepared from EST-bearing mice was significantly increased 48 h after radiation, although the level of IL-4 was unchanged. IL-12 secretion from macrophages was also enhanced by radiation. These results suggest that low-dose gamma-rays induce Th1 polarization and enhance the activities of tumoricidal effector cells, leading to an inhibition of tumor growth.

Short Tandem Repeat DNA Internet Database

National Institute of Standards and Technology Data Gateway

SRD 130 Short Tandem Repeat DNA Internet Database (Web, free access)   Short Tandem Repeat DNA Internet Database is intended to benefit research and application of short tandem repeat DNA markers for human identity testing. Facts and sequence information on each STR system, population data, commonly used multiplex STR systems, PCR primers and conditions, and a review of various technologies for analysis of STR alleles have been included.

Portable compton gamma-ray detection system

DOEpatents

Rowland, Mark S [Alamo, CA; Oldaker, Mark E [Pleasanton, CA

2008-03-04

A Compton scattered gamma-ray detector system. The system comprises a gamma-ray spectrometer and an annular array of individual scintillators. The scintillators are positioned so that they are arrayed around the gamma-ray spectrometer. The annular array of individual scintillators includes a first scintillator. A radiation shield is positioned around the first scintillator. A multi-channel analyzer is operatively connected to the gamma-ray spectrometer and the annular array of individual scintillators.

Very High-Energy Gamma-Ray Sources.

ERIC Educational Resources Information Center

Weekes, Trevor C.

1986-01-01

Discusses topics related to high-energy, gamma-ray astronomy (including cosmic radiation, gamma-ray detectors, high-energy gamma-ray sources, and others). Also considers motivation for the development of this field, the principal results to date, and future prospects. (JN)

Nifty Nines and Repeating Decimals

ERIC Educational Resources Information Center

Brown, Scott A.

2016-01-01

The traditional technique for converting repeating decimals to common fractions can be found in nearly every algebra textbook that has been published, as well as in many precalculus texts. However, students generally encounter repeating decimal numerals earlier than high school when they study rational numbers in prealgebra classes. Therefore, how…

Repeated Prescribed Burning in Aspen

Treesearch

Donald A. Perala

1974-01-01

Infrequent burning weather, low flammability of the aspen-hardwood association, and prolific sprouting and seeding of shrubs and hardwoods made repeated dormant season burning a poor tool to convert good site aspen to conifers. Repeat fall burns for wildlife habitat maintenance is workable if species composition changes are not important.

Updated level scheme of 172Yb from 171Yb(nth, γ) reaction studied via gamma-gamma coincidence spectrometer

NASA Astrophysics Data System (ADS)

Nguyen, Ngoc Anh; Nguyen, Xuan Hai; Pham, Dinh Khang; Nguyen, Quang Hung; Ho, Huu Thang

2017-08-01

This paper provides the updated information on the level scheme of 172Yb nucleus studied via 171Yb(nth, γ) reaction using the gamma-gamma coincidence spectrometer at Dalat Nuclear Research Institute (Viet Nam). The latter is used because of its advantages in achieving the low Compton background as well as in identifying the correlated gamma transitions. We have detected in total the energies and intensities of 128 two-step gamma cascades corresponding to 79 primary transitions. By comparing the measured data with those extracted from the ENSDF library, 61 primary gamma transitions and corresponding energy levels together with 20 secondary gamma transitions are found to be the same as the ENSDF data. Beside that, 18 additional primary gamma transitions and corresponding energy levels plus 108 secondary ones are not found to currently exist in this library and they are therefore considered as the new data.

Measurement of the {sup 157}Gd(n,{gamma}) reaction with the DANCE {gamma} calorimeter array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chyzh, A.; Dashdorj, D.; Lawrence Livermore National Laboratory, Livermore, California 94551

2011-07-15

The {sup 157}Gd(n,{gamma}) reaction was measured with the DANCE {gamma} calorimeter (consisting of 160 BaF{sub 2} scintillation detectors) at the Los Alamos Neutron Science Center. The multiplicity distributions of the {gamma} decay were used to determine the resonance spins up to E{sub n}=300 eV. The {gamma}-ray energy spectra for different multiplicities were measured for the s-wave resonances. The shapes of these spectra were compared with simulations based on the use of the DICEBOX statistical model code. Simulations showed that the scissors mode is required not only for the ground-state transitions but also for transitions between excited states.

Lunar occultations for gamma-ray source measurements

NASA Technical Reports Server (NTRS)

Koch, David G.; Hughes, E. B.; Nolan, Patrick L.

1990-01-01

The unambiguous association of discrete gamma-ray sources with objects radiating at other wavelengths, the separation of discrete sources from the extended emission within the Galaxy, the mapping of gamma-ray emission from nearby galaxies and the measurement of structure within a discrete source cannot presently be accomplished at gamma-ray energies. In the past, the detection processes used in high-energy gamma-ray astronomy have not allowed for good angular resolution. This problem can be overcome by placing gamma-ray detectors on the moon and using the horizon as an occulting edge to achieve arcsec resolution. For purposes of discussion, this concept is examined for gamma rays above 100 MeV for which pair production dominates the detection process and locally-generated nuclear gamma rays do not contribute to the background.

Disease-associated repeat instability and mismatch repair.

PubMed

Schmidt, Monika H M; Pearson, Christopher E

2016-02-01

Expanded tandem repeat sequences in DNA are associated with at least 40 human genetic neurological, neurodegenerative, and neuromuscular diseases. Repeat expansion can occur during parent-to-offspring transmission, and arise at variable rates in specific tissues throughout the life of an affected individual. Since the ongoing somatic repeat expansions can affect disease age-of-onset, severity, and progression, targeting somatic expansion holds potential as a therapeutic target. Thus, understanding the factors that regulate this mutation is crucial. DNA repair, in particular mismatch repair (MMR), is the major driving force of disease-associated repeat expansions. In contrast to its anti-mutagenic roles, mammalian MMR curiously drives the expansion mutations of disease-associated (CAG)·(CTG) repeats. Recent advances have broadened our knowledge of both the MMR proteins involved in disease repeat expansions, including: MSH2, MSH3, MSH6, MLH1, PMS2, and MLH3, as well as the types of repeats affected by MMR, now including: (CAG)·(CTG), (CGG)·(CCG), and (GAA)·(TTC) repeats. Mutagenic slipped-DNA structures have been detected in patient tissues, and the size of the slip-out and their junction conformation can determine the involvement of MMR. Furthermore, the formation of other unusual DNA and R-loop structures is proposed to play a key role in MMR-mediated instability. A complex correlation is emerging between tissues showing varying amounts of repeat instability and MMR expression levels. Notably, naturally occurring polymorphic variants of DNA repair genes can have dramatic effects upon the levels of repeat instability, which may explain the variation in disease age-of-onset, progression and severity. An increasing grasp of these factors holds prognostic and therapeutic potential. Copyright © 2015 Elsevier B.V. All rights reserved.

Spectral-timing analysis of the low-B magnetar SWIFT J1822.3-1606: testing our understanding of the magnetar behavior

NASA Astrophysics Data System (ADS)

Perna, Rosalba

2014-09-01

AXPs and SGRs are young neutron stars (NSs) characterized by high X-ray quiescent luminosities, outbursts, and sporadic giant flares (the SGRs). They are believed to be powered by ultra-strong B fields. However, the observation of outbursts from 'low-B' NSs has been a long-standing puzzle. Theoretical work by our group has shown that a) outbursts from a 'low-B' NS can be produced if the NS has a very strong internal toroidal field; b) a strong internal toroidal field can be revealed by spectral and timing analysis of the NS pulse profile. Here we propose to perform a detailed modeling of the spectra and pulse profile of the low-B magnetar SWIFT J1822.3-1606 with the aim of inferring its magnetic field topology and viewing geometry.

Mercuric iodine room temperature gamma-ray detectors

NASA Technical Reports Server (NTRS)

Patt, Bradley E.; Markakis, Jeffrey M.; Gerrish, Vernon M.; Haymes, Robert C.; Trombka, Jacob I.

1990-01-01

high resolution mercuric iodide room temperature gamma-ray detectors have excellent potential as an essential component of space instruments to be used for high energy astrophysics. Mercuric iodide detectors are being developed both as photodetectors used in combination with scintillation crystals to detect gamma-rays, and as direct gamma-ray detectors. These detectors are highly radiation damage resistant. The list of applications includes gamma-ray burst detection, gamma-ray line astronomy, solar flare studies, and elemental analysis.

About cosmic gamma ray lines

NASA Astrophysics Data System (ADS)

Diehl, Roland

2017-06-01

Gamma ray lines from cosmic sources convey the action of nuclear reactions in cosmic sites and their impacts on astrophysical objects. Gamma rays at characteristic energies result from nuclear transitions following radioactive decays or high-energy collisions with excitation of nuclei. The gamma-ray line from the annihilation of positrons at 511 keV falls into the same energy window, although of different origin. We present here the concepts of cosmic gamma ray spectrometry and the corresponding instruments and missions, followed by a discussion of recent results and the challenges and open issues for the future. Among the lessons learned are the diffuse radioactive afterglow of massive-star nucleosynthesis in 26Al and 60Fe gamma rays, which is now being exploited towards the cycle of matter driven by massive stars and their supernovae; large interstellar cavities and superbubbles have been recognised to be of key importance here. Also, constraints on the complex processes making stars explode as either thermonuclear or core-collapse supernovae are being illuminated by gamma-ray lines, in this case from shortlived radioactivities from 56Ni and 44Ti decays. In particular, the three-dimensionality and asphericities that have recently been recognised as important are enlightened in different ways through such gamma-ray line spectroscopy. Finally, the distribution of positron annihilation gamma ray emission with its puzzling bulge-dominated intensity disctribution is measured through spatially-resolved spectra, which indicate that annihilation conditions may differ in different parts of our Galaxy. But it is now understood that a variety of sources may feed positrons into the interstellar medium, and their characteristics largely get lost during slowing down and propagation of positrons before annihilation; a recent microquasar flare was caught as an opportunity to see positrons annihilate at a source.

The Effects of Repeated Writing and Repeated Revision Strategies on Composing Fluency of Learning Disabled Adolescents. Final Report.

ERIC Educational Resources Information Center

Harriman, Nancy E.; Gajar, Anna H.

The study investigated the use of repeated writings as a means of increasing written language fluency with 48 learning disabled students in senior high school resource room English classes. Subjects received one of four treatments for 4 days: repeated writing with structural cues, repeated revision with structural cues, writing on a new topic with…

The relationship between gamma frequency and running speed differs for slow and fast gamma rhythms in freely behaving rats

PubMed Central

Zheng, Chenguang; Bieri, Kevin Wood; Trettel, Sean Gregory; Colgin, Laura Lee

2015-01-01

In hippocampal area CA1 of rats, the frequency of gamma activity has been shown to increase with running speed (Ahmed and Mehta, 2012). This finding suggests that different gamma frequencies simply allow for different timings of transitions across cell assemblies at varying running speeds, rather than serving unique functions. However, accumulating evidence supports the conclusion that slow (~25–55 Hz) and fast (~60–100 Hz) gamma are distinct network states with different functions. If slow and fast gamma constitute distinct network states, then it is possible that slow and fast gamma frequencies are differentially affected by running speed. In this study, we tested this hypothesis and found that slow and fast gamma frequencies change differently as a function of running speed in hippocampal areas CA1 and CA3, and in the superficial layers of the medial entorhinal cortex (MEC). Fast gamma frequencies increased with increasing running speed in all three areas. Slow gamma frequencies changed significantly less across different speeds. Furthermore, at high running speeds, CA3 firing rates were low, and MEC firing rates were high, suggesting that CA1 transitions from CA3 inputs to MEC inputs as running speed increases. These results support the hypothesis that slow and fast gamma reflect functionally distinct states in the hippocampal network, with fast gamma driven by MEC at high running speeds and slow gamma driven by CA3 at low running speeds. PMID:25601003

GammaLib and ctools. A software framework for the analysis of astronomical gamma-ray data

NASA Astrophysics Data System (ADS)

Knödlseder, J.; Mayer, M.; Deil, C.; Cayrou, J.-B.; Owen, E.; Kelley-Hoskins, N.; Lu, C.-C.; Buehler, R.; Forest, F.; Louge, T.; Siejkowski, H.; Kosack, K.; Gerard, L.; Schulz, A.; Martin, P.; Sanchez, D.; Ohm, S.; Hassan, T.; Brau-Nogué, S.

2016-08-01

The field of gamma-ray astronomy has seen important progress during the last decade, yet to date no common software framework has been developed for the scientific analysis of gamma-ray telescope data. We propose to fill this gap by means of the GammaLib software, a generic library that we have developed to support the analysis of gamma-ray event data. GammaLib was written in C++ and all functionality is available in Python through an extension module. Based on this framework we have developed the ctools software package, a suite of software tools that enables flexible workflows to be built for the analysis of Imaging Air Cherenkov Telescope event data. The ctools are inspired by science analysis software available for existing high-energy astronomy instruments, and they follow the modular ftools model developed by the High Energy Astrophysics Science Archive Research Center. The ctools were written in Python and C++, and can be either used from the command line via shell scripts or directly from Python. In this paper we present the GammaLib and ctools software versions 1.0 that were released at the end of 2015. GammaLib and ctools are ready for the science analysis of Imaging Air Cherenkov Telescope event data, and also support the analysis of Fermi-LAT data and the exploitation of the COMPTEL legacy data archive. We propose using ctools as the science tools software for the Cherenkov Telescope Array Observatory.

Analysis of sequence repeats of proteins in the PDB.

PubMed

Mary Rajathei, David; Selvaraj, Samuel

2013-12-01

Internal repeats in protein sequences play a significant role in the evolution of protein structure and function. Applications of different bioinformatics tools help in the identification and characterization of these repeats. In the present study, we analyzed sequence repeats in a non-redundant set of proteins available in the Protein Data Bank (PDB). We used RADAR for detecting internal repeats in a protein, PDBeFOLD for assessing structural similarity, PDBsum for finding functional involvement and Pfam for domain assignment of the repeats in a protein. Through the analysis of sequence repeats, we found that identity of the sequence repeats falls in the range of 20-40% and, the superimposed structures of the most of the sequence repeats maintain similar overall folding. Analysis sequence repeats at the functional level reveals that most of the sequence repeats are involved in the function of the protein through functionally involved residues in the repeat regions. We also found that sequence repeats in single and two domain proteins often contained conserved sequence motifs for the function of the domain. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nova Eruptions from Radio to Gamma-raysówith AAVSO Data in the Middle (Abstract)

NASA Astrophysics Data System (ADS)

Mukai, K.; Kafka, S.; Chomiuk, L.; Li, R.; Finzell, T.; Linford, J.; Sokoloski, J.; Nelson, T.; Rupen, M.; Mioduszewski, A.; Weston, J.

2018-06-01

(Abstract only) Novae are among the longest-known class of optical transients. In recent years, V1369 Cen in the south reached magnitude 3.3 in late 2013, and had repeated (but not periodic) cycles of re-brightening. Earlier in 2013, V339 Del almost reached magnitude 4.0 during the northern summer. An expanding ball of gas, at about 10,000 K, expelled by a nuclear explosion on the surface of a white dwarf, can explain much of the visible light outputs of novae. But these spectacular visible light displays turn out to be just a small part of the show. Novae are also transient objects in the radio through gamma-raysóin addition to the warm, visible light-emitting gas, we need cold dust particles that emit in the infra-red, 10 million degree shock-heated gas that emits hard X-rays, and the exposed surface of the nuclear-burning white dwarf that emits soft X-rays. Last but not least, we need an exotic process of particle acceleration to explain the gamma-rays and some radio data.

Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory

NASA Technical Reports Server (NTRS)

Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

1992-01-01

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

A gamma-gamma coincidence/anticoincidence spectrometer for low-level cosmogenic (22)Na/(7)Be activity ratio measurement.

PubMed

Zhang, Weihua; Ungar, Kurt; Stukel, Matthew; Mekarski, Pawel

2014-04-01

In this study, a digital gamma-gamma coincidence/anticoincidence spectrometer was developed and examined for low-level cosmogenic (22)Na and (7)Be in air-filter sample monitoring. The spectrometer consists of two bismuth germanate scintillators (BGO) and an XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The spectrometer design allows a more selective measurement of (22)Na with a significant background reduction by gamma-gamma coincidence events processing. Hence, the system provides a more sensitive way to quantify trace amounts of (22)Na than normal high resolution gamma spectrometry providing a critical limit of 3 mBq within a 20 h count. The use of a list-mode data acquisition technique enabled simultaneous determination of (22)Na and (7)Be activity concentrations using a single measurement by coincidence and anticoincidence mode respectively. Copyright © 2014 Elsevier Ltd. All rights reserved.

Gamma Ray Spectroscopy and SASSYER

NASA Astrophysics Data System (ADS)

Pauerstein, Benjamin; Bonniwell, Cain; Allmond, J. M.; Beausang, C. W.

2009-10-01

An experiment was performed to study the Gd and Tb nuclei resulting from a 27 MeV proton beam on a 156Gd target. This was conducted at Lawrence Berkeley National Laboratory using the STARS/LIBERACE array. The main focus of the experiment was on charged particle channels (p,d) into 155Gd and (p,t) into 154Gd. However, the trigger was either gamma-gamma or particle-gamma so new data was also obtained on 155Tb nuclei following fusion evaporation reactions. Preliminary analysis was conducted at Wright Nuclear Structure Lab where RADWARE programs were used to analyze the data and search for unknown gamma rays. A second, separate, experiment was conducted using the SASSYER (a gas-filled separator at Yale). In this experiment, fission fragments from a 252Cf source were focused to a DSSD and a Ge detector was used to search for either gamma-decay from long lived isomers in the fission fragments or to find gammas from recoil-beta-decay tagging on the fission fragments. The data collection seems to have gone smoothly, and the data is currently being sorted for analysis. This work was supported by the US Department of Energy under grant numbers DE-FG02-52NA26206 and DE-FG02-05ER41379.

Gamma ray spectroscopy in astrophysics. [conferences

NASA Technical Reports Server (NTRS)

Cline, T. L. (Editor); Ramaty, R. (Editor)

1978-01-01

Experimental and theoretical aspects of gamma ray spectroscopy in high energy astrophysics are discussed. Line spectra from solar, stellar, planetary, and cosmic gamma rays are examined as well as HEAO investigations, the prospects of a gamma ray observatory, and follow-on X-ray experiments in space.

Attrition resistant gamma-alumina catalyst support

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singleton, Alan H.; Oukaci, Rachid; Goodwin, James G.

2006-03-14

A .gamma.-alumina catalyst support having improved attrition resistance produced by a method comprising the steps of treating a particulate .gamma.-alumina material with an acidic aqueous solution comprising water and nitric acid and then, prior to adding any catalytic material thereto, calcining the treated .gamma.-alumina.

Structural studies of CNG repeats

PubMed Central

Kiliszek, Agnieszka; Rypniewski, Wojciech

2014-01-01

CNG repeats (where N denotes one of the four natural nucleotides) are abundant in the human genome. Their tendency to undergo expansion can lead to hereditary diseases known as TREDs (trinucleotide repeat expansion disorders). The toxic factor can be protein, if the abnormal gene is expressed, or the gene transcript, or both. The gene transcripts have attracted much attention in the biomedical community, but their molecular structures have only recently been investigated. Model RNA molecules comprising CNG repeats fold into long hairpins whose stems generally conform to an A-type helix, in which the non-canonical N-N pairs are flanked by C-G and G-C pairs. Each homobasic pair is accommodated in the helical context in a unique manner, with consequences for the local helical parameters, solvent structure, electrostatic potential and potential to interact with ligands. The detailed three-dimensional profiles of RNA CNG repeats can be used in screening of compound libraries for potential therapeutics and in structure-based drug design. Here is a brief survey of the CNG structures published to date. PMID:24939898

Pathophysiologic roles of the fibrinogen gamma chain.

PubMed

Farrell, David H

2004-05-01

Fibrinogen binds through its gamma chains to cell surface receptors, growth factors, and coagulation factors to perform its key roles in fibrin clot formation, platelet aggregation, and wound healing. However, these binding interactions can also contribute to pathophysiologic processes, including inflammation and thrombosis. This review summarizes the latest findings on the role of the fibrinogen gamma chain in these processes, and illustrates the potential for therapeutic intervention. Novel gamma chain epitopes that bind platelet integrin alpha IIbbeta3 and leukocyte integrin alphaMbeta2 have been characterized, leading to the revision of former dogma regarding the processes of platelet aggregation, clot retraction, inflammation, and thrombosis. A series of studies has shown that the gamma chain serves as a depot for fibroblast growth factor-2 (FGF-2), which is likely to play an important role in wound healing. Inhibition of gamma chain function with the monoclonal antibody 7E9 has been shown to interfere with multiple fibrinogen activities, including factor XIIIa crosslinking, platelet adhesion, and platelet-mediated clot retraction. The role of the enigmatic variant fibrinogen gamma chain has also become clearer. Studies have shown that gamma chain binding to thrombin and factor XIII results in clots that are mechanically stiffer and resistant to fibrinolysis, which may explain the association between gammaA/gamma' fibrinogen levels and cardiovascular disease. The identification of new interactions with gamma chains has revealed novel targets for the treatment of inflammation and thrombosis. In addition, several exciting studies have shown new functions for the variant gamma chain that may contribute to cardiovascular disease.

Resistance of a gamma/gamma prime - delta directionally solidified eutectic alloy to recrystallization

NASA Technical Reports Server (NTRS)

Tewari, S. N.; Scheuermann, C. M.; Andrews, C. W.

1975-01-01

The lamellar directionally solidified nickel-base eutectic alloy gamma/gamma prime-delta has potential as an advanced turbine blade material. The microstructural stability of this alloy was investigated. Specimens were plastically deformed by uniform compression or Brinell indentation, then annealed between 705 and 1120 C. Microstructural changes observed after annealing included gamma prime coarsening, pinch-off and spheroidization of delta lamellae, and the appearance of an unidentified blocky phase in surface layers. All but the first of these was localized in severely deformed regions, suggesting that microstructural instability is not a serious problem in the use of this alloy.

Gamma-ray astronomy: From Fermi up to the HAWC high-energy {gamma}-ray observatory in Sierra Negra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carraminana, Alberto; Collaboration: HAWC Collaboration

Gamma-rays represent the most energetic electromagnetic window for the study of the Universe. They are studied both from space at MeV and GeV energies, with instruments like the Fermi{gamma}-ray Space Telescope, and at TeV energies with ground based instruments profiting of particle cascades in the atmosphere and of the Cerenkov radiation of charged particles in the air or in water. The Milagro gamma-ray observatory represented the first instrument to successfully implement the water Cerenkov technique for {gamma}-ray astronomy, opening the ground for the more sensitive HAWC {gamma}-ray observatory, currently under development in the Sierra Negra site and already providing earlymore » science results.« less

A Complete and Accurate Ab Initio Repeat Finding Algorithm.

PubMed

Lian, Shuaibin; Chen, Xinwu; Wang, Peng; Zhang, Xiaoli; Dai, Xianhua

2016-03-01

It has become clear that repetitive sequences have played multiple roles in eukaryotic genome evolution including increasing genetic diversity through mutation, changes in gene expression and facilitating generation of novel genes. However, identification of repetitive elements can be difficult in the ab initio manner. Currently, some classical ab initio tools of finding repeats have already presented and compared. The completeness and accuracy of detecting repeats of them are little pool. To this end, we proposed a new ab initio repeat finding tool, named HashRepeatFinder, which is based on hash index and word counting. Furthermore, we assessed the performances of HashRepeatFinder with other two famous tools, such as RepeatScout and Repeatfinder, in human genome data hg19. The results indicated the following three conclusions: (1) The completeness of HashRepeatFinder is the best one among these three compared tools in almost all chromosomes, especially in chr9 (8 times of RepeatScout, 10 times of Repeatfinder); (2) in terms of detecting large repeats, HashRepeatFinder also performed best in all chromosomes, especially in chr3 (24 times of RepeatScout and 250 times of Repeatfinder) and chr19 (12 times of RepeatScout and 60 times of Repeatfinder); (3) in terms of accuracy, HashRepeatFinder can merge the abundant repeats with high accuracy.

Joining of Gamma Titanium Aluminides

DTIC Science & Technology

2002-09-01

AFRL-ML-WP-TR-2003-4036 JOINING OF GAMMA TITANIUM ALUMINIDES LTC William A. Baeslack, III Metals Branch (AFRL/MLLM) Metals, Ceramics, and...GAMMA TITANIUM ALUMINIDES 5c. PROGRAM ELEMENT NUMBER 62102F 5d. PROJECT NUMBER MO2R 5e. TASK NUMBER 10 6. AUTHOR(S) LTC William A...comparatively discusses the results of research and development performed on the joining of gamma titanium aluminides during the past two decades. Although

Gamma-Ray Astronomy Technology Needs

NASA Technical Reports Server (NTRS)

Gehrels, N.; Cannizzo, J. K.

2012-01-01

In recent decades gamma-ray observations have become a valuable tool for studying the universe. Progress made in diverse 8re1lS such as gamma-ray bursts (GRBs), nucleosynthesis, and active galactic nuclei (AGNs) has complimented and enriched our astrophysical understanding in many ways. We present an overview of current and future planned space y-ray missions and discussion technology needs for- the next generation of space gamma-ray instruments.

Repeated Reading. What Works Clearinghouse Intervention Report

ERIC Educational Resources Information Center

What Works Clearinghouse, 2014

2014-01-01

"Repeated reading" is an academic practice that aims to increase oral reading fluency. "Repeated reading" can be used with students who have developed initial word reading skills but demonstrate inadequate reading fluency for their grade level. During "repeated reading," a student sits in a quiet location with a…

Prospects for future very high-energy gamma-ray sky survey: Impact of secondary gamma rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inoue, Yoshiyuki; Kalashev, Oleg E.; Kusenko, Alexander

2014-02-01

Very high-energy gamma-ray measurements of distant blazars can be well explained by secondary gamma rays emitted by cascades induced by ultra-high-energy cosmic rays. The secondary gamma rays will enable one to detect a large number of blazars with future ground based gamma-ray telescopes such as Cherenkov Telescope Array (CTA). We show that the secondary emission process will allow CTA to detect 100, 130, 150, 87, and 8 blazars above 30 GeV, 100 GeV, 300 GeV, 1 TeV, and 10 TeV, respectively, up to z~8 assuming the intergalactic magnetic field (IGMF) strength B=10-17 G and an unbiased all sky survey withmore » 0.5 h exposure at each field of view, where total observing time is ~540 h. These numbers will be 79, 96, 110, 63, and 6 up to z~5 in the case of B=10-15 G. This large statistics of sources will be a clear evidence of the secondary gamma-ray scenarios and a new key to studying the IGMF statistically. We also find that a wider and shallower survey is favored to detect more and higher redshift sources even if we take into account secondary gamma rays.« less

The control and data acquisition structure for the GAMMA-400 space gamma-telescope

NASA Astrophysics Data System (ADS)

Arkhangelskiy, Andrey

2016-07-01

The GAMMA-400 space project is intended for precision investigation of the cosmic gamma-emission in the energy band from keV region up to several TeV, electrons and positrons fluxes from ˜~1~GeV up to ˜~10~TeV and high energy cosmic-ray nuclei fluxes. A description of the control and data acquisition structure for gamma-telescope involved in the GAMMA 400 space project is given. The technical capabilities of all specialized equipment providing the functioning of the scientific instrumentation and satellite support systems are unified in a single structure. Control of the scientific instruments is maintained using one-time pulse radio commands and program commands transmitted via onboard control system and scientific data acquisition system. Up to 100~GByte of data per day can be transferred to the ground segment of the project. The correctness of the proposed and implemented structure, engineering solutions and electronic elemental base selection has been verified experimentally with the scientific complex prototype in the laboratory conditions.

Gamma-ray Output Spectra from 239 Pu Fission

DOE PAGES

Ullmann, John

2015-05-25

The gamma-ray multiplicities, individual gamma-ray energy spectra, and total gamma energy spectra following neutron-induced fission of 239Pu were measured using the DANCE detector at Los Alamos. Corrections for detector response were made using a forward-modeling technique based on propagating sets of gamma rays generated from a paramaterized model through a GEANT model of the DANCE array and adjusting the parameters for best fit to the measured spectra. The results for the gamma-ray spectrum and multiplicity are in general agreement with previous results, but the measured total gamma-ray energy is about 10% higher. We found that a dependence of the gamma-raymore » spectrum on the gamma-ray multplicity was also observed. Finally, global model calculations of the multiplicity and gamma energy distributions are in good agreement with the data, but predict a slightly softer total-energy distribution.« less

Repeated lysergic acid diethylamide in an animal model of depression: Normalisation of learning behaviour and hippocampal serotonin 5-HT2 signalling.

PubMed

Buchborn, Tobias; Schröder, Helmut; Höllt, Volker; Grecksch, Gisela

2014-06-01

A re-balance of postsynaptic serotonin (5-HT) receptor signalling, with an increase in 5-HT1A and a decrease in 5-HT2A signalling, is a final common pathway multiple antidepressants share. Given that the 5-HT1A/2A agonist lysergic acid diethylamide (LSD), when repeatedly applied, selectively downregulates 5-HT2A, but not 5-HT1A receptors, one might expect LSD to similarly re-balance the postsynaptic 5-HT signalling. Challenging this idea, we use an animal model of depression specifically responding to repeated antidepressant treatment (olfactory bulbectomy), and test the antidepressant-like properties of repeated LSD treatment (0.13 mg/kg/d, 11 d). In line with former findings, we observe that bulbectomised rats show marked deficits in active avoidance learning. These deficits, similarly as we earlier noted with imipramine, are largely reversed by repeated LSD administration. Additionally, bulbectomised rats exhibit distinct anomalies of monoamine receptor signalling in hippocampus and/or frontal cortex; from these, only the hippocampal decrease in 5-HT2 related [(35)S]-GTP-gamma-S binding is normalised by LSD. Importantly, the sham-operated rats do not profit from LSD, and exhibit reduced hippocampal 5-HT2 signalling. As behavioural deficits after bulbectomy respond to agents classified as antidepressants only, we conclude that the effect of LSD in this model can be considered antidepressant-like, and discuss it in terms of a re-balance of hippocampal 5-HT2/5-HT1A signalling. © The Author(s) 2014.

Gamma-Ray Pulsar Candidates for GLAST

NASA Technical Reports Server (NTRS)

Thompson, D. J.

2008-01-01

The Gamma-ray Large Area Space Telescope (GLAST) will be launched this year, and its Large Area Telescope (LAT) is expected to discover scores to hundreds of gamma-ray pulsars. This poster discusses which of the over 1700 known pulsars, mostly visible only at radio frequencies, are likely to emit greater than 100 MeV gamma rays with intensities detectable by the LAT. The main figure of merit used to select gamma-ray pulsar candidates is sqrt(E-dot)/d2, where E-dot is the energy loss due to rotational spin-down, and d is the distance to the pulsar. The figure of merit incorporates spin-down flux at earth (proportional to E-dot/d2) times efficiency, assumed proportional to l/sqrt(E-dot). A few individual objects are cited to illustrate the issues. Since large E-dot pulsars also tend to have large timing noise and occasional glitches, their ephemerides can become inaccurate in weeks to months. To detect and study the gamma-ray emission the photons must be accurately tagged with the pulse phase. With hours to days between gamma-ray photon arrival times from a pulsar and months to years of LAT exposure needed for good detections, GLAST will rely on radio and X-ray timing measurements throughout the continuous gamma-ray observations. The poster will describe efforts to coordinate pulsar timing of the candidate gamma-ray pulsars.

Gamma-Ray Pulsar Candidates for GLAST

NASA Technical Reports Server (NTRS)

Thompson, David J.; Smith, D. A.; Dumora, D.; Guillemot, L.; Parent, D.; Reposeur, T.; Grove, E.; Romani, R. W.; Thorsett, S. E.

2007-01-01

The Gamma-ray Large Area Space Telescope (GLAST) will be launched less than a year from now, and its Large Area Telescope (LAT) is expected to discover scores to hundreds of gamma-ray pulsars. This poster discusses which of the over 1700 known pulsars, mostly visible only at radio Erequencies, are likely to emit greater than l00 MeV gamma rays with intensities detectable by the LAT. The main figure of merit used to select gamma-ray pulsar candidates is sqrt(E-dot)/d^2, where E-dot is the energy loss due to rotational spindown, and d is the distance to the pulsar. The figure of merit incorporates spin-down flux at earth (proportional to E-dot/d^2) times efficiency, assumed proportional to 1/sqrt(E-dot). A few individual objects are cited to illustrate the issues. Since large E-dot pulsars also tend to have large timing noise and occasional glitches, their ephemerides can become inaccurate in weeks to months. To detect and study the gamma-ray emission the photons must be accurately tagged with the pulse phase. With hours to days between gamma-ray photon arrival times from a pulsar and months to years of LAT exposure needed for good detections, GLAST will need timing measurements throughout the continuous gamma-ray observations. The poster will describe efforts to coordinate pulsar timing of the candidate gamma-ray pulsars.

The structure, logic of operation and distinctive features of the system of triggers and counting signals formation for gamma-telescope GAMMA-400

NASA Astrophysics Data System (ADS)

Topchiev, N. P.; Galper, A. M.; Arkhangelskiy, A. I.; Arkhangelskaja, I. V.; Kheymits, M. D.; Suchkov, S. I.; Yurkin, Y. T.

2017-01-01

Scientific project GAMMA-400 (Gamma Astronomical Multifunctional Modular Apparatus) relates to the new generation of space observatories intended to perform an indirect search for signatures of dark matter in the cosmic-ray fluxes, measurements of characteristics of diffuse gamma-ray emission and gamma-rays from the Sun during periods of solar activity, gamma-ray bursts, extended and point gamma-ray sources, electron/positron and cosmic-ray nuclei fluxes up to TeV energy region by means of the GAMMA-400 gamma-ray telescope represents the core of the scientific complex. The system of triggers and counting signals formation of the GAMMA-400 gamma-ray telescope constitutes the pipelined processor structure which collects data from the gamma-ray telescope subsystems and produces summary information used in forming the trigger decision for each event. The system design is based on the use of state-of-the-art reconfigurable logic devices and fast data links. The basic structure, logic of operation and distinctive features of the system are presented.

Repeat surfactant therapy for postsurfactant slump.

PubMed

Katz, L A; Klein, J M

2006-07-01

To evaluate repeat surfactant therapy for the treatment of respiratory failure associated with postsurfactant slump in extremely low birth weight infants (ELBW) by characterizing the population of premature infants who develop postsurfactant slump and measuring their response to a secondary course of surfactant therapy. A retrospective analysis of a cohort of all patients admitted over a 3-year period with birth weights <1000 g (ELBW infants). Information was collected by chart review and the patients were categorized into three distinct groups for analysis. Initial surfactant only, patients who received surfactant replacement therapy only for respiratory distress syndrome (RDS); repeat surfactant, patients who received both initial surfactant replacement for RDS and repeat surfactant therapy for postsurfactant slump (defined as respiratory failure after 6 days of age), and no surfactant, patients in whom no surfactant was ever administered. A respiratory severity score (RSS) was used to measure the severity of lung disease and response to surfactant therapy. Over 3 years, there were 165 ELBW infants who could develop postsurfactant slump and be eligible for repeat surfactant therapy. There were 39 infants who never received any surfactant therapy estimated gestational age (EGA) 27.7 +/- 1.7, birth weight 856 +/- 109 g) either at birth or after 6 days of life. There were 126 patients treated for RDS with initial surfactant replacement therapy (EGA 25.6 +/- 1.9 weeks, birth weight 713 +/- 179 g). Out of these RDS patients, 101 improved with an initial course of surfactant therapy (EGA 26 +/- 1.8, birth weight 751 +/- 143 g), but 25 (20% of the patients with RDS) developed postsurfactant slump and received a repeat course of surfactant therapy (EGA 24.7 +/- 1.2, birth weight 647 +/- 120 g). The repeat surfactant group (postsurfactant slump) was significantly more premature and had significantly lower birth weights compared to both the initial surfactant only group

Quantification of 235U and 238U activity concentrations for undeclared nuclear materials by a digital gamma-gamma coincidence spectroscopy.

PubMed

Zhang, Weihua; Yi, Jing; Mekarski, Pawel; Ungar, Kurt; Hauck, Barry; Kramer, Gary H

2011-06-01

The purpose of this study is to investigate the possibility of verifying depleted uranium (DU), natural uranium (NU), low enriched uranium (LEU) and high enriched uranium (HEU) by a developed digital gamma-gamma coincidence spectroscopy. The spectroscopy consists of two NaI(Tl) scintillators and XIA LLC Digital Gamma Finder (DGF)/Pixie-4 software and card package. The results demonstrate that the spectroscopy provides an effective method of (235)U and (238)U quantification based on the count rate of their gamma-gamma coincidence counting signatures. The main advantages of this approach over the conventional gamma spectrometry include the facts of low background continuum near coincident signatures of (235)U and (238)U, less interference from other radionuclides by the gamma-gamma coincidence counting, and region-of-interest (ROI) imagine analysis for uranium enrichment determination. Compared to conventional gamma spectrometry, the method offers additional advantage of requiring minimal calibrations for (235)U and (238)U quantification at different sample geometries. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

A link between prompt optical and prompt gamma-ray emission in gamma-ray bursts.

PubMed

Vestrand, W T; Wozniak, P R; Wren, J A; Fenimore, E E; Sakamoto, T; White, R R; Casperson, D; Davis, H; Evans, S; Galassi, M; McGowan, K E; Schier, J A; Asa, J W; Barthelmy, S D; Cummings, J R; Gehrels, N; Hullinger, D; Krimm, H A; Markwardt, C B; McLean, K; Palmer, D; Parsons, A; Tueller, J

2005-05-12

The prompt optical emission that arrives with the gamma-rays from a cosmic gamma-ray burst (GRB) is a signature of the engine powering the burst, the properties of the ultra-relativistic ejecta of the explosion, and the ejecta's interactions with the surroundings. Until now, only GRB 990123 had been detected at optical wavelengths during the burst phase. Its prompt optical emission was variable and uncorrelated with the prompt gamma-ray emission, suggesting that the optical emission was generated by a reverse shock arising from the ejecta's collision with surrounding material. Here we report prompt optical emission from GRB 041219a. It is variable and correlated with the prompt gamma-rays, indicating a common origin for the optical light and the gamma-rays. Within the context of the standard fireball model of GRBs, we attribute this new optical component to internal shocks driven into the burst ejecta by variations of the inner engine. The correlated optical emission is a direct probe of the jet isolated from the medium. The timing of the uncorrelated optical emission is strongly dependent on the nature of the medium.

The solar gamma ray and neutron capabilities of COMPTEL on the Gamma Ray Observatory

NASA Technical Reports Server (NTRS)

Ryan, James M.; Lockwood, John A.

1989-01-01

The imaging Compton telescope COMPTEL on the Gamma Ray Observatory (GRO) has unusual spectroscopic capabilities for measuring solar gamma-ray and neutron emission. The launch of the GRO is scheduled for June 1990 near the peak of the sunspot cycle. With a 30 to 40 percent probability for the Sun being in the COMPTEL field-of-view during the sunlit part of an orbit, a large number of flares will be observed above the 800 keV gamma-ray threshold of the telescope. The telescope energy range extends to 30 MeV with high time resolution burst spectra available from 0.1 to 10 MeV. Strong Compton tail suppression of instrumental gamma-ray interactions will facilitate improved spectral analysis of solar flare emissions. In addition, the high signal to noise ratio for neutron detection and measurement will provide new neutron spectroscopic capabilities. Specifically, a flare similar to that of 3 June 1982 will provide spectroscopic data on greater than 1500 individual neutrons, enough to construct an unambiguous spectrum in the energy range of 20 to 200 MeV. Details of the instrument and its response to solar gamma-rays and neutrons will be presented.

The Mystery of Gamma-Ray Bursts

NASA Technical Reports Server (NTRS)

Fishman, Gerald J.

2004-01-01

Gamma-ray bursts remain one of the greatest mysteries in astrophysics. Observations of gamma-ray bursts made by the BATSE experiment on the Compton Gamma-Ray Observatory will be described. Most workers in the field now believe that they originate from cosmological distances. This view has been reinforced by observations this year of several optical afterglow counterparts to gamma-ray bursts. A summary of these recent discoveries will be presented, along with their implications for models of the burst emission mechanism and the energy source of the bursts.

Quality assurance for gamma knives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, E.D.; Banks, W.W.; Fischer, L.E.

1995-09-01

This report describes and summarizes the results of a quality assurance (QA) study of the Gamma Knife, a nuclear medical device used for the gamma irradiation of intracranial lesions. Focus was on the physical aspects of QA and did not address issues that are essentially medical, such as patient selection or prescription of dose. A risk-based QA assessment approach was used. Sample programs for quality control and assurance are included. The use of the Gamma Knife was found to conform to existing standards and guidelines concerning radiation safety and quality control of external beam therapies (shielding, safety reviews, radiation surveys,more » interlock systems, exposure monitoring, good medical physics practices, etc.) and to be compliant with NRC teletherapy regulations. There are, however, current practices for the Gamma Knife not covered by existing, formalized regulations, standards, or guidelines. These practices have been adopted by Gamma Knife users and continue to be developed with further experience. Some of these have appeared in publications or presentations and are slowly finding their way into recommendations of professional organizations.« less

Regulation of PPAR{gamma} function by TNF-{alpha}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye Jianping

2008-09-26

The nuclear receptor PPAR{gamma} is a lipid sensor that regulates lipid metabolism through gene transcription. Inhibition of PPAR{gamma} activity by TNF-{alpha} is involved in pathogenesis of insulin resistance, atherosclerosis, inflammation, and cancer cachexia. PPAR{gamma} activity is regulated by TNF-{alpha} at pre-translational and post-translational levels. Activation of serine kinases including IKK, ERK, JNK, and p38 may be involved in the TNF-regulation of PPAR{gamma}. Of the four kinases, IKK is a dominant signaling molecule in the TNF-regulation of PPAR{gamma}. IKK acts through at least two mechanisms: inhibition of PPAR{gamma} expression and activation of PPAR{gamma} corepressor. In this review article, literature is reviewedmore » with a focus on the mechanisms of PPAR{gamma} inhibition by TNF-{alpha}.« less

Studying the High Energy Gamma Ray Sky with Gamma Ray Large Area Space Telescope (GLAST)

NASA Technical Reports Server (NTRS)

Kamae, T.; Ohsugi, T.; Thompson, D. J.; Watanabe, K.

1998-01-01

Building on the success of the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory, the Gamma Ray Large Area Space Telescope (GLAST) will make a major step in the study of such subjects as blazars, gamma Ray bursts, the search for dark matter, supernova remnants, pulsars, diffuse radiation, and unidentified high energy sources. The instrument will be built on new and mature detector technologies such as silicon strip detectors, low-power low-noise LSI, and a multilevel data acquisition system. GLAST is in the research and development phase, and one full tower (of 25 total) is now being built in collaborating institutes. The prototype tower will be tested thoroughly at Stanford Linear Accelerator Center (SLAC) in the fall of 1999.

The Gamma-Ray Imager GRI

NASA Astrophysics Data System (ADS)

Wunderer, Cornelia B.; GRI Collaboration

2008-03-01

Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe. While at lower wavebands the observed emission is generally dominated by thermal processes, the gamma-ray sky provides us with a view on the non-thermal Universe. Here particles are accelerated to extreme relativistic energies by mechanisms which are still poorly understood, and nuclear reactions are synthesizing the basic constituents of our world. Cosmic accelerators and cosmic explosions are major science themes that are addressed in the gamma-ray regime. ESA's INTEGRAL observatory currently provides the astronomical community with a unique tool to investigate the sky up to MeV energies and hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes have been discovered. NASA's GLAST mission will similarly take the next step in surveying the high-energy ( GeV) sky, and NuSTAR will pioneer focusing observations at hard X-ray energies (to 80 keV). There will be clearly a growing need to perform deeper, more focused investigations of gamma-ray sources in the 100-keV to MeV regime. Recent technological advances in the domain of gamma-ray focusing using Laue diffraction and multilayer-coated mirror techniques have paved the way towards a gamma-ray mission, providing major improvements compared to past missions regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow the study of particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.

Determination of the measurement threshold in gamma-ray spectrometry.

PubMed

Korun, M; Vodenik, B; Zorko, B

2017-03-01

In gamma-ray spectrometry the measurement threshold describes the lover boundary of the interval of peak areas originating in the response of the spectrometer to gamma-rays from the sample measured. In this sense it presents a generalization of the net indication corresponding to the decision threshold, which is the measurement threshold at the quantity value zero for a predetermined probability for making errors of the first kind. Measurement thresholds were determined for peaks appearing in the spectra of radon daughters 214 Pb and 214 Bi by measuring the spectrum 35 times under repeatable conditions. For the calculation of the measurement threshold the probability for detection of the peaks and the mean relative uncertainty of the peak area were used. The relative measurement thresholds, the ratios between the measurement threshold and the mean peak area uncertainty, were determined for 54 peaks where the probability for detection varied between some percent and about 95% and the relative peak area uncertainty between 30% and 80%. The relative measurement thresholds vary considerably from peak to peak, although the nominal value of the sensitivity parameter defining the sensitivity for locating peaks was equal for all peaks. At the value of the sensitivity parameter used, the peak analysis does not locate peaks corresponding to the decision threshold with the probability in excess of 50%. This implies that peaks in the spectrum may not be located, although the true value of the measurand exceeds the decision threshold. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gamma Ray Bursts-Afterglows and Counterparts

NASA Technical Reports Server (NTRS)

Fishman, Gerald J

1998-01-01

Several breakthrough discoveries were made last year of x-ray, optical and radio afterglows and counterparts to gamma-ray bursts, and a redshift has been associated with at least one of these. These discoveries were made possible by the fast, accurate gamma-ray burst locations of the BeppoSAX satellite. It is now generally believed that the burst sources are at cosmological distances and that they represent the most powerful explosions in the Universe. These observations also open new possibilities for the study of early star formation, the physics of extreme conditions and perhaps even cosmology. This session will concentrate on recent x-ray, optical and radio afterglow observations of gamma-ray bursts, associated redshift measurements, and counterpart observations. Several review and theory talks will also be presented, along with a summary of the astrophysical implications of the observations. There will be additional poster contributions on observations of gamma-ray burst source locations at wavelengths other than gamma rays. Posters are also solicited that describe new observational capabilities for rapid follow-up observations of gamma-ray bursts.

Fermi Gamma-Ray Space Telescope

NASA Technical Reports Server (NTRS)

McEnery, Julie E.; Michelson, Peter F.; Paclesas, William S.; Ritz, Steven

2012-01-01

The Fermi Gamma-ray Space Telescope, launched in June 2008, is an observatory designed to survey the high-energy gamma-ray sky. The primary instrument, the Large Area Telescope (LAT), provides observations from 20 MeV to greater than 300 GeV. A second instrument, the Gamma-ray Burst Monitor (GBM), provides observations of transients from less than 10 keV to 40 MeV. We describe the design and performance of the instruments and their subsystems, the spacecraft and the ground system.

Cortical volume and sex influence visual gamma.

PubMed

van Pelt, Stan; Shumskaya, Elena; Fries, Pascal

2018-06-05

Visually induced gamma-band activity (GBA) has been implicated in several central cognitive functions, in particular perceptual binding, the feedforward routing of attended stimulus information and memory encoding. Several studies have documented that the strength and frequency of GBA are influenced by both subject-intrinsic factors like age, and subject-extrinsic factors such as stimulus contrast. Here, we investigated the relative contributions of previously tested factors, additional factors, and their interactions, in a cohort of 158 subjects recorded with magnetoencephalography (MEG). In agreement with previous studies, we found that gamma strength and gamma peak frequency increase with stimulus contrast and stimulus velocity. Also in confirmation of previous findings, we report that gamma peak frequency declines with subject age. In addition, we found that gamma peak frequency is higher for subjects with thicker occipital cortex, but lower for larger occipital cortices. Also, gamma peak frequency is higher in female than male subjects. Extrinsic factors (stimulus contrast and velocity) and intrinsic factors (age, cortical thickness and sex) together explained 21% of the variance in gamma peak frequency and 20% of the variance in gamma strength. These results can contribute to our understanding of the mechanisms, by which gamma is generated, and the mechanisms, through which it affects the cognitive performance of a given individual subject. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Structural studies of CNG repeats.

PubMed

Kiliszek, Agnieszka; Rypniewski, Wojciech

2014-07-01

CNG repeats (where N denotes one of the four natural nucleotides) are abundant in the human genome. Their tendency to undergo expansion can lead to hereditary diseases known as TREDs (trinucleotide repeat expansion disorders). The toxic factor can be protein, if the abnormal gene is expressed, or the gene transcript, or both. The gene transcripts have attracted much attention in the biomedical community, but their molecular structures have only recently been investigated. Model RNA molecules comprising CNG repeats fold into long hairpins whose stems generally conform to an A-type helix, in which the non-canonical N-N pairs are flanked by C-G and G-C pairs. Each homobasic pair is accommodated in the helical context in a unique manner, with consequences for the local helical parameters, solvent structure, electrostatic potential and potential to interact with ligands. The detailed three-dimensional profiles of RNA CNG repeats can be used in screening of compound libraries for potential therapeutics and in structure-based drug design. Here is a brief survey of the CNG structures published to date. © Published by Oxford University Press on behalf of Nucleic Acids Research.

GRI: the gamma-ray imager mission

NASA Astrophysics Data System (ADS)

Knödlseder, Jürgen

2006-06-01

Observations of the gamma-ray sky reveal the most powerful sources and the most violent events in the Universe. While at lower wavebands the observed emission is generally dominated by thermal processes, the gamma-ray sky provides us with a view on the non-thermal Universe. Here particles are accelerated to extreme relativistic energies by mechanisms which are still poorly understood, and nuclear reactions are synthesizing the basic constituents of our world. Cosmic accelerators and cosmic explosions are the major science themes that are addressed in the gamma-ray regime. With the INTEGRAL observatory, ESA has provided a unique tool to the astronomical community revealing hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes. While INTEGRAL provides the global overview over the soft gamma-ray sky, there is a growing need to perform deeper, more focused investigations of gamma-ray sources. In soft X-rays a comparable step was taken going from the Einstein and the EXOSAT satellites to the Chandra and XMM/Newton observatories. Technological advances in the past years in the domain of gamma-ray focusing using Laue diffraction and multilayer-coated mirror techniques hav paved the way towards a gamma-ray mission, providing major improvements compared to past missions regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow to study particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.

Delayed Gamma Measurements in Different Nuclear Research Reactors Bringing Out the Importance of the Delayed Contribution in Gamma Flux Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fourmentel, D.; Radulovic, V.; Barbot, L.

Neutron and gamma flux levels are key parameters in nuclear research reactors. In Material Testing Reactors, such as the future Jules Horowitz Reactor, under construction at the French Alternative Energies and Atomic Energy Commission (CEA Cadarache, France), the expected gamma flux levels are very high (nuclear heating is of the order of 20 W/g at 100 MWth). As gamma rays deposit their energy in the reactor structures and structural materials it is important to take them into account when designing irradiation devices. There are only a few sensors which allow measurements of the nuclear heating ; a recent development atmore » the CEA Cadarache allows measurements of the gamma flux using a miniature ionization chamber (MIC). The measured MIC response is often compared with calculation using modern Monte Carlo (MC) neutron and photon transport codes, such as TRIPOLI-4 and MCNP6. In these calculations only the production of prompt gamma rays in the reactor is usually modelled thus neglecting the delayed gamma rays. Hence calculations and measurements are usually in better accordance for the neutron flux than for the gamma flux. In this paper we study the contribution of delayed gamma rays to the total MIC signal in order to estimate the systematic error in gamma flux MC calculations. In order to experimentally determine the delayed gamma flux contributions to the MIC response, we performed gamma flux measurements with CEA developed MIC at three different research reactors: the OSIRIS reactor (MTR - 70 MWth at CEA Saclay, France), the TRIGA MARK II reactor (TRIGA - 250 kWth at the Jozef Stefan Institute, Slovenia) and the MARIA reactor (MTR - 30 MWth at the National Center for Nuclear Research, Poland). In order to experimentally assess the delayed gamma flux contribution to the total gamma flux, several reactor shut down (scram) experiments were performed specifically for the purpose of the measurements. Results show that on average about 30 % of the MIC signal is

New Fermi-LAT event reconstruction reveals more high-energy gamma rays from gamma-ray bursts

DOE PAGES

Atwood, W. B.; Baldini, L.; Bregeon, J.; ...

2013-08-19

Here, based on the experience gained during the four and a half years of the mission, the Fermi-LAT Collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet finalized, we can test the improvements in the new event reconstruction with the special case of the prompt phase of bright gamma-ray bursts (GRBs), where the signal-to-noise ratio is large enough that loose selection cuts are sufficient to identify gamma rays associated with the source. Using the new event reconstruction, we have re-analyzed 10 GRBs previously detected by the Largemore » Area Telescope (LAT) for which an X-ray/optical follow-up was possible and found four new gamma rays with energies greater than 10 GeV in addition to the seven previously known. Among these four is a 27.4 GeV gamma ray from GRB 080916C, which has a redshift of 4.35, thus making it the gamma ray with the highest intrinsic energy (~147 GeV) detected from a GRB. We present here the salient aspects of the new event reconstruction and discuss the scientific implications of these new high-energy gamma rays, such as constraining extragalactic background light models, Lorentz invariance violation tests, the prompt emission mechanism, and the bulk Lorentz factor of the emitting region.« less

Process gg{yields}h{sub 0}{yields}{gamma}{gamma} in the Lee-Wick standard model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krauss, F.; Underwood, T. E. J.; Zwicky, R.

2008-01-01

The process gg{yields}h{sub 0}{yields}{gamma}{gamma} is studied in the Lee-Wick extension of the standard model (LWSM) proposed by Grinstein, O'Connell, and Wise. In this model, negative norm partners for each SM field are introduced with the aim to cancel quadratic divergences in the Higgs mass. All sectors of the model relevant to gg{yields}h{sub 0}{yields}{gamma}{gamma} are diagonalized and results are commented on from the perspective of both the Lee-Wick and higher-derivative formalisms. Deviations from the SM rate for gg{yields}h{sub 0} are found to be of the order of 15%-5% for Lee-Wick masses in the range 500-1000 GeV. Effects on the rate formore » h{sub 0}{yields}{gamma}{gamma} are smaller, of the order of 5%-1% for Lee-Wick masses in the same range. These comparatively small changes may well provide a means of distinguishing the LWSM from other models such as universal extra dimensions where same-spin partners to standard model fields also appear. Corrections to determinations of Cabibbo-Kobayashi-Maskawa (CKM) elements |V{sub t(b,s,d)}| are also considered and are shown to be positive, allowing the possibility of measuring a CKM element larger than unity, a characteristic signature of the ghostlike nature of the Lee-Wick fields.« less

Some characteristics of repeated sickness absence

PubMed Central

Ferguson, David

1972-01-01

Ferguson, D. (1972).Brit. J. industr. Med.,29, 420-431. Some characteristics of repeated sickness absence. Several studies have shown that frequency of absence attributed to sickness is not distributed randomly but tends to follow the negative binomial distribution, and this has been taken to support the concept of `proneness' to such absence. Thus, the distribution of sickness absence resembles that of minor injury at work demonstrated over 50 years ago. Because the investigation of proneness to absence does not appear to have been reported by others in Australia, the opportunity was taken, during a wider study of health among telegraphists in a large communications undertaking, to analyse some characteristics of repeated sickness absence. The records of medically certified and uncertified sickness absence of all 769 telegraphists continuously employed in all State capitals over a two-and-a-half-year period were compared with those of 411 clerks and 415 mechanics and, in Sydney, 380 mail sorters and 80 of their supervisors. All telegraphists in Sydney, Melbourne, and Brisbane, and all mail sorters in Sydney, who were available and willing were later medically examined. From their absence pattern repeaters (employees who had had eight or more certified absences in two and a half years) were separated into three types based on a presumptive origin in chance, recurrent disease and symptomatic non-specific disorder. The observed distribution of individual frequency of certified absence over the full two-and-a-half-year period of study followed that expected from the univariate negative binomial, using maximum likelihood estimators, rather than the poisson distribution, in three of the four occupational groups in Sydney. Limited correlational and bivariate analysis supported the interpretation of proneness ascribed to the univariate fit. In the two groups studied, frequency of uncertified absence could not be fitted by the negative binomial, although the numbers of

Deletion of internal structured repeats increases the stability of a leucine-rich repeat protein, YopM

PubMed Central

Barrick, Doug

2011-01-01

Mapping the stability distributions of proteins in their native folded states provides a critical link between structure, thermodynamics, and function. Linear repeat proteins have proven more amenable to this kind of mapping than globular proteins. C-terminal deletion studies of YopM, a large, linear leucine-rich repeat (LRR) protein, show that stability is distributed quite heterogeneously, yet a high level of cooperativity is maintained [1]. Key components of this distribution are three interfaces that strongly stabilize adjacent sequences, thereby maintaining structural integrity and promoting cooperativity. To better understand the distribution of interaction energy around these critical interfaces, we studied internal (rather than terminal) deletions of three LRRs in this region, including one of these stabilizing interfaces. Contrary to our expectation that deletion of structured repeats should be destabilizing, we find that internal deletion of folded repeats can actually stabilize the native state, suggesting that these repeats are destabilizing, although paradoxically, they are folded in the native state. We identified two residues within this destabilizing segment that deviate from the consensus sequence at a position that normally forms a stacked leucine ladder in the hydrophobic core. Replacement of these nonconsensus residues with leucine is stabilizing. This stability enhancement can be reproduced in the context of nonnative interfaces, but it requires an extended hydrophobic core. Our results demonstrate that different LRRs vary widely in their contribution to stability, and that this variation is context-dependent. These two factors are likely to determine the types of rearrangements that lead to folded, functional proteins, and in turn, are likely to restrict the pathways available for the evolution of linear repeat proteins. PMID:21764506

Ionizing radiation potentiates the induction of nitric oxide synthase by interferon-gamma (Ifn-gamma) or Ifn-gamma and lipopolysaccharide in bnl cl.2 murine embryonic liver cells: role of hydrogen peroxide.

PubMed

Yoo, J C; Pae, H O; Choi, B M; Kim, W I; Kim, J D; Kim, Y M; Chung, H T

2000-02-01

The effects of ionizing irradiation on the nitric oxide (NO) production in murine embryonic liver cell line, BNL CL.2 cells, were investigated. Various doses (5-40 Gy) of radiation made BNL CL.2 cells responsive to interferon-gamma alone for the production of NO in a dose-dependent manner. Small amounts of lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-alpha) synergized with IFN-gamma in the production of NO from irradiated BNL CL.2 cells, even though LPS or TNF-alpha alone did not induce NO production from the same cells. Immunoblots showed parallel induction of inducible nitric oxide synthase (iNOS). NO production in irradiated BNL CL.2 cells by IFN-gamma or IFN-gamma plus LPS was decreased by the addition of catalase, suggesting that H(2)O(2) produced by ionizing irradiation primed the cells to trigger NO production in response to IFN-gamma or IFN-gamma plus LPS. Furthermore, the treatment of nongamma-irradiated BNL CL.2 cells with H(2)O(2) made the cells responsive to IFN-gamma or IFN-gamma plus LPS for the production of NO. This study shows that ionizing irradiation has the ability to induce iNOS gene expression in responsive to IFN-gamma via the formation of H(2)O(2) in BNL CL.2 murine embryonic liver cells.

Effect of Gamma Rays on Sophora davidii and Detection of DNA Polymorphism through ISSR Marker

PubMed Central

Wang, Puchang; Mo, Bentian; Luo, Tianqiong

2017-01-01

Sophora davidii (Franch.) Kom. ex Pavol is an important medicinal plant and a feeding scrub with ecological value. The effects of different gamma irradiation doses (20–140 Kr) on seed germination and seedling morphology were investigated in S. davidii, and intersimple sequence repeat (ISSR) markers were used to identify the DNA polymorphism among mutants. Significant variations were observed for seed germination, stem diameter, and number of branches per plant. The improved agronomic traits, such as stem diameter and number of branches per plant, were recorded at 80 Kr dose and 20 Kr dose for seed germination. ISSR analysis generated in total 183 scorable fragments, of which 94 (51.37%) were polymorphic. The percentage of polymorphism ranged from 14.29 to 93.33 with an average of 45.69%. Jaccard's coefficients of dissimilarity varied from 0.6885 to 1.000, indicative of the level of genetic variation among the mutants. The constructed dendrogram grouped the entities into five clusters. Consequently, it was concluded that gamma rays irradiation of seeds generates a sufficient number of induced mutations and that ISSR analysis offered a useful molecular marker for the identification of mutants. PMID:28612030

Simultaneous optical/gamma-ray observations of GRBs

NASA Technical Reports Server (NTRS)

Greiner, J.; Wenzel, W.; Hudec, R.; Moskalenko, E. I.; Metlov, V.; Chernych, N. S.; Getman, V. S.; Ziener, Rainer; Birkle, K.; Bade, N.

1994-01-01

Details on the project to search for serendipitous time correlated optical photographic observations of Gamma Ray Bursters (GRB's) are presented. The ongoing photographic observations at nine observatories are used to look for plates which were exposed simultaneously with a gamma ray burst detected by the gamma ray instrument team (BATSE) and contain the burst position. The results for the first two years of the gamma ray instrument team operation are presented.

Regulation of the steady state level of Fc gamma RI mRNA by IFN-gamma and dexamethasone in human monocytes, neutrophils, and U-937 cells.

PubMed

Pan, L Y; Mendel, D B; Zurlo, J; Guyre, P M

1990-07-01

The high affinity IgG FcR Fc gamma RI, CD64, plays important roles in the immune response. Fc gamma RI is predominantly expressed on monocytes and macrophages, and barely detectable on neutrophils. rIFN-gamma markedly increases the expression of Fc gamma RI on neutrophils, monocytes, macrophages and myeloid cell lines such as U-937, HL-60, and THP-1. Glucocorticoids inhibit the augmentation of Fc gamma RI expression by rIFN-gamma on neutrophils and myeloid cell lines, but enhance the augmentation of Fc gamma RI expression by rIFN-gamma on monocytes. In this study, we examined the effect of rIFN-gamma and dexamethasone (Dex) on the steady state level of Fc gamma RI mRNA in U-937 cells, neutrophils, and monocytes by hybridizing total RNA with the Fc gamma RI cDNA probe, p135. We found that the amount of Fc gamma RI mRNA increased within 1 h of treatment with rIFN-gamma in all three cell types. This initial induction of Fc gamma RI mRNA by rIFN-gamma was completely blocked by an inhibitor of RNA synthesis, actinomycin D, suggesting that the rIFN-gamma-mediated induction of Fc gamma RI mRNA is dependent on gene transcription. Dex, used in combination with rIFN-gamma, partially blocked the induction of Fc gamma RI mRNA by rIFN-gamma in U-937 cells and neutrophils, but caused a synergistic increase in Fc gamma RI mRNA levels in monocytes. The inhibitory effect of Dex on the steady state level of Fc gamma RI mRNA in U-937 cells was blocked by an inhibitor of protein synthesis, cycloheximide, suggesting that Dex-induced proteins were involved in the regulation of Fc gamma RI expression. This study indicates that the regulation of Fc gamma RI expression on U-937 cells, neutrophils, and monocytes by rIFN-gamma and Dex occurs, at least in part, at the mRNA level. rIFN-gamma increases the steady state level of Fc gamma RI mRNA through a common pathway among U-937 cells, neutrophils, and monocytes, whereas the effect of Dex on rIFN-gamma-induced Fc gamma RI mRNA is cell

TEMPORAL EVOLUTION OF SUB-NANOMETER COMPOSITIONAL PROFILES ACROSS THE GAMMA/GAMMA' INTERFACE IN A MODEL Ni-Al-Cr SUPERALLOY

NASA Technical Reports Server (NTRS)

Sudbrack, Chantal K.; Noebe, Ronald D.; Seidman, David N.

2005-01-01

Early-stage phase separation in a Ni-5.2 Al-14.2 Cr at.% superalloy, isothermally decomposing at 873 K, is investigated with atom-probe tomography. Sub-nanometer scale compositional profiles across the gamma/gamma'(L12) interfaces demonstrate that both the gamma-matrix and the gamma'-precipitate compositions evolve with time. Observed chemical gradients of Al depletion and Cr enrichment adjacent to the gamma'-precipitates are transient, consistent with well-established model predictions for diffusion-limited growth, and mark the first detailed observation of this phenomenon. Furthermore, it is shown that Cr atoms are kinetically trapped in the growing precipitates.

PolyU tail of rho-independent terminator of bacterial small RNAs is essential for Hfq action.

PubMed

Otaka, Hironori; Ishikawa, Hirokazu; Morita, Teppei; Aiba, Hiroji

2011-08-09

Major bacterial small RNAs (sRNAs) regulate the translation and stability of target mRNAs through base pairing with the help of the RNA chaperone Hfq. The Hfq-dependent sRNAs consist of three basic elements, mRNA base-pairing region, Hfq-binding site, and rho-independent terminator. Although the base-pairing region and the terminator are well documented in many sRNAs, the Hfq-binding site is less well-defined except that Hfq binds RNA with a preference for AU-rich sequences. Here, we performed mutational and biochemical studies to define the sRNA site required for Hfq action using SgrS as a model sRNA. We found that shortening terminator polyU tail eliminates the ability of SgrS to bind to Hfq and to silence ptsG mRNA. We also demonstrate that the SgrS terminator can be replaced with any foreign rho-independent terminators possessing a polyU tail longer than 8 without losing the ability to silence ptsG mRNA in an Hfq-dependent manner. Moreover, we found that shortening the terminator polyU tail of several other sRNAs also eliminates the ability to bind to Hfq and to regulate target mRNAs. We conclude that the polyU tail of sRNAs is essential for Hfq action in general. The data also indicate that the terminator polyU tail plays a role in Hfq-dependent stabilization of sRNAs.

PolyU tail of rho-independent terminator of bacterial small RNAs is essential for Hfq action

PubMed Central

Otaka, Hironori; Ishikawa, Hirokazu; Morita, Teppei; Aiba, Hiroji

2011-01-01

Major bacterial small RNAs (sRNAs) regulate the translation and stability of target mRNAs through base pairing with the help of the RNA chaperone Hfq. The Hfq-dependent sRNAs consist of three basic elements, mRNA base-pairing region, Hfq-binding site, and rho-independent terminator. Although the base-pairing region and the terminator are well documented in many sRNAs, the Hfq-binding site is less well-defined except that Hfq binds RNA with a preference for AU-rich sequences. Here, we performed mutational and biochemical studies to define the sRNA site required for Hfq action using SgrS as a model sRNA. We found that shortening terminator polyU tail eliminates the ability of SgrS to bind to Hfq and to silence ptsG mRNA. We also demonstrate that the SgrS terminator can be replaced with any foreign rho-independent terminators possessing a polyU tail longer than 8 without losing the ability to silence ptsG mRNA in an Hfq-dependent manner. Moreover, we found that shortening the terminator polyU tail of several other sRNAs also eliminates the ability to bind to Hfq and to regulate target mRNAs. We conclude that the polyU tail of sRNAs is essential for Hfq action in general. The data also indicate that the terminator polyU tail plays a role in Hfq-dependent stabilization of sRNAs. PMID:21788484

Insights into transcription termination of Hfq-binding sRNAs of Escherichia coli and characterization of readthrough products

PubMed Central

Morita, Teppei; Ueda, Masaki; Kubo, Kento; Aiba, Hiroji

2015-01-01

The genes encoding Hfq-dependent sRNAs possess a typical Rho-independent transcription terminator. Here, we have studied the molecular events occurring at Rho-independent terminators of sRNA genes, focusing on two well-characterized Hfq-binding sRNAs, SgrS and RyhB. We constructed several hybrid genes in which the DNA sequence corresponding to a strong Rho-independent terminator was placed just downstream from the Rho-independent terminators of sRNA genes. By using this system, we demonstrate that transcripts frequently read through the Rho-independent terminators of sgrS and ryhB in normally growing cells. We show that Hfq does not affect the transcriptional readthrough event itself. We also find that the readthrough products no longer bind to Hfq in vivo. We have developed a competition assay based on a biotin–streptavidin system to analyze the interaction of Hfq and a particular RNA molecule in vitro. By using this method, we verify that the 3′-extended form of SgrS does not bind to Hfq in vitro. Finally, we demonstrate that transcription termination is significantly enhanced under stress conditions where transcription initiation of sRNA genes on the chromosome is induced. We conclude that the production of sRNAs is regulated not only at the step of transcription initiation but also at the step of transcription termination. The mechanism by which transcription termination is enhanced under stress conditions remains to be understood. PMID:26106215

Interferon-gamma (INF-gamma) release test can detect cutaneous adverse effects to statins.

PubMed

Goldberg, Ilan; Isman, Gila; Shirazi, Idit; Brenner, Sarah

2009-12-01

An increasing number of cutaneous adverse effects are being reported as use of statins becomes more widespread. A study was undertaken to establish the relationship between statin and a cutaneous reaction by the in vitro interferon-gamma (INF-gamma) release test. The lymphocytes of 20 patients with suspected drug-induced skin reaction were incubated with and without the drug. The level of INF-gamma from the supernatant was measured by enzyme-linked immunosorbent assay (ELISA), and the increase calculated. Response was positive in 27 (21.43%) of the 126 drugs. Statin was the only drug with a positive response in 80% of those cases. Nine of 20 patients (45.0%) had complete resolution after discontinuation of the drug; 6 (30.0%) who replaced one drug by another statin had partial or no resolution; and 5 (20.0%) had no resolution despite cessation of statins of all kinds. A positive INF-gamma release test was found in patients who developed skin reactions while taking statins; the test's reliability was strengthened by prompt improvement following elimination of the suspected drug in the majority of patients.

DSC studies on gamma irradiated poly(vinylidene fluoride) applied to high gamma dose dosimetry

NASA Astrophysics Data System (ADS)

Batista, Adriana S. M.; Faria, Luiz O.

2017-11-01

Poly(vinylidene fluoride) homopolymer (PVDF) was investigated for use on high gamma dose dosimetry. Samples were irradiated with gamma doses ranging from 100 kGy to 3000 kGy. Differential scanning calorimetry (DSC) was used to construct an unambiguous relationship between the melting transition latent heat (LM) and the absorbed dose (D). DSC thermograms were taken immediately, 1, 2 and 8 months after the irradiation process revealing that the LMx D relationship presented no change for doses ranging from 100 to 2750 kGy. FTIR and UV-Vis spectroscopy data revealed the radio-induction of C˭O and C˭C bonds. These radio-induced bonds were responsible by the chain stiffening and chain oxidation, respectively. SEM microscopy demonstrates that the spherulitic large crystalline structures present in pristine PVDF are destroyed with doses as low as 100 kGy. The DRX analysis revealed that the main effect of high gamma doses in the crystalline structure of PVDF is to provoke a change from the pristine PVDF α-phase to the γ-phase. Both the ability to detect gamma doses in a large dose range and the low fading features make PVDF homopolymers good candidates to be investigated as high gamma dose dosimeters.

Human EEG gamma oscillations in neuropsychiatric disorders.

PubMed

Herrmann, C S; Demiralp, T

2005-12-01

Due to their small amplitude, the importance of high-frequency EEG oscillations with respect to cognitive functions and disorders is often underestimated as compared to slower oscillations. This article reviews the literature on the alterations of gamma oscillations (about 30-80 Hz) during the course of neuropsychiatric disorders and relates them to a model for the functional role of these oscillations for memory matching. The synchronous firing of neurons in the gamma-band has been proposed to bind multiple features of an object, which are coded in a distributed manner in the brain, and is modulated by cognitive processes such as attention and memory. In certain neuropsychiatric disorders the gamma activity shows significant changes. In schizophrenic patients, negative symptoms correlate with a decrease of gamma responses, whereas a significant increase in gamma amplitudes is observed during positive symptoms such as hallucinations. A reduction is also observed in Alzheimer's Disease (AD), whereas an increase is found in epileptic patients, probably reflecting both cortical excitation and perceptual distortions such as déjà vu phenomena frequently observed in epilepsy. ADHD patients also exhibit increased gamma amplitudes. A hypothesis of a gamma axis of these disorders mainly based on the significance of gamma oscillations for memory matching is formulated.

Fatigue crack propagation behaviour of unidirectionally solidified gamma/gamma-prime-delta eutectic alloys. [Ni-Nb-Al alloys

NASA Technical Reports Server (NTRS)

Bretz, P. E.; Hertzberg, R. W.

1979-01-01

Fatigue crack propagation studies were carried out on unidirectionally solidified gamma/gamma-prime-delta (Ni-Nb-Al) alloys over an aluminum content range of 1.5-2.5% by weight. The variation of Al content of as-grown alloys did not significantly affect the crack growth behavior of these eutectic composites. The results indicate that the addition of Al to the eutectic dramatically improved the FCP behavior. The gamma/gamma-prime-delta alloy exhibited crack growth rates for a given stress intensity range that are an order of magnitude lower than those for the gamma-delta alloy. It is suggested that this difference in FCP behavior can be explained on the basis of stacking fault energy considerations. Extensive delaminations at the crack tip were also revealed, which contributed to the superior fatigue response. Delamination was predominantly intergranular in nature.

Digital repeat analysis; setup and operation.

PubMed

Nol, J; Isouard, G; Mirecki, J

2006-06-01

Since the emergence of digital imaging, there have been questions about the necessity of continuing reject analysis programs in imaging departments to evaluate performance and quality. As a marketing strategy, most suppliers of digital technology focus on the supremacy of the technology and its ability to reduce the number of repeats, resulting in less radiation doses given to patients and increased productivity in the department. On the other hand, quality assurance radiographers and radiologists believe that repeats are mainly related to positioning skills, and repeat analysis is the main tool to plan training needs to up-skill radiographers. A comparative study between conventional and digital imaging was undertaken to compare outcomes and evaluate the need for reject analysis. However, digital technology still being at its early development stages, setting a credible reject analysis program became the major task of the study. It took the department, with the help of the suppliers of the computed radiography reader and the picture archiving and communication system, over 2 years of software enhancement to build a reliable digital repeat analysis system. The results were supportive of both philosophies; the number of repeats as a result of exposure factors was reduced dramatically; however, the percentage of repeats as a result of positioning skills was slightly on the increase for the simple reason that some rejects in the conventional system qualifying for both exposure and positioning errors were classified as exposure error. The ability of digitally adjusting dark or light images reclassified some of those images as positioning errors.

Microstructural changes caused by thermal treatment and their effects on mechanical properties of a gamma/gamma prime - delta eutectic alloy

NASA Technical Reports Server (NTRS)

Tewari, S. N.; Dreshfield, R. L.

1976-01-01

Microstructural changes due to thermal treatments of a directionally solidified gamma/gamma'-delta eutectic alloy were investigated. Aging treatments of 8 to 48 hours and ranging from 750 to 1120 C were given to the alloy in both its as directionally solidified condition and after gamma' solutioning. Aging resulted in gamma' coarsening gamma precipitates in delta, and delta and gamma'' precipitates in delta. The tensile strength was increased about 12 percent at temperatures up to 900 C by a heat treatment. Times to rupture were essentially the same or greater than for as directionally solidified material. Tensile and rupture ductility in the growth direction of the alloy were reduced by the heat treatment.

High-speed and low-power repeater for VLSI interconnects

NASA Astrophysics Data System (ADS)

Karthikeyan, A.; Mallick, P. S.

2017-10-01

This paper proposes a repeater for boosting the speed of interconnects with low power dissipation. We have designed and implemented at 45 and 32 nm technology nodes. Delay and power dissipation performances are analyzed for various voltage levels at these technology nodes using Spice simulations. A significant reduction in delay and power dissipation are observed compared to a conventional repeater. The results show that the proposed high-speed low-power repeater has a reduced delay for higher load capacitance. The proposed repeater is also compared with LPTG CMOS repeater, and the results shows that the proposed repeater has reduced delay. The proposed repeater can be suitable for high-speed global interconnects and has the capacity to drive large loads.

Combination neutron-gamma ray detector

DOEpatents

Stuart, Travis P.; Tipton, Wilbur J.

1976-10-26

A radiation detection system capable of detecting neutron and gamma events and distinguishing therebetween. The system includes a detector for a photomultiplier which utilizes a combination of two phosphor materials, the first of which is in the form of small glass beads which scintillate primarily in response to neutrons and the second of which is a plastic matrix which scintillates in response to gammas. A combination of pulse shape and pulse height discrimination techniques is utilized to provide an essentially complete separation of the neutron and gamma events.

Use of interferon-gamma release assays in a health care worker screening program: experience from a tertiary care centre in the United States.

PubMed

Joshi, Manish; Monson, Thomas P; Woods, Gail L

2012-01-01

Interferon-gamma release assays including the QuantiFERON-TB Gold In-Tube test (QFT-GIT [Cellestis Ltd, Australia]) may be used in place of the tuberculin skin test (TST) in surveillance programs for Mycobacterium tuberculosis infection control. However, data on performance and practicality of the QFT-GIT in such programs for health care workers (HCWs) are limited. To assess the performance, practicality and reversion rate of the QFT-GIT among HCWs at a tertiary health care institution in the United States. Retrospective chart review of HCWs at Central Arkansas Veterans Healthcare System (Arkansas, USA) who underwent QFT-GIT testing as a part of their employee screening between November 1, 2008 and October 31, 2009. QFT-GIT was used to screen 3290 HCWs. The initial QFT-GIT was interpreted as positive for 129 (3.9%) HCWs, negative for 3155 (95.9%) and indeterminate for six (0.2%). Testing with QFT-GIT was repeated in 45 HCWs who had positive results on the initial test. The QFT-GIT reverted to negative in 18 (40.0%) HCWs, all of whom had negative TST status and initial interferon-gamma values of 0.35 IU⁄mL to 2.0 IU⁄mL. The QFT-GIT test is feasible in large health care setting as an alternative to TST for M tuberculosis infection screening in HCWs but is not free from challenges. The major concerns are the high number of positive test results and high reversion rates on repeat testing, illustrating poor short-term reproducibility of positive QFT-GIT test results. These results suggest adopting a borderline zone between interferon-gamma values of 0.35 IU⁄mL to 2.0 IU⁄mL, and cautious clinical interpretation of values in this range.

Gamma ray astrophysics. [emphasizing processes and absorption

NASA Technical Reports Server (NTRS)

Stecker, F. W.

1974-01-01

Gamma ray production processes are reviewed, including Compton scattering, synchrotron radiation, bremsstrahlung interactions, meson decay, nucleon-antinucleon annihilations, and pion production. Gamma ray absorption mechanisms through interactions with radiation and with matter are discussed, along with redshifts and gamma ray fluxes.

Coexistence of 3G repeaters with LTE base stations.

PubMed

Yeo, Woon-Young; Lee, Sang-Min; Hwang, Gyung-Ho; Kim, Jae-Hoon

2013-01-01

Repeaters have been an attractive solution for mobile operators to upgrade their wireless networks at low cost and to extend network coverage effectively. Since the first LTE commercial deployment in 2009, many mobile operators have launched LTE networks by upgrading their 3G and legacy networks. Because all 3G frequency bands are shared with the frequency bands for LTE deployment and 3G mobile operators have an enormous number of repeaters, reusing 3G repeaters in LTE networks is definitely a practical and cost-efficient solution. However, 3G repeaters usually do not support spatial multiplexing with multiple antennas, and thus it is difficult to reuse them directly in LTE networks. In order to support spatial multiplexing of LTE, the role of 3G repeaters should be replaced with small LTE base stations or MIMO-capable repeaters. In this paper, a repeater network is proposed to reuse 3G repeaters in LTE deployment while still supporting multilayer transmission of LTE. Interestingly, the proposed network has a higher cluster throughput than an LTE network with MIMO-capable repeaters.

Coexistence of 3G Repeaters with LTE Base Stations

PubMed Central

Yeo, Woon-Young

2013-01-01

Repeaters have been an attractive solution for mobile operators to upgrade their wireless networks at low cost and to extend network coverage effectively. Since the first LTE commercial deployment in 2009, many mobile operators have launched LTE networks by upgrading their 3G and legacy networks. Because all 3G frequency bands are shared with the frequency bands for LTE deployment and 3G mobile operators have an enormous number of repeaters, reusing 3G repeaters in LTE networks is definitely a practical and cost-efficient solution. However, 3G repeaters usually do not support spatial multiplexing with multiple antennas, and thus it is difficult to reuse them directly in LTE networks. In order to support spatial multiplexing of LTE, the role of 3G repeaters should be replaced with small LTE base stations or MIMO-capable repeaters. In this paper, a repeater network is proposed to reuse 3G repeaters in LTE deployment while still supporting multilayer transmission of LTE. Interestingly, the proposed network has a higher cluster throughput than an LTE network with MIMO-capable repeaters. PMID:24459420

Multiwavelength Study of Gamma-Ray Bright Blazars

NASA Astrophysics Data System (ADS)

Morozova, Daria; Larionov, V. M.; Hagen-Thorn, V. A.; Jorstad, S. G.; Marscher, A. P.; Troitskii, I. S.

2011-01-01

We investigate total intensity radio images of 6 gamma-ray bright blazars (BL Lac, 3C 279, 3C 273, W Com, PKS 1510-089, and 3C 66A) and their optical and gamma-ray light curves to study connections between gamma-ray and optical brightness variations and changes in the parsec-scale radio structure. We use high-resolution maps obtained by the BU group at 43 GHz with the VLBA, optical light curves constructed by the St.Petersburg State U. (Russia) team using measurements with the 0.4 m telescope of St.Petersburg State U. (LX200) and the 0.7 m telescope of the Crimean Astrophysical Observatory (AZT-8), and gamma-ray light curves, which we have constructed with data provided by the Fermi Large Area Telescope. Over the period from August 2008 to November 2009, superluminal motion is found in all 6 objects with apparent speed ranging from 2c to 40c. The blazars with faster apparent speeds, 3C 273, 3C 279, PKS 1510-089, and 3C 66A, exhibit stronger variability of the gamma-ray emission. There is a tendency for sources with sharply peaked gamma-ray flares to have faster jet speed than sources with gamma-ray light curves with no sharp peaks. Gamma-ray light curves with sharply peaked gamma-ray flares possess a stronger gamma-ray/optical correlations. The research at St.Petersburg State U. was funded by the Minister of Education and Science of the Russian Federation (state contract N#P123). The research at BU was funded in part by NASA Fermi Guest Investigator grant NNX08AV65G and by NSF grant AST-0907893. The VLBA is an instrument of the National Radio Astronomy Observatory, a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.

Accurate Wavelength Measurement of High-Energy Gamma Rays from the 35Cl(n,{gamma}) Reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belgya, T.; Molnar, G.L.; Mutti, P.

2005-05-24

The energies of eight gamma rays in the 36Cl level scheme have been measured with high precision using the 35Cl(n,{gamma}) reaction and the GAMS4 spectrometer. From these energies, a skeleton decay scheme for 36Cl was constructed, and the binding energy of 36Cl was determined to higher precision than previously. It is shown that using this new information, binding energy determination from Ge detector experiments for other nuclei can also be made with higher precision than now available. The measurement of additional weaker 36Cl gamma rays is continuing.

Search of the energetic gamma-ray experiment telescope (EGRET) data for high-energy gamma-ray microsecond bursts

NASA Technical Reports Server (NTRS)

Fichtel, C. E.; Bertsch, D. L.; Dingus, B. L.; Esposito, J. A.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.

1994-01-01

Hawking (1974) and Page & Hawking (1976) investigated theoretically the possibility of detecting high-energy gamma rays produced by the quantum-mechanical decay of a small black hole created in the early universe. They concluded that, at the very end of the life of the small black hole, it would radiate a burst of gamma rays peaked near 250 MeV with a total energy of about 10(exp 34) ergs in the order of a microsecond or less. The characteristics of a black hole are determined by laws of physics beyond the range of current particle accelerators; hence, the search for these short bursts of high-energy gamma rays provides at least the possibility of being the first test of this region of physics. The Compton Observatory Energetic Gamma-Ray Experiment Telescope (EGRET) has the capability of detecting directly the gamma rays from such bursts at a much fainter level than SAS 2, and a search of the EGRET data has led to an upper limit of 5 x 10(exp -2) black hole decays per cu pc per yr, placing constraints on this and other theories predicting microsecond high-energy gamma-ray bursts.

Gamma-ray transfer and energy deposition in supernovae

NASA Technical Reports Server (NTRS)

Swartz, Douglas A.; Sutherland, Peter G.; Harkness, Robert P.

1995-01-01

Solutions to the energy-independent (gray) radiative transfer equations are compared to results of Monte Carlo simulations of the Ni-56 and Co-56 decay gamma-ray energy deposition in supernovae. The comparison shows that an effective, purely absorptive, gray opacity, kappa(sub gamma) approximately (0. 06 +/- 0.01)Y(sub e) sq cm/g, where Y is the total number of electrons per baryon, accurately describes the interaction of gamma-rays with the cool supernova gas and the local gamma-ray energy deposition within the gas. The nature of the gamma-ray interaction process (dominated by Compton scattering in the relativistic regime) creates a weak dependence of kappa(sub gamma) on the optical thickness of the (spherically symmetric) supernova atmosphere: The maximum value of kappa(sub gamma) applies during optically thick conditions when individual gamma-rays undergo multiple scattering encounters and the lower bound is reached at the phase characterized by a total Thomson optical depth to the center of the atmosphere tau(sub e) approximately less than 1. Gamma-ray deposition for Type Ia supernova models to within 10% for the epoch from maximum light to t = 1200 days. Our results quantitatively confirm that the quick and efficient solution to the gray transfer problem provides an accurate representation of gamma-ray energy deposition for a broad range of supernova conditions.

Escherichia coli K-12 can utilize an exogenous gamma-glutamyl peptide as an amino acid source, for which gamma-glutamyltranspeptidase is essential.

PubMed

Suzuki, H; Hashimoto, W; Kumagai, H

1993-09-01

Escherichia coli K-12 can utilize a gamma-glutamyl peptide as an amino acid source, for which gamma-glutamyltranspeptidase (EC 2.3.2.2) is essential. We suggest that the gamma-glutamyl linkage of a gamma-glutamyl peptide is hydrolyzed by gamma-glutamyltranspeptidase located in the periplasmic space, and the released amino acid is taken up and utilized by E. coli.

Technical Note: Relationships between gamma criteria and action levels: Results of a multicenter audit of gamma agreement index results.

PubMed

Crowe, Scott B; Sutherland, Bess; Wilks, Rachael; Seshadri, Venkatakrishnan; Sylvander, Steven; Trapp, Jamie V; Kairn, Tanya

2016-03-01

The aim of this work was to use a multicenter audit of modulated radiotherapy quality assurance (QA) data to provide a practical examination of gamma evaluation criteria and action level selection. The use of the gamma evaluation method for patient-specific pretreatment QA is widespread, with most commercial solutions implementing the method. Gamma agreement indices were calculated using the criteria 1%/1 mm, 2%/2 mm, 2%/3 mm, 3%/2 mm, 3%/3 mm, and 5%/3 mm for 1265 pretreatment QA measurements, planned at seven treatment centers, using four different treatment planning systems, delivered using three different delivery systems (intensity-modulated radiation therapy, volumetric-modulated arc therapy, and helical tomotherapy) and measured using three different dose measurement systems. The sensitivity of each pair of gamma criteria was evaluated relative to the gamma agreement indices calculated using 3%/3 mm. A linear relationship was observed for 2%/2 mm, 2%/3 mm, and 3%/2 mm. This result implies that most beams failing at 3%/3 mm would also fail for those criteria, if the action level was adjusted appropriately. Some borderline plans might be passed or failed depending on the relative priority (tighter tolerance) used for dose difference or distance to agreement evaluation. Dosimeter resolution and treatment modality were found to have a smaller effect on the results of QA measurements than the number of dimensions (2D or 3D) over which the gamma evaluation was calculated. This work provides a method (and a large sample of results) for calculating equivalent action levels for different gamma evaluation criteria. This work constitutes a valuable guide for clinical decision making and a means to compare published gamma evaluation results from studies using different evaluation criteria. More generally, the data provided by this work support the recommendation that gamma criteria that specifically prioritize the property of greatest clinical importance for each

Characteristics of gamma-ray line flares

NASA Technical Reports Server (NTRS)

Bai, T.; Dennis, B.

1983-01-01

Observations of solar gamma rays by the Solar Maximum Mission (SMM) demonstrate that energetic protons and ions are rapidly accelerated during the impulsive phase. To understand the acceleration mechanisms for these particles, the characteristics of the gamma ray line flares observed by SMM were studied. Some very intense hard X-ray flares without detectable gamma ray lines were also investigated. Gamma ray line flares are distinguished from other flares by: (1) intense hard X-ray and microwave emissions; (2) delay of high energy hard X-rays; (3) emission of type 2 and/or type 4 radio bursts; and (4) flat hard X-ray spectra (average power law index: 3.1). The majority of the gamma ray line flares shared all these characteristics, and the remainder shared at least three of them. Positive correlations were found between durations of spike bursts and spatial sizes of flare loops as well as between delay times and durations of spike bursts.

GRI: The Gamma-Ray Imager mission

NASA Astrophysics Data System (ADS)

Knödlseder, Jürgen; GRI Consortium

With the INTEGRAL observatory ESA has provided a unique tool to the astronomical community revealing hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes. While INTEGRAL provides the global overview over the soft gamma-ray sky, there is a growing need to perform deeper, more focused investigations of gamma-ray sources. In soft X-rays a comparable step was taken going from the Einstein and the EXOSAT satellites to the Chandra and XMM/Newton observatories. Technological advances in the past years in the domain of gamma-ray focusing using Laue diffraction have paved the way towards a new gamma-ray mission, providing major improvements regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow studies of particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.

GRI: The Gamma-Ray Imager mission

NASA Astrophysics Data System (ADS)

Knödlseder, Jürgen; GRI Consortium

2006-06-01

With the INTEGRAL observatory, ESA has provided a unique tool to the astronomical community revealing hundreds of sources, new classes of objects, extraordinary views of antimatter annihilation in our Galaxy, and fingerprints of recent nucleosynthesis processes. While INTEGRAL provides the global overview over the soft gamma-ray sky, there is a growing need to perform deeper, more focused investigations of gamma-ray sources. In soft X-rays a comparable step was taken going from the Einstein and the EXOSAT satellites to the Chandra and XMM/Newton observatories. Technological advances in the past years in the domain of gamma-ray focusing using Laue diffraction have paved the way towards a new gamma-ray mission, providing major improvements regarding sensitivity and angular resolution. Such a future Gamma-Ray Imager will allow the study of particle acceleration processes and explosion physics in unprecedented detail, providing essential clues on the innermost nature of the most violent and most energetic processes in the Universe.

Identification and characterization of gamma-glutamylamine cyclotransferase, an enzyme responsible for gamma-glutamyl-epsilon-lysine catabolism.

PubMed

Oakley, Aaron J; Coggan, Marjorie; Board, Philip G

2010-03-26

Gamma-glutamylamine cyclotransferase (GGACT) is an enzyme that converts gamma-glutamylamines to free amines and 5-oxoproline. GGACT shows high activity toward gamma-glutamyl-epsilon-lysine, derived from the breakdown of fibrin and other proteins cross-linked by transglutaminases. The enzyme adopts the newly identified cyclotransferase fold, observed in gamma-glutamylcyclotransferase (GGCT), an enzyme with activity toward gamma-glutamyl-alpha-amino acids (Oakley, A. J., Yamada, T., Liu, D., Coggan, M., Clark, A. G., and Board, P. G. (2008) J. Biol. Chem. 283, 22031-22042). Despite the absence of significant sequence identity, several residues are conserved in the active sites of GGCT and GGACT, including a putative catalytic acid/base residue (GGACT Glu(82)). The structure of GGACT in complex with the reaction product 5-oxoproline provides evidence for a common catalytic mechanism in both enzymes. The proposed mechanism, combined with the three-dimensional structures, also explains the different substrate specificities of these enzymes. Despite significant sequence divergence, there are at least three subfamilies in prokaryotes and eukaryotes that have conserved the GGCT fold and GGCT enzymatic activity.

GLAST and Ground-Based Gamma-Ray Astronomy

NASA Technical Reports Server (NTRS)

McEnery, Julie

2008-01-01

The launch of the Gamma-ray Large Area Space Telescope together with the advent of a new generation of ground-based gamma-ray detectors such as VERITAS, HESS, MAGIC and CANGAROO, will usher in a new era of high-energy gamma-ray astrophysics. GLAST and the ground based gamma-ray observatories will provide highly complementary capabilities for spectral, temporal and spatial studies of high energy gamma-ray sources. Joint observations will cover a huge energy range, from 20 MeV to over 20 TeV. The LAT will survey the entire sky every three hours, allowing it both to perform uniform, long-term monitoring of variable sources and to detect flaring sources promptly. Both functions complement the high-sensitivity pointed observations provided by ground-based detectors. Finally, the large field of view of GLAST will allow a study of gamma-ray emission on large angular scales and identify interesting regions of the sky for deeper studies at higher energies. In this poster, we will discuss the science returns that might result from joint GLAST/ground-based gamma-ray observations and illustrate them with detailed source simulations.

RoboPol: the optical polarization of gamma-ray-loud and gamma-ray-quiet blazars

NASA Astrophysics Data System (ADS)

Angelakis, E.; Hovatta, T.; Blinov, D.; Pavlidou, V.; Kiehlmann, S.; Myserlis, I.; Böttcher, M.; Mao, P.; Panopoulou, G. V.; Liodakis, I.; King, O. G.; Baloković, M.; Kus, A.; Kylafis, N.; Mahabal, A.; Marecki, A.; Paleologou, E.; Papadakis, I.; Papamastorakis, I.; Pazderski, E.; Pearson, T. J.; Prabhudesai, S.; Ramaprakash, A. N.; Readhead, A. C. S.; Reig, P.; Tassis, K.; Urry, M.; Zensus, J. A.

2016-12-01

We present average R-band optopolarimetric data, as well as variability parameters, from the first and second RoboPol observing season. We investigate whether gamma-ray-loud and gamma-ray-quiet blazars exhibit systematic differences in their optical polarization properties. We find that gamma-ray-loud blazars have a systematically higher polarization fraction (0.092) than gamma-ray-quiet blazars (0.031), with the hypothesis of the two samples being drawn from the same distribution of polarization fractions being rejected at the 3σ level. We have not found any evidence that this discrepancy is related to differences in the redshift distribution, rest-frame R-band luminosity density, or the source classification. The median polarization fraction versus synchrotron-peak-frequency plot shows an envelope implying that high-synchrotron-peaked sources have a smaller range of median polarization fractions concentrated around lower values. Our gamma-ray-quiet sources show similar median polarization fractions although they are all low-synchrotron-peaked. We also find that the randomness of the polarization angle depends on the synchrotron peak frequency. For high-synchrotron-peaked sources, it tends to concentrate around preferred directions while for low-synchrotron-peaked sources, it is more variable and less likely to have a preferred direction. We propose a scenario which mediates efficient particle acceleration in shocks and increases the helical B-field component immediately downstream of the shock.

30 CFR 57.5047 - Gamma radiation surveys.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines where...

30 CFR 57.5047 - Gamma radiation surveys.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Gamma radiation surveys. 57.5047 Section 57..., Radiation, Physical Agents, and Diesel Particulate Matter Radiation-Underground Only § 57.5047 Gamma radiation surveys. (a) Gamma radiation surveys shall be conducted annually in all underground mines where...

Regulation of gamma-Secretase in Alzheimer's Disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Shuxia; Zhou, Hua; Walian, Peter

2007-02-07

The {gamma}-secretase complex is an intramembrane aspartyl protease that cleaves its substrates along their transmembrane regions. Sequential proteolytic processing of amyloid precursor protein by {beta}- and {gamma}-secretase produces amyloid {beta}-peptides, which are the major components of amyloid plaques in the brains of Alzheimer's disease patients. The {gamma}-secretase complex is therefore believed to be critical in the pathogenesis of Alzheimer's disease. Here we review the range of factors found to affect the nature and degree of {gamma}-secretase complex activity; these include {gamma}-secretase complex assembly and activation, the integral regulatory subunit CD147, transient or weak binding partners, the levels of cholesterol andmore » sphingolipids in cell membranes, and inflammatory cytokines. Integrated knowledge of the molecular mechanisms supporting the actions of these factors is expected to lead to a comprehensive understanding of the functional regulation of the {gamma}-secretase complex, and this, in turn, should facilitate the development of novel therapeutic strategies for the treatment of Alzheimer's disease.« less

Models for Supernovae and Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Woosley, Stan

. These stars may have been born more massive than nowadays, and certainly died more massive if mass loss depends upon metallicity. We will explore the bright signal from shock breakout in these stars, a signal that should be detectable even after traversing almost all the universe. We will also study a particular class of ultra-luminous supernovae resulting from the collisions of shells ejected by repeated thermonuclear explosions in very massive stars, the so called ``pulsational pair instability supernovae''. Shock break out will also be studied in more nearby stars using the large library of supernova models we have computed over the years. And we will study the effects that the black holes and neutron stars have on the light emitted by the supernovae that made them. If the outer layers of the star that made the black hole rotate too fast to fall straight into the hole, a long duration (minutes to days) gamma-ray burst can result. If the neutron star has an exceptionally strong magnetic field and rotates rapidly, it may contribute to the supernova light curve. In some cases the supernova would be ultraluminous. Finding compelling evidence for either of these effects would have important implications for how supernovae and gamma-ray bursts work. We are seeking support for one month's summer salary for the PI and full time support for a graduate student. The student is already at UCSC and working on similar projects.

Gamma-ray Albedo of the Moon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moskalenko, Igor V.; Porter, Troy A.

2007-06-14

We use the GEANT4 Monte Carlo framework to calculate the gamma-ray albedo of the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our calculation of the albedo spectrum agrees with the EGRET data. We show that the spectrum of gamma-rays from the Moon is very steep with an effective cutoff around 3 GeV (600 MeV for the inner part of the Moon disc). Since it is the only (almost) black spot in the gamma-ray sky, it provides a unique opportunity for calibration of gamma-ray telescopes, such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST).more » The albedo flux depends on the incident CR spectrum which changes over the solar cycle. Therefore, it is possible to monitor the CR spectrum using the albedo gamma-ray flux. Simultaneous measurements of CR proton and helium spectra by the Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics (PAMELA), and observations of the albedo -rays by the GLAST Large Area Telescope (LAT), can be used to test the model predictions and will enable the GLAST LAT to monitor the CR spectrum near the Earth beyond the lifetime of PAMELA.« less

Measuring B to S Gamma, B to D Gamma and |V(Td)/V(Ts)| at BaBar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bard, Deborah; /SLAC

2012-06-01

Using a sample of 471 million B{bar B} events collected with the BaBar detector, we study the sum of seven exclusive final states b {yields} X{sub s(d)}{gamma}, where X{sub s(d)} is a strange (non-strange) hadronic system with a mass of up to 2.0 Gev/c{sup 2}. After correcting for unobserved decay modes, we obtain a branching fraction for b {yields} d{gamma} of (9.2 {+-} 2.0(stat.) {+-} 2.3(syst.)) x 10{sup -6} in this mass range, and a branching fraction for b {yields} s{gamma} of (23.0 {+-} 0.8(stat.) {+-} 3.0(syst.)) x 10{sup -5} in the same mass range. We find BF(b {yields} d{gamma})/BF(bmore » {yields} s{gamma}) = 0.040 {+-} 0.009(stat.) {+-} 0.010(syst.), from which we determine |V{sub td}/V{sub ts}| = 0.199 {+-} 0.022(stat.) {+-} 0.024(syst.) {+-} 0.002(th.).« less

EEG-Informed fMRI Reveals a Disturbed Gamma-Band–Specific Network in Subjects at High Risk for Psychosis

PubMed Central

Leicht, Gregor; Vauth, Sebastian; Polomac, Nenad; Andreou, Christina; Rauh, Jonas; Mußmann, Marius; Karow, Anne; Mulert, Christoph

2016-01-01

Objectives. Abnormalities of oscillatory gamma activity are supposed to reflect a core pathophysiological mechanism underlying cognitive disturbances in schizophrenia. The auditory evoked gamma-band response (aeGBR) is known to be reduced across all stages of the disease. The present study aimed to elucidate alterations of an aeGBR-specific network mediated by gamma oscillations in the high-risk state of psychosis (HRP) by means of functional magnetic resonance imaging (fMRI) informed by electroencephalography (EEG). Methods. EEG and fMRI were simultaneously recorded from 27 HRP individuals and 26 healthy controls (HC) during performance of a cognitively demanding auditory reaction task. We used single trial coupling of the aeGBR with the corresponding blood oxygen level depending response (EEG-informed fMRI). Results. A gamma-band–specific network was significantly lower active in HRP subjects compared with HC (random effects analysis, P < .01, Bonferroni-corrected for multiple comparisons) accompanied by a worse task performance. This network involved the bilateral auditory cortices, the thalamus and frontal brain regions including the anterior cingulate cortex, as well as the bilateral dorsolateral prefrontal cortex. Conclusions. For the first time we report a reduced activation of an aeGBR-specific network in HRP subjects brought forward by EEG-informed fMRI. Because the HRP reflects the clinical risk for conversion to psychotic disorders including schizophrenia and the aeGBR has repeatedly been shown to be altered in patients with schizophrenia the results of our study point towards a potential applicability of aeGBR disturbances as a marker for the prediction of transition of HRP subjects to schizophrenia. PMID:26163477

EEG-Informed fMRI Reveals a Disturbed Gamma-Band-Specific Network in Subjects at High Risk for Psychosis.

PubMed

Leicht, Gregor; Vauth, Sebastian; Polomac, Nenad; Andreou, Christina; Rauh, Jonas; Mußmann, Marius; Karow, Anne; Mulert, Christoph

2016-01-01

Abnormalities of oscillatory gamma activity are supposed to reflect a core pathophysiological mechanism underlying cognitive disturbances in schizophrenia. The auditory evoked gamma-band response (aeGBR) is known to be reduced across all stages of the disease. The present study aimed to elucidate alterations of an aeGBR-specific network mediated by gamma oscillations in the high-risk state of psychosis (HRP) by means of functional magnetic resonance imaging (fMRI) informed by electroencephalography (EEG). EEG and fMRI were simultaneously recorded from 27 HRP individuals and 26 healthy controls (HC) during performance of a cognitively demanding auditory reaction task. We used single trial coupling of the aeGBR with the corresponding blood oxygen level depending response (EEG-informed fMRI). A gamma-band-specific network was significantly lower active in HRP subjects compared with HC (random effects analysis, P < .01, Bonferroni-corrected for multiple comparisons) accompanied by a worse task performance. This network involved the bilateral auditory cortices, the thalamus and frontal brain regions including the anterior cingulate cortex, as well as the bilateral dorsolateral prefrontal cortex. For the first time we report a reduced activation of an aeGBR-specific network in HRP subjects brought forward by EEG-informed fMRI. Because the HRP reflects the clinical risk for conversion to psychotic disorders including schizophrenia and the aeGBR has repeatedly been shown to be altered in patients with schizophrenia the results of our study point towards a potential applicability of aeGBR disturbances as a marker for the prediction of transition of HRP subjects to schizophrenia. © The Author 2015. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.

Hippocampal theta, gamma, and theta-gamma coupling: effects of aging, environmental change, and cholinergic activation

PubMed Central

Jacobson, Tara K.; Howe, Matthew D.; Schmidt, Brandy; Hinman, James R.; Escabí, Monty A.

2013-01-01

Hippocampal theta and gamma oscillations coordinate the timing of multiple inputs to hippocampal neurons and have been linked to information processing and the dynamics of encoding and retrieval. One major influence on hippocampal rhythmicity is from cholinergic afferents. In both humans and rodents, aging is linked to impairments in hippocampus-dependent function along with degradation of cholinergic function. Cholinomimetics can reverse some age-related memory impairments and modulate oscillations in the hippocampus. Therefore, one would expect corresponding changes in these oscillations and possible rescue with the cholinomimetic physostigmine. Hippocampal activity was recorded while animals explored a familiar or a novel maze configuration. Reexposure to a familiar situation resulted in minimal aging effects or changes in theta or gamma oscillations. In contrast, exploration of a novel maze configuration increased theta power; this was greater in adult than old animals, although the deficit was reversed with physostigmine. In contrast to the theta results, the effects of novelty, age, and/or physostigmine on gamma were relatively weak. Unrelated to the behavioral situation were an age-related decrease in the degree of theta-gamma coupling and the fact that physostigmine lowered the frequency of theta in both adult and old animals. The results indicate that age-related changes in gamma and theta modulation of gamma, while reflecting aging changes in hippocampal circuitry, seem less related to aging changes in information processing. In contrast, the data support a role for theta and the cholinergic system in encoding and that hippocampal aging is related to impaired encoding of new information. PMID:23303862

The network impact of hijacking a quantum repeater

NASA Astrophysics Data System (ADS)

Satoh, Takahiko; Nagayama, Shota; Oka, Takafumi; Van Meter, Rodney

2018-07-01

In quantum networking, repeater hijacking menaces the security and utility of quantum applications. To deal with this problem, it is important to take a measure of the impact of quantum repeater hijacking. First, we quantify the work of each quantum repeater with regards to each quantum communication. Based on this, we show the costs for repeater hijacking detection using distributed quantum state tomography and the amount of work loss and rerouting penalties caused by hijacking. This quantitative evaluation covers both purification-entanglement swapping and quantum error correction repeater networks. Naive implementation of the checks necessary for correct network operation can be subverted by a single hijacker to bring down an entire network. Fortunately, the simple fix of randomly assigned testing can prevent such an attack.

LPA gene: interaction between the apolipoprotein(a) size ('kringle IV' repeat) polymorphism and a pentanucleotide repeat polymorphism influences Lp(a) lipoprotein level.

PubMed

Røsby, O; Berg, K

2000-01-01

In order to search for factors influencing the Lp(a) lipoprotein level, we have examined the apolipoprotein(a) (apo(a)) size polymorphism as well as a pentanucleotide (TTTTA) repeat polymorphism in the 5' control region of the LPA gene. Lp(a) lipoprotein levels were compared between individuals with different genotypes as defined by pulsed field gel electrophoresis of DNA plugs, and PCR of DNA samples followed by polyacrylamide gel electrophoresis. DNA plugs and DNA were prepared from blood samples collected from blood donors. Twenty-seven different K IV repeat alleles were observed in the 71 women and 92 men from which apo(a) size polymorphism results were obtained. Alleles encoding 26-32 Kringle IV repeats were the most frequent. Alleles encoding seven to 11 TTTTA repeats were detected in the 84 women and 122 men included in the pentanucleotide polymorphism study, and homozygosity for eight TTTTA repeats was the most common genotype. The eight TTTTA repeat allele occurred with almost any apo(a) allele. An inverse relationship between number of K IV repeats and Lp(a) concentration was confirmed. The contributions of the apo(a) size polymorphism and the pentanucleotide repeat polymorphism to the interindividual variance of Lp(a) lipoprotein concentrations were 9.7 and 3.5%, respectively (type IV sum of squares). Nineteen per cent of the variance in Lp(a) lipoprotein level appeared to be the result of the multiplication product (interaction) between the apo(a) size polymorphism and the pentanucleotide repeat polymorphism. The contribution of the apo(a) size polymorphism alone to the variation in Lp(a) lipoprotein level was lower than previously reported. However, the multiplicative interaction effect between the K IV repeat polymorphism and the pentanucleotide repeat polymorphism may be an important factor explaining the variation in Lp(a) lipoprotein levels among the populations.

Role of memory errors in quantum repeaters

NASA Astrophysics Data System (ADS)

Hartmann, L.; Kraus, B.; Briegel, H.-J.; Dür, W.

2007-03-01

We investigate the influence of memory errors in the quantum repeater scheme for long-range quantum communication. We show that the communication distance is limited in standard operation mode due to memory errors resulting from unavoidable waiting times for classical signals. We show how to overcome these limitations by (i) improving local memory and (ii) introducing two operational modes of the quantum repeater. In both operational modes, the repeater is run blindly, i.e., without waiting for classical signals to arrive. In the first scheme, entanglement purification protocols based on one-way classical communication are used allowing to communicate over arbitrary distances. However, the error thresholds for noise in local control operations are very stringent. The second scheme makes use of entanglement purification protocols with two-way classical communication and inherits the favorable error thresholds of the repeater run in standard mode. One can increase the possible communication distance by an order of magnitude with reasonable overhead in physical resources. We outline the architecture of a quantum repeater that can possibly ensure intercontinental quantum communication.

Comparison of myocardial perfusion imaging between the new high-speed gamma camera and the standard anger camera.

PubMed

Tanaka, Hirokazu; Chikamori, Taishiro; Hida, Satoshi; Uchida, Kenji; Igarashi, Yuko; Yokoyama, Tsuyoshi; Takahashi, Masaki; Shiba, Chie; Yoshimura, Mana; Tokuuye, Koichi; Yamashina, Akira

2013-01-01

Cadmium-zinc-telluride (CZT) solid-state detectors have been recently introduced into the field of myocardial perfusion imaging. The aim of this study was to prospectively compare the diagnostic performance of the CZT high-speed gamma camera (Discovery NM 530c) with that of the standard 3-head gamma camera in the same group of patients. The study group consisted of 150 consecutive patients who underwent a 1-day stress-rest (99m)Tc-sestamibi or tetrofosmin imaging protocol. Image acquisition was performed first on a standard gamma camera with a 15-min scan time each for stress and for rest. All scans were immediately repeated on a CZT camera with a 5-min scan time for stress and a 3-min scan time for rest, using list mode. The correlations between the CZT camera and the standard camera for perfusion and function analyses were strong within narrow Bland-Altman limits of agreement. Using list mode analysis, image quality for stress was rated as good or excellent in 97% of the 3-min scans, and in 100% of the ≥4-min scans. For CZT scans at rest, similarly, image quality was rated as good or excellent in 94% of the 1-min scans, and in 100% of the ≥2-min scans. The novel CZT camera provides excellent image quality, which is equivalent to standard myocardial single-photon emission computed tomography, despite a short scan time of less than half of the standard time.

Deployment Repeatability

DTIC Science & Technology

2016-04-01

environment. Modeling is suitable for well- characterized parts, and stochastic modeling techniques can be used for sensitivity analysis and generating a...large cohort of trials to spot unusual cases. However, deployment repeatability is inherently a nonlinear phenomenon, which makes modeling difficult...recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the U.S. Air Force. 1. Test the flight model

Future Facilities for Gamma-Ray Pulsar Studies

NASA Technical Reports Server (NTRS)

Thompson, D. J.

2003-01-01

Pulsars seen at gamma-ray energies offer insight into particle acceleration to very high energies, along with information about the geometry and interaction processes in the magnetospheres of these rotating neutron stars. During the next decade, a number of new gamma-ray facilities will become available for pulsar studies. This brief review describes the motivation for gamma-ray pulsar studies, the opportunities for such studies, and some specific discussion of the capabilities of the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) for pulsar measurements.

Determination of repeatability of kinect sensor.

PubMed

Bonnechère, Bruno; Sholukha, Victor; Jansen, Bart; Omelina, Lubos; Rooze, Marcel; Van Sint Jan, Serge

2014-05-01

The Kinect™ (Microsoft™, Redmond, WA) sensor, originally developed for gaming purposes, may have interesting possibilities for other fields such as posture and motion assessment. The ability of the Kinect sensor to perform biomechanical measurements has previously been studied and shows promising results. However, interday repeatability of the device is still not known. This study assessed the intra- and interday repeatability of the Kinect sensor compared with a standard stereophotogrammetric device during posture assessment for measuring segment lengths. Forty subjects took part in the study. Five motionless captures were performed in one session to assess posture. Data were simultaneously recorded with both devices. Similar intraclass correlations coefficient (ICC) values were found for intraday (ICC=0.94 for the Kinect device and 0.98 for the stereophotogrammetric device) and interday (ICC=0.88 and 0.87, respectively) repeatability. Results of this study suggest that a cost-effective, easy-to-use, and portable single markerless camera offers the same repeatability during posture assessment as an expensive, time-consuming, and nontransportable marker-based device.

Measurement of absolute gamma emission probabilities

NASA Astrophysics Data System (ADS)

Sumithrarachchi, Chandana S.; Rengan, Krish; Griffin, Henry C.

2003-06-01

The energies and emission probabilities (intensities) of gamma-rays emitted in radioactive decays of particular nuclides are the most important characteristics by which to quantify mixtures of radionuclides. Often, quantification is limited by uncertainties in measured intensities. A technique was developed to reduce these uncertainties. The method involves obtaining a pure sample of a nuclide using radiochemical techniques, and using appropriate fractions for beta and gamma measurements. The beta emission rates were measured using a liquid scintillation counter, and the gamma emission rates were measured with a high-purity germanium detector. Results were combined to obtain absolute gamma emission probabilities. All sources of uncertainties greater than 0.1% were examined. The method was tested with 38Cl and 88Rb.

Gamma Rays at Very High Energies

NASA Astrophysics Data System (ADS)

Aharonian, Felix

This chapter presents the elaborated lecture notes on Gamma Rays at Very High Energies given by Felix Aharonian at the 40th Saas-Fee Advanced Course on "Astrophysics at Very High Energies". Any coherent description and interpretation of phenomena related to gammarays requires deep knowledge of many disciplines of physics like nuclear and particle physics, quantum and classical electrodynamics, special and general relativity, plasma physics, magnetohydrodynamics, etc. After giving an introduction to gamma-ray astronomy the author discusses the astrophysical potential of ground-based detectors, radiation mechanisms, supernova remnants and origin of the galactic cosmic rays, TeV emission of young supernova remnants, gamma-emission from the Galactic center, pulsars, pulsar winds, pulsar wind nebulae, and gamma-ray loud binaries.

Strength of Gamma Rhythm Depends on Normalization

PubMed Central

Ray, Supratim; Ni, Amy M.; Maunsell, John H. R.

2013-01-01

Neuronal assemblies often exhibit stimulus-induced rhythmic activity in the gamma range (30–80 Hz), whose magnitude depends on the attentional load. This has led to the suggestion that gamma rhythms form dynamic communication channels across cortical areas processing the features of behaviorally relevant stimuli. Recently, attention has been linked to a normalization mechanism, in which the response of a neuron is suppressed (normalized) by the overall activity of a large pool of neighboring neurons. In this model, attention increases the excitatory drive received by the neuron, which in turn also increases the strength of normalization, thereby changing the balance of excitation and inhibition. Recent studies have shown that gamma power also depends on such excitatory–inhibitory interactions. Could modulation in gamma power during an attention task be a reflection of the changes in the underlying excitation–inhibition interactions? By manipulating the normalization strength independent of attentional load in macaque monkeys, we show that gamma power increases with increasing normalization, even when the attentional load is fixed. Further, manipulations of attention that increase normalization increase gamma power, even when they decrease the firing rate. Thus, gamma rhythms could be a reflection of changes in the relative strengths of excitation and normalization rather than playing a functional role in communication or control. PMID:23393427

Gamma-delta t-cell lymphomas.

PubMed

Foppoli, Marco; Ferreri, Andrés J M

2015-03-01

Gamma-delta T-cell lymphomas are aggressive and rare diseases originating from gamma-delta lymphocytes. These cells, which naturally play a role in the innate, non-specific immune response, develop from thymic precursor in the bone marrow, lack the major histocompatibility complex restrictions and can be divided into two subpopulations: Vdelta1, mostly represented in the intestine, and Vdelta2, prevalently located in the skin, tonsils and lymph nodes. Chronic immunosuppression such as in solid organ transplanted subjects and prolonged antigenic exposure are probably the strongest risk factors for the triggering of lymphomagenesis. Two entities are recognised by the 2008 WHO Classification: hepatosplenic gamma-delta T-cell lymphoma (HSGDTL) and primary cutaneous gamma-delta T-cell lymphoma (PCGDTL). The former is more common among young males, presenting with B symptoms, splenomegaly and thrombocytopenia, usually with the absence of nodal involvement. Natural behaviour of HSGDTL is characterised by low response rates, poor treatment tolerability, common early progression of disease and disappointing survival figures. PCGDTL accounts for <1% of all primary cutaneous lymphomas, occurring in adults with relevant comorbidities. Cutaneous lesions may vary, but its clinical behaviour is usually aggressive and long-term survival is anecdotal. Available literature on gamma-delta T-cell lymphomas is fractioned, mostly consisting of case reports or small cumulative series. Therefore, clinical suspicion and diagnosis are usually delayed, and therapeutic management remains to be established. This review critically analyses available evidence on diagnosis, staging and behaviour of gamma-delta T-cell lymphomas, provides recommendations for therapeutic management in routine practice and discusses relevant unmet clinical needs for future studies. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

AN ORIENTATIONAL RESPONSE TO WEAK GAMMA RADIATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brown, F.A. Jr.

1963-10-01

The common planarian worm, Duesia dorotocephsla, displays a significant orientational response to increase in Cs/sup 137/ gamma radiation when the increase is no greater than six times background. The worms are able to distinguish the direction of the weak gamma source, turning away from it, whether it is presented on the right or left side. The response sign is, therefore, the same as that of the response of these negatively phototactic worms to visible light. There is a clear compass-directional relationship of the responsiveness to the experimental gamma radiation. A conspicuous negative response is present when the worms are travelingmore » northward or southward in the earth's field with the gamma change in an east-west axis. No statistically significant mean turning response to the gamma radiation is found when the worms are traveling eastward or westward in the earth's field with the gamma change in a north-south axis. The previously observed annual fluctuation in the character of the monthly orientational rhythm of north-directed worms has been confirmed in an additional year of study. During colder months, the rhythm is monthly; during warmer months it is semi-monthly. There is a semi-monthly fluctuation in the response of Dugesia to weak gamma radiation during mid-morning hours, the worms turning away from the source for four days prior to new end full moon, and toward it for two days following new and full moon. The stronger the field strength, up to 9 times backgound, the larger the amplitude of the rhythm. There is a direct relationship between intensities of gamma radiation between that of background and nine times backgound, and the strength of the negative response of the worms. Evidence suggests that the negative response of Dugesia to a gamma source may be modified by experimental alteration of the natural ambient electrostatic field. Some possible biological significances of this remarkable responsiveness to gamma radiation, and its particular

Dental Fear in Children with Repeated Tooth Injuries.

PubMed

Negovetić Vranić, Dubravka; Ivančić Jokić, Nataša; Bakarčić, Danko; Carek, Andreja; Rotim, Željko; Verzak, Željko

2016-06-01

Tooth injuries are serious clinical conditions. Some children experience dental trauma only once, while others are more prone to repeated tooth injuries. Repeated dental trauma occurs in 19.4% to 30% of patients. Pain and dental trauma are the most common reasons for fear and anxiety. The main objective of this study was to investigate how dental trauma, as well as repeated dental trauma affects the occurrence and development of dental fear in children. The study was conducted on a random sample of 147 subjects (88 boys and 59 girls) aged 5-8 and 9-12 years. Subjects in both age groups were divided into subroups without dental trauma, with one dental trauma and with repeated dental trauma. The validated Children’s Fear Survey Schedule – Dental Subscale was used on fear assessment. Results showed that only 12.2% of children without trauma, 33.3% with one trauma and 51.7% with repeated trauma were not afraid of injection. Older children had a significantly lower fear of injections, touch of an unknown person, choking, going to the hospital and people in white uniforms. Dentist was not the cause of fear in 65.5% of patients with repeated trauma. With each repeated injury of teeth, the degree of their fear of dental treatment was lower.

Discoveries by the Fermi Gamma Ray Space Telescope

NASA Technical Reports Server (NTRS)

Gehrels, Neil

2011-01-01

Fermi is a large space gamma-ray mission developed by NASA and the DOE with major contributions from France, Germany, Italy, Japan and Sweden. It was launched in June 2008 and has been performing flawlessly since then. The main instrument is the Large Area Telescope (LAT) operating in the 20 MeV to 300 GeV range and a smaller monitor instrument is the Gamma-ray Burst Monitor (GBM) operating in the 8 keV to 40 MeV range. New findings are occurring every week. Some of the key discoveries are: 1) Discovery of many new gamma-ray pulsars, including gamma-ray only and millisecond pulsars. 2) Detection of high energy gamma-ray emission from globular clusters, most likely due to summed emission from msec pulsars. 3) Discovery of delayed and extended high energy gamma-ray emission from short and long gamma-ray busts. 4) Detection of approximately 250 gamma-ray bursts per year with the GBM instrument. 5) Most accurate measurement of the cosmic ray electron spectrum between 30 GeV and 1 TeV, showing some excess above the conventional diffusion model. The talk will present the new discoveries and their implications.

Erroneous Memories Arising from Repeated Attempts to Remember

ERIC Educational Resources Information Center

Henkel, Linda A.

2004-01-01

The impact of repeated and prolonged attempts at remembering on false memory rates was assessed in three experiments. Participants saw and imagined pictures and then made repeated recall attempts before taking a source memory test. Although the number of items recalled increased with repeated tests, the net gains were associated with more source…

Human antirabies gamma globulin*

PubMed Central

Hosty, Thomas S.; Kissling, R. E.; Schaeffer, M.; Wallace, Gordon A.; Dibble, E. H.

1959-01-01

To obviate the foreign protein reactions experienced with the use of hyperimmune serum in rabies-exposed individuals, an attempt was made to produce a rabies antiserum of human origin. Five doses of an inactivated rabies virus duck-egg vaccine were administered to 34 volunteers at 4-day intervals (i.e., on days 0, 4, 8, 12 and 16). An additional dose of chick-embryo attenuated virus vaccine—Flury HEP (high egg passage)—was given on the 46th day, followed by a final booster dose of duck-egg vaccine on the 288th day. Twenty-four days later, i.e., on the 312th day after the first dose, the participants were bled and the serum pooled and converted to gamma globulin. These volunteers, having no initial antibody, responded with variable titres, the pooled serum having a titre of 1: 100 against 50 LD50 of rabies virus in neutralization tests and the gamma globulin prepared from this pool a titre of 1: 300. In five individuals inoculated with the antirabies gamma globulin, blood samples tested at intervals for residual antibody showed significant titres through 21 days. While the passive antibody levels resulting from the administration of a more potent immune horse serum were much higher than those achieved by the weaker human antirabies gamma globulin used, the decrease in titre was more gradual with the human globulin. With more booster inoculations in a larger group of human volunteers, it is believed that a human rabies immune gamma globulin could be produced which would be equal in effect to immune horse serum. The advantages of a human source of antibody in rabies prophylaxis are discussed. PMID:14403320

Increased visual gamma power in schizoaffective bipolar disorder.

PubMed

Brealy, J A; Shaw, A; Richardson, H; Singh, K D; Muthukumaraswamy, S D; Keedwell, P A

2015-03-01

Electroencephalography and magnetoencephalography (MEG) studies have identified alterations in gamma-band (30-80 Hz) cortical activity in schizophrenia and mood disorders, consistent with neural models of disturbed glutamate (and GABA) neuron influence over cortical pyramidal cells. Genetic evidence suggests specific deficits in GABA-A receptor function in schizoaffective bipolar disorder (SABP), a clinical syndrome with features of both bipolar disorder and schizophrenia. This study investigated gamma oscillations in this under-researched disorder. MEG was used to measure induced gamma and evoked responses to a visual grating stimulus, known to be a potent inducer of primary visual gamma oscillations, in 15 individuals with remitted SABP, defined using Research Diagnostic Criteria, and 22 age- and sex-matched healthy controls. Individuals with SABP demonstrated increased sustained visual cortical power in the gamma band (t 35 = -2.56, p = 0.015) compared to controls. There were no group differences in baseline gamma power, transient or sustained gamma frequency, alpha band responses or pattern onset visual-evoked responses. Gamma power is increased in remitted SABP, which reflects an abnormality in the cortical inhibitory-excitatory balance. Although an interaction between gamma power and medication can not be ruled out, there were no group differences in evoked responses or baseline measures. Further work is needed in other clinical populations and at-risk relatives. Pharmaco-magnetoencephalography studies will help to elucidate the specific GABA and glutamate pathways affected.

Limitations on quantum key repeaters.

PubMed

Bäuml, Stefan; Christandl, Matthias; Horodecki, Karol; Winter, Andreas

2015-04-23

A major application of quantum communication is the distribution of entangled particles for use in quantum key distribution. Owing to noise in the communication line, quantum key distribution is, in practice, limited to a distance of a few hundred kilometres, and can only be extended to longer distances by use of a quantum repeater, a device that performs entanglement distillation and quantum teleportation. The existence of noisy entangled states that are undistillable but nevertheless useful for quantum key distribution raises the question of the feasibility of a quantum key repeater, which would work beyond the limits of entanglement distillation, hence possibly tolerating higher noise levels than existing protocols. Here we exhibit fundamental limits on such a device in the form of bounds on the rate at which it may extract secure key. As a consequence, we give examples of states suitable for quantum key distribution but unsuitable for the most general quantum key repeater protocol.

Cen A Optical Gamma Composite

NASA Image and Video Library

2017-12-08

NASA release April 1, 2010 The gamma-ray output from Cen A's lobes exceeds their radio output by more than ten times. High-energy gamma rays detected by Fermi's Large Area Telescope are depicted as purple in this gamma ray/optical composite of the galaxy. Credit: NASA/DOE/Fermi LAT Collaboration, Capella Observatory To learn more about these images go to: www.nasa.gov/mission_pages/GLAST/news/smokestack-plumes.html NASA Goddard Space Flight Center is home to the nation's largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

Gamma Ray Bursts

NASA Technical Reports Server (NTRS)

Gehrels, Neil; Meszaros, Peter

2012-01-01

Gamma-ray bursts (GRBs) are bright flashes of gamma-rays coming from the cosmos. They occur roughly once per day ,last typically lOs of seconds and are the most luminous events in the universe. More than three decades after their discovery, and after pioneering advances from space and ground experiments, they still remain mysterious. The launch of the Swift and Fermi satellites in 2004 and 2008 brought in a trove of qualitatively new data. In this review we survey the interplay between these recent observations and the theoretical models of the prompt GRB emission and the subsequent afterglows.

Gamma-Terpinene Modulates Acute Inflammatory Response in Mice.

PubMed

Ramalho, Theresa Raquel de Oliveira; Oliveira, Maria Talita Pacheco de; Lima, Ana Luisa de Araujo; Bezerra-Santos, Claudio Roberto; Piuvezam, Marcia Regina

2015-09-01

The monoterpene gamma-terpinene is a natural compound present in essential oils of a wide variety of plants, including the Eucalyptus genus, which has been reported to possess anti-inflammatory activity. The goal of this study was to evaluate the effect of gamma-terpinene on several in vivo experimental models of acute inflammation. Swiss mice were pretreated with gamma-terpinene and subjected to protocols of paw edema with different phlogistic agents such as carrageenan, prostaglandin-E2, histamine, or bradykinin. The microvascular permeability was measured by intraperitoneal injection of acetic acid and measuring the amount of protein extravasation. Carrageenan-induced peritonitis was used to analyze the effect of gamma-terpinene on inflammatory cell migration and cytokine production. We also developed an acute lung injury protocol to define the anti-inflammatory effect of gamma-terpinene. Mice pretreated with gamma-terpinene displayed reduced paw edema induced by carrageenan from 1-24 h after challenge. A similar reduction was observed when gamma-terpinene was administered after stimulation with PGE2, bradykinin, and histamine. Treatment with gamma-terpinene also inhibited fluid extravasation in the acetic acid model of microvascular permeability. In a carrageenan-induced peritonitis model, gamma-terpinene treatment reduced neutrophil migration as well as the production of interleukin-1β and tumor necrosis factor-α when compared to nontreated animals, and in the acute lung injury protocol, gamma-terpinene diminished the neutrophil migration into lung tissue independently of the total protein extravasation in the lung. These data demonstrate that, in different models of inflammation, treatment with gamma-terpinene alleviated inflammatory parameters such as edema and pro-inflammatory cytokine production, as well as cell migration into the inflamed site, and that this monoterpene has anti-inflammatory properties. Georg Thieme Verlag KG Stuttgart · New York.

Impact of Image Noise on Gamma Index Calculation

NASA Astrophysics Data System (ADS)

Chen, M.; Mo, X.; Parnell, D.; Olivera, G.; Galmarini, D.; Lu, W.

2014-03-01

Purpose: The Gamma Index defines an asymmetric metric between the evaluated image and the reference image. It provides a quantitative comparison that can be used to indicate sample-wised pass/fail on the agreement of the two images. The Gamma passing/failing rate has become an important clinical evaluation tool. However, the presence of noise in the evaluated and/or reference images may change the Gamma Index, hence the passing/failing rate, and further, clinical decisions. In this work, we systematically studied the impact of the image noise on the Gamma Index calculation. Methods: We used both analytic formulation and numerical calculations in our study. The numerical calculations included simulations and clinical images. Three different noise scenarios were studied in simulations: noise in reference images only, in evaluated images only, and in both. Both white and spatially correlated noises of various magnitudes were simulated. For clinical images of various noise levels, the Gamma Index of measurement against calculation, calculation against measurement, and measurement against measurement, were evaluated. Results: Numerical calculations for both the simulation and clinical data agreed with the analytic formulations, and the clinical data agreed with the simulations. For the Gamma Index of measurement against calculation, its distribution has an increased mean and an increased standard deviation as the noise increases. On the contrary, for the Gamma index of calculation against measurement, its distribution has a decreased mean and stabilized standard deviation as the noise increases. White noise has greater impact on the Gamma Index than spatially correlated noise. Conclusions: The noise has significant impact on the Gamma Index calculation and the impact is asymmetric. The Gamma Index should be reported along with the noise levels in both reference and evaluated images. Reporting of the Gamma Index with switched roles of the images as reference and

Effects of aberrant gamma frequency oscillations on prepulse inhibition.

PubMed

Jones, Nigel C; Anderson, Paul; Rind, Gil; Sullivan, Caley; van den Buuse, Maarten; O'Brien, Terence J

2014-10-01

Emerging literature implicates abnormalities in gamma frequency oscillations in the pathophysiology of schizophrenia, with hypofunction of N-methyl-D-aspartate (NMDA) receptors implicated as a key factor. Prepulse inhibition (PPI) is a behavioural measure of sensorimotor gating, which is disrupted in schizophrenia. We studied relationships between ongoing and sensory-evoked gamma oscillations and PPI using pharmacological interventions designed to increase gamma oscillations (ketamine, MK-801); reduce gamma oscillations (LY379268); or disrupt PPI (amphetamine). We predicted that elevating ongoing gamma power would lead to increased 'neural noise' in cortical circuits, dampened sensory-evoked gamma responses and disrupted behaviour. Wistar rats were implanted with EEG recording electrodes. They received ketamine (5 mg/kg), MK-801 (0.16 mg/kg), amphetamine (0.5 mg/kg), LY379268 (3 mg/kg) or vehicle and underwent PPI sessions with concurrent EEG recording. Ketamine and MK-801 increased the power of ongoing gamma oscillations and caused time-matched disruptions of PPI, while amphetamine marginally affected ongoing gamma power. In contrast, LY379268 reduced ongoing gamma power, but had no effect on PPI. The sensory gamma response evoked by the prepulse was reduced following treatment with all psychotomimetics, associating with disruptions in PPI. This was most noticeable following treatment with NMDA receptor antagonists. We found that ketamine and MK-801 increase ongoing gamma power and reduce evoked gamma power, both of which are related to disruptions in sensorimotor gating. This appears to be due to antagonism of NMDA receptors, since amphetamine and LY379268 differentially impacted these outcomes and possess different neuropharmacological substrates. Aberrant gamma frequency oscillations caused by NMDA receptor hypofunction may mediate the sensory processing deficits observed in schizophrenia.

Identification, variation and transcription of pneumococcal repeat sequences

PubMed Central

2011-01-01

Background Small interspersed repeats are commonly found in many bacterial chromosomes. Two families of repeats (BOX and RUP) have previously been identified in the genome of Streptococcus pneumoniae, a nasopharyngeal commensal and respiratory pathogen of humans. However, little is known about the role they play in pneumococcal genetics. Results Analysis of the genome of S. pneumoniae ATCC 700669 revealed the presence of a third repeat family, which we have named SPRITE. All three repeats are present at a reduced density in the genome of the closely related species S. mitis. However, they are almost entirely absent from all other streptococci, although a set of elements related to the pneumococcal BOX repeat was identified in the zoonotic pathogen S. suis. In conjunction with information regarding their distribution within the pneumococcal chromosome, this suggests that it is unlikely that these repeats are specialised sequences performing a particular role for the host, but rather that they constitute parasitic elements. However, comparing insertion sites between pneumococcal sequences indicates that they appear to transpose at a much lower rate than IS elements. Some large BOX elements in S. pneumoniae were found to encode open reading frames on both strands of the genome, whilst another was found to form a composite RNA structure with two T box riboswitches. In multiple cases, such BOX elements were demonstrated as being expressed using directional RNA-seq and RT-PCR. Conclusions BOX, RUP and SPRITE repeats appear to have proliferated extensively throughout the pneumococcal chromosome during the species' past, but novel insertions are currently occurring at a relatively slow rate. Through their extensive secondary structures, they seem likely to affect the expression of genes with which they are co-transcribed. Software for annotation of these repeats is freely available from ftp://ftp.sanger.ac.uk/pub/pathogens/strep_repeats/. PMID:21333003

Fermi: The Gamma-Ray Large Area Telescope

NASA Technical Reports Server (NTRS)

McEnery, Julie

2015-01-01

Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of an population of pulsars pulsing only in gamma rays; the detection of photons up to 10s of GeV from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as supersymmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

Fermi: The Gamma-Ray Large Area Telescope

NASA Technical Reports Server (NTRS)

McEnery, Julie

2014-01-01

Following its launch in June 2008, high-energy gamma-ray observations by the Fermi Gamma-ray Space Telescope have unveiled over 1000 new sources and opened an important and previously unexplored window on a wide variety of phenomena. These have included the discovery of an population of pulsars pulsing only in gamma rays; the detection of photons up to 10 seconds of gigaelectronvolts from gamma-ray bursts, enhancing our understanding of the astrophysics of these powerful explosions; the detection of hundreds of active galaxies; a measurement of the high energy cosmic-ray electron spectrum which may imply the presence of nearby astrophysical particle accelerators; the determination of the diffuse gamma-ray emission with unprecedented accuracy and the constraints on phenomena such as super-symmetric dark-matter annihilations and exotic relics from the Big Bang. Continuous monitoring of the high-energy gamma-ray sky has uncovered numerous outbursts from active galaxies and the discovery of transient sources in our galaxy. In this talk I will describe the current status of the Fermi observatory and review the science highlights from Fermi.

Identification of the low affinity receptor for immunoglobulin E on mouse mast cells and macrophages as Fc gamma RII and Fc gamma RIII.

PubMed

Takizawa, F; Adamczewski, M; Kinet, J P

1992-08-01

In addition to their well characterized high affinity immunoglobulin E (IgE) receptors (Fc epsilon RI) mast cells have long been suspected to express undefined Fc receptors capable of binding IgE with low affinity. In this paper, we show that Fc gamma RII and Fc gamma RIII, but not Mac-2, on mouse mast cells and macrophages bind IgE-immune complexes. This binding is efficiently competed by 2.4G2, a monoclonal antibody against the extracellular homologous region of both Fc gamma RII and Fc gamma RIII. Furthermore, IgE-immune complexes bind specifically to Fc gamma RII or Fc gamma RIII transfected into COS-7 cells. The association constants of IgE binding estimated from competition experiments are about 3.1 x 10(5) M-1 for Fc gamma RII, and 4.8 x 10(5) M-1 for Fc gamma RIII. Engagement of Fc gamma RII and Fc gamma RIII with IgE-immune complexes (after blocking access to Fc epsilon RI) or with IgG-immune complexes triggers C57.1 mouse mast cells to release serotonin. This release is inhibited by 2.4G2, and at maximum, reaches 30-40% of the intracellular content, about half of the maximal release (60-80%) obtained after Fc epsilon RI engagement. These data demonstrate that mouse Fc gamma RII and Fc gamma RIII are not isotype specific, and that the binding of IgE-immune complexes to these receptors induces cell activation.

Fermi gamma-ray imaging of a radio galaxy.

PubMed

Abdo, A A; Ackermann, M; Ajello, M; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cavazzuti, E; Cecchi, C; Celik, O; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Colafrancesco, S; Cominsky, L R; Conrad, J; Costamante, L; Cutini, S; Davis, D S; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Dubois, R; Dumora, D; Farnier, C; Favuzzi, C; Fegan, S J; Finke, J; Focke, W B; Fortin, P; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Georganopoulos, M; Germani, S; Giebels, B; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hughes, R E; Jackson, M S; Jóhannesson, G; Johnson, A S; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rochester, L S; Rodriguez, A Y; Romani, R W; Roth, M; Ryde, F; Sadrozinski, H F-W; Sambruna, R; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Starck, J-L; Stawarz, Ł; Strickman, M S; Suson, D J; Tajima, H; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wallace, E; Wang, P; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M; Hardcastle, M J; Kazanas, D

2010-05-07

The Fermi Gamma-ray Space Telescope has detected the gamma-ray glow emanating from the giant radio lobes of the radio galaxy Centaurus A. The resolved gamma-ray image shows the lobes clearly separated from the central active source. In contrast to all other active galaxies detected so far in high-energy gamma-rays, the lobe flux constitutes a considerable portion (greater than one-half) of the total source emission. The gamma-ray emission from the lobes is interpreted as inverse Compton-scattered relic radiation from the cosmic microwave background, with additional contribution at higher energies from the infrared-to-optical extragalactic background light. These measurements provide gamma-ray constraints on the magnetic field and particle energy content in radio galaxy lobes, as well as a promising method to probe the cosmic relic photon fields.

Reasons sought for repeat drinking and driving

DOT National Transportation Integrated Search

1996-06-01

This document summarizes the results of a study about why some individuals repeatedly drive while under the influence or intoxicated, even after being convicted of DWI and after experiencing sanctions. Qualified interviewers asked repeat offenders di...

Nuclear gamma rays from energetic particle interactions

NASA Technical Reports Server (NTRS)

Ramaty, R.; Kozlovsky, B.; Lingenfelter, R. E.

1978-01-01

Gamma ray line emission from nuclear deexcitation following energetic particle reactions is evaluated. The compiled nuclear data and the calculated gamma ray spectra and intensities can be used for the study of astrophysical sites which contain large fluxes of energetic protons and nuclei. A detailed evaluation of gamma ray line production in the interstellar medium is made.

Metabolic modulation of neuronal gamma-band oscillations.

PubMed

Vodovozov, Wadim; Schneider, Justus; Elzoheiry, Shehabeldin; Hollnagel, Jan-Oliver; Lewen, Andrea; Kann, Oliver

2018-05-28

Gamma oscillations (30-100 Hz) represent a physiological fast brain rhythm that occurs in many cortex areas in awake mammals, including humans. They associate with sensory perception, voluntary movement, and memory formation and require precise synaptic transmission between excitatory glutamatergic neurons and inhibitory GABAergic interneurons such as parvalbumin-positive basket cells. Notably, gamma oscillations are exquisitely sensitive to shortage in glucose and oxygen supply (metabolic stress), with devastating consequences for higher cognitive functions. Herein, we explored the robustness of gamma oscillations against changes in the availability of alternative energy substrates and amino acids, which is partially regulated by glial cells such as astrocytes. We used organotypic slice cultures of the rat hippocampus expressing acetylcholine-induced persistent gamma oscillations under normoxic recording conditions (20% oxygen fraction). Our main findings are (1) partial substitution of glucose with pyruvate and the ketone body β-hydroxybutyrate increases the frequency of gamma oscillations, even at different stages of neuronal tissue development. (2) Supplementation with the astrocytic neurotransmitter precursor glutamine has no effect on the properties of gamma oscillations. (3) Supplementation with glycine increases power, frequency, and inner coherence of gamma oscillations in a dose-dependent manner. (4) During these treatments switches to other frequency bands or pathological network states such as neural burst firing or synchronized epileptic activity are absent. Our study indicates that cholinergic gamma oscillations show general robustness against these changes in nutrient and amino acid composition of the cerebrospinal fluid; however, modulation of their properties may impact on cortical information processing under physiological and pathophysiological conditions.

A Gammaherpesviral Internal Repeat Contributes to Latency Amplification

PubMed Central

Thakur, Nagendra N.; El-Gogo, Susanne; Steer, Beatrix; Freimüller, Klaus; Waha, Andreas; Adler, Heiko

2007-01-01

Background Gammaherpesviruses cause important infections of humans, in particular in immunocompromised patients. The genomes of gammaherpesviruses contain variable numbers of internal repeats whose precise role for in vivo pathogenesis is not well understood. Methodology/Principal Findings We used infection of laboratory mice with murine gammaherpesvirus 68 (MHV-68) to explore the biological role of the 40 bp internal repeat of MHV-68. We constructed several mutant viruses partially or completely lacking this repeat. Both in vitro and in vivo, the loss of the repeat did not substantially affect lytic replication of the mutant viruses. However, the extent of splenomegaly, which is associated with the establishment of latency, and the number of ex vivo reactivating and genome positive splenocytes were reduced. Since the 40 bp repeat is part of the hypothetical open reading frame (ORF) M6, it might function as part of M6 or as an independent structure. To differentiate between these two possibilities, we constructed an N-terminal M6STOP mutant, leaving the repeat structure intact but rendering ORF M6 unfunctional. Disruption of ORF M6 did neither affect lytic nor latent infection. In contrast to the situation in lytically infected NIH3T3 cells, the expression of the latency-associated genes K3 and ORF72 was reduced in the latently infected murine B cell line Ag8 in the absence of the 40 bp repeat. Conclusions/Significance These data suggest that the 40 bp repeat contributes to latency amplification and might be involved in the regulation of viral gene expression. PMID:17710133

More Gamma More Predictions: Gamma-Synchronization as a Key Mechanism for Efficient Integration of Classical Receptive Field Inputs with Surround Predictions

PubMed Central

Vinck, Martin; Bosman, Conrado A.

2016-01-01

During visual stimulation, neurons in visual cortex often exhibit rhythmic and synchronous firing in the gamma-frequency (30–90 Hz) band. Whether this phenomenon plays a functional role during visual processing is not fully clear and remains heavily debated. In this article, we explore the function of gamma-synchronization in the context of predictive and efficient coding theories. These theories hold that sensory neurons utilize the statistical regularities in the natural world in order to improve the efficiency of the neural code, and to optimize the inference of the stimulus causes of the sensory data. In visual cortex, this relies on the integration of classical receptive field (CRF) data with predictions from the surround. Here we outline two main hypotheses about gamma-synchronization in visual cortex. First, we hypothesize that the precision of gamma-synchronization reflects the extent to which CRF data can be accurately predicted by the surround. Second, we hypothesize that different cortical columns synchronize to the extent that they accurately predict each other’s CRF visual input. We argue that these two hypotheses can account for a large number of empirical observations made on the stimulus dependencies of gamma-synchronization. Furthermore, we show that they are consistent with the known laminar dependencies of gamma-synchronization and the spatial profile of intercolumnar gamma-synchronization, as well as the dependence of gamma-synchronization on experience and development. Based on our two main hypotheses, we outline two additional hypotheses. First, we hypothesize that the precision of gamma-synchronization shows, in general, a negative dependence on RF size. In support, we review evidence showing that gamma-synchronization decreases in strength along the visual hierarchy, and tends to be more prominent in species with small V1 RFs. Second, we hypothesize that gamma-synchronized network dynamics facilitate the emergence of spiking output that

SkyRepeater

DTIC Science & Technology

2005-01-01

MUSIC.consultant, Doug Lewis, host of WVGN’s Doug Lewis Show, cddick@viaccess.net Being For The Benefit of Mr. Kite, Beatles , Writer, lead vocal...and in the case of a repeater failure. Tested on both VHF and UHF bands, one person can setup in 15 minutes. Cost is approximately $2,000.00. Minimum...This was originally written as a term paper for the Center for Homeland Defense and Security at the Naval Postgraduate

Shear rupture of a directionally solidified eutectic gamma/gamma prime - alpha (Mo) alloy

NASA Technical Reports Server (NTRS)

Harf, F. H.

1978-01-01

Directionally solidified Mo alloys are evaluated to determine the shear rupture strength and to possibly improve it by microstructural and heat treatment variations. Bars of the alloy containing nominally 5.7% Al and 33.5% Mo by weight with balance Ni were directionally solidified at rates between 10 and 100 mm per hour in furnaces with thermal gradients at the liquid-solid interface of 250 or 100 C per cm. A limited number of longitudinal shear rupture tests were conducted at 760 C and 207 MPa in the as - solidified and in several heat treated conditions. It is shown that shear rupture failures are partly transgranular and that resistance to failure is prompted by good fiber alignment and a matrix structure consisting mainly of gamma prime. Well aligned as - solidified specimens sustained the shear stress for an average of 81 hours. A simulated coating heat treatment appeared to increase the transformation of gamma to gamma prime and raised the average shear life of aligned specimens to 111 hours. However, heat treatments at 1245 C and especially at 1190 C appeared to be detrimental by causing partial solutioning of the gamma prime, and reducing lives to 47 and 10 hours, respectively.

‘Gamma Anna’: a classroom demonstration for teaching the concepts of gamma imaging

NASA Astrophysics Data System (ADS)

Wolff, Nicola; Griffiths, Jennifer; Yerworth, Rebecca

2017-01-01

Gamma imaging is at the interface of medicine and physics and thus its teaching is important in both fields. Pedagogic literature highlights the benefits of interactive demonstrations in teaching: an increase in enjoyment and interest, as well as improvement in academic achievement. However gamma imaging uses radioactive sources, which are potentially dangerous and thus their use is tightly controlled. We have developed a demonstration which uses a localised exothermic reaction within a rag doll as an analogue of radioactivity. This can be safely used in classrooms to demonstrate the principles of gamma imaging. The tool is easy to make, cheap, robust and portable. The supplementary material in this paper gives teacher notes and a description of how to make the rag doll demonstrator. We have tested the tool using six participants, acting as ‘teachers’, who carried out the demonstration and described the doll as easy to use, and the ‘tumour’ clearly identifiable. The teaching tool was separately demonstrated to a group of 12 GCSE physics students and a group of 12 medical students. Feedback showed increased student engagement, enjoyment and understanding of gamma imaging. Previous research has shown that these benefits have an impact on learning and academic outcomes.

R-loops: targets for nuclease cleavage and repeat instability.

PubMed

Freudenreich, Catherine H

2018-01-11

R-loops form when transcribed RNA remains bound to its DNA template to form a stable RNA:DNA hybrid. Stable R-loops form when the RNA is purine-rich, and are further stabilized by DNA secondary structures on the non-template strand. Interestingly, many expandable and disease-causing repeat sequences form stable R-loops, and R-loops can contribute to repeat instability. Repeat expansions are responsible for multiple neurodegenerative diseases, including Huntington's disease, myotonic dystrophy, and several types of ataxias. Recently, it was found that R-loops at an expanded CAG/CTG repeat tract cause DNA breaks as well as repeat instability (Su and Freudenreich, Proc Natl Acad Sci USA 114, E8392-E8401, 2017). Two factors were identified as causing R-loop-dependent breaks at CAG/CTG tracts: deamination of cytosines and the MutLγ (Mlh1-Mlh3) endonuclease, defining two new mechanisms for how R-loops can generate DNA breaks (Su and Freudenreich, Proc Natl Acad Sci USA 114, E8392-E8401, 2017). Following R-loop-dependent nicking, base excision repair resulted in repeat instability. These results have implications for human repeat expansion diseases and provide a paradigm for how RNA:DNA hybrids can cause genome instability at structure-forming DNA sequences. This perspective summarizes mechanisms of R-loop-induced fragility at G-rich repeats and new links between DNA breaks and repeat instability.

POCKET $beta$ AND $gamma$ RADIOMETER (in Russian)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Markelov, V.V.; Lushikhin, A.M.; Nikoforov, V.I.

A pocket BETA and gamma rate meter was designed by the Academy of Medical Sciences of U.S.S.R. for detecting gamma radiation of 0.25 to 2 Mev and for BETA particles of 0 to 50 and 0 to 500 particles/cm/sup 2/sec, with energies of 0.5 to 2 Mev. Measurements of BETA particles are made through the hack wall opening in the appuratus. The opening is closed durtng the recording of gamma radiation, which permits differentiation between the BETA and gamma radiation. The accuracy of the counter is within plus or minus 15%. (R.V.J.)

Gamma ray astronomy and black hole astrophysics

NASA Technical Reports Server (NTRS)

Liang, Edison P.

1990-01-01

The study of soft gamma emissions from black-hole candidates is identified as an important element in understanding black-hole phenomena ranging from stellar-mass black holes to AGNs. The spectra of Cyg X-1 and observations of the Galactic Center are emphasized, since thermal origins and MeV gamma-ray bumps are evident and suggest a thermal-pair cloud picture. MeV gamma-ray observations are suggested for studying black hole astrophysics such as the theorized escaping pair wind, the anticorrelation between the MeV gamma bump and the soft continuum, and the relationship between source compactness and temperature.

Stable homotopical algebra and [Gamma]-spaces

NASA Astrophysics Data System (ADS)

Schwede, Stefan

1999-03-01

In this paper we advertise the category of [Gamma]-spaces as a convenient framework for doing ‘algebra’ over ‘rings’ in stable homotopy theory. [Gamma]-spaces were introduced by Segal [Se] who showed that they give rise to a homotopy category equivalent to the usual homotopy category of connective (i.e. ([minus sign]1)-connected) spectra. Bousfield and Friedlander [BF] later provided model category structures for [Gamma]-spaces. The study of ‘rings, modules and algebras’ based on [Gamma]-spaces became possible when Lydakis [Ly] introduced a symmetric monoidal smash product with good homotopical properties. Here we develop model category structures for modules and algebras, set up (derived) smash products and associated spectral sequences and compare simplicial modules and algebras to their Eilenberg-MacLane spectra counterparts.

Neurochemical abnormalities in brains of renal failure patients treated by repeated hemodialysis.

PubMed

Perry, T L; Yong, V W; Kish, S J; Ito, M; Foulks, J G; Godolphin, W J; Sweeney, V P

1985-10-01

We examined autopsied brain from 10 patients with end-stage renal failure who had undergone repeated hemodialysis. Eight had classic symptoms, and two had suggestive symptoms of dialysis encephalopathy. Findings were compared with those in autopsied brain from control adults who had never been hemodialyzed. Mean gamma-aminobutyric acid (GABA) contents were significantly reduced in frontal and occipital cortex, cerebellar cortex, dentate nucleus, caudate nucleus, and medial-dorsal thalamus of the hemodialyzed patients, the reduction being greater than 40% in cerebral cortex and thalamus. Choline acetyltransferase activity was reduced by 25-35% in three cortical regions in the hemodialyzed patients. These two abnormalities were observed in the brain of each hemodialyzed patient, regardless of whether or not the patient died with unequivocal dialysis encephalopathy. Pyridoxal phosphate contents were substantially reduced in brains of the hemodialyzed patients, but metabolites of noradrenaline, 3,4-dihydroxyphenylethylamine (dopamine), and 5-hydroxytryptamine (serotonin) were present in normal amounts. Aluminum levels were abnormally high in frontal cortical gray matter in the hemodialyzed patients. Although this study does not clarify the role played by aluminum toxicity in the pathogenesis of dialysis encephalopathy, the abnormalities we found suggest the need for further neurochemical investigations in this disorder.

Evolution of genes and repeats in the Nimrod superfamily.

PubMed

Somogyi, Kálmán; Sipos, Botond; Pénzes, Zsolt; Kurucz, Eva; Zsámboki, János; Hultmark, Dan; Andó, István

2008-11-01

The recently identified Nimrod superfamily is characterized by the presence of a special type of EGF repeat, the NIM repeat, located right after a typical CCXGY/W amino acid motif. On the basis of structural features, nimrod genes can be divided into three types. The proteins encoded by Draper-type genes have an EMI domain at the N-terminal part and only one copy of the NIM motif, followed by a variable number of EGF-like repeats. The products of Nimrod B-type and Nimrod C-type genes (including the eater gene) have different kinds of N-terminal domains, and lack EGF-like repeats but contain a variable number of NIM repeats. Draper and Nimrod C-type (but not Nimrod B-type) proteins carry a transmembrane domain. Several members of the superfamily were claimed to function as receptors in phagocytosis and/or binding of bacteria, which indicates an important role in the cellular immunity and the elimination of apoptotic cells. In this paper, the evolution of the Nimrod superfamily is studied with various methods on the level of genes and repeats. A hypothesis is presented in which the NIM repeat, along with the EMI domain, emerged by structural reorganizations at the end of an EGF-like repeat chain, suggesting a mechanism for the formation of novel types of repeats. The analyses revealed diverse evolutionary patterns in the sequences containing multiple NIM repeats. Although in the Nimrod B and Nimrod C proteins show characteristics of independent evolution, many internal NIM repeats in Eater sequences seem to have undergone concerted evolution. An analysis of the nimrod genes has been performed using phylogenetic and other methods and an evolutionary scenario of the origin and diversification of the Nimrod superfamily is proposed. Our study presents an intriguing example how the evolution of multigene families may contribute to the complexity of the innate immune response.

Using gamma index to flag changes in anatomy during image-guided radiation therapy of head and neck cancer.

PubMed

Schaly, Bryan; Kempe, Jeff; Venkatesan, Varagur; Mitchell, Sylvia; Battista, Jerry J

2017-11-01

During radiation therapy of head and neck cancer, the decision to consider replanning a treatment because of anatomical changes has significant resource implications. We developed an algorithm that compares cone-beam computed tomography (CBCT) image pairs and provides an automatic alert as to when remedial action may be required. Retrospective CBCT data from ten head and neck cancer patients that were replanned during their treatment was used to train the algorithm on when to recommend a repeat CT simulation (re-CT). An additional 20 patients (replanned and not replanned) were used to validate the predictive power of the algorithm. CBCT images were compared in 3D using the gamma index, combining Hounsfield Unit (HU) difference with distance-to-agreement (DTA), where the CBCT study acquired on the first fraction is used as the reference. We defined the match quality parameter (MQP x ) as a difference between the x th percentiles of the failed-pixel histograms calculated from the reference gamma comparison and subsequent comparisons, where the reference gamma comparison is taken from the first two CBCT images acquired during treatment. The decision to consider re-CT was based on three consecutive MQP values being less than or equal to a threshold value, such that re-CT recommendations were within ±3 fractions of the actual re-CT order date for the training cases. Receiver-operator characteristic analysis showed that the best trade-off in sensitivity and specificity was achieved using gamma criteria of 3 mm DTA and 30 HU difference, and the 80 th percentile of the failed-pixel histogram. A sensitivity of 82% and 100% was achieved in the training and validation cases, respectively, with a false positive rate of ~30%. We have demonstrated that gamma analysis of CBCT-acquired anatomy can be used to flag patients for possible replanning in a manner consistent with local clinical practice guidelines. © 2017 The Authors. Journal of Applied Clinical Medical Physics

The Effects of Composition and gamma'/gamma Lattice Parameter Mismatch on the Critical Resolved Shear Stresses for Octahedral and Cube Slip in NiAlCrX Alloys

NASA Technical Reports Server (NTRS)

Miner, R. V.

1997-01-01

Prototypical single-crystal NiAlCrX superalloys were studied to examine the effects of the common major alloying elements, Co, Mo, Nb, Ta, Ti, and W, on yielding behavior. The alloys contained about 10 at. pct Cr, 60 vol pct of the gamma' phase, and about 3 at. pct of X in the gamma'. The critical resolved shear stresses (CRSSs) for octahedral and primary cube slip were measured at 760 C, which is about the peak strength temperature. The CRSS(sub oct) and CRSS(sub cube) are discussed in relation to those of Ni, (Al, X) gamma' alloys taken from the literature and the gamma'/gamma lattice mismatch. The CRSS(sub oct) of the gamma + gamma' alloys reflected a similar compositional dependence to that of both the CRSS(sub cube) of the gamma' phase and the gamma'/gamma lattice parameter mismatch. The CRSS(sub cube) of the gamma + gamma' alloys also reflected the compositional dependence of the gamma'/gamma mismatch, but bore no similarity to that of CRSS(sub cube) for gamma' alloys since it is controlled by the gamma matrix. The ratio of CRSS(sub cube)/CRSS(sub oct) was decreased by all alloying elements except Co, which increased the ratio. The decrease in CRSS(sub cube)/CRSS(sub oct) was related to the degree in which elements partition to the gamma' rather than the gamma phase.

Gamma-gamma coincidence performance of LaBr 3:Ce scintillation detectors vs HPGe detectors in high count-rate scenarios

DOE PAGES

Drescher, A.; Yoho, M.; Landsberger, S.; ...

2017-01-15

In this study, a radiation detection system consisting of two cerium doped lanthanum bromide (LaBr 3:Ce) scintillation detectors in a gamma-gamma coincidence configuration has been used to demonstrate the advantages that coincident detection provides relative to a single detector, and the advantages that LaBr 3:Ce detectors provide relative to high purity germanium (HPGe) detectors. Signal to noise ratios of select photopeak pairs for these detectors have been compared to high-purity germanium (HPGe) detectors in both single and coincident detector configurations in order to quantify the performance of each detector configuration. The efficiency and energy resolution of LaBr 3:Ce detectors havemore » been determined and compared to HPGe detectors. Coincident gamma-ray pairs from the radionuclides 152Eu and 133Ba have been identified in a sample that is dominated by 137Cs. Gamma-gamma coincidence successfully reduced the Compton continuum from the large 137Cs peak, revealed several coincident gamma energies characteristic of these nuclides, and improved the signal-to-noise ratio relative to single detector measurements. LaBr 3:Ce detectors performed at count rates multiple times higher than can be achieved with HPGe detectors. The standard background spectrum consisting of peaks associated with transitions within the LaBr 3:Ce crystal has also been significantly reduced. Finally, it is shown that LaBr 3:Ce detectors have the unique capability to perform gamma-gamma coincidence measurements in very high count rate scenarios, which can potentially benefit nuclear safeguards in situ measurements of spent nuclear fuel.« less

Gamma-gamma coincidence performance of LaBr 3:Ce scintillation detectors vs HPGe detectors in high count-rate scenarios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drescher, A.; Yoho, M.; Landsberger, S.

In this study, a radiation detection system consisting of two cerium doped lanthanum bromide (LaBr 3:Ce) scintillation detectors in a gamma-gamma coincidence configuration has been used to demonstrate the advantages that coincident detection provides relative to a single detector, and the advantages that LaBr 3:Ce detectors provide relative to high purity germanium (HPGe) detectors. Signal to noise ratios of select photopeak pairs for these detectors have been compared to high-purity germanium (HPGe) detectors in both single and coincident detector configurations in order to quantify the performance of each detector configuration. The efficiency and energy resolution of LaBr 3:Ce detectors havemore » been determined and compared to HPGe detectors. Coincident gamma-ray pairs from the radionuclides 152Eu and 133Ba have been identified in a sample that is dominated by 137Cs. Gamma-gamma coincidence successfully reduced the Compton continuum from the large 137Cs peak, revealed several coincident gamma energies characteristic of these nuclides, and improved the signal-to-noise ratio relative to single detector measurements. LaBr 3:Ce detectors performed at count rates multiple times higher than can be achieved with HPGe detectors. The standard background spectrum consisting of peaks associated with transitions within the LaBr 3:Ce crystal has also been significantly reduced. Finally, it is shown that LaBr 3:Ce detectors have the unique capability to perform gamma-gamma coincidence measurements in very high count rate scenarios, which can potentially benefit nuclear safeguards in situ measurements of spent nuclear fuel.« less

Identification of the low affinity receptor for immunoglobulin E on mouse mast cells and macrophages as Fc gamma RII and Fc gamma RIII

PubMed Central

1992-01-01

In addition to their well characterized high affinity immunoglobulin E (IgE) receptors (Fc epsilon RI) mast cells have long been suspected to express undefined Fc receptors capable of binding IgE with low affinity. In this paper, we show that Fc gamma RII and Fc gamma RIII, but not Mac-2, on mouse mast cells and macrophages bind IgE-immune complexes. This binding is efficiently competed by 2.4G2, a monoclonal antibody against the extracellular homologous region of both Fc gamma RII and Fc gamma RIII. Furthermore, IgE-immune complexes bind specifically to Fc gamma RII or Fc gamma RIII transfected into COS-7 cells. The association constants of IgE binding estimated from competition experiments are about 3.1 x 10(5) M-1 for Fc gamma RII, and 4.8 x 10(5) M-1 for Fc gamma RIII. Engagement of Fc gamma RII and Fc gamma RIII with IgE-immune complexes (after blocking access to Fc epsilon RI) or with IgG-immune complexes triggers C57.1 mouse mast cells to release serotonin. This release is inhibited by 2.4G2, and at maximum, reaches 30-40% of the intracellular content, about half of the maximal release (60-80%) obtained after Fc epsilon RI engagement. These data demonstrate that mouse Fc gamma RII and Fc gamma RIII are not isotype specific, and that the binding of IgE-immune complexes to these receptors induces cell activation. PMID:1386873

Hypoxic Repeat Sprint Training Improves Rugby Player's Repeated Sprint but Not Endurance Performance

PubMed Central

Hamlin, Michael J.; Olsen, Peter D.; Marshall, Helen C.; Lizamore, Catherine A.; Elliot, Catherine A.

2017-01-01

This study aims to investigate the performance changes in 19 well-trained male rugby players after repeat-sprint training (six sessions of four sets of 5 × 5 s sprints with 25 s and 5 min of active recovery between reps and sets, respectively) in either normobaric hypoxia (HYP; n = 9; FIO2 = 14.5%) or normobaric normoxia (NORM; n = 10; FIO2 = 20.9%). Three weeks after the intervention, 2 additional repeat-sprint training sessions in hypoxia (FIO2 = 14.5%) was investigated in both groups to gauge the efficacy of using “top-up” sessions for previously hypoxic-trained subjects and whether a small hypoxic dose would be beneficial for the previously normoxic-trained group. Repeated sprint (8 × 20 m) and Yo-Yo Intermittent Recovery Level 1 (YYIR1) performances were tested twice at baseline (Pre 1 and Pre 2) and weekly after (Post 1–3) the initial intervention (intervention 1) and again weekly after the second “top-up” intervention (Post 4–5). After each training set, heart rate, oxygen saturation, and rate of perceived exertion were recorded. Compared to baseline (mean of Pre 1 and Pre 2), both the hypoxic and normoxic groups similarly lowered fatigue over the 8 sprints 1 week after the intervention (Post 1: −1.8 ± 1.6%, −1.5 ± 1.4%, mean change ± 90% CI in HYP and NORM groups, respectively). However, from Post 2 onwards, only the hypoxic group maintained the performance improvement compared to baseline (Post 2: −2.1 ± 1.8%, Post 3: −2.3 ± 1.7%, Post 4: −1.9 ± 1.8%, and Post 5: −1.2 ± 1.7%). Compared to the normoxic group, the hypoxic group was likely to have substantially less fatigue at Post 3–5 (−2.0 ± 2.4%, −2.2 ± 2.4%, −1.6 ± 2.4% Post 3, Post 4, Post 5, respectively). YYIR1 performances improved throughout the recovery period in both groups (13–37% compared to baseline) with unclear differences found between groups. The addition of two sessions of “top-up” training after intervention 1, had little effect on either

Experimental review of light quark spectroscopy from e/sup +/e/sup -/ production and. gamma gamma. collisions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toki, W.H.

1987-07-01

This is an experimental review of light quark spectroscopy from e/sup +/e/sup -/ production and ..gamma gamma.. collision results presented at the 2nd International Conference on Hadron Spectroscopy at KEK, Japan. The recent results in ..gamma gamma.. production have evidence for the J/sup PC/ = 1/sup + +/, E/f/sub 1/(1420) and D/f/sub 1/(1285), mesons from the TPC and Mark II collaborations and upper limits for pseudoscalar resonances from the Crystal Ball collaboration. The results in J/psi reactions include D/f/sub 1/(1285) meson production in radiative decays and a complete measurement of the hadronic decays into pseudoscalar-vector pairs from the DM2 collaborationmore » and evidence for phi phi production in radiative decays and a study of the iota line shape from the Mark III collaboration. A short review of simple theoretical ideas is presented.« less

Fluorescence-Assisted Gamma Spectrometry for Surface Contamination Analysis

NASA Astrophysics Data System (ADS)

Ihantola, Sakari; Sand, Johan; Perajarvi, Kari; Toivonen, Juha; Toivonen, Harri

2013-02-01

A fluorescence-based alpha-gamma coincidence spectrometry approach has been developed for the analysis of alpha-emitting radionuclides. The thermalization of alpha particles in air produces UV light, which in turn can be detected over long distances. The simultaneous detection of UV and gamma photons allows detailed gamma analyses of a single spot of interest even in highly active surroundings. Alpha particles can also be detected indirectly from samples inside sealed plastic bags, which minimizes the risk of cross-contamination. The position-sensitive alpha-UV-gamma coincidence technique reveals the presence of alpha emitters and identifies the nuclides ten times faster than conventional gamma spectrometry.

Absence of Fc epsilonRI alpha chain results in upregulation of Fc gammaRIII-dependent mast cell degranulation and anaphylaxis. Evidence of competition between Fc epsilonRI and Fc gammaRIII for limiting amounts of FcR beta and gamma chains.

PubMed Central

Dombrowicz, D; Flamand, V; Miyajima, I; Ravetch, J V; Galli, S J; Kinet, J P

1997-01-01

In mouse mast cells, both Fc epsilonRI and Fc gammaRIII are alpha beta gamma2 tetrameric complexes in which different alpha chains confer IgE or IgG ligand recognition while the signaling FcR beta and gamma chains are identical. We used primarily noninvasive techniques (changes in body temperature, dye extravasation) to assess systemic anaphylactic responses in nonanesthetized wild-type, Fc epsilonRI alpha chain -/- and FcR gamma chain -/- mice. We confirm that systemic anaphylaxis in mice can be mediated largely through IgG1 and Fc gammaRIII and we provide direct evidence that these responses reflect activation of Fc gammaRIII rather than Fc gammaRI. Furthermore, we show that Fc gammaRIII-dependent responses are more intense in normal than in congenic mast cell-deficient KitW/KitW-v mice, indicating that Fc gammaRIII responses have mast cell-dependent and -independent components. Finally, we demonstrate that the upregulation of cell surface expression of Fc gammaRIII seen in Fc epsilonRI alpha chain -/- mice corresponds to an increased association of Fc gammaRIII alpha chains with FcR beta and gamma chains and is associated with enhanced Fc gammaRIII-dependent mast cell degranulation and systemic anaphylactic responses. Therefore, the phenotype of the Fc epsilonRI alpha chain -/- mice suggests that expression of Fc epsilonRI and Fc gammaRIII is limited by availability of the FcR beta and gamma chains and that, in normal mice, changes in the expression of one receptor (Fc epsilonRI) may influence the expression of functional responses dependent on the other (Fc gammaRIII). PMID:9062349

Gamma-ray Astrophysics with AGILE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Longo, Francesco; Tavani, M.; Barbiellini, G.

2007-07-12

AGILE will explore the gamma-ray Universe with a very innovative instrument combining for the first time a gamma-ray imager and a hard X-ray imager. AGILE will be operational in spring 2007 and it will provide crucial data for the study of Active Galactic Nuclei, Gamma-Ray Bursts, unidentified gamma-ray sources. Galactic compact objects, supernova remnants, TeV sources, and fundamental physics by microsecond timing. The AGILE instrument is designed to simultaneously detect and image photons in the 30 MeV - 50 GeV and 15 - 45 keV energy bands with excellent imaging and timing capabilities, and a large field of view coveringmore » {approx} 1/5 of the entire sky at energies above 30 MeV. A CsI calorimeter is capable of GRB triggering in the energy band 0.3-50 MeV AGILE is now (March 2007) undergoing launcher integration and testing. The PLSV launch is planned in spring 2007. AGILE is then foreseen to be fully operational during the summer of 2007.« less

Long-latency reductions in gamma power predict hemodynamic changes that underlie the negative BOLD signal.