75 research outputs found
Redshift Dependent Lag-Luminosity Relation in 565 BASTE Gamma Ray Bursts
We compared redshifts from Yonetoku relation and from the
lag-luminosity relation for 565 BASTE GRBs and were surprised to find that the
correlation is very low. Assuming that the luminosity is a function of both
and the intrinsic spectral lag , we found a new redshift
dependent lag-luminosity relation as with the correlation coefficient of 0.77
and the chance probability of . To check the validity of
this method, we examined the other luminosity indicator, Amati relation, using
and the observed fluence and found the correlation coefficient of 0.92
and the chance probability of . Although the spectral lag
is computed from two channels of BATSE, our new lag-luminosity relation
suggests that a possible lag-luminosity relation in the \swift era should also
depend on redshift
Constraints on and of Dark Energy from High Redshift Gamma Ray Bursts
We extend the Hubble diagram up to using 63 gamma-ray bursts (GRBs)
via peak energy-peak luminosity relation (so called Yonetoku relation), and
obtain constraints on cosmological parameters including dynamical dark energy
parametrized by . It is found that
the current GRB data are consistent with the concordance model, (), within two sigma level.
Although constraints from GRBs themselves are not so strong, they can improve
the conventional constraints from SNeIa because GRBs have much higher
redshifts. Further we estimate the constraints on the dark-energy parameters
expected by future observations with GLAST (Gamma-ray Large Area Space
Telescope) and \swift by Monte-Carlo simulation. Constraints would improve
substantially with another 150 GRBs.Comment: 5 pages, 6 figures. Submitted tu MNRA
Gamma-Ray Bursts in Suggest that the Time Variation of the Dark Energy is Small
We calibrated the peak energy-peak luminosity relation of GRBs (so called
Yonetoku relation) using 33 events with the redshift without
assuming any cosmological models. The luminosity distances to GRBs are
estimated from those of large amount of Type Ia supernovae with . This
calibrated Yonetoku relation can be used as a new cosmic distance ladder toward
higher redshifts. We determined the luminosity distances of 30 GRBs in using the calibrated relation and plotted the likelihood contour in
plane. We obtained for a flat universe. Since our
method is free from the circularity problem, we can say that our universe in
is compatible with the so called concordance cosmological model
derived for . This suggests that the time variation of the dark energy
is small or zero up to .Comment: 4 pages, 4 figures, accepted to MNRA
Dietary intake, mental status, physical activity, and lifestyle affecting bowel movement frequency and stool texture in young Japanese women
Constipation is a symptom-based disorder, and its definition is mainly subjective. Patients are more concerned with ease ofpassage and consistency rather than frequency of bowel movement. Studies on bowel movement frequency and stool texture inthe general population are sparse, especially in young women. In this cross-sectional study, data obtained from self-administered questionnaires, including age, height, body weight, lifestyle, food habits, anxiety, depressive status, frequency of bowel movements,stool texture, and defecation-related symptoms were analyzed in 245 female Japanese university students. An establishedsemiquantitative questionnaire available for clinical investigation (FFQg) was used to obtain a detailed assessment of food intake and physical activity levels. Of the participants, 21.4% had bowel movements ?3 times per week and 33.3% had hard or lumpy stools ?25% and loose (mushy) or watery stools <25% of bowel movements. There was a positive association between infrequent bowel movements and hard or lumpy stools. These two situations both caused similar symptoms such as a sensation of incomplete evacuation and straining. There was no association of bowel movement frequency and stool texture with any specificnutrients and foods, dietary intake, mental status, or physical activity. Several lifestyle factors such as regular bowel movements and hesitation with evacuation were associated with bowel movement frequency and stool texture. Several lifestyle factors, but not mental, physical, or dietary intake factors, were associated with bowel movement frequency and stool texture in young Japanese women
Pathological characteristics of reoperated regrowing clinically nonfunctioning pituitary tumor cases in comparison with initial surgical cases
ObjectivePostoperative nonfunctioning pituitary tumor (NFPT) regrowth is a significant concern, but its predictive factors are not well established. This study aimed to elucidate the pathological characteristics of NFPTs indicated for reoperation for tumor regrowth.MethodsPathological, radiological, and clinical data were collected from patients who underwent repeat operation for NFPT at Moriyama Memorial Hospital (MMH) between April 2018 and September 2023. For comparison, we also gathered data from patients who underwent initial surgery for NFPT during the same period at MMH.ResultsOverall, 61 and 244 NFPT patients who respectively underwent reoperation and initial operation were evaluated. The mean period between the previous operation and reoperation was 113 months. Immunonegativity for any adenohypophyseal hormone was significantly more frequent in the reoperation group than in the initial operation group. In addition, the rate of hormone-negative but transcription factor–positive (H-/TF+) tumors among silent gonadotroph tumors was significantly higher in the reoperation group than in the initial operation group. Furthermore, seven silent corticotroph tumors (SCTs) in the reoperation group were ACTH-negative but TPIT-positive. Because most of the previous surgeries were performed in other hospitals a long time ago, we could procure the previous pathological results with immunohistochemistry (IHC) only from 21 patients. IHC for TF had not been performed in all the previous specimens. IHC for adenohypophyseal hormone was almost the same as the current results, and many H-/TF+ tumors were previously diagnosed as NCT. In addition, the reoperated patients were classified into 3 groups on the basis of the condition of the previous operation: gross total resection (GTR), 12 patients; subtotal resection (STR), 17 patients; and partial resection (PR), 32 patients. The mean Ki-67 LI in the GTR, STR, and PR subgroups were 1.82, 1.37, and 0.84, respectively, with the value being significantly higher in the GTR subgroup than in the PR subgroup (P < 0.05).ConclusionsThe ratio of H-/TF+ tumors is significantly higher in symptomatically regrown tumors than in the initial cases, which used to be diagnosed as NCT. PR cases tend to grow symptomatically in a shorter period, even with lower Ki-67 LI than GTR cases
Spectral evolution of GRB 060904A observed with Swift and Suzaku -- Possibility of Inefficient Electron Acceleration
We observed an X-ray afterglow of GRB 060904A with the Swift and Suzaku
satellites. We found rapid spectral softening during both the prompt tail phase
and the decline phase of an X-ray flare in the BAT and XRT data. The observed
spectra were fit by power-law photon indices which rapidly changed from to within a few hundred
seconds in the prompt tail. This is one of the steepest X-ray spectra ever
observed, making it quite difficult to explain by simple electron acceleration
and synchrotron radiation. Then, we applied an alternative spectral fitting
using a broken power-law with exponential cutoff (BPEC) model. It is valid to
consider the situation that the cutoff energy is equivalent to the synchrotron
frequency of the maximum energy electrons in their energy distribution. Since
the spectral cutoff appears in the soft X-ray band, we conclude the electron
acceleration has been inefficient in the internal shocks of GRB 060904A. These
cutoff spectra suddenly disappeared at the transition time from the prompt tail
phase to the shallow decay one. After that, typical afterglow spectra with the
photon indices of 2.0 are continuously and preciously monitored by both XRT and
Suzaku/XIS up to 1 day since the burst trigger time. We could successfully
trace the temporal history of two characteristic break energies (peak energy
and cutoff energy) and they show the time dependence of while the following afterglow spectra are quite stable. This fact
indicates that the emitting material of prompt tail is due to completely
different dynamics from the shallow decay component. Therefore we conclude the
emission sites of two distinct phenomena obviously differ from each other.Comment: 19 pages, 9 figures, accepted for publication in PASJ (Suzaku 2nd
Special Issue
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