341 research outputs found

    Massive Graviton Geons

    Get PDF
    We find vacuum solutions such that massive gravitons are confined in a local spacetime region by their gravitational energy in asymptotically flat spacetimes in the context of the bigravity theory. We call such self-gravitating objects massive graviton geons. The basic equations can be reduced to the Schr\"odinger-Poisson equations with the tensor "wavefunction" in the Newtonian limit. We obtain a non-spherically symmetric solution with j=2,=0j=2,\ell=0 as well as a spherically symmetric solution with j=0,=2j=0,\ell=2 in this system where jj is the total angular momentum quantum number and \ell is the orbital angular momentum quantum number, respectively. The energy eigenvalue of the Schr\"odinger equation in the non-spherical solution is smaller than that in the spherical solution. We then study the perturbative stability of the spherical solution and find that there is an unstable mode in the quadrupole mode perturbations which may be interpreted as the transition mode to the non-spherical solution. The results suggest that the non-spherically symmetric solution is the ground state of the massive graviton geon. The massive graviton geons may decay in time due to emissions of gravitational waves but this timescale can be quite long when the massive gravitons are non-relativistic and then the geons can be long-lived. We also argue possible prospects of the massive graviton geons: applications to the ultralight dark matter scenario, nonlinear (in)stability of the Minkowski spacetime, and a quantum transition of the spacetime.Comment: 16 pages, 7 tables, 3 figures; v2: references added, improved discussion, published versio

    Flow Pattern and Switching Mechanism in a Wall Attachment Type Fluid Amplifier

    Get PDF
    An experimental investigation has been performed to determine the steady-state pattern and the switching mechanism of the airflow in a wall attachment type fluid amplifier. With the experimental results, it is shown that the jet flow is considerably affected by the splitter distance and the step height of the device, and switching action of the flow caused by a step control jet, i.e. the switching time and the critical velocity range of control jet, is determined. By using some simple assumptions, approximate calculation have been carried out to obtain the relations between the switching time and the step control jet flow, and are compared with the experimental results

    Unraveling the Nature of Unidentified High Galactic Latitude Fermi/LAT Gamma-ray Sources with Suzaku

    Full text link
    We report on the results of deep X-ray follow-up observations of four unidentified Fermi/LAT gamma-ray sources at high Galactic latitudes using Suzaku. The studied objects were detected with high significance during the first 3 months of Fermi/LAT operation, and subsequently better localized in the Fermi/LAT 1 year catalog (1FGL). Possible associations with pulsars and active galaxies have subsequently been discussed, and our observations provide an important contribution to this debate. In particular, an X-ray point source was found within the 95% confidence error circle of 1FGL J1231.1-1410. X-ray spectrum is well-fitted by a blackbody with an additional power-law. This supports the recently claimed identification of this source with a millisecond pulsar (MSP) PSR J1231-1411. Concerning 1FGL J1311.7-3429, two X-ray sources were found within the LAT error circle. Even though the X-ray spectral and variability properties were accessed, their nature and relationship with the gamma-ray source remain uncertain. We found several weak X-ray sources in the field of 1FGL J1333.2+5056, one coinciding with CLASS J1333+5057. We argue the available data are consistent with the association between these two objects. Finally, we have detected an X-ray source in the vicinity of 1FGL J2017.3+0603. This object was recently suggested to be associated with a newly discovered MSP PSR J2017+0603, because of the spatial-coincidence and the gamma-ray pulse detection. We have only detected the X-ray counterpart of the CLASS J2017+0603, while we determined an X-ray flux upper limit at the pulsar position. All in all, our studies indicate while a significant fraction of unidentified high Galactic latitude gamma-ray sources is related to the pulsar and blazar phenomena, associations with other classes of astrophysical objects are still valid options.Comment: Accepted for publication in the Ap

    Breath Hydrogen Gas Concentration Linked to Intestinal Gas Distribution and Malabsorption in Patients with Small-bowel Pseudo-obstruction

    Get PDF
    Background: The patient with colonic obstruction may frequently have bacterial overgrowth and increased breath hydrogen (H2) levels because the bacterium can contact with food residues for longer time. We experienced two cases with intestinal obstruction whose breath H2 concentrations were measured continuously.Case 1: A 70-year-old woman with small bowel obstruction was treated with a gastric tube. When small bowel gas decreased and colonic gas was demonstrated on the plain abdominal radiograph, the breath H2 concentration increased to 6 ppm and reduced again shortly.Case 2: A 41-year-old man with functional small bowel obstruction after surgical treatment was treated with intravenous administration of erythromycin. Although the plain abdominal radiograph demonstrated a decrease of small-bowel gas, the breath H2 gas kept the low level. After a clear-liquid meal was supplied, fasting breath H2 concentration increased rapidly to 22 ppm and gradually decreased to 9 ppm despite the fact that the intestinal gas was unchanged on X-ray. A rapid increase of breath H2 concentration may reflect the movement of small bowel contents to the colon in patients with small-bowel pseudo-obstruction or malabsorption following diet progression.Conclusions: Change in breath H2 concentration had a close association with distribution and movement of intestinal gas

    Incidence and associated factors of sudden unexpected death in advanced cancer patients: A multicenter prospective cohort study

    Get PDF
    [Purpose] A sudden unexpected death has significant negative impacts on patients, family caregivers, and medical staff in hospice/palliative care. This study aimed to clarify the incidence and associated factors of sudden unexpected death according to four definitions in advanced cancer patients. [Methods] We performed a prospective cohort study in 23 inpatient hospices/palliative care units in Japan. Advanced cancer patients aged ≥18 years who were admitted to inpatient hospices/palliative care units were included. The incidence and associated factors of sudden unexpected death were evaluated in all enrolled patients according to four definitions: (a) rapid decline death, defined as a sudden death preceded by functional decline over 1–2 days; (b) surprise death, defined if the primary responsible palliative care physician answered “yes” to the question, “Were you surprised by the timing of the death?”; (c) unexpected death, defined as a death that occurred earlier than the physicians had anticipated; and (d) performance status (PS)-defined sudden death, defined as a death that occurred within 1 week of functional status assessment with an Australia-modified Karnofsky PS ≥50. [Results] Among 1896 patients, the incidence of rapid decline death was the highest (30-day cumulative incidence: 16.8%, 95% CI: 14.8–19.0%), followed by surprise death (9.6%, 8.1–11.4%), unexpected death (9.0%, 7.5–10.8%), and PS-defined sudden death (6.4%, 5.2–8.0%). Male sex, liver metastasis, dyspnea, malignant skin lesion, and fluid retention were significantly associated with the occurrence of sudden unexpected death. [Conclusion] Sudden unexpected death is not uncommon even in inpatient hospices/palliative care units, with range of 6.4–16.8% according to the different definitions

    Characteristics of Grouped Discharge Waveforms Observed in Long-term Masseter Muscle Electromyographic Recording: A Preliminary Study

    Get PDF
    We investigated the characteristics of grouped discharge (GD) waveforms obtained from long-term masseter electromyogram (EMG) recording in 6 female temporomandibular disorder (TMD) patients with myofascial pain and 6 healthy females. The EMG measurement was performed from the morning of the experiment day until the subject woke up the next day. We observed a significantly larger number of GD waveforms in the TMD group compared to the control group (p=0.002). Our results indicate that the existence of GD waveforms in masseter EMGs might be a predictor of future TMD with myofascial pain

    Isolated gestational proteinuria preceding the diagnosis of preeclampsia : an observational study

    Get PDF
    Introduction. Some pregnant women develop significant proteinuria in the absence of hypertension. However, clinical significance of isolated gestational proteinuria (IGP) is not well understood. This study aimed to determine the prevalence of IGP in singleton pregnancies and the proportion of women with IGP who subsequently developed preeclampsia (IGP-PE) among all PE cases. Material and methods. This was an observational study of 6819 women with singleton pregnancies at 12 centers, including 938 women with at least once determination of protein-to-creatinine ratio (P/Cr). Significant proteinuria in pregnancy (SPIP) was defined as P/Cr (mg/mg) level >0.27. IGP was defined as SPIP in the absence of hypertension. Gestational hypertension (GH) preceding preeclampsia (GH-PE) was defined as preeclampsia (PE) in which GH preceded SPIP. Simultaneous PE (S-PE) was defined as PE in which both SPIP and hypertension occurred simultaneously. Results. IGP and PE were diagnosed in 130 (1.9%) and 158 (2.3%) of 6819 women, respectively. Of 130 women with IGP, 32 (25%) progressed to PE and accounted for 20% of all women with PE. Hence, women with IGP had a relative risk of 13.1 (95% CI; 9.2-18.5) for developing PE compared with those without IGP [25% (32/130) vs. 1.9% (126/6689)]. At diagnosis of SPIP, P/Cr levels already exceeded 1.0 more often in women with S-PE than in those with IGP-PE [67% (33/49) vs. 44% (14/32), respectively, p = 0.031]. Conclusions. IGP is a risk factor for PE, and IGP-PE accounts for a considerable proportion (20%) of all PE
    corecore