2,857 research outputs found
Comparative long-term evaluation of tacrolimus and cyclosporine in pediatric liver transplantation
Background. In this report, we compare the long-term outcome of pediatric liver transplantation (LTx) patients maintained with tacrolimus-based and with cyclosporine (CsA)-based immunosuppressive therapy. We examine long-term patient and graft survival, the incidence of rejection, and immunosuppression-related complications. Method. There were 233 consecutive primary LTx in children (ages <18 years) performed between October 1989 and December 1994 with tacrolimus-based immunosuppressive therapy (Group I). These were compared with 120 consecutive primary LTx performed with CsA-based immunosuppressive therapy between January 1988 and October 1989(Group II). Children in both groups were followed until July 1999. Mean follow-up was 91.41±17.7 months (range 55.6-117.8) for Group I, and 128±6.1 months (range 116.7-138.6) for Group II. Results. At 9 years of follow-up, actuarial patient and graft survival were significantly improved (patient survival 85.4% in Group I vs. 63.8% in Group II, P=0.0001; graft survival Group I 78.9% vs. 60.8% Group II, P=0.0003) and the rate of re -transplantation was significantly lower among patients in Group I (12% in Group I vs. 22.5% in Group II P=0.01). Children in Group I also experienced a significantly reduced incidence of acute rejection (0.97 per patient Group I vs. 1.5 per patient Group II P=0.002) and significantly less steroid resistant acute rejection episodes (3.1% in Group I vs. 8.6% in Group II P=0.0001). The mean steroid dose was significantly lower in Group I compared with Group II at all time points (P=0.0001) after LTx. Freedom from steroid was also significantly higher in Group I compared with Group H at all time points after LTx (ranging from 78% to 84% in Group I and 9% to 32% in Group H during a 1- to 7-year posttransplant period P=0.0001). The rate of hypertension was significantly lower in Group I than Group II (P=0.0001), and the severity of hypertension (need for more than one anti-hypertensive medication) was also significantly lower in Group I than Group II (P=0.0001). Although the rate of posttransplant lymphoproliferative disorder (PTLD) was not significantly different (13.7% Group I vs.8.3% Group II, P=0.13), the survival after PTLD was significantly better for Group I at 81.2% than for Group II at 50% after 5 years (P=0.034). Conclusion. The results suggest that tacrolimus-based therapy provides significant long-term benefit to pediatric LTx patients, evidenced by significantly improved patient and graft survival, reduced rate of rejection, and hypertension with lower steroid doses
Chronic Mountain Sickness-Phobrang Type
Clinical0 features of 27 cases of Chronic Mountain Sickness (CMS) from the Himalayas are reported. They are compared with 75 native highlanders (NH). All CMS patients were immigrants to high altitude. Mean duration of stay at high altitude was seven years. Mean values for haematocrit and haemoglobin were 80% and 23 G% respectively for the CMS group and 40% and 17.9 G% respectively for the native highlande group. Mean QRS axis in the former was +118 and in the latter +76. Incidence and quantum of protienuria were significantly higher in the CMS group. Cardiac catheteri -sation studies done in eight CMS cases showed elevated Pulmonary Artery (PA) pressures even after a mean of 14.2 days at sea level. The disease which has four diagnostic elements-hypoxemia and polycythemia, pulmonary hypertension, right ventricular enlargement and nephropathy with dense proteinuria-is a variant of 'Monge's Disease' and a name CMS Phobrang Type is suggested, along with a new approach to clinical classification which may help in diagnosis before cor pulmonale sets in. Limited therapeutic trials conducted at highaltitude seem to indicate that yogic deep breathing exercises, low-dose aspirin and diamox may be beneficial in the prevention and therapy of CMS Phobrang Type at high altitude
Incorporating Uncertainties in Atomic Data Into the Analysis of Solar and Stellar Observations: A Case Study in Fe XIII
Information about the physical properties of astrophysical objects cannot be
measured directly but is inferred by interpreting spectroscopic observations in
the context of atomic physics calculations. Ratios of emission lines, for
example, can be used to infer the electron density of the emitting plasma.
Similarly, the relative intensities of emission lines formed over a wide range
of temperatures yield information on the temperature structure. A critical
component of this analysis is understanding how uncertainties in the underlying
atomic physics propagates to the uncertainties in the inferred plasma
parameters. At present, however, atomic physics databases do not include
uncertainties on the atomic parameters and there is no established methodology
for using them even if they did. In this paper we develop simple models for the
uncertainties in the collision strengths and decay rates for Fe XIII and apply
them to the interpretation of density sensitive lines observed with the EUV
Imagining spectrometer (EIS) on Hinode. We incorporate these uncertainties in a
Bayesian framework. We consider both a pragmatic Bayesian method where the
atomic physics information is unaffected by the observed data, and a fully
Bayesian method where the data can be used to probe the physics. The former
generally increases the uncertainty in the inferred density by about a factor
of 5 compared with models that incorporate only statistical uncertainties. The
latter reduces the uncertainties on the inferred densities, but identifies
areas of possible systematic problems with either the atomic physics or the
observed intensities.Comment: in press at Ap
Coronal Emission Measures and Abundances for Moderately Active K Dwarfs Observed by Chandra
We have used Chandra to resolve the nearby 70 Oph (K0 V+K5 V) and 36 Oph (K1
V+K1 V) binary systems for the first time in X-rays. The LETG/HRC-S spectra of
all four of these stars are presented and compared with an archival LETG
spectrum of another moderately active K dwarf, Epsilon Eri. Coronal densities
are estimated from O VII line ratios and emission measure distributions are
computed for all five of these stars. We see no substantial differences in
coronal density or temperature among these stars, which is not surprising
considering that they are all early K dwarfs with similar activity levels.
However, we do see significant differences in coronal abundance patterns.
Coronal abundance anomalies are generally associated with the first ionization
potential (FIP) of the elements. On the Sun, low-FIP elements are enhanced in
the corona relative to high-FIP elements, the so-called "FIP effect." Different
levels of FIP effect are seen for our stellar sample, ranging from 70 Oph A,
which shows a prominent solar-like FIP effect, to 70 Oph B, which has no FIP
bias at all or possibly even a weak inverse FIP effect. The strong abundance
difference exhibited by the two 70 Oph stars is unexpected considering how
similar these stars are in all other respects (spectral type, age, rotation
period, X-ray flux). It will be difficult for any theoretical explanation for
the FIP effect to explain how two stars so similar in all other respects can
have coronae with different degrees of FIP bias. Finally, for the stars in our
sample exhibiting a FIP effect, a curious difference from the solar version of
the phenomenon is that the data seem to be more consistent with the high-FIP
elements being depleted in the corona rather than a with a low-FIP enhancementComment: 35 pages, 8 figures, AASTEX v5.0 plus EPSF extensions in mkfig.sty;
accepted by Ap
The extremely X-ray luminous radio-loud quasar CFHQS J142952+544717 at under Chandra high-angular resolution lens
We present the first X-ray observation at sub-arcsecond resolution of the
high-redshift () radio-loud quasar CFHQS J142952+544717 (J1429). The
~100 net-count 0.3-7 keV spectrum obtained from ksec Chandra exposure
is best fit by a single power-law model with a photon index
and no indication of an intrinsic absorber, implying a 3.6-72 keV rest-frame
luminosity erg s. We
identify a second X-ray source at 30 arcsec, distance from J1429 position, with
a soft () and absorbed (equivalent hydrogen column density
cm) spectrum, which likely contaminated
J1429 spectra obtained in lower angular resolution observations. Based on the
analysis of the Chandra image, the bulk of the X-ray luminosity is produced
within the central kpc region, either by the disk/corona system, or by
a moderately aligned jet. In this context, we discuss the source properties in
comparison with samples of low- and high-redshift quasars. We find indication
of a possible excess of counts over the expectations for a point-like source in
a 0.5 arcsec-1.5 arcsec ( kpc) annular region. The corresponding
X-ray luminosity at J1429 redshift is erg s. If
confirmed, this emission could be related to either a large-scale X-ray jet, or
a separate X-ray source.Comment: 9 pages, 4 figures, accepted for publication in MNRA
Detailed diagnostics of an X-ray flare in the single giant HR 9024
We analyze a 96 ks Chandra/HETGS observation of the single G-type giant HR
9024. The high flux allows us to examine spectral line and continuum
diagnostics at high temporal resolution, to derive plasma parameters. A
time-dependent 1D hydrodynamic model of a loop with half-length cm (), cross-section radius
cm, with a heat pulse of 15 ks and ~erg cm s
deposited at the loop footpoints, satisfactorily reproduces the observed
evolution of temperature and emission measure, derived from the analysis of the
strong continuum emission. For the first time we can compare predictions from
the hydrodynamic model with single spectral features, other than with global
spectral properties. We find that the model closely matches the observed line
emission, especially for the hot ( K) plasma emission of the FeXXV
complex at \AA. The model loop has and aspect
ratio as typically derived for flares observed in active stellar
coronae, suggesting that the underlying physics is the same for these very
dynamic and extreme phenomena in stellar coronae independently on stellar
parameters and evolutionary stage.Comment: 26 pages. Accepted for publication on the Astrophysical Journa
Chandra Multiwavelength Project: Normal Galaxies at Intermediate Redshift
(abridged) We have investigated 136 Chandra extragalactic sources without
broad optical emission lines, including 93 galaxies with narrow emission lines
(NELG) and 43 with only absorption lines (ALG). Based on fx/fo, Lx, X-ray
spectral hardness and optical emission line diagnostics, we have conservatively
classified 36 normal galaxies (20 spirals and 16 ellipticals) and 71 AGNs. We
found no statistically significant evolution in Lx/LB, within the limited z
range. We have built log(N)-log(S), after correcting for completeness based on
a series of simulations. The best-fit slope is -1.5 for both S and B energy
bands, which is considerably steeper than that of the AGN-dominated cosmic
background sources, but slightly flatter than the previous estimate, indicating
normal galaxies will not exceed the AGN population until fx ~ 2 x 10-18 erg s-1
cm-2 (a factor of ~5 lower than the previous estimate). A group of NELGs appear
to be heavily obscured in X-rays, i.e., a typical type 2 AGN. After correcting
for intrinsic absorption, their X-ray luminosities could be Lx > 10^44 erg s-1,
making them type 2 quasar candidates. While most X-ray luminous ALGs (XBONG -
X-ray bright, optically normal galaxy candidates) do not appear to be
significantly absorbed, we found two heavily obscured objects, which could be
as luminous as an unobscured broad-line quasar. Among 43 ALGs, we found two E+A
galaxy candidates with strong Balmer absorption lines, but no [OII] line. The
X-ray spectra of both galaxies are soft and one of them has a nearby close
companion galaxy, supporting the merger/interaction scenario rather than the
dusty starburst hypothesis.Comment: 31 pages, 9 figures, accepted for publication in ApJ (20 June 2006,
v644), replaced with minor correction
Continuous monitoring of mining induced strain in a road pavement using fiber Bragg grating sensors
Abstrakt
Få samhällsproblem har under de senaste åren mött så allmän uppmärksamhet som ungdomsbrottsligheten. Den polisanmälda ungdomsbrottsligheten har i stort sett följt brottslighetens utvecklingskurva avseende antal begångna brott, denna kurva visar en tydlig ökning sedan efterkrigstiden.
Detta är en komparativ uppsats som är inriktad på ungdomsbrottsligheten i två av Malmö stadsdelar där vi undersöker antalet polisanmälda ungdomar till socialtjänsten mellan åren 2007-2009. Vi har studerat vilka brott ungdomarna var anmälda, analyserat brottstrender och i den mån det var möjligt granskat hur könsfördelningen har sett ut. Vi har undersökt vilka insatser som tillämpas från socialtjänstens håll för att motverka ungdomsbrottslighet samt förhindra fortsatt brottslighet hos redan polisanmälda ungdomar samt granska hur socialsekreterare vid våra undersökningsverksamheter upplever och uppfattar ungdomsbrottsligheten. Våra resultat har delvis ställts i relation till hur ungdomsbrottsligheten enligt tidigare forskning och redan befintlig statistik ser ut i Sverige.
Vi har i uppsatsen använt oss av kvalitativ och kvantitativ datainsamlingsmetod samt ställt analysavsnitt och diskussionsavsnitt i relation till tidigare forskning och den av Travis Hirschis konstruerade teorin om sociala band.
Studiens resultat visar bland annat att antalet polisanmälningar till socialtjänsterna har ökat, att killar begår fler brott än tjejer, att brottstyperna skiljer sig åt beroende på kön samt att ett mindre antal ungdomar ansvarar för en stor del av socialtjänsternas inkomna polisanmälningar
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