1,566 research outputs found

    The Hubble Constant determined through an inverse distance ladder including quasar time delays and Type Ia supernovae

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    Context. The precise determination of the present-day expansion rate of the Universe, expressed through the Hubble constant H0H_0, is one of the most pressing challenges in modern cosmology. Assuming flat Λ\LambdaCDM, H0H_0 inference at high redshift using cosmic-microwave-background data from Planck disagrees at the 4.4σ\sigma level with measurements based on the local distance ladder made up of parallaxes, Cepheids and Type Ia supernovae (SNe Ia), often referred to as "Hubble tension". Independent, cosmological-model-insensitive ways to infer H0H_0 are of critical importance. Aims. We apply an inverse-distance-ladder approach, combining strong-lensing time-delay-distance measurements with SN Ia data. By themselves, SNe Ia are merely good relative distance indicators, but by anchoring them to strong gravitational lenses one can obtain an H0H_0 measurement that is relatively insensitive to other cosmological parameters. Methods. A cosmological parameter estimate is performed for different cosmological background models, both for strong-lensing data alone and for the combined lensing + SNe Ia data sets. Results. The cosmological-model dependence of strong-lensing H0H_0 measurements is significantly mitigated through the inverse distance ladder. In combination with SN Ia data, the inferred H0H_0 consistently lies around 73-74 km s−1^{-1} Mpc−1^{-1}, regardless of the assumed cosmological background model. Our results agree nicely with those from the local distance ladder, but there is a >2σ\sigma tension with Planck results, and a ~1.5σ\sigma discrepancy with results from an inverse distance ladder including Planck, Baryon Acoustic Oscillations and SNe Ia. Future strong-lensing distance measurements will reduce the uncertainties in H0H_0 from our inverse distance ladder.Comment: 5 pages, 3 figures, A&A letters accepted versio

    Muscle plasticity related to changes in tubulin and αB-crystallin levels induced by eccentric contraction in rat skeletal muscles

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    We used the model of eccentric contraction of the hindlimb muscle by Ochi et al. to examine the role of eccentric contraction in muscle plasticity. This model aims to focus on stimulated skeletal muscle responses by measuring tissue weights and tracing the quantities of αB-crystallin and tubulin. The medial gastrocnemius muscle (GCM) responded to electrically induced eccentric contraction (EIEC) with significant increases in tissue weight (p < 0.01) and the ratio of tissue weight to body weight (p < 0.05); however, there was a decrease in soleus muscle weight after EIEC. EIEC in the GCM caused contractile-induced sustenance of the traced proteins, but the soleus muscle exhibited a remarkable decrease in α-tubulin and a 19% decrease in αB-crystallin. EIEC caused fast-to-slow myosin heavy chain (MHC) isoform type-oriented shift within both the GCM and soleus muscle. These results have shown that different MHC isoform type-expressing slow and fast muscles commonly undergo fast-to-slow type MHC isoform transformation. This suggests that different levels of EIEC affected each of the slow and fast muscles to induce different quantitative changes in the expression of αB-crystallin and α-tubulin

    Dependence Of Binary Encounter Electron Production On The Charge State Of The Recoil Ion

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    We study the dependence of the production of binary encounter electrons on the charge state of recoil ions for 2.4 MeV u-l Xe21+ on He and Ar. Doubly differential cross sections of electron emission are calculated with the ncrMC method. We find that the contributions to the binary electron cross section from various recoil ion charge states reach a maximum near Ar5+ for the Ar target. In the case of the He target; double ionization dominates over single ionization for alt ejected electron energies above 100 eV. However, an unexpected local drop of double ionization in the binary peak region has been observed. This decrease is found to be related to a two-step, sequential removal of the two electrons. © 1993 IOP Publishing Ltd

    Scaling Relations and Overabundance of Massive Clusters at z>~1 from Weak-Lensing Studies with HST

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    We present weak gravitational lensing analysis of 22 high-redshift (z >~1) clusters based on Hubble Space Telescope images. Most clusters in our sample provide significant lensing signals and are well detected in their reconstructed two-dimensional mass maps. Combining the current results and our previous weak-lensing studies of five other high-z clusters, we compare gravitational lensing masses of these clusters with other observables. We revisit the question whether the presence of the most massive clusters in our sample is in tension with the current LambdaCDM structure formation paradigm. We find that the lensing masses are tightly correlated with the gas temperatures and establish, for the first time, the lensing mass-temperature relation at z >~ 1. For the power law slope of the M-TX relation (M propto T^{\alpha}), we obtain \alpha=1.54 +/- 0.23. This is consistent with the theoretical self-similar prediction \alpha=3/2 and with the results previously reported in the literature for much lower redshift samples. However, our normalization is lower than the previous results by 20-30%, indicating that the normalization in the M-TX relation might evolve. After correcting for Eddington bias and updating the discovery area with a more conservative choice, we find that the existence of the most massive clusters in our sample still provides a tension with the current Lambda CDM model. The combined probability of finding the four most massive clusters in this sample after marginalization over current cosmological parameters is less than 1%.Comment: ApJ in press. See http://www.supernova.lbl.gov for additional information pertaining to the HST Cluster SN Surve

    Diffraction In The Binary Encounter Electron Peak Observed In Collisions Of 0.6 MeV Amu⁻Âč I7+, I23+ And Au11+ Projectiles With He And Ar

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    Relative double differential cross sections for electron emission from collisions of 0.6 MeV amu-1I7+and I23+ projectiles with Ar and Au11+projectiles with He were measured for electron energies from 100 eV to 2000 eV and for angles from 0° to 50°. Experimentally observed sudden shifts of the position of the binary encounter peak were interpreted as resulting from quantum interference in the scattering of target electrons from the partially stripped projectile ion. To this end calculations for the elastic scattering of free electrons initially at rest in the laboratory reference frame from the screened projectile field as well as model calculations of binary encounter electron production taking into account the target Compton profile were performed and compared with the experimental results. Good agreement was obtained for the angular locations of these shifts as well as for the angular distribution of the binary encounter electron yield. © 1992 IOP Publishing Ltd

    Relative dosimetry using active matrix flatĂą panel imager (AMFPI) technology

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135008/1/mp8649.pd

    X-ray imaging with amorphous silicon active matrix flat-panel imagers (AMFPIs)

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    Recent advances in thin-film electronics technology have opened the way for the use of flat-panel imagers in a number of medical imaging applications. These novel imagers offer real time digital readout capabilities ( ∌ 30(∌30 frames per second), radiation hardness (>106 cGy),(>106cGy), large area (30×40 cm2)(30×40cm2) and compactness ( ∌ 1 cm).(∌1cm). Such qualities make them strong candidates for the replacement of conventional x-ray imaging technologies such as film-screen and image intensifier systems. In this report, qualities and potential of amorphous silicon based active matrix flat-panel imagers are outlined for various applications such as radiation therapy, radiography, fluoroscopy and mammography. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87833/2/241_1.pd

    Bone mineral content after renal transplantation

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    Forearm bone mineral content (BMC), as evaluated by photonabsorption densitometry, was measured in 28 cadaver kidney donor recipients who entered the study 8 weeks postoperatively and were followed up for 18 months. BMC decreased signifiantly (p<0.05) but marginally in placebo-treated patients (n=14) (initial BMC 1.09±0.25 g/cm; final BMC 1.05±0.24). Fourteen patients were prophylactically given 1,25(OH)2vitamin D3 in a dose which avoided hypercalcemia and hypercalciuria (sim0.25 ”g/day); under 1,25(OH)2 vitamin D3 prophylaxis a significant decrease of forearm BMC was observed no longer (initial BMC 0.94±0.21 g/cm; final BMC 0.95±0.21), but the difference between placebo and 1,25(OH)2 vitamin D3 narrowly missed statistical significance (p=0.066). It is concluded that the decrease of forearm BMC is negligible in transplant recipients with low steroid regimens. The data suggest a trend for prophylaxis with 1,25(OH)2 vitamin D3 to slightly ameliorate forearm (cortical) BMC loss

    Bilateral Ageusia in a Patient with a Left Ventroposteromedial Thalamic Infarct: Cortical Localization of Taste Sensation by Statistical Parametric Mapping Analysis of PET Images

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    Unilateral taste loss is usually observed on the side contralateral to a thalamic infarction, despite gustatory function being represented bilaterally. We report a rare case of bilateral taste loss in a patient with an acute left unilateral thalamic infarction, with unilateral left insular hypometabolism demonstrated by statistical parametric map analysis of PET images. Our observations suggest that the left insular cortex and left ventroposteromedial thalamic nuclei are critical to bilateral gustatory sensation

    Deep VLA Observations of the Cluster 1RXS J0603.3+4214 in the Frequency Range of 1–2 GHz

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    We report L-band VLA observations of 1RXS J0603.3+4214, a cluster that hosts a bright radio relic, known as the Toothbrush, and an elongated giant radio halo. These new observations allow us to study the surface brightness distribution down to one arcsec resolution with very high sensitivity. Our images provide an unprecedented detailed view of the Toothbrush, revealing enigmatic filamentary structures. To study the spectral index distribution, we complement our analysis with published LOFAR and GMRT observations. The bright `brush' of the Toothbrush shows a prominent narrow ridge to its north with a sharp outer edge. The spectral index at the ridge is in the range −0.70≀α≀−0.80-0.70\leq\alpha\leq-0.80. We suggest that the ridge is caused by projection along the line of sight. With a simple toy model for the smallest region of the ridge, we conclude that the magnetic field is below 5 ΌG5\,\rm\mu G and varies significantly across the shock front. Our model indicates that the actual Mach number is higher than that obtained from the injection index and agrees well with the one derived from the overall spectrum, namely M=3.78−0.2+0.3{\cal M}=3.78^{+0.3}_{-0.2}. The radio halo shows an average spectral index of α=−1.16±0.05\alpha=-1.16\pm0.05 and a slight gradient from north to south. The southernmost part of the halo is steeper and possibly related to a shock front. Excluding the southernmost part, the halo morphology agrees very well with the X-ray morphology. A power-law correlation is found between the radio and X-ray surface brightnessComment: 23 pages, 21 figures, accepted for publication in Ap
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