Critical behavior of ion mobilities near the superfluid transition

Measurements are reported of the mobilities of helium ions in superfluid helium very close to the λ transition. The mobilities of both positive and negative ions appear to be singular in the sense of having infinite slope at the transition. The measurements are made by a new differential technique, based on the space-charge-limited method, which makes possible a sensitivity to changes in mobility of the order of parts in 104. This allows mobility measurements into the range |ε|<10-4, where ε=(T/Tλ)-1. Most of the reported measurements are taken along isotherms which cross the λ line at elevated pressures, although a series at saturated vapor pressure is also reported. Means of transforming the data between various thermodynamic paths are discussed. Uncertainty as to which thermodynamic path should be considered fundamental together with experimental problems in the technique at this stage in its development make quantitative assessment of the singularity difficult. However, if we assume a limiting form (μ-μλ)/μλ∼(-ε)ρ′, where μ is the mobility and μλ its value at the transition, we find for the exponent ρ′=0.94±0.02

Experiments on Quantum and Thermal Desorption from ^4He Films

Desorption of He atoms from thin films may be resolved experimentally into quantum and thermal components. We show that quantum desorption becomes the dominant part of the signal in submonolayer films. We also show that, when all effects of collisions between desorbed atoms are eliminated, quantum desorption is not focused normal to the surface of optically polished sapphire crystals

Decade-long profile of imaging biomarker use in ophthalmic clinical trials

PURPOSE. The purpose of this study was to investigate the use of imaging biomarkers in published clinical trials (CTs) in ophthalmology and its eventual changes during the past 10 years. METHODS. We sampled from published CTs in the fields of cornea, retina, and glaucoma between 2005\u20132006 and 2015\u20132016. Data collected included year of publication, phase, subspecialty, location, compliance with Consolidated Standards for Reporting Trials, impact factor, presence and use of imaging biomarkers (diagnostic, prognostic and predictive; primary and secondary surrogate endpoints), and use of centralized reading centers. RESULTS. We included 652 articles for analysis, equally distributed in three timeframes (2005\u2013 2006, 2010\u20132011, and 2015\u20132016), mainly reporting phase IV CTs and trials on procedures (42.2% and 35.4%, respectively). Imaging biomarkers were included in 46.3% of the analyzed CTs and their use significantly increased over time (P < 0.05). Optical coherence tomography was the most frequently used device (27.7%), whereas diagnostic biomarkers and secondary surrogate endpoints were the most frequent biomarker types (19.5% and 22.5%, respectively). Early-phase CTs showed an increase in the use of biomarkers for patient selection and stratification over time (P < 0.05), but not in the use of imaging surrogate endpoints (P = 0.90). Only 3 of 59 (5.1%) of phase III CTs included primary surrogate imaging endpoints, whereas secondary surrogate imaging endpoints were present in 50.8% of these trials (P < 0.001). Retinal CTs had the highest prevalence for each type of imaging biomarker (P < 0.001). Reading centers were used in 52 of 302 CTs (17.2%), with no significant time-related increase. CONCLUSIONS. Imaging biomarkers are increasingly used in published CTs in ophthalmology. Additional efforts, including centralized reading centers, are needed to improve their validation and use, allowing a wider use of these tools as primary surrogate endpoints in phase III CTs

Viscosity and positive-ion mobility near the melting transition in liquid ^4He

New measurements are presented of the shear viscosity η and the positive-ion mobility μ near the melting transition in liquid 4He. Interpreted in terms of the Stokes law for the drag on a sphere in a viscous medium, it is found, contrary to expectation, that the effective radius of the ion remains constant or decreases slightly as the melting transition is approached at constant temperature. Attempts to explain this observation have not been successful. On the other hand, an older mystery concerning the effective radius of the ion is cleared up: Ahlers and Gamota, comparing data for η and μ at the vapor pressure curve found that the effective radius has a maximum 40 mK below the λ transition (i.e., the lower triple point). We have observed a similar maximum on the melting curve, 40 mK below the upper triple point. It is shown that these maxima may be accounted for by an electrostrictively induced λ transition around the ion. In this interpretation, the maximum along the melting curve serves as the first empirical evidence that the λ line extends into the region of supercooled liquid at pressures above the melting curve

Foregrounds in the BOOMERANG-LDB data: a preliminary rms analysis

We present a preliminary analysis of the BOOMERanG LDB maps, focused on foregrounds. BOOMERanG detects dust emission at moderately low galactic latitudes ($b > -20^o$) in bands centered at 90, 150, 240, 410 GHz. At higher Galactic latitudes, we use the BOOMERanG data to set conservative upper limits on the level of contamination at 90 and 150 GHz. We find that the mean square signal correlated with the IRAS/DIRBE dust template is less than 3% of the mean square signal due to CMB anisotropy

Loss of renal function in the elderly italians: a physiologic or pathologic process?

Abstract BACKGROUND: Nowadays it seems that chronic kidney disease (CKD) is outbreaking, mostly in the elderly participants. The aim of this study was to assess the progression of CKD in different ages. METHODS: We conducted a monocentric, retrospective, observational study enrolling 116 patients afferent to our outpatient clinic. INCLUSION CRITERIA: age >18 years, follow-up ≥5 years, estimated glomerular filtration rate (eGFR) <60mL/min/1.73 m(2), and/or diagnosed renal disease and/or presence of renal damage. Patients were divided into four groups according to their age: 25-55 years (n = 27), 56-65 (25), 66-75 (42), and 76-87 (22). eGFR was calculated using the modification of diet in renal disease and the CKD-epidemiology collaboration formulas. RESULTS: Younger patients had a significantly longer follow-up and less comorbidities, evaluated by the cumulative illness rating scale score, compared with the other groups. There was no difference between creatinine at baseline and at the end-of-follow-up period among the groups. Even though renal function significantly decreased in all groups, we noticed a slower progression as the age increased, and the difference between basal and end-of-follow-up eGFR was minimal in the group of patients aged 76-87 years. Analyzing the eGFR of every ambulatory control plotted against the year of follow-up, we showed a more rapid loss of filtrate in the younger group. Instead, loss of renal function decreased as the age of patients increased. CONCLUSIONS: This study demonstrates that, in elderly Italian participants, progression of CKD occurs more slowly than in younger patients. This implies that we may probably face an epidemic of CKD but that most of elderly patients diagnosed with CKD may not evolve to end-stage renal disease and require renal replacement therapy

Extinction of the Kapitza Anomaly for Phonons along the Surface Normal Direction

We have succeeded in extinguishing the anomalous Kapitza transmission of phonons whose wave vector is normal to a surface treated by conventional means and handled in air. In the same experiments, phonons approaching the surface with oblique wave vectors are anomalously transmitted. We argue that these results demonstrate that the Kapitza anomaly is due to surface defects which couple to the phonon strain field

First Estimations of Cosmological Parameters From BOOMERANG

The anisotropy of the cosmic microwave background radiation contains information about the contents and history of the universe. We report new limits on cosmological parameters derived from the angular power spectrum measured in the first Antarctic flight of the BOOMERANG experiment. Within the framework of inflation-motivated adiabatic cold dark matter models, and using only weakly restrictive prior probabilites on the age of the universe and the Hubble expansion parameter $h$, we find that the curvature is consistent with flat and that the primordial fluctuation spectrum is consistent with scale invariant, in agreement with the basic inflation paradigm. We find that the data prefer a baryon density $\Omega_b h^2$ above, though similar to, the estimates from light element abundances and big bang nucleosynthesis. When combined with large scale structure observations, the BOOMERANG data provide clear detections of both dark matter and dark energy contributions to the total energy density $\Omega_{\rm {tot}}$, independent of data from high redshift supernovae.Comment: As submitted to PRD, revised longer version with an additional figur

The BOOMERANG North America Instrument: a balloon-borne bolometric radiometer optimized for measurements of cosmic background radiation anisotropies from 0.3 to 4 degrees

We describe the BOOMERANG North America (BNA) instrument, a balloon-borne bolometric radiometer designed to map the Cosmic Microwave Background (CMB) radiation with 0.3 deg resolution over a significant portion of the sky. This receiver employs new technologies in bolometers, readout electronics, millimeter-wave optics and filters, cryogenics, scan and attitude reconstruction. All these subsystems are described in detail in this paper. The system has been fully calibrated in flight using a variety of techniques which are described and compared. It has been able to obtain a measurement of the first peak in the CMB angular power spectrum in a single balloon flight, few hours long, and was a prototype of the BOOMERANG Long Duration Balloon (BLDB) experiment.Comment: 40 pages, 22 figures, submitted to Ap

Mapping the CMB Sky: The BOOMERANG experiment

We describe the BOOMERanG experiment, a stratospheric balloon telescope intended to measure the Cosmic Microwave Background anisotropy at angular scales between a few degrees and ten arcminutes. The experiment has been optimized for a long duration (7 to 14 days) flight circumnavigating Antarctica at the end of 1998. A test flight was performed on Aug.30, 1997 in Texas. The level of performance achieved in the test flight was satisfactory and compatible with the requirements for the long duration flight.Comment: 11 pages, 6 figure