Observed forest trait velocities have not kept pace with hydraulic stress from climate change.

The extent to which future climate change will increase forest stress and the amount to which species and forest ecosystems can acclimate or adapt to increased stress is a major unknown. We used high-resolution maps of hydraulic traits representing the diversity in tree drought tolerance across the United States, a hydraulically enabled tree model, and forest inventory observations of demographic shifts to quantify the ability for within-species acclimation and between-species range shifts to mediate climate stress. We found that forests are likely to experience increases in both acute and chronic hydraulic stress with climate change. Based on current species distributions, regional hydraulic trait diversity was sufficient to buffer against increased stress in 88% of forested areas. However, observed trait velocities in 81% of forested areas are not keeping up with the rate required to ameliorate projected future stress without leaf area acclimation.

Imaging the nanoscale phase separation in vanadium dioxide thin films at terahertz frequencies.

Vanadium dioxide (VO2) is a material that undergoes an insulator-metal transition upon heating above 340 K. It remains debated as to whether this electronic transition is driven by a corresponding structural transition or by strong electron-electron correlations. Here, we use apertureless scattering near-field optical microscopy to compare nanoscale images of the transition in VO2 thin films acquired at both mid-infrared and terahertz frequencies, using a home-built terahertz near-field microscope. We observe a much more gradual transition when THz frequencies are utilized as a probe, in contrast to the assumptions of a classical first-order phase transition. We discuss these results in light of dynamical mean-field theory calculations of the dimer Hubbard model recently applied to VO2, which account for a continuous temperature dependence of the optical response of the VO2 in the insulating state.

[Ultrasound diagnosis of kidney abnormalities]. / Ultraschalldiagnostik der Nierenfehlbildungen.

By means of sonography, it is possible to monitor the growth of the kidney from the 20th week of foetal life up to adulthood. Anomalies of number and position, hydronephrosis, cysts, multicystic kidneys and polycystic diseases can be demonstrated. Some specific problems of sonography arising in this field are discussed.

[Possibilities of abdominal ultrasonics]. / Les possibilités de l'ultrasonographie abdominale.

The potentialities of abdominal ultrasonography are discussed and illustrated by a number of cases. It is particularly indicated whenever aortic aneurysm, gallstones or obstructive jaundice are suspected. However, good results are obtained in research of most forms of abdominal mass lesion.

[Value of abdominal ultrasonography for indication of cholecystectomy]. / Valeur de l'ultrasonographie abdominale dans l'indication à une cholécystectomie.

A review of the gall-bladder content of the 193 patients that underwent a cholecystectomy at the University Hospital of Lausanne, Switzerland, in 1977, was done in order to find out the diagnostic accuracy of sonographic examination of the gall-bladder, oral cholecystography and intravenous cholangiography. Sonographic examination of the gall-bladder proofed to be accurate in 92.5% of 109 cases. We found a false negative rate of 4.5% (5 cases) and a false positive rate of 1% (1 case) as well as an indeterminate rate of 2% (2 cases). In 37% (46 cases) of the 124 patients that underwent oral cholecystography and/or intravenous cholangiography the gall-bladder was not visualized. Sonographic examination of gall-bladder is free of side effects and can be done on emergency, on jaundiced or pregnant patients, and it is enough reliable for the surgeon to make a decision to operate the gall-bladder. Low cost of the procedure is another point in favour of sonographic examination of the gall-bladder.