Local measurements in turbulent flows through cross correlation of optical signals

Crossed beam correlation method measures turbulent fluctuations in transonic and supersonic flows. Two collimated beams of radiation are crossed at the point of interest in the flow, and the power loss of each beam is measured with two independent photodetectors, which yield information about the turbulent properties

Fractal Droplets in Two Dimensional Spin Glasses

The two-dimensional Edwards-Anderson model with Gaussian bond distribution is investigated at T=0 with a numerical method. Droplet excitations are directly observed. It turns out that the averaged volume of droplets is proportional to l^D with D = 1.80(2) where l is the spanning length of droplets, revealing their fractal nature. The exponent characterizing the l dependence of the droplet excitation energy is estimated to be -0.42(4), clearly different from the stiffness exponent for domain wall excitations.Comment: 4 pages 4 figure

Fatalism and Future Contingents

In this paper I address issues related to the problem of future contingents and the metaphysical doctrine of fatalism. Two classical responses to the problem of future contingents are the third truth value view and the all-false view. According to the former, future contingents take a third truth value which goes beyond truth and falsity. According to the latter, they are all false. I here illustrate and discuss two ways to respectively argue for those two views. Both ways are similar in spirit and intimately connected with fatalism, in the sense that they engage with the doctrine of fatalism and accept a large part of a standard fatalistic machinery

Research opportunities in loss of red blood cell mass in space flight

Decreases of red blood cell mass and plasma volume have been observed consistently following manned space flights. Losses of red cell mass by United States astronauts have averaged 10 to 15% (range: 2 to 21%). Based on postflight estimates of total hemoglobin, Soviet cosmonauts engaged in space missions lasting from 1 to 7 months have exhibited somewhat greater losses. Restoration of red cell mass requires from 4 to 6 weeks following return to Earth, regardless of the duration of space flight

Investigation looking at the repeatability of 20 Society of Master Saddlers (SMS) qualified saddle fitters’ observations during static saddle fit

Saddle fit is widely considered to be a crucial factor for the health and performance of riding horses; however, there have been no studies looking at the agreement between professionals who fit and assess saddles. The aim of the study was to determine the agreement between Society of Master Saddlers (SMSs) qualified saddle fitters when statically fitting a saddle following the SMS guidelines. Twenty SMS qualified saddle fitter volunteers were recruited via social media and asked to statically assess the fit of the saddle following the “7 points of saddle fit” guidelines of the SMS in 10 horses. Descriptive statistics and Fleiss Kappa (as a measure of agreement beyond chance) were used to determine agreement between fitters. Agreement varied from slight to substantial between the different saddle assessment criteria with the assessment of overall saddle fit resulting in a fair agreement of k = 0.32. Substantial agreement was found for saddle clearance front (k = 0.66), top (k = 0.78), and rear (k = 0.81). Fair agreement was found for clearance of the saddle—side (k = 0.28) and how the girth straps line up with girth groove (k = 0.31) and panel contact (k = 0.38). Slight agreement was found for tree width and length (k = 0.12) and tree length (k = 0.12). Horse height in some criteria affected agreement. Agreement varied between the standard criteria. In cases where it was difficult to visually evaluate saddle fit, agreement was lower. Further work should aim to standardize the criteria which had suboptimal agreement

Variables controlling fatigue crack growth of short cracks

A study was conducted to evaluate the roles of crack closure and microstructure in the fatigue growth of short cracks. Testing was performed at R ratios of 0.1, 0.5, and 0.7. At all R ratios short cracks exhibited accelerated growth rates in comparison to long cracks. It was concluded that crack closure could not entirely account for the accelerated growth rates of short cracks. The accelerated growth rates occurred over crack lengths on the order of grain size, suggesting a strong influence of microstructure. A significant effect of grain boundaries and inclusions on short crack FCG behavior was observed. For very short crack lengths, fatigue growth rates do not appear to be a function of either delta K or R ratio

Evidence for realignment of the charge density wave state in ErTe3_3 and TmTe3_3 under uniaxial stress via elastocaloric and elastoresistivity measurements

We report the evolution of a charge density wave (CDW) state in the quasi-2D rare-earth tritellurides ($R$Te$_3$ for $R$=Er,Tm) as a function of in-plane uniaxial stress. Measurements of the elastocaloric effect, resistivity, and elastoresistivity allow us to demonstrate the importance of in-plane antisymmetric strain on the CDW and to establish a phase diagram. We show that modest tensile stress parallel to the in-plane $a$-axis can reversibly switch the direction of the ordering wavevector between the two in-plane directions. This work establishes $R$Te$_3$ as a promising model system for the study of strain-CDW interactions in a quasi-2D square lattice.Comment: 18 pages, 12 figure

Numerical Results for the Ground-State Interface in a Random Medium

The problem of determining the ground state of a $d$-dimensional interface embedded in a $(d+1)$-dimensional random medium is treated numerically. Using a minimum-cut algorithm, the exact ground states can be found for a number of problems for which other numerical methods are inexact and slow. In particular, results are presented for the roughness exponents and ground-state energy fluctuations in a random bond Ising model. It is found that the roughness exponent $\zeta = 0.41 \pm 0.01, 0.22 \pm 0.01$, with the related energy exponent being $\theta = 0.84 \pm 0.03, 1.45 \pm 0.04$, in $d = 2, 3$, respectively. These results are compared with previous analytical and numerical estimates.Comment: 10 pages, REVTEX3.0; 3 ps files (separate:tar/gzip/uuencoded) for figure