X-Ray Emission from Two Infrared-Selected Galaxy Clusters at z>1.4 in
  the IRAC Shallow Cluster Survey
  We report the X-ray detection of two z>1.4 infrared-selected galaxy clusters
from the IRAC Shallow Cluster Survey (ISCS). We present new data from the
Hubble Space Telescope and the W. M. Keck Observatory that spectroscopically
confirm cluster ISCS J1432.4+3250 at z=1.49, the most distant of 18 confirmed
z>1 clusters in the ISCS to date. We also present new spectroscopy for ISCS
J1438.1+3414, previously reported at z = 1.41, and measure its dynamical mass.
Clusters ISCS J1432.4+3250 and ISCS J1438.1+3414 are detected in 36ks and 143ks
Chandra exposures at significances of 5.2 sigma and 9.7 sigma, from which we
measure total masses of log(M_{200,Lx}/Msun) = 14.4 +/- 0.2 and
14.35^{+0.14}_{-0.11}, respectively. The consistency of the X-ray and dynamical
properties of these high redshift clusters further demonstrates that the ISCS
is robustly detecting massive clusters to at least z = 1.5.
