A frequently proposed method of reducing unsolicited bulk email (“spam”) is for senders to pay for each email they send. Proof-ofwork schemes avoid charging real money by requiring senders to demonstrate that they have expended processing time in solving a cryptographic puzzle. We attempt to determine how difficult that puzzle should be so as to be effective in preventing spam. We analyse this ...

OBJECTIVE Cerebral blood flow (CBF) estimation with C15O2 PET usually assumes a single tissue compartment model and a fixed brain-blood partition coefficient of water. However, the partition coefficient may change in pathological conditions. The purpose of this study was to investigate the changes in the partition coefficient of water in pathological regions and its effect on regional CBF asses...

BACKGROUND In vitro and in vivo evidence suggests that atrial natriuretic peptide can enhance fluid flux from intravascular to extravascular compartments. The relevance of this to human pathophysiology remains unclear. OBJECTIVES To determine whether a central haemodynamic change associated with increased plasma concentrations of atrial natriuretic peptide produces detectable change in the ca...

Abstract Jefferson County in Texas has experienced devastating storms recent years resulting billions of dollars damages. The county gone through temporal milestones terms population growth and industrial development. Many studies have shown that urban development increases the risk flooding by decreasing soil infiltration capacity. current study focuses on estimating extent to which led increa...

Thin films of GeTe2 were deposited on glass substrates using radio-frequency magnetron sputtering with various hydrogen flow rates in the growth chamber. Transmission data of deposited films were taken and used to determine optical constants refractive index n , extinction coefficient , and absorption coefficient and the energies corresponding to absorption coefficients of 104 and 103 cm−1 E04,...

Retrievals of ocean surface chlorophyll-a concentration (Chla) by multiple ocean color satellite sensors (SeaWiFS, MODIS-Terra, MODIS-Aqua, MERIS, VIIRS) using standard algorithms were evaluated in the California Current using a large archive of in situ measurements. Over the full range of in situ Chla, all sensors produced a coefficient of determination (R) between 0.79 and 0.88 and a median a...