spectral decomposition of time series has a significant role in seismic data processing and interpretation. since the earth acts as a low-pass filter, it changes frequency content of passing seismic waves. conventional representing methods of signals in time domain and frequency domain cannot show time and frequency information simultaneously. time-frequency transforms upgraded spectral decompo...

to identify temporal and spatial precipitation models in the southern coasts of caspian sea, principle component analysis (pca) and clustering analysis (ca) were used. in this study, using daily precipitation data, measure of central tendency, statistical dispersion and percentages of three variables of duration, amount and intensity of precipitation events in 46 synoptic, climatic and rain gau...

recurrent aphthous stomatitis (ras) is known as the most common chronic disease of the oral cavity, which affects a range of 5-25% of the population. ras appears to be associated with some human leukocyte antigen (hla) class ii alleles and haplotypes. this study attempts to survey the distribution of hla-drb and -dqb alleles among iranian ras patients and healthy controls. in order to evaluate ...

abstract  background: the brain response to temporal frequencies (tf) has been already reported, but with no study reported for different tf with respect to various spatial frequencies (sf).  materials and methods: fmri was performed by 1.5t ge-system in 14 volunteers during checkerboard, with tfs of 4, 6, 8 and 10hz in low and high sfs of 0.5 and 8cpd.  results: average percentage bold signal ...

this paper presents a new centralized adaptive method under frequency load shedding. sometimes, after initial frequency drop following severe disturbances, although the system frequency returns to its permissible value, however, the system might become unstable due to voltage problems. in this regard, the paper proposes a new centralized adaptive load shedding method to enhance the voltage stab...

results no significant difference was observed between the two groups in terms of chronic low back pain; frequency of low back pain in clinical staff was 18% (18 individuals) and in office staff this was 17% (17 individuals) (p < 0.05). chronic low back pain in the clinical group might be related to flexion and extension, twisting, pulling or pushing, carrying, handling of patients, and sitting...