... study highlights a key conceptual difference between DCM and GCM (see Table 1): namely, that DCM has an explicit model of hidden states causing observed data; whereas GCM tries to...

2019年10月15日 · In this guide, we step through an exemplar fMRI analysis in detail, reviewing the current implementation of DCM and demonstrating recent developments in group-level connectivity analysis. In the appendices, we detail the theory underlying DCM and the assumptions (i.e., priors) in the models.

2019年10月15日 · In this paper, we address the practicalities of hierarchical modelling in brain connectivity studies. Dynamic Causal Modelling (DCM) is the predominant analysis framework for inferring effective connectivity; namely, the directed causal influences among neural populations that mediate an effect of one population on another (Friston et al., 2003).

In the first level DCM tutorial, we saw how to specify and compare Dynamic Causal Models (DCMs) for a single participant’s data. In this tutorial we will test for similarities and differences in connectivity between participants, using the Parametric Empirical …

2011年9月15日 · Despite the common goal, there are also differences between the two methods. Whereas GCA explicitly models temporal precedence and uses the concept of Granger causality (or G-causality), DCM employs a biophysically motivated generative model of neuronal population dynamics and hemodynamic processes.

2013年3月27日 · GCM should be considered superior to CCM for most applications that require authenticated encryption. Because of the authentication that happens, GCM is not susceptible to the bit flipping and other attacks that can be mounted against counter mode …

Based on the use of the Bayes factor, we show that the obtained GC connectivity network compares well to a reference model that has been selected through DCM analysis among other candidate models.

2020年4月20日 · Recent x64 CPU (from Intel core 4xxx [*] / AMD Bulldozer) have dedicated hardware instructions (AES-NI) computing AES-GCM 2-10 times faster. ChaCha20-Poly1305 is much faster than AES on systems that do not have AES hardware (anything mobile or ARM).

Over the last decade, there has been significant amount of research and effort involved to invent the dedicated AE modes CCM, GCM, EAX, and OCB [7]. Rather than using the authenticity and privacy techniques separately, these AE schemes provide more proficient results and have very few chances of being incorrect.

GCM provides stronger authentication assurance than a (non-cryptographic) checksum or error detecting code; in particular, GCM can detect both 1) accidental modifications of the data and 2) intentional, unauthorized modifications. The two functions of GCM are called authenticated encryption and authenticated decryption.