Notes

The synaptic connections that define such circuits are typically made in a dense tangle of dendrites, axons terminals, and glial cell processes that together constitute what is called neuropil. Knee-Jerk Response The knee-jerk reflex (also known as the patellar reflex) is a classic example of a mono-synaptic reflex arc, which involves a direct connection between sensory and motor neurons, as well as inhibitory circuits to regulate movement. This is important for us if we fall and hit something. ...

Humans are not rational. See (Dostoevsky 1864), the parable of the destroying free will. In this note we will describe some behavioural economics ideas that could be interesting in this side. We will see dopamine response will be very important in this context, and see how we can interpret it as an utility. Economical Games The rules of the Ultimatum game The proposer makes an offer as to how this money should be split between the two. The second player (the risponder) can either accept or reject this offer. If it is accepted, the money is split as proposed, but if the risponder rejects the offer, then neither player receives anything. ...

CIAA principles of security We have already outlined these principles in Sicurezza delle reti and talked about the concepts of authentication and integrity. Here we try to deepen these concepts and delve a little bit more on the attack vectors. This note mainly focuses on the principles summarized by the acronyms CIA and AAA. Confidentiality This is one concerns about the secrecy of the sent message. We do not want others to be able to access and read what we are doing. ...

Mixture of Experts There is a gate that opens a subset of the experts, and the output is the weighted sum of the outputs of the experts. The weights are computed by a gating network. One problem is load balancing, non uniform assignment. And there is a lot of communication overhead when you place them in different devices. LoRA: Low-Rank Adaptation We only finetune a part of the network, called lora adapters, not the whole thing. There are two matrices here, a matrix A and B, they are some sort of an Autoencoders, done for every Q nd V matrices in the LLM attention layer. The nice thing is that there are not many inference costs if adapters are merged post training: ...

Queueing theory is the theory behind what happens when you have lots of jobs, scarce resources, and subsequently long queues and delays. It is literally the “theory of queues”: what makes queues appear and how to make them go away. This is basically what happens in clusters, where you have a limited number of workers that need to execute a number of jobs. We need some little maths to model the stochastic process of request arrivals. ...

Introduzione ai Redundant Array of Indipendent Disks I RAID ne abbiamo citato per la prima volta in Memoria. Come facciamo a stare su alla velocità del processore se questa va a crescere in modo esponenziale? Parallelizzazione della ricerca!. Ecco perché ci serve raid (oltre alla ridondanza quindi più sicuro). E possono anche fallire. → ammette recovery. E una altra cosa bella dei raid è che sono hot-swappable cioè li puoi sostituire anche quando stanno runnando. ...

Synapses are the connections that exist between one neuron and another, so we can think of them as the communication channel between neurons. Gap Junctions Electrical based These are also called Gap Junctions These are more direct connections between neurons, allowing excitation ions to pass through quite directly (this is the difference compared to chemically based ones). It’s a circuit more similar to an electronic one because it’s faster. The end of the presynapsic part is called axon bouton, or axon terminal. Another characteristic of these kinds of synapses is that they are two-way channels. ...

Introduction to the Course What is a neural system? A neural system is an intricately organized network of specialized cells—primarily neurons, along with a variety of supportive glial cells—that processes and transmits information via electrical and chemical signals. In biological organisms, such systems underpin the entire nervous system, coordinating functions that range from basic reflexes to the complex interplay of perception, thought, and behavior. Early studies in neurobiology revealed that even simple neural circuits can generate coordinated responses, while modern neuroscience has shown that vast, hierarchically structured networks (such as the central and peripheral nervous systems) are responsible for the rich tapestry of animal behavior and cognition ...

The fundamental idea behind a virtual machine is to abstract the hardware of a single computer (the CPU, memory, disk drives, network interface cards, and so forth) into several different execution environments, thereby creating the illusion that each separate environment is running on its own private computer. (Silberschatz et al. 2018). Virtualization allows a single computer to host multiple virtual machines, each potentially running a completely different operating system. È virtuale nel senso che la macchina virtuale ha la stessa percezione della realtà di una macchina reale. Qualcosa che non è la realtà ma appare molto simile ad essa. ...

A seconda dell’utilizzatore l’OS può essere molte cose, come solamente l’interfaccia se sei un programmatore, servizi (se sei un utente, ma gran parte dei servizi sono astratti e l’utente ne può anche essere a non-conoscenza). Ma se sei un programmatore OS ti interessa capire le componenti principali dell’OS Slide componenti OS alto livello Introduzione sui componenti (salto) Questa parte la salto perché è una descrizione molto generale di cosa si occupa L’os verso drivers, processi, filesystem I/O, quindi non è molto importante ...