On the characters of Sylow pp-subgroups of finite Chevalley groups G(pf)G(p^f) for arbitrary primes

We develop in this work a method to parametrize the set $\mathrm{Irr}(U)$ of irreducible characters of a Sylow $p$-subgroup $U$ of a finite Chevalley group $G(p^f)$ which is valid for arbitrary primes $p$, in particular when $p$ is a very bad prime for $G$. As an application, we parametrize $\mathrm{Irr}(U)$ when $G=\mathrm{F}_4(2^f)$.Comment: 22 page

The Information Complexity of Learning Tasks, their Structure and their Distance

We introduce an asymmetric distance in the space of learning tasks, and a framework to compute their complexity. These concepts are foundational for the practice of transfer learning, whereby a parametric model is pre-trained for a task, and then fine-tuned for another. The framework we develop is non-asymptotic, captures the finite nature of the training dataset, and allows distinguishing learning from memorization. It encompasses, as special cases, classical notions from Kolmogorov complexity, Shannon, and Fisher Information. However, unlike some of those frameworks, it can be applied to large-scale models and real-world datasets. Our framework is the first to measure complexity in a way that accounts for the effect of the optimization scheme, which is critical in Deep Learning

The irreducible characters of Sylow p-subgroups of split finite groups of Lie type

Let $G$ be a split finite group of Lie type defined over F$_q$, where $q$=$p$$^e$ is a prime power and $p$ is not a very bad prime for $G$. Let $U$ be a Sylow $p$-subgroup of $G$. In this thesis, we provide a full parametrization of the set Irr($U$) of irreducible characters of $U$ when $G$ is of rank 5 or less. In particular, for every character χ ∈ Irr($U$) we determine an abelian subquotient of $U$ such that χ is obtained by an inflation, followed by an induction of a linear character of this subquotient. The characters are given in most cases as the output of algorithm that has been implemented in the computer system GAP, whose validity is proved in this thesis using classical results in representation theory and properties of the root system associated to $G$. We also develop a method to determine a parametrization of the remaining irreducible characters, which applies for every split finite group of Lie type of rank at most 5, and lays the groundwork to provide such a parametrization in rank 6 and higher

Assessing the real benefits of surgery for degenerative lumbar spinal stenosis without instability and spondylolisthesis: a single surgeon experience with a mean 8-year follow-up

Background: The degenerative lumbar spinal stenosis is one of the most commonly treated spinal disorders in older adults; despite its increasing frequency, it is not yet clear what the most effective therapy might be. The aim of this study is to investigate the very long term results of a homogenized cohort of patients suffering from lumbar spinal stenosis: the first subset of patients operated on with laminectomy and the second subset of patients was also advised to undergo laminectomy but never operated on. Methods: Patients from both subgroups were advised to undergo surgery, according to the same criteria, in the period between 2000 and 2010 and were re-evaluated in the period between January and December 2016. Results: Comparing the two subsets of patients, both suffering from clinically relevant LSS, the first subset returns a statistically significant clinical improvement at follow-up. The rate of excellent results decreases over years. Iatrogenic spinal instability incidence was found to be 3.8% in the present cohort. Conclusions: Although the improvement of the first postoperative years decreases over time and despite the lack of general consensus, the lack of established shared guidelines and the limitations of this research, the results support the utilisation of surgery for the management of this condition. Level of Evidence: 3

Le proteine motrici chinesine come target per la terapia del cancro.

La mitosi è risultata un valido target per lo sviluppo di terapie anticancro e molti farmaci antimitotici sono stati utilizzati con successo nella pratica clinica. Tutti gli antimitotici approvati finora hanno come target il fuso dei microtubuli, interferendo così con la dinamica del fuso che porta all'arresto della mitosi e all'apoptosi. Anche se efficaci, questi farmaci hanno vari effetti secondari, compresa la neurotossicità. Negli ultimi anni, le proteine motrici chinesine hanno attirato notevolmente l'attenzione dei ricercatori come target alternativo. Grazie alla loro specifica funzione nella mitosi, modulare queste proteine crea un'opportunità per lo sviluppo di antimitotici più selettivi e con un migliore indice terapeutico. Inoltre, gli inibitori delle chinesine possono superare le resistenze ai farmaci che agiscono sul microtubulo. La ricerca in questo settore si è inizialmente concentrata su una proteina del fuso con direzionalità positiva, la chinesina-5 (Eg5), la quale ha una struttura omotetramerica capace di legare i microtubuli antiparalleli e farli scivolare separatamente. Questo membro della superfamiglia delle proteine motrici chinesine, svolge funzioni cruciali durante la mitosi, quali la separazione dei centrosomi, l'assemblaggio e il mantenimento del fuso bipolare. L'inibizione della funzione di Eg5 porta all'arresto del ciclo cellulare in mitosi, con la formazione di schieramenti di microtubuli monoastrali, e infine alla morte cellulare. Sono stati scoperti molti inibitori specifici di Eg5, fra i quali monastrolo, S-trifenilmetil-L-cisteina (STLC) e ispinesib. Questi inibitori esercitano la loro azione attraverso il legame in un sito allosterico localizzato fra l’alfaelica 3 e il loop 5 del dominio motore di Eg5. Il loop 5 così esteso è stato trovato solo nella classe 5 delle chinesine e questo è il motivo per cui questi inibitori sono specifici solo per Eg5. Alcuni di questi inibitori sono attualmente in fase di sperimentezione clinica I o II come farmaci anticancro