Time-changed normalizing flows for accurate SDE modeling

The generative paradigm has become increasingly important in machine learning and deep learning models. Among popular generative models are normalizing flows, which enable exact likelihood estimation by transforming a base distribution through diffeomorphic transformations. Extending the normalizing flow framework to handle time-indexed flows gave dynamic normalizing flows, a powerful tool to model time series, stochastic processes, and neural stochastic differential equations (SDEs). In this work, we propose a novel variant of dynamic normalizing flows, a Time Changed Normalizing Flow (TCNF), based on time deformation of a Brownian motion which constitutes a versatile and extensive family of Gaussian processes. This approach enables us to effectively model some SDEs, that cannot be modeled otherwise, including standard ones such as the well-known Ornstein-Uhlenbeck process, and generalizes prior methodologies, leading to improved results and better inference and prediction capability

Custom ASIC design for SHA-256 using open-source tools

The growth of digital communications has driven the development of numerous cryptographic methods for secure data transfer and storage. The SHA-256 algorithm is a cryptographic hash function widely used for validating data authenticity, identity, and integrity. The inherent SHA-256 computational overhead has motivated the search for more efficient hardware solutions, such as application-specific integrated circuits (ASICs). This work presents a custom ASIC hardware accelerator for the SHA-256 algorithm entirely created using open-source electronic design automation tools. The integrated circuit was synthesized using SkyWater SKY130 130 nm process technology through the OpenLANE automated workflow. The proposed final design is compatible with 32-bit microcontrollers, has a total area of 104,585 µm2, and operates at a maximum clock frequency of 97.9 MHz. Several optimization configurations were tested and analyzed during the synthesis phase to enhance the performance of the final design.This research was funded by Brazil’s National Council for Scientific and Technological Development (CNPq) grant number 120527/2022-7

QUALIDADE PÓS COLHEITA DE LARANJAS EMBALADAS INTEIRAS COM E SEM ALBEDO: RELATO DE AULA PRÁTICA

A conservação pós colheita é de suma importância tendo em vista que estes produtos serão levados ao comércio e nele necessitam estar visualmente apresentáveis para que assim possam atrair o consumidor. Tendo em vista esta conservação este estudo buscou avaliar alguns fatores importantes para tal quesito na laranja, dentre eles a perda de massa, pH (potencial hidrogeniônico), graus Brix, acidez total titulável (ATT) e Ratio. Os testes foram realizados utilizando 6 laranjas, sendo duas para determinar valores de padrão colheita, duas laranjas inteiras com albedo e duas laranjas inteiras sem albedo. As quatro últimas foram processadas para análise 8 dias após armazenamento em geladeira a 0,9 ºC. Como resultado a perda de massa foi maior quando o fruto estava sem albedo, ou seja, com um pouco mais de processamento; o pH encontrado quando houve processamento se aproximou da neutralidade; o Brix foi maior quando houve processamento; a ATT foi maior no fruto com albedo e o Ratio no fruto sem albedo

A dose-effect relationship for deltaretrovirus-dependent leukemogenesis in sheep

<p>Abstract</p> <p>Background</p> <p>Retrovirus-induced tumors develop in a broad range of frequencies and after extremely variable periods of time, from only a few days to several decades, depending mainly on virus type. For hitherto unexplained reasons, deltaretroviruses cause hematological malignancies only in a minority of naturally infected organisms and after a very prolonged period of clinical latency.</p> <p>Results</p> <p>Here we demonstrate that the development of malignancies in sheep experimentally infected with the deltaretrovirus bovine leukemia virus (BLV) depends only on the level of BLV replication. Animals were experimentally infected with leukemogenic or attenuated, but infectious, BLV molecular clones and monitored prospectively through 8 months for viral replication. As early as 2 weeks after infection and subsequently at any time during follow-up, leukemogenic viruses produced significantly higher absolute levels of reverse transcription (RT), clonal expansion of infected cells, and circulating proviruses with RT- and somatic-dependent mutations than attenuated viruses. These differences were only quantitative, and both kinds of viruses triggered parallel temporal fluctuations of host lymphoid cells, viral loads, infected cell clonality and proliferation.</p> <p>Conclusion</p> <p>Deltaretrovirus-associated leukemogenesis in sheep appears to be a two-hit process over time depending on the amounts of first horizontally and then vertically expanded viruses.</p

Early and transient reverse transcription during primary deltaretroviral infection of sheep

<p>Abstract</p> <p>Background</p> <p>Intraindividual genetic variability plays a central role in deltaretrovirus replication and associated leukemogenesis in animals as in humans. To date, the replication of these viruses has only been investigated during the chronic phase of the infection when they mainly spread through the clonal expansion of their host cells, vary through a somatic mutation process without evidence for reverse transcriptase (RT)-associated substitution. Primary infection of a new organism necessary involves allogenic cell infection and thus reverse transcription.</p> <p>Results</p> <p>Here we demonstrate that the primary experimental bovine leukemia virus (BLV) infection of sheep displays an early and intense burst of horizontal replicative dissemination of the virus generating frequent RT-associated substitutions that account for 69% of the in vivo BLV genetic variability during the first 8 months of the infection. During this period, evidence has been found of a cell-to-cell passage of a mutated sequence and of a sequence having undergone both RT-associated and somatic mutations. The detection of RT-dependent proviral substitution was restricted to a narrow window encompassing the first 250 days following seroconversion.</p> <p>Conclusion</p> <p>In contrast to lentiviruses, deltaretroviruses display two time-dependent mechanisms of genetic variation that parallel their two-step nature of replication <it>in vivo</it>. We propose that the early and transient RT-based horizontal replication helps the virus escape the first wave of host immune response whereas somatic-dependent genetic variability during persistent clonal expansion helps infected clones escape the persistent and intense immune pressure that characterizes the chronic phase of deltaretrovirus infection.</p