Una Macchina Nozionale per Architetture dei Calcolatori come possibile collegamento tra gli insegnamenti del primo anno della laurea in Informatica

In questo articolo presentiamo un esperimento basato sull’adozione del modello RAM di Cook e Reckhow come macchina nozionale per introdurre il linguaggio macchina RISC-V e di un linguaggio visuale a blocchi per avvicinare i novizi ai concetti di base dell’assembler e delle architetture di calcolo. L’esperimento si `e tenuto nella prima parte del corso di Ar chitetture dei Calcolatori nell’anno accademico 2022/23 con 320 studenti con conoscenze molto eterogenee. La scelta di combinare RISC-V, modello RAM e linguaggio a blocchi `e stata dettata dal tentativo di adottare una macchina nozionale in grado di rappresentare i concetti di base di architetture load-store anche per novizi e dalla quale poter ricostrui re i costrutti che nel corso di Introduzione alla Programmazione venivano nel frattempo presentati attraverso il C++

ボゴ ニヨル コクゴ ノ ガクシュウ オ オヤコ デ ジッセンスル ワタシ ノ ブンカ オ イカシテ

There has been a large focus on the genetics of traits involved in adaptation, but knowledge of the environmental variables leading to adaptive changes is surprisingly poor. Combined use of environmental data with morphological and genomic data should allow us to understand the extent to which patterns of phenotypic and genetic diversity within a species can be explained by the structure of the environment. Here we analyse the variation of populations of three-spined stickleback from 27 freshwater lakes on North Uist, Scotland, that vary greatly in their environment, to understand how environmental and genetic constraints contribute to phenotypic divergence. We collected 35 individuals per population and 30 abiotic and biotic environmental parameters to characterize variation across lakes and analyse phenotype – environment associations. Additionally we used RAD sequencing to estimate the genetic relationships among a subset of these populations. We found a large amount of phenotypic variation among populations, most prominently in armour and spine traits. Despite large variation in the abiotic environment, namely in ion composition, depth and Dissolved Organic Carbon, more phenotypic variation was explained by the biotic variables (presence of predators and density of predator and competitors), than by associated abiotic variables. Genetic structure among populations was partly geographic, with closer populations being more similar. Altogether our results suggest that differences in body shape among stickleback populations are the result of both canalized genetic and plastic responses to environmental factors, which shape fish morphology in a predictable direction regardless of their genetic starting point

On the origins of phenotypic parallelism in benthic and limnetic stickleback

Rapid evolution of similar phenotypes in similar environments, giving rise to in situ parallel adaptation, is an important hallmark of ecological speciation. However, what appears to be in situ adaptation can also arise by dispersal of divergent lineages from elsewhere. We test whether two contrasting phenotypes repeatedly evolved in parallel, or have a single origin, in an archetypal example of ecological adaptive radiation: benthic–limnetic three-spined stickleback (Gasterosteus aculeatus) across species pair and solitary lakes in British Columbia. We identify two genomic clusters across freshwater populations, which differ in benthic–limnetic divergent phenotypic traits and separate benthic from limnetic individuals in species pair lakes. Phylogenetic reconstruction and niche evolution modeling both suggest a single evolutionary origin for each of these clusters. We detected strong phylogenetic signal in benthic–limnetic divergent traits, suggesting that they are ancestrally retained. Accounting for ancestral state retention, we identify local adaptation of body armor due to the presence of an intraguild predator, the sculpin (Cottus asper), and environmental effects of lake depth and pH on body size. Taken together, our results imply a predominant role for retention of ancestral characteristics in driving trait distribution, with further selection imposed on some traits by environmental factors

SAT-based Explicit LTL Reasoning

We present here a new explicit reasoning framework for linear temporal logic (LTL), which is built on top of propositional satisfiability (SAT) solving. As a proof-of-concept of this framework, we describe a new LTL satisfiability tool, Aalta\_v2.0, which is built on top of the MiniSAT SAT solver. We test the effectiveness of this approach by demonnstrating that Aalta\_v2.0 significantly outperforms all existing LTL satisfiability solvers. Furthermore, we show that the framework can be extended from propositional LTL to assertional LTL (where we allow theory atoms), by replacing MiniSAT with the Z3 SMT solver, and demonstrating that this can yield an exponential improvement in performance

Adding systematic biopsy to magnetic resonance ultrasound fusion targeted biopsy of the prostate in men with previous negative biopsy or enrolled in active surveillance programs

Magnetic resonance imaging (MRI) targeted biopsy (TBx) of the prostate demonstrated to improve detection rate (DR) of clinically significant prostate cancer (csPCa) in biopsy-naive patients achieving strong level of evidence. Nevertheless, the csPCa yield for TBx alone versus TBx plus systematic biopsy (SBx) after accounting for overlapping of SBx cores with TBx cores, in prior-negative or active surveillance (AS) patients has not been well established.The objective of the study was to investigate benefits in terms of detection rate and pathological stratification of prostate cancer (PCa) using contextual SBx during MRI-TBx.Patients previously submitted to negative-SBx (cohort A) and those enrolled in an AS program (cohort B) who showed at least 1 suspicious area with a PIRADSv2 score ≥ 3 were prospectively and randomly assigned to only TBx strategy versus TBx plus SBx strategy. SBx locations could not encompass the TBx sites, so that the results of each type of biopsy were independent and did not overlap.A total of 312 patients were included in the 2 cohorts (cohort A: 213 cases; cohort B: 99 cases). No significant differences were found in terms of overall PCa-DR (77.6% vs 69.6% respectively; P = .36) and csPCa-DR (48.2% vs 60.9 respectively; P = .12). The MRI-TBx alone cohort showed higher csPCa/PCa ratio (87.5% vs 62.2%; P = .03). The MRI-TBx plus SBx group subanalysis showed significantly higher csPCa-DR obtained at the MRI-TBx cores when compared with the SBx cores (43.7% vs 24.1%, respectively; P = .01). Independently to age, prostatic-specific antigen and prostate imaging-reporting and data system score, either in rebiopsy (OR 0.43, 0.21-0.97) or AS (OR 0.46, 0.32-0.89) setting, SBx cores were negatively associated with the csPCa-DR when combined to TBx cores.MRI-TBx should be considered the elective method to perform prostate biopsy in patients with previous negative SBx and those considered for an AS program. Adding SBx samples to MRI-TBx did not improve detection rate of csPCa

On the origins of phenotypic parallelism in benthic and limnetic stickleback

Rapid evolution of similar phenotypes in similar environments, giving rise to in situ parallel adaptation, is an important hallmark of ecological speciation. However, what appears to be in situ adaptation can also arise by dispersal of divergent lineages from elsewhere. We test whether two contrasting phenotypes repeatedly evolved in parallel, or have a single origin, in an archetypal example of ecological adaptive radiation: benthic-limnetic three-spined stickleback (Gasterosteus aculeatus) across species-pair and solitary lakes in British Columbia. We identify two genomic clusters across freshwater populations, which differ in benthic-limnetic divergent phenotypic traits and separate benthic from limnetic individuals in species pair lakes. Phylogenetic reconstruction and niche evolution modelling both suggest a single evolutionary origin for each of these clusters. We detected strong phylogenetic signal in benthic-limnetic divergent traits, suggesting they are ancestrally retained. Accounting for ancestral state retention, we identify local adaptation of body armour due to the presence of an intraguild predator, the sculpin (Cottus asper) and environmental effects of lake depth and pH on body size. Taken together, our results imply a predominant role for retention of ancestral characteristics in driving trait distribution, with further selection imposed on some traits by environmental factors

Intravascular lithotripsy (IVL) enabled the percutaneous closure of a severely calcified paravalvular leak regurgitation following implantation of a self-expandable transcatheter aortic valve: a case report

BackgroundClosure of paravalvular leak (PVL) regurgitation after self-expandable (SE) transcatheter aortic valve implantation (TAVI) may be more challenging than after balloon-expandable (BE) valve implantation.Case summaryAn 85-year-old woman suffering from long-standing atrial fibrillation and severe symptomatic aortic stenosis underwent SE TAVI (26 mm Evolut™ R®, Medtronic Inc., MN, USA). A total of eighteen months after TAVI she was admitted for congestive heart failure and two-dimensional (2D) transesophageal echocardiography (TEE) color Doppler showed moderate-severe PVL regurgitation due to a long and heavily calcified leak located below the left coronary sinus. The patient was deemed to be at prohibitive surgical risk and a catheter-based PVL closure procedure was planned. A first attempt to cross the PVL from the femoral artery was unsuccessful due to an inappropriate angle between the catheter and the entry site of this hard-to-approach calcified leak. A Terumo hydrophilic guidewire 0.35 inch-260 cm from the right radial artery was then successfully advanced across the leak to the left ventricle (LV); however, of most of the catheters used, only a Glidecath 4-Fr could cross the leak over the hydrophilic wire. The hydrophilic guidewire was replaced with a stiffer guidewire that, after creating a loop in the LV, was advanced across the self-expandable valve into the descending aorta where it was snared and externalized through the left femoral artery, thus creating an arterio-arterial (AA) loop. A 6-Fr Multipurpose guiding catheter was advanced over the exchange wire and the leak was crossed with an additional 0.0014 coronary guidewire (PILOT, Abbott Vascular), predilated with two non-compliant balloon dilatation catheters, and finally, the PVL was engaged with a 3.0 mm × 12 mm Shockwave balloon (Shockwave Medical Inc, Santa Clara, California, USA). Intravascular lithotripsy (IVL) application to this highly calcified leak and the increased support provided by the stiff guidewire finally allowed the progression of the 6-Fr dedicated delivery sheath (ODS III) into the LV. A 5 mm square twist (ST) device (PLD, Occlutech, Helsingborg, Sweden) was successfully deployed within the leak and the final echocardiographic and angiographic control confirmed the effective PVL closure.DiscussionIn patients at high surgical risk with moderate to severe regurgitation after SE TAVI due to a hard-to-approach calcified long tract, an extra AA support loop is mandatory during percutaneous PVL closure. Furthermore, IVL application greatly facilitates the progression of the delivery sheath and occluder which is key to a successful procedure

Phylogeography of a commercially important reef fish, Lutjanus ehrenbergii, from the coastal waters of the Arabian Peninsula

The coastal waters of the Arabian Peninsula include a heterogeneous marine region comprising the Persian/Arabian Gulf and Sea of Oman at its northeastern boundary and the Arabian Sea, Gulf of Aden, and Red Sea at its southern and western boundary. The environment within this region shifts from highly variable coral cover and extreme temperatures within the Persian/Arabian Gulf to sparse coral cover, lower summer temperatures, and nutrient-rich upwelling within the Sea of Oman. Within the Gulf of Aden and Red Sea there is high coral cover and warm, stable conditions. We tested for barriers to pelagic dispersal across this peninsula for the commercially important blackspot snapper Lutjanus ehrenbergii using mitochondrial DNA sequences. We found scant evidence for population genetic differences when comparing within northern and southern sections, but instead found strong evidence of genetic differentiation between northern and southern sections, with the Persian/Arabian Gulf and Sea of Oman populations being highly differentiated from the Gulf of Aden and Red Sea populations. Low levels of haplotype sharing between the Persian/Arabian Gulf – Sea of Oman and the Gulf of Aden – Red Sea probably reflect scenarios of historical colonization into these peripheral bodies of water, or the presence of a contemporary ecological barrier preventing further genetic exchange

Intercontinental genomic parallelism in multiple three-spined stickleback adaptive radiations

© 2020, The Author(s), under exclusive licence to Springer Nature Limited. Parallelism, the evolution of similar traits in populations diversifying in similar conditions, provides strong evidence of adaptation by natural selection. Many studies of parallelism focus on comparisons of different ecotypes or contrasting environments, defined a priori, which could upwardly bias the apparent prevalence of parallelism. Here, we estimated genomic parallelism associated with components of environmental and phenotypic variation at an intercontinental scale across four freshwater adaptive radiations (Alaska, British Columbia, Iceland and Scotland) of the three-spined stickleback (Gasterosteus aculeatus). We combined large-scale biological sampling and phenotyping with restriction site associated DNA sequencing (RAD-Seq) data from 73 freshwater lake populations and four marine ones (1,380 fish) to associate genome-wide allele frequencies with continuous distributions of environmental and phenotypic variation. Our three main findings demonstrate that (1) quantitative variation in phenotypes and environments can predict genomic parallelism; (2) genomic parallelism at the early stages of adaptive radiations, even at large geographic scales, is founded on standing variation; and (3) similar environments are a better predictor of genome-wide parallelism than similar phenotypes. Overall, this study validates the importance and predictive power of major phenotypic and environmental factors likely to influence the emergence of common patterns of genomic divergence, providing a clearer picture than analyses of dichotomous phenotypes and environments

β2-adrenoreceptor Signaling Increases Therapy Resistance in Prostate Cancer by Upregulating MCL1

There is accumulating evidence that continuous activation of the sympathetic nervous system due to psychosocial stress increases resistance to therapy and accelerates tumor growth via β2-adrenoreceptor signaling (ADRB2). However, the effector mechanisms appear to be specific to tumor type. Here we show that activation of ADRB2 by epinephrine, increased in response to immobilization stress, delays the loss of MCL1 apoptosis regulator (MCL1) protein expression induced by cytotoxic drugs in prostate cancer cells; and thus, increases resistance of prostate cancer xenografts to cytotoxic therapies. The effect of epinephrine on MCL1 protein depended on protein kinase A (PKA) activity, but was independent from androgen receptor expression. Furthermore, elevated blood epinephrine levels correlated positively with an increased MCL1 protein expression in human prostate biopsies. In summary, we demonstrate that stress triggers an androgen-independent antiapoptotic signaling via the ADRB2/PKA/MCL1 pathway in prostate cancer cells. IMPLICATIONS: Presented results justify clinical studies of ADRB2 blockers as therapeutics and of MCL1 protein expression as potential biomarker predicting efficacy of apoptosis-targeting drugs in prostate cancer