The Role of Deontic Logic in the Specification of Information Systems

In this paper we discuss the role that deontic logic plays in the specification of information systems, either because constraints on the systems directly concern norms or, and even more importantly, system constraints are considered ideal but violable (so-called `soft¿ constraints).\ud To overcome the traditional problems with deontic logic (the so-called paradoxes), we first state the importance of distinguishing between ought-to-be and ought-to-do constraints and next focus on the most severe paradox, the so-called Chisholm paradox, involving contrary-to-duty norms. We present a multi-modal extension of standard deontic logic (SDL) to represent the ought-to-be version of the Chisholm set properly. For the ought-to-do variant we employ a reduction to dynamic logic, and show how the Chisholm set can be treated adequately in this setting. Finally we discuss a way of integrating both ought-to-be and ought-to-do reasoning, enabling one to draw conclusions from ought-to-be constraints to ought-to-do ones, and show by an example the use(fulness) of this

Game saturation of intersecting families

We consider the following combinatorial game: two players, Fast and Slow, claim $k$-element subsets of $[n]=\{1,2,...,n\}$ alternately, one at each turn, such that both players are allowed to pick sets that intersect all previously claimed subsets. The game ends when there does not exist any unclaimed $k$-subset that meets all already claimed sets. The score of the game is the number of sets claimed by the two players, the aim of Fast is to keep the score as low as possible, while the aim of Slow is to postpone the game's end as long as possible. The game saturation number is the score of the game when both players play according to an optimal strategy. To be precise we have to distinguish two cases depending on which player takes the first move. Let $gsat_F(\mathbb{I}_{n,k})$ and $gsat_S(\mathbb{I}_{n,k})$ denote the score of the saturation game when both players play according to an optimal strategy and the game starts with Fast's or Slow's move, respectively. We prove that $\Omega_k(n^{k/3-5}) \le gsat_F(\mathbb{I}_{n,k}),gsat_S(\mathbb{I}_{n,k}) \le O_k(n^{k-\sqrt{k}/2})$ holds

Towards atomically precise manipulation of 2D nanostructures in the electron microscope

Despite decades of research, the ultimate goal of nanotechnology—top-down manipulation of individual atoms—has been directly achieved with only one technique: scanning probe microscopy. In this review, we demonstrate that scanning transmission electron microscopy (STEM) is emerging as an alternative method for the direct assembly of nanostructures, with possible applications in plasmonics, quantum technologies, and materials science. Atomically precise manipulation with STEM relies on recent advances in instrumentation that have enabled non-destructive atomicresolution imaging at lower electron energies. While momentum transfer from highly energetic electrons often leads to atom ejection, interesting dynamics can be induced when the transferable kinetic energies are comparable to bond strengths in the material. Operating in this regime, very recent experiments have revealed the potential for single-atom manipulation using the Ångströmsized electron beam. To truly enable control, however, it is vital to understand the relevant atomicscale phenomena through accurate dynamical simulations. Although excellent agreement between experiment and theory for the specific case of atomic displacements from graphene has been recently achieved using density functional theory molecular dynamics, in many other cases quantitative accuracy remains a challenge. We provide a comprehensive reanalysis of available experimental data on beam-driven dynamics in light of the state-of-the-art in simulations, and identify important targets for improvement. Overall, the modern electron microscope has great potential to become an atom-scale fabrication platform, especially for covalently bonded 2D nanostructures. We review the developments that have made this possible, argue that graphene is an ideal starting material, and assess the main challenges moving forward

Test-enhanced learning of clinical reasoning: a crossover randomised trial

CONTEXT: Clinical reasoning is an essential skill, the foundations of which should be acquired during undergraduate medical education. Student performance in clinical reasoning can be assessed using key feature examinations. However, within a paradigm of test-enhanced learning, such examinations may also be used to enhance long-term retention of procedural knowledge relevant to clinical reasoning. OBJECTIVES: This study tested the hypothesis that repeated testing with key feature questions is more effective than repeated case-based learning in fostering clinical reasoning. METHODS: In this randomised crossover trial, Year 4 medical students attended 10 weekly computer-based seminars during which patient case histories covering general medical conditions were displayed. The presentation format was switched between groups every week. In the control condition, students studied long case narratives. The intervention condition used the same content but augmented case presentation with a sequence of key feature questions. Using a within-subjects design, student performance on intervention and control items was assessed at 13 weeks (exit examination) and 9 months (retention test) after the first day of term. RESULTS: A total of 87 of 124 eligible students provided complete data for the longitudinal analysis (response rate: 70.2%). In the retention test, mean ± standard deviation student scores on intervention items were significantly higher than those on control items (56.0 ± 25.8% versus 48.8 ± 24.7%; p < 0.001). The results remained unchanged after accounting for exposure time in a linear regression analysis that also adjusted for sex and general student performance levels. CONCLUSIONS: This is the first study to demonstrate an effect of test-enhanced learning on clinical reasoning as assessed with key feature questions. In this randomised trial, repeated testing was more effective than repeated case-based learning alone. Curricular implementation of longitudinal key feature testing may considerably enhance student learning outcomes in relevant aspects of clinical medicine

Correlation between nucleotide composition and folding energy of coding sequences with special attention to wobble bases

Background: The secondary structure and complexity of mRNA influences its accessibility to regulatory molecules (proteins, micro-RNAs), its stability and its level of expression. The mobile elements of the RNA sequence, the wobble bases, are expected to regulate the formation of structures encompassing coding sequences. Results: The sequence/folding energy (FE) relationship was studied by statistical, bioinformatic methods in 90 CDS containing 26,370 codons. I found that the FE (dG) associated with coding sequences is significant and negative (407 kcal/1000 bases, mean +/- S.E.M.) indicating that these sequences are able to form structures. However, the FE has only a small free component, less than 10% of the total. The contribution of the 1st and 3rd codon bases to the FE is larger than the contribution of the 2nd (central) bases. It is possible to achieve a ~ 4-fold change in FE by altering the wobble bases in synonymous codons. The sequence/FE relationship can be described with a simple algorithm, and the total FE can be predicted solely from the sequence composition of the nucleic acid. The contributions of different synonymous codons to the FE are additive and one codon cannot replace another. The accumulated contributions of synonymous codons of an amino acid to the total folding energy of an mRNA is strongly correlated to the relative amount of that amino acid in the translated protein. Conclusion: Synonymous codons are not interchangable with regard to their role in determining the mRNA FE and the relative amounts of amino acids in the translated protein, even if they are indistinguishable in respect of amino acid coding.Comment: 14 pages including 6 figures and 1 tabl

Activities across Africa to improve antimicrobial utilisation and reduce AMR

There are concerns with current prescribing and dispensing of antimicrobials in Africa. Point prevalence studies in hospitals shown variable rates with high rates HIV in some. Variable ASPs, extended prophylaxis and high rates self purchasing in some

Investigating the effect of proactive interference control training on intrusive memories = Investigando el efecto del entrenamiento de control de interferencias proactivas en las memorias intrusivas = 研究主动干扰控制训练对闯入性记忆的影响

Intrusive re-experiencing is a hallmark symptom of Posttraumatic Stress Disorder (PTSD). According to prominent models of intrusive phenomena, intrusive memories may result from impairments in the efficiency of working memory capacity (WMC), more specifically proactive interference control. Yet, experimental research is scarce. Therefore, the present study aimed to investigate experimentally the role of proactive interference control in intrusive memories. We randomly assigned 57 healthy participants to either receive a high interference control training or a low interference control training. Participants were then exposed to highly distressing film clips. WMC was assessed before and after the training. Intrusion symptoms were assessed directly post-training and after one week using an Intrusion Provocation Task (IPT), a one-week intrusions diary, and the retrospective intrusion subscale of the Impact of Event Sale – Revised (IES-R). Results indicated that both groups reported improvements in WMC and fewer intrusions on the second IPT post-training, with no differences between groups. Similarly, no group differences on intrusions were found at one-week follow-up (i.e., intrusion diary and IES-R). To conclude, these data are not consistent with the hypothesis that WMC plays a role in intrusive re-experiencing. Implications for future research are discussed. / La re-experiencia intrusiva es un síntoma distintivo del trastorno por estrés postraumático (TEPT). De acuerdo con los prominentes modelos de fenómenos intrusivos, las memorias intrusivas pueden resultar en deterioros en la eficiencia de la capacidad de memoria de trabajo (CMT), más específicamente del control proactivo de interferencias. Sin embargo, la investigación experimental a este respecto es escasa. Por lo tanto, el presente estudio tuvo como objetivo investigar experimentalmente el papel del control proactivo de interferencias en las memorias intrusivas. Asignamos aleatoriamente 57 participantes sanos a recibir, ya sea, un entrenamiento de control de alta interferencia o un entrenamiento de control de baja interferencia. Luego, los participantes fueron expuestos a videoclips de películas altamente angustiantes. La CMT fue evaluada antes y después del entrenamiento. Los síntomas de intrusión se evaluaron directamente después del entrenamiento y después de una semana utilizando una Tarea de Provocación de Intrusión (IPT), registro diario de intrusiones (por una semana), y la subescala de intrusión retrospectiva de la Escala del Impacto del Evento - Revisada (IES-R). Los resultados indicaron que ambos grupos experimentaron mejoras en la CMT y reducción de intrusiones en la segunda IPT posterior al entrenamiento, sin diferencias entre los grupos. De manera similar, no se encontraron diferencias de grupo en las intrusiones en el seguimiento de una semana (es decir, en el diario de intrusiones y la IES-R). Para concluir, estos datos no son consistentes con la hipótesis de que la CMT desempeña un papel en la re-experiencia intrusiva. Se discuten las implicaciones para futuras investigaciones. / 闯入性再体验是创伤后应激障碍（PTSD）的标志性症状。根据闯入现象的经典模型，闯入性记忆可能是由工作记忆容量（WMC）效率的损害引起的，更具体地说是主动干扰控制。然而，这方面实验研究很少。因此，本研究通过实验研究主动干扰控制在闯入性记忆中的作用。我们随机分配了57名健康被试，以接受高干扰控制训练或低干扰控制训练。然后被试接触到令人非常痛苦的电影片段。在训练前后对WMC进行了评估。在训练后和一周后随访使用闯入激发任务（IPT），一周闯入症状日记以及事件影响量表修订版（IES－R）的回顾性闯入子量表直接评估闯入症状。结果表明，两组均报告WMC改善，第二次IPT训练后闯入较少，两组间无差异。同样，在一周的随访中没有发现闯入的群体差异（即闯入日记和IES-R）。总之，这些数据与WMC在闯入性再体验中发挥作用的假设不一致。文中讨论了对未来研究的启示

Aharonov-Bohm interferences from local deformations in graphene

One of the most interesting aspects of graphene is the tied relation between structural and electronic properties. The observation of ripples in the graphene samples both free standing and on a substrate has given rise to a very active investigation around the membrane-like properties of graphene and the origin of the ripples remains as one of the most interesting open problems in the system. The interplay of structural and electronic properties is successfully described by the modelling of curvature and elastic deformations by fictitious gauge fields that have become an ex- perimental reality after the suggestion that Landau levels can form associated to strain in graphene and the subsequent experimental confirmation. Here we propose a device to detect microstresses in graphene based on a scanning-tunneling-microscopy setup able to measure Aharonov-Bohm inter- ferences at the nanometer scale. The interferences to be observed in the local density of states are created by the fictitious magnetic field associated to elastic deformations of the sample.Comment: Some bugs fixe

Single-atom spectroscopy of phosphorus dopants implanted into graphene

One of the keys behind the success of modern semiconductor technology has been the ion implantation of silicon, which allows its electronic properties to be tailored. For similar purposes, heteroatoms have been introduced into carbon nanomaterials both during growth and using post-growth methods. However, due to the nature of the samples, it has been challenging to determine whether the heteroatoms have been incorporated into the lattice as intended. Direct observations have so far been limited to N and B dopants, and incidental Si impurities. Furthermore, ion implantation of these materials is challenging due to the requirement of very low ion energies and atomically clean surfaces. Here, we provide the first atomic-resolution imaging and electron energy loss spectroscopy (EELS) evidence of phosphorus atoms in the graphene lattice, implanted by low-energy ion irradiation. The measured P L ₂‚₃-edge shows excellent agreement with an ab initio spectrum simulation, conclusively identifying the P in a buckled substitutional configuration. While advancing the use of EELS for single-atom spectroscopy, our results demonstrate the viability of phosphorus as a lattice dopant in sp ²-bonded carbon structures and provide its unmistakable fingerprint for further studies